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ARM Software Development Toolkit User Guide

1. Memory Maps Follow these steps to configure Memory Maps 1 Click the Memory Maps tab of the Debugger Configuration dialog Figure 3 17 Debugger Configuration Target Debugger Memon Maps Memon Map Global Map File pa Local Map File Figure 3 17 Configuration of ARM Debugger memory maps Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 2 Change the following configuration settings as required Memory Map This allows you to specify a memory map file containing information about a simulated memory map that the ARMulator uses It is applicable to ARMulator only The file includes details of the databus widths and access times for each memory region in the simulated system See Chapter 12 ARMulator for more information You can select one of three Memory Map options do not use a memory map use a global memory map which means using the specified memory map for every image that is loaded during the current debug session use a local memory map which means using a memory map that is local to a project The three Memory Map options are explained in greater detail as follows No Map File Select this Memory Map option to use the ARMulator default memory map This is a flat 4GB bank of ideal 32 bit memory having no wait States Global Map File Select this option to use the specified memory map file for every image loa
2. Load the register directly by using ADR or ADRL to construct an address from an offset and the current pc or other register Load the address from a literal pool using the LDR Rd label form of the LDR pseudo instruction 5 6 1 Direct loading with ADR and ADRL ARM DUI 0040D The ADR and ADRL pseudo instructions enable you to load a range of addresses without performing a memory access ADR and ADRL accept either A program relative expression A program relative expression is a label with an optional offset where the address of the label is relative to the current pc A register relative expression A register relative expression is a label with an optional offset where the address of the label is relative to an address held in a specified general purpose register See Describing data structures with MAP and directives on page 5 46 for information on specifying register relative expressions The assembler converts an ADR rn label pseudo instruction by generating a single ADD or SUB instruction that loads the address if it is in range an error message if the address cannot be reached in a single instruction The offset range is 255 bytes for an offset to a non word aligned address and 1020 bytes 255 words for an offset to a word aligned address The assembler converts an ADRL rn label pseudo instruction by generating two data processing instructions that load the address if it is in range an error
3. TENE Cancel Figure 3 19 Configuration of remote connection 5 Change the following configuration settings as required Remote Connection Chooses either Serial or Serial Parallel depending on the connections For Ethernet enter either an IP address or the hostname of the target board Heartbeat Ensures reliable transmission by sending heartbeat messages If not enabled there is a danger that the host and the target can get into a deadlock situation with both waiting for a packet Copyright 1997 1998 ARM Limited All rights reserved 3 59 ARM Debuggers for Windows and UNIX 3 7 4 3 60 Ports Allows the correct serial and parallel devices to be chosen for the debug connection Serial Line Speed Selects the Baud rate used to transmit data along the serial line Channel Viewers Channel viewers are not supported by the ARM Debugger for UNIX ADU In the ARM Debugger for Windows ADW you can enable or disable the selected channel viewer DLL See ThumbCV channel viewer on page 3 49 for more information Click the Add button to add a channel viewer DLL to the displayed list Click the Remove button to remove the currently selected channel viewer DLL from the displayed list EmbeddediCE configuration Use the EmbeddedICE Configuration dialog to select the settings for an EmbeddedICE target This option is enabled only if you have EmbeddedICE connected to your machine Follow these steps to chan
4. select Step from the Execute menu click the Step button The program moves to the next line of code which is highlighted in the Execution window Function calls are treated as one statement If only C code is displayed Step moves to the next line of C If disassembled code is shown possibly interleaved with C source Step moves to the next line of disassembled code Step in to a function call Step in to a function call in either of the following ways select Step In from the Execute menu click the Step In button The program moves to the next line of code If the code is in a called function the function source appears in the Execution window with the current line highlighted Step out of a function Step out of a function in either of the following ways select Step Out from the Execute menu click the Step Out button The program completes execution of the function and halts at the line immediately following the function call Run execution to the cursor Follow these steps to execute your program to a specific line in the source code 1 Position the cursor in the line where execution should stop 2 Select Run to Cursor from the Execute menu or click the Run to Cursor button This executes the code between the current execution and the position of the cursor Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Note Be sure that the executi
5. Evaluation board Instead of testing programs under the ARMulator you can use an ARM evaluation board to evaluate performance In this case you use Angel running as a debug monitor on the ARM evaluation board You do not need to rebuild Angel or to be familiar with the way Angel works You can build images that are linked with an Angel targeted ARM C or C library and then download the images with an ARM debugger Stage 2 Building applications on a development board highly dependent on Angel After evaluating your application you move to the development stage At this stage the target board is either your own development board or an ARM development board Using an ARM development board You can use the ARM PID board to closely emulate the configuration of your production hardware You can develop your application on the PID board and port it to your final hardware with minimal effort Using your own development board If you are developing on your own hardware it is likely to have different peripheral hardware different memory maps and so on from the ARM evaluation boards or development boards This means that you must port Angel to your development board The porting procedure includes writing device drivers for your hardware devices Refer to Porting Angel to new hardware on page 13 43 for more information ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 15 Angel 13 16 When you have chosen
6. Interrupt handlers for timers might be required in the final product but debug support code is not At this stage it is not desirable to include any parts of Angel that are not required in the final product You can choose to remove Angel functionality completely or you can continue to link your application with a minimal Angel library to provide initialization raw device and exception support 13 2 4 Developing an application under full Angel ARM DUI 0040D This section gives useful information on how to develop applications under Angel including Planning your development project Programming restrictions on page 13 18 Using Angel with an RTOS on page 13 19 Using Supervisor mode on page 13 20 Chaining exception handlers on page 13 20 Linking Angel C library functions on page 13 21 Using assertions when debugging on page 13 21 Setting breakpoints on page 13 22 Changing from little endian to big endian Angel on page 13 23 Planning your development project Before you begin your development project you must make basic decisions about such things as the APCS variant to be used for your project whether or not ARM Thumb interworking is required the endianness of your target system Refer to the appropriate chapters of the ARM Software Development Toolkit Reference Guide and this book for more information on interworking ARM and Thumb code and specifying APCS options Copyright
7. converting old projects stopping a build 2 4 1 Configuring tools You can change how a tool such as a compiler or assembler is executed by changing its configuration within the Project Manager You can change either the system wide configuration see Making system wide configuration changes on page 2 22 or project specific configuration see Making project specific configuration changes on page 2 22 Tool configuration can be associated with the whole project a project variant a particular version of the project a partition all files of the same kind an individual file When a tool configuration is associated with a file it is associated with that file as an input to a build step not with that file as an output from a build step For example if you select an image you can change the debugger configuration but not the linker configuration Linker configuration is associated with object files The Tool Configuration dialog The appearance of the Tool Configuration dialog varies with the tool you are configuring Tools that are APM compliant such as armcc tcc armcpp tcpp armasm and armlink respond by displaying their configuration interface For most ARM tools this consists of sets of property sheets Figure 2 9 on page 2 21 shows the configuration dialog for the ARM C compiler 2 20 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Project Manager Co
8. 1 2 Supported platforms ARM DUI 0040D This release of the ARM Software Development Toolkit supports the following platforms Sun workstations running Solaris 2 5 or 2 6 Hewlett Packard workstations running HP UX 10 IBM compatible PCs running Windows 95 Windows 98 or Windows NT 4 The Windows development tools ADW and APM are supported on IBM compatible PCs running Windows 95 Windows 98 and Windows NT 4 The SDT is no longer supported on the following platforms Windows NT 3 51 SunOS 4 1 3 HP UX 9 DEC Alpha NT Copyright 1997 1998 ARM Limited All rights reserved 1 5 Introduction 1 3 What is new This section describes the major changes that have been made to the Software Development Toolkit since version 2 1 1a The most important new features are Improved support for debug of optimized code Instruction scheduling compilers Reduced debug data size New supported processors ARMulator now supports the latest ARM processors ADW enhancements SDT 2 50 provides a new ADW capable of remote debugging with Multi ICE and able to accept DWARF 1 and DWARF 2 debug images The preferred and default debug table format for the SDT is now DWARF 2 The ASD debug table format is supported for this release but its use is deprecated and support for it will be withdrawn in future ARM software development tools The preferred and default executable image format is now ELF Refer t
9. 1997 1998 ARM Limited All rights reserved 3 15 ARM Debuggers for Windows and UNIX Information remains in the window until you select Clear from the Console window menu You can also save the contents of the Console window to disk by selecting Save from the Console window menu Console Window Program compiled without register attribute Please give the number of runs through the benchmark 10000 Execution starts 10000 runs through Dhrystone Execution ends Final values of the variables used in the benchmark he he he he 5 5 1 1 A E E T he o 7 10010 should he Number Of Runs 10 Ptr _Glob i Figure 3 4 Console window Initially the Console window displays the startup messages of your target processor for example the ARMulator or ARM Development board Note When input is required from the debugger keyboard by your executable image most ARM Debugger functions are disabled until the required information has been entered Command window Use the Command window Figure 3 5 on page 3 17 to enter armsd instructions when you are debugging an image 3 16 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Command Window Debug help help lt keyworrd gt Display help information on one of the following commands Fpregisters Coproc CRegisters otep Istep Examine Ohey oO RETurn Watch UNWwateh Print I
10. 3 5 7 Profiling ARM DUI 0040D A high level symbol for a procedure refers to the address of the first instruction that has been generated within the procedure and is denoted by the function name shown in the Function Names window A low level symbol for a procedure refers to the address that is the target for a branch instruction when execution of the procedure is required The low level and high level symbols can refer to the same address Any code between the addresses referred to by the low level and high level symbols generally concerns the stack backtrace structure in procedures that conform to the appropriate variants of the ARM Procedure Call Standard APCS or argument lists in other procedures You can display a list of the low level symbols in your program in the Low Level Symbols window In a regular expression indicate high level and low level symbols as follows precede the symbol with to indicate a low level symbol precede the symbol with to indicate a high level symbol Profiling involves sampling the pc at specific time intervals This information is used to build up a picture of the percentage of time spent in each procedure Using the armprof command line program on the data generated by either armsd or the ARM Debugger you see where effort can be most effectively spent to make the program more efficient Note Profiling is supported by ARMulator but not by the EmbeddedICE interface or by Multi ICE Pro
11. ARM Debuggers for Windows and UNIX 4 Entera format string for the item or items in the window You can enter any single print conversion specifier that is acceptable as an argument to ANSI C sprintf as a format string except that cannot be used as a precision For example enter x to format values in hexadecimal or f to format values as a character string 5 Click OK to apply the format change Changing the contents of watched items Follow these steps to change the contents of items in the Watch window 1 Display the Watch window 2 Click the right mouse button in the Watch window to display the Watch window menu 3 Select Edit value from the Watch window menu The Modify Item window is displayed Figure 3 28 Modify Item x Please enter new value for ch Cancel Figure 3 28 The Modify Item window 4 Enter a new value for the variable 5 Click OK to change the contents of the variable Recalculating watches Select Recalculate Watches from the C menu or click on the Recalculate Watches button in the toolbar to reinitialize the Watch window to its original state with all structures and classes expanded by one level This menu item can be used if the value of any variable may have been changed by external hardware while the debugger is not stepping through code 3 8 5 Evaluating expressions The Evaluate Expression window allows you to enter a simple C expression to be evaluated The Evaluate E
12. ARM SDT v2 50 ARM Project Manager When APM starts the last file or project you accessed is loaded Select Exit from the File menu to stop APM The source files and projects you currently have open will be re opened the next time you start APM 2 2 2 Projects and sub projects An APM project is a description of how you build something such as an image or object library and a list of the files you need such as source files include files and any sub projects APM describes what you are building and how you build it by means of a project template A template consists of a series of build step patterns that define the build steps used to construct the output of your project A sub project is simply an APM project that has been added to another project For example if you have a project that builds a library it could become a sub project of another project that makes an image using routines from that library Project files A project manages source files and derived files created from source files by the build tools 2 4 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager Source files form the basis of a project Symbols in the Project window indicate various types of source file as shown in the following list The source file types recognized by the standard templates are L La i a C or C source file ARM assembly language file include file sub project this is also
13. Angel 13 48 Follow these steps to edit the makefile 1 Open the appropriate makefile for your platform in a texteditor For example if you are working under Solaris open your_board b gccsunos Makefi le 2 Change all occurrences of the original directory name to the new directory name For example if your port is based on the pid pid b directory pair change all occurrences of the pid directory to your_board Be careful with search and replace utilities because there are files named pid in the target directories 3 Set up the make parameters required See Editing makefile build options below Setting command line build options The PID makefile supports three command line build options ENDIAN BIG This option builds a big endian version of Angel The objects and images are stored in a sub directory named big_rel By default the makefile builds a little endian Angel ETHERNET_SUPPORTED 1 This option enables ethernet support for the PID board It includes the ethernet drivers and the Fusion IP stack in the Angel build to enable communications through the PC Card Ethernet Adapter The default is 0 no Ethernet support FUSION_BUILD 1 DEBUG 1 This option rebuilds the Fusion stack sources if they are available The Fusion stack binaries are supplied by ARM under a license from Pacific Softworks with the Ethernet Upgrade Kit No KPI 0015A for the PID board The fusion sources are available from ARM after yo
14. B gcd end Because of the number of branches the code is seven instructions long Every time a branch is taken the processor must refill the pipeline and continue from the new location The other instructions and non executed branches use a single cycle each By using the conditional execution feature of the ARM instruction set you can implement the gcd function in only four instructions Copyright 1997 1998 ARM Limited All rights reserved 5 19 Basic Assembly Language Programming gcd CMP r rl SUBGT r0 r rl SUBLT r1 rl r BNE gcd In addition to improving code size this code executes faster in most cases Table 5 2 and Table 5 3 show the number of cycles used by each implementation for the case where rO equals 1 and rl equals 2 In this case replacing branches with conditional execution of all instructions saves three cycles The conditional version of the code executes in the same number of cycles for any case where rO equals r1 In all other cases the conditional version of the code executes in fewer cycles Table 5 2 Conditional branches only r0 a r1 b Instruction Cycles 1 2 CMP r0 rl 1 1 2 BEQ end 1 Not executed 1 2 BLT less 3 1 2 SUB r1 r1 r 1 1 2 B gcd 3 1 1 CMP rQ rl 1 1 1 BEQ end 3 Total 13 Table 5 3 All instructions conditional r0 a ri b Instruction Cycles 1 2 CMP rQ rl 1 1 2 SUBCT r0 r0 r1 1 Not executed 1 1 SUBLT r1 ri1 rQ 1 1
15. Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 3 The APM desktop If you have followed the steps to build the example hello world project in Getting started on page 2 4 you have already used some features of the APM desktop This section gives further details of APM and includes descriptions of 2 3 1 Project window the Project window how to change the way a project is displayed the Edit window the View window The Project window contains a pane showing the project view a pane showing the build log and a status area Figure 2 6 shows an example of the project window The following sections describe the parts of the project window ARM DUI 0040D fe C examples hello ap S8 ARM Executable Image CebugRel Build DebugRel variant i Information C examples hello apj Executin hello c armcc o C examples DebugRel hello o c MD C Serious Error hello c line 1 Expecting lt decla Error stdio h line 99 prototype and o Error stdio h line 99 function protot int assumed Error stdio h line 150 expected o Build Debugkel Figure 2 6 Project window tE EI 45 oS Copyright 1997 1998 ARM Limited All rights reserved 2 15 ARM Project Manager Project view The project view occupies the upper pane and displays the project hierarchy The following symbols are used to denote variants and partitions File symbols are
16. For parent functions it shows the percentage time spent in the current function on behalf of the parent For child functions it shows the percentage time spent in this child on behalf of the current function desc Shows the percentage time spent in a function for the current function it shows the percentage time spent in children of the current function on the current function s behalf for parent functions it shows the percentage time spent in children of the current function on behalf of this parent for child functions it shows the percentage time spent in this child s children on behalf of the current function ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 11 21 Benchmarking Performance Analysis and Profiling calls Shows the number of times a function is called for the current function it shows the number of times this function was called for parent functions it shows the number of times this parent called the current function for child functions it shows the number of times this child was called by the current function Below is a section of the output from armprof for a call graph profile Name cum self main 96 04 0 16 qsort 0 44 _printf 0 00 clock 0 00 _sprintf 0 34 check_order 0 29 randomise 0 12 shell_sort 1 59 insert_sort 19 91 main 19 91 insert_sort 79 35 19 91 strcmp 59 44 desc 88 75 00 00 56 28 6
17. Introduction New APM configuration dialogs The Tool Configurer dialog boxes have been modified to reflect the new features available in the compilers assembler and the linker the new default behavior of these tools Each selectable option on the dialog boxes now has a tool tip that displays the command line equivalent for the option 1 3 2 Changes in default behavior The changes that have been made to the default behavior of the SDT are described in Stack disciplines Default Procedure Call Standard APCS and TPCS Default debug table format on page 1 13 Default image file format on page 1 13 Default processor in the compilers and assembler on page 1 14 RDI 1 0 and RDI 1 5 support on page 1 14 Register names permitted by the assembler on page 1 14 Stack disciplines The ARM and Thumb compilers now adjust the stack pointer only on function entry and exit In previous toolkits they adjusted the stack pointer on block entry and exit The new scheme gives improved code size Default Procedure Call Standard APCS and TPCS The default Procedure Call Standard PCS for the ARM and Thumb compilers and the assembler in SDT 2 50 and C 1 10 is now apcs 3 32 nofp noswst narrow softfp Note The new default PCS will not perform software stack checking and does not use a frame pointer register This generates more efficient and smaller code for use in embedded systems The default procedure c
18. Remember that if interworking takes place within an application you must use an interworking main library See Simple rules for interworking on page 7 15 If you need to select the ARM or Thumb version of a standard C library routine explicitly or if you want to include both ARM and Thumb versions of a routine you can force the inclusion of specific modules from a library To force inclusion of a library module put the name of the module in parentheses after the library name Ensure that there are no spaces between the library name and the opening parenthesis You can specify more than one module by separating module names with a comma Ensure that there are no spaces in the list of module names Examples To force the use of the ARM version of strlen and take all other routines from the interworking Thumb library enter armlink o prog thumb o arm o armlib 321 strlen o armlib_1 161 To force the inclusion of both ARM and Thumb versions of all functions starting with str and take all other routines from the interworking Thumb library enter armlink o prog thumb o arm o armlib 161 str armlib 321 str armlib_1 161 Note On UNIX platforms depending on the command shell you are using you may need to put the characters and in quotes in order to enter them on the command line Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb 7 4 Assembly language interworking usin
19. arm_function printf And goodbye from Thumb World n return 0 KK SHER BEEEEEK EET arm c include lt stdio h gt void arm_function void printf Hello and Goodbye from ARM world n Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb To compile and link these modules 1 Type tcc c apcs interwork o thumb o thumb c at the system prompt to compile the Thumb code for interworking 2 Type armcc c apcs interwork o arm o arm c to compile the ARM code for interworking 3 Type armlink o hello thumb o to link the object files Alternatively type armlink info size thumb o arm o to view the size of the interworking veneers in the lt anon gt column see Figure 7 2 on page 7 14 7 3 3 Simple rules for interworking The following rules apply to interworking within an application You must use the apcs interwork command line option to compile any C or C modules that contain functions that are called by interworking calls You may compile modules that are never called by an interworking call without the apcs interwork option These modules may make interworking calls but may not be called by interworking calls Never make indirect calls such as calls using function pointers to non interworking code from code in the other state By default the linker selects the appropriate interworking ANSI C or C library based on the area
20. int b 10 10 9 8 6 53 4 ss 2 1 J int main void printf Dotproduct 11d should be d n dotprod a b 10 220 return Q Long multiplies You can use the inline assembler to optimize long multiplies on processors that support MULL instructions Example 8 4 on page 8 12 shows a simple long multiply routine in C ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 8 11 Mixed Language Programming Example 8 5 shows how you can use inline assembly language to generate optimal code for the same routine You can use the inline assembler to write the high word and the low word of the long long separately The compiler optimization routines detect this case and optimize the code as if the address of res was not taken Note This works only at the highest compiler optimization level 02 compiler option The inline assembly language code depends on the word ordering of long long types because it assumes that the low 32 bits are at offset 0 Example 8 4 Writing the multiply routine in C ong multiply routine in C long long smull int x int y return long long x long long y The compiler generates the following code MOV a3 al MOV al a2 MOV a2 a3 SMULL 1p a2 al a2 MOV al ip MOV pc Ir Example 8 5 Writing the same routine using inline assembly language long long smull int x int y long long res __asm SMULL int amp res 0 ints amp res 1 x y return
21. 13 88 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 14 SYS REMOVE 0x0e Deletes a specified file Entry On entry rl contains a pointer to a two word argument block word 1 points to a null terminated string that gives the pathname of the file to be deleted word 2 is the length of the string Return On exit rO contains 0 if the delete is successful a non zero host specific error code if the delete fails 13 7 15 SYS RENAME Oxf ARM DUI 0040D Renames a specified file Entry On entry rl contains a pointer to a four word data block word 1 is a pointer to the name of the old file word 2 is the length of the old file name word 3 is a pointer to the new file name word 4 is the length of the new file name Both strings are null terminated Return On exit rO contains 0 if the rename is successful a non zero host specific error code if the rename fails Copyright 1997 1998 ARM Limited All rights reserved 13 89 Angel 13 7 16 SYS CLOCK 0x10 Returns the number of centiseconds since the support code started executing Values returned by this SWI can be of limited use for some benchmarking purposes because of communication overhead or other agent specific factors For example with the Multi ICE debug agent the request is passed back to the host for execution This can lead to unpredictable delays in transmission and process scheduling
22. 2 rather than Ir 4 the instruction itself is 16 bit and so requires a halfword load the SWI number is held in 8 bits instead of the 24 bits in ARM state comment field Figure 9 5 Thumb SWI instruction Example 9 18 shows ARM code that handles a SWI from both sources Note the following points Each of the do_swi_x routines could carry out a switch to Thumb state and back again to improve code density if required The jump table could be replaced by a call to a C function containing a switch statement to implement the SWIs It would be possible for a SWI number to be handled differently depending upon the state it was called from The range of SWI numbers accessible from Thumb state can be increased by calling SWIs dynamically as described in SWI handlers on page 9 14 Example 9 18 T_bit EQU 0x20 Thumb bit of CPSR SPSR that is bit 5 SWIHandler 9 42 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D STMFD sp rQ r3 Ir MRS rQ spsr TST rO T_bit LDRNEH rQ Ir 2 BICNE rQ r0 0xff00 LDREQ r ir 4 BICEQ r r0 0xff000000 ADR rl switable LDR pc rl rQ LSL 2 switable DCD do_sw1_1 DCD do_sw1_2 do_sw1_1 Handle the SWI LDMFD sp r r12 pc A do_swi_2 ARM DUI 0040D Handling Processor Exceptions Store the registers Move SPSR into general purpose register Test if bit 5 is set T_bit set so load halfword Thumb and clear
23. Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 ARM Debuggers for Windows and UNIX 3 1 About the ARM Debug els VU 3 2 3 2 GOTO StaMO ch otis nck chs 58 3 A Ne secousses Resales 3 7 3 3 ARM Debugger desktop windows ssssssssssssssserrrnsrrrnrrrrrrrrerrresrrrerenrene 3 14 3 4 Breakpoints watchpoints and stepping sssssssssssssrsesrrrrsrrrrsrrrerrrrerrerne 3 26 3 5 Debugger further details ses ne un sen nn ds ds 3 36 3 6 Channel viewers Windows only Us 3 49 3 7 CO MMO UV AON So scacctcsemessatees sn en ses Sen eee ie tan 3 51 3 8 ARM DEDUGGER WIN CF pen a nie Msn a 3 62 Command Line Development 4 1 The hello world example is aise anen na hhnnnenehilten nes 4 2 4 2 anm Si PP n tees edisaae ows etevad uaeen ened 4 6 Basic Assembly Language Programming 5 1 EE CCUG TION ed ae ee es de Nes 5 2 5 2 Overview of the ARM architecture cccccseeceecceeseeeeceseeeeecsesseeeseaaeeeees 5 3 5 3 Structure of assembly language modules cccccsseeeeeceeeeeeeeseeeeeeeaeees 5 10 5 4 Conditional execution 4 5 17 5 5 Loading constants into registers cee eeceeeeeee eee eee eee eee eee eeeeaeeeeeeeeaeeeeeeas 5 22 5 6 Loading addresses into registers ccceeeeeeeee eee eeee eee eeeeeeeeeaaeeeeesaeeeeeeens 5 27 5 7 Load and store multiple register instructions 5 34 5 8 SING INACTOS PP EE CL I 5 43 5 9 Describing data structures with MAP
24. Copyright 1997 1998 ARM Limited All rights reserved 12 1 ARMulator 12 1 About the ARMulator The ARMulator is a program that emulates the instruction sets and architecture of various ARM processors It provides an environment for the development of ARM targeted software on your workstation or PC ARMiulator is transparently connected to armsd or the ARM GUI debuggers to provide a hardware independent ARM software development environment Communication takes place through the Remote Debug Interface RDI The ARMulator is instruction accurate It models the instruction set but not the precise timing characteristics of the processor The ARMulator supports a full ANSI C library to allow complete C programs to run on the emulated system You can supply models written in C that interface to the ARMulator s external interface 12 2 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 2 ARMulator models You can add extra models to ARMulator without altering the existing models Each model is entirely self contained and communicates with the ARMulator through a set of defined interfaces The full definition of these interfaces is in Chapter 12 ARMulator in the ARM Software Development Toolkit Reference Guide The source of a number of sample models can be found in the rebuild kit on UNIX in armsd source or on PC in C ARM250 Source Wi1n32 ARMu late 12 2 1 Sample models ARM DUI 0040D
25. Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D AREA ENTRY Start BL BL stop MOV LDR SWI func1 LDR LDR LDR MOV LTORG func2 LDR LDR MOV ARM DUI 0040D Basic Assembly Language Programming For example LDR rn pc offset to literal pool load register n with one word from the address pc offset You must ensure that there is a literal pool within range See Placing literal pools on page 5 25 for more information Unlike the ADR and ADRL pseudo instructions you can use LDR with labels that are outside the current area If the label is outside the current area the assembler places a relocation directive in the object code when the source file is assembled The relocation directive instructs the linker to resolve the address at link time The address remains valid wherever the linker places the area containing the LDR and the literal pool Example 5 8 shows how this works It is supplied as 1drlabel s in the examples asm subdirectory of the toolkit Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example The instructions listed in the comments are the ARM instructions that are generated by the assembler Example 5 8 LDRlabel CODE READONLY Mark first instruction to execute funcl Branch to first subroutine func2 Branch to second subroutine rQ 0x18 angel_SwIreason_ReportException rl 0x20026 ADP_Stopped_Ap
26. END ifdef __thumb x Define Angel Semihosting SWI to be Thumb one define SemiSWI QxAB else x Define Angel Semihosting SWI to be ARM one define SemiSWI x123456 endif x Use the following Debug Monitor SWIs to write things out In this example x Write a character _ Swi Semi SWI void _WriteC unsigned op const char c define WriteC c _WriteC 0x3 c Write a string x __swi SemiSWI void _WriteQ unsigned op const char string define WriteQ string _WriteQ 0x4 string fx Exit x __swi SemiSWI void _Exit unsigned op unsigned except define Exit _Exit 0x18 0x20026 x The following symbols are defined by the linker and define various memory regions which may need to be copied or initialized x i extern char Image RO Limit extern char Image RW Base x Define some more meaningful names here define rom_data_base Image RO Limit define ram_data_base Image RW Base x This is an example of a pre initialized variable static unsigned factory_id xAA55AA55 Factory set ID x This is an example of an uninitialized or zero initialized variable static char display 8 40 Screen buffer static const char hex 17 Q123456789ABCDEF static void pr_hex unsigned n i Int 1 for 1 0 1 lt 8 i WriteC amp hex n gt gt 28 n lt lt 4 j ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights res
27. Example 8 14 Calling a C function from assembly language Define the function to be called in C Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Mixed Language Programming struct S has no base classes S int s i s or virtual functions int 1 i extern C void cppfunc S p Definition of the C p gt 1 5 function to be called from Asm The body is C only the linkage is C In ARM assembly language import the name of the C function and use a Branch with link instruction to call it AREA Asm CODE IMPORT cppfunc Import the name of the C function to be called from Asm EXPORT f f STMDB sp lr MOV rO 2 STR r0 sp 4 initialize struct MOV rQ sp argument is pointer to struct BL cppfunc call cppfunc so it can change the struct LDR rQ sp 4 ADD r rO r LSL 1 LDMIA sp pc END Example 8 15 Calling a C member function from C or assembly language The following code demonstrates how to call a non static non virtual C member function from C or assembly language In C struct T T int i t i int t int f int 1 int T f int 1 return 1 t Definition of the C function to be called from C extern C int cfunc T declaration of the C function to be called from C int f Copyright 1997 1998 ARM Limited All rights reserved 8 23 Mixed Langu
28. Partitions are a construct of APM used to organize the source and derived files in your project in the same way that you might use a directory structure The partitions used by your project are determined by the build step patterns Variants define different versions of the project output created from the same set of source files Variants are discussed in Adding a new variant to a project on page 2 27 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 39 ARM Project Manager Variables Variables are used within the definition of build steps to change how a tool is used in the various levels of a project hierarchy For example you could use a variable to change the configuration settings for armcc so that a single source or a particular set of sources in a separate partition is compiled in one way and the rest of the source is compiled in another See Editing a variable on page 2 42 Using a template to create a project To create a new project select an existing blank template that defines the tools to be used the organization of project files into partitions and the variants that can be built Add your source files to the blank template and save it as the new project template A project template helps you to build your project output repeatedly and consistently See Creating a new project on page 2 5 for more information Modifying a project template You can modify a project template after the project h
29. Qxf0000020 Qxf0000024 Qxf0000028 Qxf000002c 0xF0000030 0xF0000034 0xF0000038 Qxf000003c 10 18 Example 10 6 shows a disassembly of the first part of init s Example 10 6 Disassembly of init s Qxe3a08000 mov r8 0 Oxe28F900c add r9 pc 0xc Oxe8b900FF Idmia r9 r0 r7 Qxe8a800ff stmia r8 r0 r7 Oxe8b900FF Idmia r9 r0 r7 Qxe8a800ff stmia r8 r0 r7 Qxe59fF018 ldr pc Oxf0000038 0xf0000070 Qxe59fF018 ldr pc Oxf000003c 0xf0000058 Oxe59ff018 ldr pc 0xf0000040 0xf000005c Qxe59fF018 ldr pc Oxf0000044 0xf0000060 Qxe59fF018 ldr pc Oxf0000048 0xf0000064 xe1a00000 nop Oxe59ff018 ldr pc Oxf0000050 0xf0000068 Qxe59fF018 ldr pc Oxf0000054 0xf000006c Qxf 000070 p andnv rQ rQ rQ ror rQ Oxf0000058 X andnv rQ r0 r8 asr rQ Note If the disassembly produces output that has each word byte reversed that is the word at OxfOO000000 is 0x0080a0e3 instead of Oxe3a08000 there is a problem with endianness Check that your compiler assembler and debugger are all configured for the same endianness Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 6 Example 3 Using the embedded C library This example shows an application that makes use of a function from the Embedded C library in this case sprintf The code for startup s and print c i
30. ROM locations Angel supports two types of ROM system ROM mapped to address 0 on reset and mapped out to RAM during Angel bootstrap ROM permanently mapped to address 0 For the first type 1 Define ROMBase in devconf h as the normal mapped out address of the ROM 2 Set the ROM only build variable in target s to FALSE 3 Provide an assembler macro called UNMAPROM in target s that maps the ROM away from 0 4 Declare the makefile macro FIRST as startrom o ROMStartup including the quote characters For the second type 1 Define ROMBase in devconf h as 0 2 Set the ROMonly build variable in target s to TRUE 3 Declare the makefile macro FIRST as except o __Vectors including the single quote characters Processor exception vectors Regardless of where you declare RWADDR and ROADDR to be the ARM processor requires the exception vector table to be located at zero There are a number of situations where this happens by default for example when RWADDR is set to 0 or in ROM at zero systems When this does not happen by default Angel explicitly copies everything in AREA __Vectors from RWADDR to zero All code within the __Vectors area must be position independent because it is linked to run at ROADDR not zero Copyright 1997 1998 ARM Limited All rights reserved 13 71 Angel In most configurations Angel is able to detect a branch through zero by application code and report it as an err
31. 0 Ox00000c e3500001 P CMP r0 1 Qx000010 Obfffffa BLEQ C_int_handler Ox000014 e5940000 LDR r0 r4 0 0x000018 e5840004 STR rO r4 4 Qx00001c e8bd8010 LDMFD sp r4 pc 9 5 2 Reentrant interrupt handlers Note The following method works for both IRQ and FIQ interrupts However because FIQ interrupts are meant to be serviced as quickly as possible there will normally be only one interrupt source so it may not be necessary to allow for reentrancy 9 24 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Handling Processor Exceptions If an interrupt handler re enables interrupts then calls a subroutine and another interrupt occurs the return address of the subroutine stored in Ir_IRQ is corrupted when the second IRQ is taken Using the __irq keyword in C does not store all the state information required for reentrant interrupt handlers so you must write your top level interrupt handler in assembly language A reentrant interrupt handler must save the necessary IRQ state switch processor modes and save the state for the new processor mode before branching to a nested subroutine or C function In ARM architecture 4 or later you can switch to System mode System mode uses the User mode registers and allows privileged access that may be required by your exception handler Refer to System mode on page 9 44 for more information In ARM architectures prior to architec
32. 1997 1998 ARM Limited All rights reserved 5 5 Basic Assembly Language Programming 5 2 6 5 6 ARM instruction set overview All ARM instructions are 32 bits long and are stored word aligned in memory Instructions are stored word aligned so the bottom two bits of addresses are always set to zero in ARM state These bits are ignored by all ARM instructions that have an address operand except the Branch Exchange BX instruction The BX instruction uses the bottom bit to determine whether the code being branched to is Thumb code or ARM code See Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide for additional information ARM instructions can be classified into a number of functional groups Branch instructions These instructions are used to branch backwards to form loops to branch forward in conditional structures to branch to subroutines or to change the processor from ARM state to Thumb state Data processing instructions These instructions operate on the general purpose registers Generally they perform operations such as addition subtraction or bitwise logic on the contents of two registers and place the result in a third register Long multiply instructions unavailable in some architectures give a 64 bit result in two registers Status register access instructions These instructions move the contents of the CPSR or an SPSR to or from a general purpose register Single register load and s
33. 4 MOV pc Ir Comparing this to the C source you can see that the first ADD instruction produces the low order word and the second produces the high order word To correct this get the carry from the low to high word by changing the first ADD to ADDS add and set flags the second ADD to an ADC add with carry You can find this modified code in the directory examples candasm as add64_3 s Looking at the effects of the APCS The most obvious effect of the APCS on the example code is the change in register names al holds a pointer to the destination structure Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Using the Procedure Call Standards a2 and a3 hold pointers to the operand structures a4 and ip are used as temporary registers that are not preserved The conditions under which ip can be corrupted are discussed in A more detailed look at APCS register usage on page 6 10 This is a simple leaf function that uses few temporary registers so none are saved to the stack and restored on exit Therefore you can use a simple MOV pc Ir to return If you wish to return another result such as the carry out from the addition you must load it into al prior to exit You can do this as follows Change the second ADD to ADCS add with carry and set flags Add the following instructions to load al with 1 or 0 depending on the carry out from the high order addition MOV
34. ARM Executable Image P DebugPel A Sources Ce hello c IncludedFiles Objects A hello o SubProjects Libraries Y Image M hello axt Miscellanea Debug Release BulaDebughet DebugRel Figure 2 3 Expanded view You can see that hello c the file you added to the project is now in the Sources partition The files hello o and hello axf have been added to the Objects and Image partitions These are the derived files that are the anticipated output of the project build steps The work in progress symbol indicates that they have not yet been built Other options for viewing a project are discussed in Changing the way a project is displayed on page 2 17 Note APM displays nested source dependencies only if the compiler and assembler are invoked with the MD command line option This option instructs the assembler and compiler to output source dependencies to the Project Manager The project templates shipped with APM specify this option in the build step pattern Either a build or a force build processes the source files of a selected variant through the defined build steps to create the project output A build executes a build step only if some input to it is newer than its outputs A force build executes all build steps The actions performed in the various build steps and the type of project output are determined by the project template The project template also
35. ARM Project Manager Blank template A blank template from which to make your own templates Change the description using the Details dialog Editing project template details on page 2 46 This template defines DebugRel Debug and Release variants and the Miscellanea partition 2 8 3 Editing a variable A variable holds a value used by either APM or by a build step pattern to specify a changeable aspect of your project such as a filename or directory path You can set variables for any level of the project hierarchy For example you could set the variable specifying the C compiler cc to be one tool for the entire project cc armcc and create a special configuration for a particular source file cc tcc Follow these steps to edit the variables for a particular level of the project hierarchy 1 Select an element from the Project view for example the Debug variant 2 Select Edit Variable from the Project menu The Edit Variables dialog is displayed Figure 2 20 The title of the dialog box reflects the scope of the changes that are being made Edit Variables for hello apj Name c fbuila_target DepthOMotAP JBelowProjectRoot ProjectName ProjectName ach armlink Delete Cancel Help Apply Kprojecmame ad Figure 2 20 Edit Variables dialog 3 Select a variable from the scroll box or type the variable name 4 Type the new Value 5 Ifyou have additional variables to modify click Apply to save the c
36. Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example Example 5 10 Block copy Word CODE READONLY name this block of code 20 set number of words to be copied mark the first instruction to call r src gt r0 pointer to source block rl dst rl pointer to destination block r2 num r2 number of words to copy r3 r0 4 load a word from the source and r3 r1 4 store it to the destination r2 r2 1 decrement the counter wordcopy 5 COPY more rQ 0x18 gt angel_SwIreason_ReportException rl 0x20026 ADP_Stopped_ApplicationExit Q0x123456 Angel semihosting ARM SWI BlockData DATA READWRITE 1 2 5 4 5506 7 8 L 2 3 4 5 0 7 0 1 2 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 This module can be made more efficient by using LDM and STM for as much of the copying as possible Eight is a sensible number of words to transfer at a time given the number of registers that the ARM has The number of eight word multiples in the block to be copied can be found if r2 number of words to be copied using MOVS r3 r2 LSR 3 number of eight word multiples This value can be used to control the number of iterations through a loop that copies eight words per iteration When there are less than eight words left the number of words left can be found assuming that r2 has not been corrupted using ANDS r2 r2 7 Example 5 11 on page 5 40 list
37. SYS_CLOSE SYS_READ SYS_WRITE SYS_SEEK Whether or not and to what value errno is set is completely host specific except where the ANSI C standard defines the behavior Entry There are no parameters Register rl must be null Return On exit rO contains the value of the C library errno variable Copyright 1997 1998 ARM Limited All rights reserved 13 91 Angel 13 7 20 SYS GET CMDLINE 0x15 Returns the command line used to call the executable Entry On entry rl points to a two word data block in which the command string and its length are to be returned word 1 is a pointer to a buffer of at least the number of bytes specified in word two word 2 is the length of the buffer Return On exit 13 92 Register rl points to a two word data block word 1 is a pointer to null terminated string of the command line word 2 isthe length of the string The debug agent might impose limits on the maximum length of the string that can be transferred However the agent must be able to transfer a command line of at least 80 bytes In the case of the Angel debug monitor using ADP the minimum is slightly more than 200 characters Register rO contains an error code Oif the call is successful l if the call is unsuccessful for example because of a communications error Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 21 SYS HEAPINFO 0x16 Retur
38. The file is opened in its own Source File window Note You can have more than one source file open at a time 3 5 2 Working with variables ARM DUI 0040D To display a list of local or global variables select the appropriate item from the View menu A Locals Globals window is displayed You can also display the value of a single variable or you can display additional variable information from the Locals Globals window Follow these steps to display the value of a single variable 1 Select View Variables Expression 2 Enter the name of the variable in the View Expression dialog 3 Click OK The variable and its value are displayed in the Expression window Copyright 1997 1998 ARM Limited All rights reserved 3 37 ARM Debuggers for Windows and UNIX Alternatively 1 Highlight the name of the variable Era 2 Select View Variables Immediate Evaluation or click the Evaluate Expression button The value of the variable is displayed in a message box and in the Command window Note If you select a local variable that is not in the current context an error message is displayed Changing display formats If the currently active window is the Locals Globals Expressions or Debugger Internals window you can change the format of a variable Follow these steps to change the format of a variable 1 Right click on the variable and select the Change line format from the Locals or Globals windo
39. This function should be used only to calculate time intervals the length of time some action took by calculating the difference in the result on two occasions Entry There are no parameters Register rl must contain zero Return On exit rO contains the number of centiseconds since some arbitrary start point if the call is successful 1 if the call is unsuccessful for example because of a communications error 13 7 17 SYS_TIME 0x11 13 90 Returns the number of seconds since 00 00 January 1 1970 Entry There are no parameters Register rl must contain zero Return On exit rO contains the number of seconds Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 18 SYS SYSTEM 0x12 Passes a command to the host command line interpreter This SWI enables you to execute a system command such as 1s or pwd The terminal I O is on the host and is not visible to the target Entry On entry rl contains a pointer to a two word argument block word 1 points to a string that is to be passed to the host command line interpreter word 2 is the length of the string Return On exit rO contains the return status 13 7 19 SYS_ERRNO 0x13 ARM DUI 0040D Returns the value of the C library errno variable associated with the host support for the debug monitor The errno variable can be set by a number of C library support SWIs including SYS_REMOVE SYS_OPEN
40. Treat function code as unsigned integer DoAdd If code is gt 2 then do operation 0 r3 JumpTable pc r3 r LSL 2 Load address of jump table Jump to the appropriate routine DoAdd DoSub r rl r2 Operation 0 gt 1 pc Ir gt Return r rl r2 Operation 1 pc Ir gt Return Mark the end of this file Converting to Thumb To convert Example 5 7 on page 5 29 to Thumb code you must modify the LDR instruction that is used to implement the jump This is because you cannot increment the base register of LDR and STR instructions in Thumb state In addition LDR cannot load a value into the pc or do an inline shift of a value held in a register The equivalent code to cause the jump to the appropriate routine is LSL r0 rQ0 2 LDR r3 r3 rQ MOV pc r3 You must place an ALIGN directive before the Jumptable label to ensure that the table is aligned on a 32 bit boundary 5 6 2 Loading addresses with LDR Rd label 5 30 The LDR Rd pseudo instruction can load any 32 bit constant into a register See Loading with LDR Rd const on page 5 25 It also accepts program relative expressions such as labels and labels with offsets The assembler converts an LDR r abel pseudo instruction by placing the address of label1 in a literal pool a portion of memory embedded in the code to hold constant values generating a program relative LDR instruction that reads the address from the literal pool
41. Windows development tools utilities supporting software These are described in more detail below Command line development tools The following command line development tools are provided armcc The ARM C compiler The compiler is tested against the Plum Hall C Validation Suite for ANSI conformance It compiles ANSI or PCC source into 32 bit ARM code tec The Thumb C compiler The compiler is tested against the Plum Hall C Validation Suite for ANSI conformance It compiles ANSI or PCC source into 16 bit Thumb code armasm The ARM and Thumb assembler This assembles both ARM assembly language and Thumb assembly language source armlink The ARM linker This combines the contents of one or more object files with selected parts of one or more object libraries to produce an executable program The ARM linker creates ELF executable images armsd The ARM and Thumb symbolic debugger This enables source level debugging of programs You can single step through C or assembly language source set breakpoints and watchpoints and examine program variables or memory 1 2 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Introduction Windows development tools The following windows development tools are provided ADW The ARM Debugger for Windows This provides a full Windows environment for debugging your C C and assembly language source APM The ARM Project Manager This is a graphical user interface too
42. and RAM to store data The amount of ROM Flash and RAM required varies depending on your configuration Additional RAM is required to download a new version of Angel if you download a new version of Angel to Flash memory you will require enough RAM to store the flash download program if you download a new version of Angel using the loadagent debugger command you will require RAM to store the downloaded copy of Angel Note The loadagent command cannot write to Flash If you use loadagent Angel must be compiled to run from RAM Exception vectors Angel requires some control over the ARM exception vectors Exception vectors are initialized by Angel and are not written to after initialization This supports systems with ROM at address 0 where the vectors cannot be overwritten Angel installs itself by initializing the vector table so that it takes control of the target when an exception occurs For example debug communications from the host cause an interrupt that halts the application and calls the appropriate code within Angel Interrupts Angel requires use of at least one interrupt to support communication between the host and target systems You can set up Angel to use IRQ FIQ both IRQ and FIQ Copyright 1997 1998 ARM Limited All rights reserved 13 9 Angel It is recommended that you use FIQ for your own interrupt requirements because Angel has no fast interrupt requirements Refer to devc
43. armprof sortl prf gt profl The profiler generates the report and sends the output to text file prof1 that you can examine If you are using the Windows toolkit L If you use ADW and are running APM then a Select Open from the Project menu to load the project file sorts apj into APM b Build the project by clicking the Force Build button The project is built and any messages are displayed in the build log c Load the debugger by clicking the Debug button ADW is started and the application 1s loaded If you use ADU then a Compile and link the sorts c example program with the command armcc Otime o sorts sorts c b Start ADU Select Load Image from the File menu to load the sorts exe program file into ADU Select Options Profiling Toggle Profiling to turn profiling on in ADW or ADU Click Go to start the program The program runs and stops at the breakpoint on main Copyright 1997 1998 ARM Limited All rights reserved 11 23 Benchmarking Performance Analysis and Profiling 11 24 Click Go again The program resumes execution When execution completes select Options Profiling Write to File to write the profile data to the file sort1 prf Exit ADW or ADU and start a DOS session Make the profile directory the current directory Generate the profile for the collected profile data by entering the following at the system prompt armprof sortl prf gt profl armprof generates
44. info totals startup o print o c ARM250 1i1b embedded armlib_1 161 4 Start armsd ADW or ADU and type the following on the command line load print axf go 10 6 4 Code listings for example 3 AREA asm_code CODE If assembled with ARMASM 16 the variable CONFIG will be set to 16 If assembled with ARMASM the variable CONFIG will be set to 32 Set the variable THUMB to TRUE or false depending on whether the file is being assembled for ARM or Thumb GBLL THUMB CONFIG 16 THUMB SETL TRUE If assembling with ARMASM 16 go into 32 bit mode as the ARMulator will Start up the program in ARM state CODE32 THUMB SETL FALSE IMPORT C_Entry ENTRY gt Set up the stack pointer to point to the 512K MOV sp 0x80000 Get the address of the C entry point LDR Ir C_Entry THUMB If building a Thumb version pass control to C_entry using the BX gt Instruction so the processor will switch to THUMB state BX Ir Otherwise just pass control to C_entry in ARM state MOV pc Ir END 10 20 Copyright 1997 1998 ARM Limited All rights reserved Example 10 7 startup s ARM DUI 0040D Writing Code for ROM Example 10 8 print c include lt stdio h gt ifdef __thumb x Define Angel Semihosting SWI to be Thumb one define SemiSWI Q xAB else x Define Angel Semihosting SWI to be ARM one define SemiSWI x123456 endif x We use the following Debug Monitor SWIs in this
45. ip is not preserved in either its dedicated or non dedicated APCS role Holds the address to which control must return on function exit It can be and often is used as a temporary register after pushing its contents onto the stack This value can be loaded directly into the program counter when returning lr is not preserved in either its dedicated or non dedicated APCS role Is the stack pointer It is always valid in strictly conforming code but need only be preserved in handwritten code Note however that if any handwritten code makes use of the stack or if interrupts can use the user mode stack sp must be valid In its non dedicated APCS role sp must be preserved sp must be preserved on function exit for APCS conforming code Is the stack limit register If stack limit checking is enabled sl must be valid whenever sp is valid In its non dedicated APCS role sl must be preserved Is the frame pointer register In the obsolete APCS variants that use fp this register contains either zero or a pointer to the most recently created stack backtrace data structure As with the stack pointer the frame pointer must be preserved but in handwritten code it does not need to be available at every instant However it must be valid whenever any strictly conforming function is called fp must always be preserved Is the static base register This register is used to access static data If sb is not used it is available as an additional reg
46. macro_RegionInit 32b1tRAM macro_RegionInit 16bitRAM To re use this code in your own scatter loaded applications call the macro RegionInit for each of your execution regions Note The initialization code should move all the execution regions from their load addresses to their execution addresses before creating any zero initialized areas This ensures that the creation of a zero initialized area does not overwrite any execution region contents before they are moved from their load address to their execution address Failure to do so may produce unpredictable results when the image executes The C entry point is called C_Entry not main to prevent the semihosted ANSI C libraries being pulled in during the link step because the Embedded C libraries are being used here instead The Embedded C libraries do not contain printf so here Angel SWIs together with sprintf are used to display text onto the console This mechanism is portable across ARMulator Angel EmbeddedICE and Multi ICE Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 7 6 Building the example To build the example do one of the following load the supplied scatter apj into APM use a batch file or makefile containing the following armasm g boot s list armasm g regioninit s list armasm g vectors s list armcc g c C_main c armcc g c C_func c armlink boot o regioninit o vectors o C_main o C
47. messages If you are porting Angel to your own hardware your device driver must be able to handle messages that are longer than 256 bytes The actual length of memory write messages is determined by your Angel port Message length is defined in devconf h with define BUFFERLONGSIZE Setting breakpoints Angel uses three undefined instructions to set breakpoints The instruction used depends on the endianness of the target system Copyright 1997 1998 ARM Limited All rights reserved 13 31 Angel 13 32 the processor state ARM or Thumb ARM state In ARM state Angel recognizes the following words as breakpoints 0xE7FDDEFE for little endian systems 0xE7FFDEFE for big endian systems Thumb state In Thumb state Angel recognizes 0xDEFE as a breakpoint Note These are not the same as the breakpoint instructions used by Multi ICE or EmbeddedICE These instructions are used for normal user interrupt and vector hit breakpoints In all cases no arguments are passed in registers The breakpoint address itself is where the breakpoint occurs When you set a breakpoint Angel stores the original instruction to ensure that it is returned 1f the area containing it is examined replaces the instruction with the appropriate undefined instruction The original instruction is restored when the breakpoint is removed or when a request to read the memory that contains the instruction is made in the debugger
48. non integer like structures 6 15 noos c ARMulator model 12 4 Numeric constants assembly language 5 12 O Object library APM template 2 52 Olicom 13 99 Online help accessing 2 2 3 2 Operand expressions inline assemblers 8 4 Operators in ADW ADU expressions 3 72 Operators assembly language BASE 5 53 INDEX 5 53 AND 5 51 Optimization and DWARF 3 74 and DWARF debug tables 3 75 Overloaded functions in ADW ADU expressions 3 72 ARM DUI 0040D P Padding 5 51 Page table model access permissions 12 16 ARM740T protection unit 12 17 ARM810 flags 12 15 ARM940T flags 12 15 ARM940T protection unit 12 17 bufferable B bit 12 16 cacheable C bit 12 16 contents 12 16 domain access control 12 15 domain field 12 16 initializing the MMU 12 15 physical base address 12 16 region size 12 16 regions in 12 16 SA 110 flags 12 15 translation faults 12 16 translation table base register 12 15 updateable U bit 12 16 virtual base address 12 16 pagetab c ARMulator model 12 3 Parameters assembly macros 5 43 Partitions in APM 2 24 passing structures 6 13 Paths search 3 36 Patterns build step 2 39 2 47 PC sampling 11 20 PCMCIA Ethernet card 13 99 pc assembly 5 38 pc assembly language 5 4 5 9 5 11 5 35 5 37 5 41 Performance improving 11 16 measuring 11 6 Peripherals accessing 3 5 PERMITTED macro 13 62 13 69 PID board and Angel 13 15 Angel device drivers 13 63 Angel porting 13 43 PMCIA and Angel 13 6
49. numbers on page 13 72 for information on changing the default Angel SWI numbers If you are using SWIs in your application and using EmbeddedICE or Multi ICE for debugging you should usually set a break point on the SWI handler routine where you know it is an Angel SWI rather than at the SWI vector itself If you are using SWIs in your application you must restore registers to the state that they were when you entered the SWI If you want to use the Undefined instruction exception for any reason you must remember that Angel uses this to set breakpoints Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel Using Angel with an RTOS From the application perspective Angel is single threaded modified by the ability to use interrupts provided the interrupt is not context switching External functions must not change processor modes through interrupts This means that running Angel and an RTOS together 1s difficult and is not recommended unless you are prepared for a significant amount of development effort If you are using an RTOS you will have difficulties with contention between the RTOS and Angel when handling interrupts Angel requires control over its own stacks task scheduling and the processor mode when processing an IRQ or FIQ An RTOS task scheduler must not perform context switches while Angel is running Context switches should be disabled until Angel has finished processing F
50. r2 0 r3 ri r2 r3 4 B2 10 3 8 Enabling interrupts 10 3 9 Changing processor mode ARM DUI 0040D Example 10 1 Initializing variables End of ROM code start of ROM data Base of RAM to initialize Base and limit of area to zero initialize Get pointer to ROM data and RAM copy Zero init base gt top of initialized data Check that they are different Copy init data Top of zero init segment Zero init The initialization code should enable interrupts if necessary by clearing the interrupt disable bits in the CPSR At this stage the processor is in Supervisor mode If your application runs in User mode change to User mode and initialize the User mode sp register sp_USR Copyright 1997 1998 ARM Limited All rights reserved Writing Code for ROM 10 3 10 Changing processor state On Thumb capable processors the processor starts up in ARM state If the application entry point is Thumb code you must change to Thumb state for example using ORR Ir pc 1 BX Ir For more details on changing between ARM and Thumb state refer to Chapter 7 Interworking ARM and Thumb 10 3 11 Entering C code It is now safe to call C code for example IMPORT C_Entry BL C_Entry Notes on using the main function When building a ROM image using the Embedded C Library call the C entry point something other than main for example C_entry or ROM_entry When the compiler compiles a function called main it gen
51. save Ir_USR and non callee Saved registers branch to C IRQ handler restore registers Switch to IRQ mode and disable IRQs FIQ is still enabled restore work regs and spsr_IRQ return from IRQ Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 5 3 Example interrupt handlers in assembly language Interrupt handlers are often written in assembly language to ensure that they execute quickly The following sections give some examples Single channel DMA transfer Example 9 14 shows an interrupt handler that performs interrupt driven I O to memory transfers soft DMA The code is an FIQ handler It uses the banked FIQ registers to maintain state between interrupts This code is best situated at location OxIc In the example code r8 Points to the base address of the I O device that data is read from IOData Is the offset from the base address to the 32 bit data register that is read Reading this register clears the interrupt r9 Points to the memory location to where that data is being transferred r10 Points to the last address to transfer to The entire sequence for handling a normal transfer is four instructions Code situated after the conditional return is used to signal that the transfer is complete Example 9 14 LDR r11 r8 10Data Load port data from the IO device STR r11 r9 4 Store it to memory update the pointer CMP r9 r10 S
52. string 5 48 The same map can be used to describe many instances of the data structure These may be located anywhere in memory There are restrictions on what addresses can be loaded into a register using the MOV instruction See Loading addresses into registers on page 5 27 for details of how to load arbitrary addresses Register based maps In many cases you can use the same register as the base register every time you access a data structure You can include the name of the register in the base address of the map Example 5 17 shows such a register based map The labels defined in the map include the register Example 5 17 consta uses four bytes located at offset 0 from r9 constb uses four bytes located at offset 4 x uses eight bytes located at offset 8 y uses eight bytes located at offset 16 String is up to 256 bytes long starting at offset 24 Using the map in Example 5 17 you can access the data structure wherever it is ADR r9 datastart LDR r4 constb gt LDR r4 r9 4 constb contains the offset of the data item from the start of the data structure and also includes the base register In this case the base register is r9 defined in the MAP directive Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 9 4 Program relative maps You can use the program counter r15 as the base register for a map In this case each STM or LDM in
53. the Angel PID port determines whether or not the IRQ signals the receipt of a complete ADP packet If it does Angel task management is called to control the packet decode operation Refer to Example of Angel processing a simple IRQ on page 13 40 for more information Other Angel ports can make other choices for IRQ processing provided the relevant task is eventually run The task management code maintains two values that relate to priority Task type The task type indicates type of task being performed For example the application task is of type TP_Application and Angel tasks are usually TP_AngelCallback The task type labels a task for the lifetime of the task Task priority The task priority is initially derived from the task type but thereafter it is independent Actual priority is indicated in two ways in the value of a variable in the task structure in the relative position of the task structure in the task queue The task priority of the application task changes when an application SWI is processed to ensure correct interleaving of processing Table 13 1 shows the relative task priorities used by Angel Table 13 1 Task priorities Priority Task Description Highest AngelWantLock High priority callback AngelCal1Back Callbacks for Angel App1Cal1Back Callbacks for the user application Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel Table 13 1 Task pr
54. 10 li bi Start the debugger in LIttle endian or BIg endian mode armul Start the debugger using the ARMulator adp linespeed baudrate port s serzal port p parallel port e ethernet address Start the debugger using Remote_A if available in the current RDI connection list You can use linespeed baudrate only in conjunction with adp to specify the baud rate of the connection You can use port only in conjunction with adp to specify the connection to the device For example to launch ADW from the command line and load sorts axf for debugging but without setting a breakpoint on main type adw debug sorts axf nomainbreak To launch ADW with arguments from APM select Project Edit Variables adw and enter the arguments after adw in the Value box Refer to Specifying command line arguments for your program on page 3 46 for more information on specifying command line options When you start the ARM Debugger the windows you were using last time are again displayed These usually include the Console Command and Execution windows and you can load your executable image Closing the ARM Debugger Select Exit from the File menu to close down the ARM Debugger Loading reloading and executing a program image You must load a program image before you can execute it or step through it Loading an image Follow these steps to load a program image Select Load Image from the File menu or click the Open
55. 12 3 1 Configuring the Tracer 12 6 The Tracer has its own section in the ARMulator configuration file armul cnf Find the EarlyModels section in the configuration file and the Tracer section below it Tracer Output options can be plaintext to file binary to file or to RDI log window Checked in the order RDILog File BinFile RDILog False Fi le armul trc BinFile armul trc gt Tracer options what to trace TraceInstructions True TraceMemory False TraceIdle False TraceNonAccounted False Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARMulator TraceEvents False gt Where to trace memory if not set it will trace at the core TraceBus I rue gt Flags disassemble instructions start with tracing enabled Disassemble True StartOn False where RDILog instructs the Tracer to output to the RDI Log window the console under armsd File defines the file where the trace information is written using the default Tracer_Open functions Alternatively you can use BinFile to store data in a binary format The other options control what is being traced TraceMemory traces real memory accesses Traceldle traces idle cycles TraceNonAccounted traces unaccounted RDI accesses to memory TraceEvents traces events For more information refer to Events on page 12 87 of the ARM Software Development Toolkit Reference Guide TraceBus controls the trace
56. 1997 1998 ARM Limited All rights reserved 13 17 Angel 13 18 In addition you should consider Whether you are to move to a production system that includes minimal Angel or a stand alone system If you are not using minimal Angel you must write your own initialization and exception handling code Whether or not you require C library support in your final application You must decide how you will implement C library support if it is required because the Angel semihosting SWI mechanism will not be available Refer to Linking Angel C library functions on page 13 21 for more information Whether or not debug information is included You should be aware of the size overhead when using debuggable images as production code Communications requirements You must write your own device drivers for your production hardware Memory requirements You must ensure that your hardware has sufficient memory to hold both Angel and your program images Programming restrictions Angel resource requirements introduce a number of restrictions on application development under Angel Angel requires control of its own Supervisor stack If you are using an RTOS you must ensure that it does not change processor state while Angel is running Refer to Using Angel with an RTOS on page 13 19 for more information You should avoid using SWI 0x123456 or SWI Oxab These SWIs are used by Angel to support C library semihosting requests Refer to Configuring SWI
57. 1997 1998 ARM Limited All rights reserved 6 13 Using the Procedure Call Standards 6 4 2 Example 6 6 max STMDB sp al a3 LDRB a3 sp 4 LDRB a2 sp 8 CMP a3 a2 ADDLE a2 sp 8 ADDGT a2 sp 4 LDR a2 a2 0 STR a2 al 0 ADD Sp Sp 0xc MOV pc ir The STMDB instruction saves the arguments onto the stack Registers a2 and a3 are used as temporary registers to hold the required part of the structures passed and al is a pointer to an area in memory in which the resulting structure is placed Returning integer like structures The APCS specifies different rules for returning integer like structures An integer like Structure is no larger than one word in size has addressable subfields all of which have an offset of 0 The following structures are integer like struct i unsigned a 8 b 8 c 8 d 8 f union polymorphic_ptr 1 struct A xa struct B b int 1 whereas the structure used in Example 6 5 on page 6 13 is not struct char chl ch2 An integer like structure has its contents returned in al This means that al is not needed to pass a pointer to a result structure in memory and is instead used to pass the first argument Example 6 7 on page 6 15 demonstrates this Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Using the Procedure Call Standards Example 6 7 typedef struct half_words_struct unsigned field1 16 unsigned field2 16 thalf_words ha
58. 2 50 and ARM C 1 10 versions of the compilers Impact Any makefile or APM project file that uses a frame pointer call standard apcs fp will now generate a warning from the compilers Future release A new procedure call standard will be introduced with a future release of the compilers Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Introduction Reentrant code Use of the reentrant procedure call standard when compiling C or C code is warned against in the SDT 2 50 and ARM C 1 10 versions of the compilers Impact Any makefile or APM project file that uses the reentrant procedure call standard apcs reent will now generate a warning from the compilers Future release A new procedure call standard will be introduced with a future release of the compilers ARM Symbolic Debug Table format ASD Because the preferred and default debug table format is now DWARF 2 the compilers and assembler will warn when asked to generate ASD debug tables Impact Any makefiles with a compiler or assembler command line option of g asd will now produce a warning For existing APM projects in which debugging information has been requested there will be no warning and DWARF 2 debug tables will be emitted instead because this is the new default for the compilers and assembler Future release In a future release of the compilers and assembler ASD will be made obsolete and its use
59. 32 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 7 Undefined instruction handlers Instructions that are not recognized by the processor are offered to any coprocessors attached to the system If the instruction remains unrecognized an undefined instruction exception is generated It could be the case that the instruction is intended for a coprocessor but that the relevant coprocessor for example a Floating Point Accelerator is not attached to the system However a software emulator for such a coprocessor might be available Such an emulator should l Attach itself to the undefined instruction vector and store the old contents pA Examine the undefined instruction to see 1f it should be emulated This is similar to the way in which a SWI handler extracts the number of a SWI but rather than extracting the bottom 24 bits the emulator must extract bits 27 24 These bits determine whether the instruction is a coprocessor operation in the following way If bits 27 to 24 b1110 or b110x the instruction is a coprocessor instruction If bits 8 11 show that this coprocessor emulator should handle the instruction the emulator should process the instruction and return to the user program 3 Otherwise the emulator should pass the exception onto the original handler or the next emulator in the chain using the vector stored when the emulator was installed When a chain
60. 57 Barrel shifter 5 7 5 17 Barrel shifter Thumb 5 9 Base classes in ADW ADU 3 67 in ADW ADU expressions 3 72 in mixed languages 8 18 8 22 BASE operator 5 53 Base register 5 47 Benchmarks 11 2 11 6 Bit 0 use in BX instruction 7 4 BL instruction 5 15 8 6 BL instruction Thumb 5 17 Blank templates 2 41 Index 4 Block copy assembly language 5 39 Block copy Thumb 5 41 Boolean constants assembly language 5 12 boot s initialization file 10 24 Branch instructions 5 6 scatter loading 10 30 Branch instructions Thumb 5 8 Breakpoints 4 6 and Angel 13 31 Angel restrictions 13 32 data dependent 3 5 MultiICE and EmbeddedICE 13 32 setting in ADW ADU 3 27 setting editing and deleting 3 26 simple 3 27 simple and complex 3 26 using 4 3 window 3 18 3 26 Build log 2 12 Build step 2 11 patterns 2 39 2 47 Building an interworking image 2 52 C projects in APM 2 52 project output 2 9 variants of projects 2 11 BX instruction 5 3 5 6 5 8 5 16 7 4 8 8 bit O usage 7 4 long range branching 7 5 non Thumb processors 7 5 without state change 7 5 bytelane c ARMulator model 12 4 C C calling assembler 8 19 combining with assembler 6 2 compiling 4 2 linkage 8 17 listing source 4 3 4 9 using header files from C 8 15 C global variables from assembly language 8 14 C library and Angel 13 21 Copyright 1997 1998 ARM Limited All rights reserved Angel SWIs 13 79 Call graph profiling 11 19 11 20 Calling
61. 7 LDM and STM instructions 5 41 popping pe 5 38 procedure call standard 6 11 return address 9 41 using duplicate function names 7 17 Time analysis 3 43 Tool configuration in APM 2 20 Toolbar 3 8 Toolkit for software development 3 1 Tools for license management A 14 TPCS 6 11 interworking ARM and Thumb 7 2 register names and usage 6 11 TQI 13 38 13 39 Trace files address 12 10 disassembly 12 11 event lines 12 9 events 12 11 instruction addresses 12 11 instruction lines 12 9 12 10 locked access 12 10 memory access 12 9 memory cycles 12 9 memory lines 12 9 opcode 12 11 opcode fetch 12 10 output 12 8 read write operations 12 10 return address 12 10 speculative instruction fetch 12 10 Tracer configuring under ARMulator 12 6 debug support 12 8 disabling 12 8 disassembling instructions 12 7 enabling 12 8 Index 12 events 12 7 12 8 flushing output to the trace file 12 6 idle cycles 12 7 initializing 12 6 output to the RDI log window 12 7 quitting from 12 6 source of trace data 12 7 trace file 12 7 tracing options 12 7 unaccounted RDI access 12 7 tracer c ARMulator model 12 3 12 4 Tracer_Close ARMulator function 12 6 Tracer_Dispatch ARMulator function 12 6 Tracer_Flush ARMulator function 12 6 Tracer_Open ARMulator function 12 6 Tracing 11 26 trickbox c ARMulator model 12 4 U UDP IP 13 99 Undefined instruction exception 9 2 Undefined instruction handler 9 7 9 33 9 41 Undefined symbols ROM code 10 34 Unha
62. ARM Limited shall not be liable for any loss or damage arising from the use of any information in this document or any error or omission in such information or any incorrect use of the product Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Contents ARM Software Development Toolkit User Guide Preface ADONIS DOOK is den a E E ee amet Vill RE AG LE Ie AC UIN Ns serioena Rese cca aaa asent neces a made seen aes oetanet ret avans numcnentors X Typographical conventions EN es ee eee eee xii FecdDaACK PR aa E a xiii Chapter 1 Introduction 1 1 About the ARM Software Development Toolkit 1 2 1 2 Supported platforms ss 1 5 1 3 WV GUIS RENE nn men es othe nee oc anne 1 6 Chapter 2 ARM Project Manager 2 1 About the ARM Project Manager cccccseeceeeseeeeseeeeseeeeeeseeeeeseeeeseneeesaes 2 2 2 2 GeHINdS ATEN Tr Anne ie nn ii dns 2 4 2 3 TEARM desktop esse NN ee eee ele mac 2 15 2 4 Additional APM IUNCUONS S she necessite see 2 20 2 5 SEUNG preferentes ain na nn cd aa et 2 31 2 6 Working With SOUNCE TGS Eh ri in ne ni ne 2 34 2 7 Viewing object and executable files ccccccccssseeeeeeeeeeeeeeseeeeeeeseaeeeeeens 2 37 2 8 Working with project templates VU 2 39 2 9 B ld Step panes iraro nn nr nn sl nine ae 2 47 2 10 CSI APM WINO ER nana esse Donne ca ee 2 52 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved ili Contents Chapter 3
63. ARMulator the required stacks are set up for you Otherwise you must set them up yourself Refer to Chapter 10 Writing Code for ROM for more information Note As supplied the assembler does not predeclare symbolic register names of the form register_mode To use this form you must declare the appropriate symbolic names with the RN assembler directive For example 1r_FIQRN r14 declares the symbolic register name r_FIQ for r14 Refer to the ARM Software Development Toolkit Reference Guide for more information on the RN directive 9 1 3 Exception priorities ARM DUI 0040D When several exceptions occur simultaneously they are serviced in a fixed order of priority Each exception is handled in turn before execution of the user program continues It is not possible for all exceptions to occur concurrently For example the undefined instruction and SWI exceptions are mutually exclusive because they are both triggered by executing an instruction Copyright 1997 1998 ARM Limited All rights reserved 9 3 Handling Processor Exceptions Table 9 2 shows the exceptions their corresponding processor modes and their handling priorities Because the Data Abort exception has a higher priority that the FIQ exception the Data Abort is actually registered before the FIQ is handled The Data Abort handler is entered but control is then passed immediately to the FIQ handler When the FIQ has been handled control returns to the Data Abort
64. All rights reserved ARM DUI 0040D Benchmarking Performance Analysis and Profiling 11 43 Changing the source ARM DUI 0040D You can make further improvements to code size and performance in addition to those achieved by good use of compiler options by modifying the code to take advantage of the ARM processor features Use of shorts ARM cores that implement an ARM Architecture earlier than version 4 do not have the ability to directly load or store halfword quantities or short types This affects code size Generally code generated for Architecture 3 that makes use of short is larger than equivalent code that only performs byte or word transfers Storing a short is particularly expensive because the ARM processor must make two byte stores Similarly loading a short requires a word load followed by shifting out the unwanted halfword If your processor supports halfwords use the appropriate architecture or processor options Refer to Chapter 2 The ARM Compilers in the ARM Software Development Toolkit Reference Guide This ensures that the resulting code contains the Architecture 4 halfword instructions By default the compiler generates halfword instructions If you are writing or porting for processors that do not have halfword support you should minimize the use of short values However this is sometimes impossible C programs ported from x86 or 68k architectures for example frequently make heavy use of short If the code has
65. EQU directive to define the end of available memory a directive with an operand of 0 to label the end of the data structure An ASSERT directive checks that the end of the data structure does not overrun the available memory Example 5 19 StartOfData EQU 0x1000 EndOfData EQU 0x2000 MAP StartOfData Integer 4 Integer2 4 String MaxStrLen Array ArrayLenx8 BitMask 4 EndOfUsedData Q ASSERT EndOfUsedData lt EndOfData Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 9 6 Forcing correct alignment ARM DUI 0040D You are likely to have problems if you include some character variables in the data structure as in Example 5 20 This is because a lot of words are misaligned Example 5 20 StartOfData EQU 0x1000 EndOfData EQU 0x2000 MAP StartOfData Char 1 Char2 1 Char3 1 Integer 4 gt alignment 3 Integer2 4 String MaxStrLen Array ArrayLenx8 BitMask 4 EndOfUsedData Q ASSERT EndOfUsedData lt EndOfData You cannot use the ALIGN directive because the ALIGN directive aligns the current location within memory MAP and directives do not allocate any memory for the structures they define You could insert a dummy 1 after Char3 1 However this makes maintenance difficult if you change the number of character variables You must recalculate the right amount of padding each time Example 5 21 on page 5 52 shows a bet
66. FlexLM license management utilities 2 0 0 0 cece eeee cree ee eeeeeeeeeeeeeeees A 14 Frequently asked questions about licensing ccccceseeeeeeeeeeeeeeeeeneeees A 18 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Preface This preface introduces the ARM Software Development Toolkit and its user documentation It contains the following sections About this book on page viii Further reading on page x Typographical conventions on page xii Feedback on page xiii ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved vii Preface About this book Organization viii This book provides user information for the ARM Software Development Toolkit It describes the major graphical user interface components of the toolkit and provides tutorial information on important aspects of developing applications for ARM processors This book is organized into the following chapters Chapter 1 Introduction Read this chapter for an introduction to the ARM Software Development Toolkit version 2 5 and details of the changes that have been made since version 2 1 1a Chapter 2 ARM Project Manager Read this chapter for information on the graphical user interface to the ARM tools APM runs under Windows 95 and NT and provides a graphical user interface to configure the ARM development tools and manage your software development projects Chapter 3 ARM Debuggers for Windows and U
67. Handler This means that the data transfer error does not escape detection as it would if the FIQ were handled first Vector Address Exception Type Exception Mode Table 9 2 Priority 1 High 6 Low 0x0 Reset supervisor SVC 1 0x4 Undefined Instruction undef 6 0x8 Software Interrupt SWI supervisor SVC 6 OxC Prefetch Abort abort 5 0x10 Data Abort abort 2 0x14 Reserved Not Applicable Not Applicable 0x18 Interrupt IRQ interrupt irq 4 Ox1C Fast Interrupt FIQ fast interrupt fiq 3 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 2 Entering and leaving an exception This section describes the processor response to an exception and how to return to the place where an exception occurred after the exception has been handled The method for returning is different depending on the exception type 9 2 1 The processor response to an exception When an exception is generated the processor takes the following actions l Copies the Current Program Status Register CPSR into the Saved Program Status Register SPSR for the mode in which the exception is to be handled This saves the current mode interrupt mask and condition flags Changes the appropriate CPSR mode bits in order to Change to the appropriate mode and map in the appropriate banked registers for that mode Disable interrupts IRQs are disabled when any exception o
68. If a large buffer is required but is not available the packet is treated as a bad packet and a resend request results Buffer life cycle When sending data the user of a channel must explicitly allocate a buffer before requesting a write Buffers must be released either by Passing the buffer to one of the channel transmit functions in the case of reliable data transmission In this case the channels code releases the buffer Copyright 1997 1998 ARM Limited All rights reserved 13 75 Angel Explicitly releasing it with the release function in the case of unreliable data transmission Receive buffers must be explicitly released with the release function see Figure 13 13 Unreliable data buffer lifecycle Reliable data buffer lifecycle callback callback release no release Figure 13 13 Send buffer lifecycle Channel packet format Channel packets contain information including channel ID such as the HADP ID packet number acknowledged packet number flags used for distinguishing data from control information Refer to the Angel debug protocol specification in c ARM250 PDF specs for a complete description of the channel packet format The length of the complete data packet is returned by the device driver layer An overall length field for the user data portion of the packet it not required because the channel header is fixed length 13 76 Copyright 1997 1998 ARM Limited All rights
69. Name and a Directory in which to create it and click OK An empty project based on the template is created in the directory you specified The project tree view is displayed press on the numeric keypad to expand all branches ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 7 23 Interworking ARM and Thumb 7 5 2 7 24 press to expand the selected branch press to collapse the selected branch Alternatively click the mouse on the plus minus icons in the tree view Double clicking on an item toggles expansion Using the Thumb ARM interworking image project This section describes how to use the Thumb ARM interworking image project to start a new interworking project Adding files Follow these steps to add files to the project 1 Select the appropriate partition before adding the file If the file is C or C source that should be compiled to Thumb code select the Thumb Sources partition and then select Add files to Thumb Sources from the Project menu If the file is C or C source that is to be compiled to ARM code select the ARM Sources partition and then select Add files to ARM Sources from the Project menu If the file is assembly language source select the ASM Sources partition and then select Add files to ASM Sources from the Project menu The Add Files to Project dialog is displayed 2 Inthe Add Files to Project dialog find the directory containing the files to b
70. Ptr_Glob Rec Pointer malloc sizeof Rec Typeii Ptr_Glob gt Ptr_Comp Ptr _Glob gt Diser Ident_1 Ptr_Glob variant var_1l Enum_Comp Ident_3 Ptr_Gloh variant var_1l Int_Comp 40 strepy Ptr_Glob varliant var_1l str_Comp DHRYSTONE PROGRAM SOME STRING strepy Str_l_Loc DHRYSTONE PROGRAM 1 ST STRING Next Ptr Glob Arr_2 Glob 9 7 10 ruil Default 4A Figure 3 21 The ARM Debugger C interface 3 8 2 Using the C debugging tools The menu items in the C menu give access to three new debugger windows The Class View window This window displays the class hierarchy of a C program in outline format The Watch View window This window displays a list of watches It enables you to add and remove variables and expressions to be watched and change the contents of watched variables The Evaluate Expression window This window enables you to enter an expression to be evaluated and to add that expression to the Watch window These windows are described in detail in the sections below 3 8 3 Using the Class View window You can use the Class View window to view the class structure of your C program Classes are displayed in an outline format that allows you to navigate through the hierarchy to display the member functions for each class A special branch of the hierarchy called Global displays global functions ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserve
71. ROM image using armlink armlink o ram0 axf ro base Oxf0Q000000 rw base 0x10000000 first init o Init map info Sizes init o ex o or for Thumb armlink o tram axf ro base Qxf 0Q0000 ro base 0x10000000 First init o Init map info Sizes init o ex o The only difference between this and the command used in Example is that here you use ro 0xf0000000 to specify the ROM base address Run the fromELF utility to produce a plain binary version of the image fromelf nozeropad ram axf bin ram bin ARM fromelf nozeropad tram axf bin tram bin Thumb Load and execute the ROM image under ARMulator by starting armsd ADW or ADU then type the following on the command line getfile ram bin xf0000000 ARM getfile tram0 bin Qxf0000000 Thumb Copyright 1997 1998 ARM Limited All rights reserved 10 17 Writing Code for ROM This tells armsd to load the file ram at address Oxf0000000 in the ARMulator memory map 6 Check that the ROM has been loaded correctly by disassembling its first section list 0xf0000000 Sample output is shown in Sample disassembly below 7 Set the program counter to the base of the ROM image then run it pc 0x 0000000 go This produces the following output factory_id is at address 10000000 contents AASSAASS display is at address 10000004 10 5 2 Sample disassembly 0xF0000000 0xF0000004 0xF0000008 OxF000000c Qxf0000010 Qxf0000014 0xf0000018 Qxf000001c
72. RW variables and ZI data Here the RW and ZI areas of C_main and C_func are relocated initialized to the region 16bitRAM All other read only code R0 for example region initialization and library code is executed from FLASH by using a wildcard in the description file Example 10 9 scat txt FLASH 0x04000000 0x04000000 FLASH 0x04000000 boot o Boot First RO 32b1tRAM Ox00000000 vectors o Vect FIRST 16b1tRAM Qx02080000 C_main o RW ZI C_func o RW ZI1 Copyright 1997 1998 ARM Limited All rights reserved 10 23 Writing Code for ROM 10 7 3 Initialization code This example illustrates the use of boot code boot s which is an extended version of the init s code used in Example 1 Building a ROM to be loaded at address 0 on page 10 9 The boot code defines the ENTRY point and initializes the stack pointers for each mode 10 7 4 Initializing execution regions 10 7 5 C code 10 24 This example uses region initialization code regioninit s to perform all the initialization required before branching to the main C application code The region initialization code copies RO code and RW data from ROM to RAM and zero initializes the ZI data areas used by the C code The function InitRegions in regioninit s uses a macro called RegionInit to initialize the specified execution regions These execution region names match those given in the scatter load description file scat txt
73. Rebuild the project If you see an error message like project apj No build target named lt projectname gt bin a Remove all source files from your project by highlighting the files then pressing delete b Replace all source files into your project using the Add Files to Project from the Project menu 10 10 1 Multiple output formats This example uses bin to produce a plain binary image suitable for blowing into ROM Other output formats are also possible Motorola 32 bit Hex Intel 32 bit Hex and Intellec Hex Multiple outputs are also possible For example step 7 might read on one line lt fromelf gt lt FROMELFOPTIONS gt lt projectname gt axf m32 lt projectname gt m32 bin lt projectname gt bin 10 10 2 Configuration The Project Tool configuration menu will now contain an entry fromelf You will not need to use this configuration tool because you can change the fromELF options using the template variables ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 10 33 Writing Code for ROM 10 11 Troubleshooting hints and tips This section provides solutions to some common errors or problems The errors are organized in the following categories Problems with the Write0 SWI call Linker errors Load run errors ARMulator errors 10 11 1 Replacing the Write0 SWI call Users of EmbeddedICE 2 04 or earlier may find problems with the semihosting SWI SYS_W
74. Receiving information The information that is received by the channel viewer is converted into ASCII character codes and displayed in the window if the channel viewers are active However if OxfffffffF is received the following word is treated and displayed as a number Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 7 Configurations You can examine and change the configuration of the Debugger which includes configuration of the target environment for the image being debugged debugger parameters startup parameters ARMulator Angel remote connection EmbeddedICE or Multi ICE 3 7 1 Debugger configuration The Debugger Configuration dialog consists of three tabbed screens Target Debugger Memory Maps These are described below Select Configure Debugger from the Options menu to open the Debugger Configuration dialog Target environment Follow these steps to configure the target environment 1 Click the Target tab of the Debugger Configuration dialog Figure 3 15 on page 3 52 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 51 ARM Debuggers for Windows and UNIX 3 52 Debugger Configuration x Target Debugger Memory Maps Target Environment Use the ARM Debugger with the ARMulator Instruction set Simulator This allows you to execute ARM programs without physical ARM hardware
75. Refer to the ARM Software Development Toolkit Reference Guide for more detailed instructions on how to use armsd Starting armsd and loading an image To start armsd and load the image you want to debug enter the command armsd options imagename arguments You can specify any armsd options before the image name any arguments for the image after the image name Use the armsd command line to debug your target If you regularly issue the same set of armsd commands you can run these automatically by adding them to a text file called armsd ini This file must be in the current directory or the directory specified by the environment variable HOME The commands are run whenever you start armsd Obtaining help on the armsd commands Help is available from the armsd command line To display a list of all the armsd commands available enter help To display help on a particular command enter help command_name help can be abbreviated to h Setting and removing simple breakpoints A breakpoint halts the image at a specified location To set a simple breakpoint on the first statement of a function enter break function_name You can also use the break command to set breakpoints on the statement specified by its line number using break 7ne_number Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Command Line Development To list all the current breakpoints and their corresponding numb
76. Select C C source from the scroll box Click OK An Edit window is displayed Enter the following code deliberately omitting the semicolon at the end of the printf function call include lt stdio h gt int main void printf Hello World n return Q Save the code in a source file by selecting Save or Save As from the File menu or by clicking the Save button Enter hello c when you are prompted for a filename Close the Edit window by selecting Close from the File menu You are now returned to the Project window with the hello project loaded The source files and files inferred by the build steps are organized in a project using partitions as described under Partitions on page 2 24 APM uses variants to create different versions of your project output By default the following variants are defined DebugRel This variant is designed for projects where you intend to release the same code that you are debugging It provides an adequate debug view together with good optimization This variant sets the debug and optimization command line options to g 01 Debug This variant is designed for projects where you intend to have separate ARM DUI 0040D debug and release builds of your code It contains the debug version of your project and provides maximum debug information at the expense of optimization This variant sets the debug and optimization command line options to g 00 Copyright 1997 1998 ARM Limit
77. StrongARM based processor and writeback is enabled the base register will be restored to the value it had before the instruction started ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 35 Handling Processor Exceptions In each of the three cases the MMU can load the required virtual memory into physical memory The MMU Fault Address Register FAR contains the address that caused the abort When this is done the handler can return and try to execute the instruction again 9 36 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 10 Chaining exception handlers In some situations there can be several different sources of a particular exception For example Angel uses an undefined instruction to implement breakpoints However undefined instruction exceptions also occur when a coprocessor instruction 1s executed and no coprocessor is present Angel uses a SWI for various purposes including getting into supervisor mode from user mode and supporting semihosting requests However an RTOS or an application may also wish to implement some SWIs In such situations there are two approaches that can be taken to extend the exception handling code These are described below 9 10 1 A single extended handler In some circumstances it is possible to extend the code in the exception handler to work out what the source of the exception was and then directly
78. The default image file format emitted by the linker has changed from AIF to ELF Impact Existing makefiles in which no linker output format was chosen and existing APM project files in which the Absolute AIF format was chosen will now generate an ELF image If you require an AIF format image use aif on your armlink command line or choose Absolute AIF on the Output tab of the APM Linker options dialog box This will then generate a warning from the linker AIF images can also be created using the new fromELF tool Note When the ARM debuggers load an executable AIF image they switch the processor mode to User32 For ELF and any format other than executable AIF the debuggers switch the processor mode to SVC32 This means that by default images now start running in SVC32 mode rather than User32 mode This better reflects how the ARM core behaves at reset Copyright 1997 1998 ARM Limited All rights reserved 1 13 Introduction C code that performs inline SWIs must be compiled with the fz option to ensure that the SVC mode link register is preserved when the SWI is handled Default processor in the compilers and assembler The default processor for the SDT 2 11a ARM not Thumb compilers was ARM6 In SDT 2 50 and C 1 10 this has been changed to ARM7TDMI The default processor for the assembler has changed from cpu generic arch 3 to cpu ARM7TDMI Impact Existing makefiles and APM project files where the processor was
79. When you step through a breakpoint Angel replaces the saved instruction and executes it Note Angel can set breakpoints only on RAM locations When Angel detects an undefined instruction it 1 Examines the instruction by executing an LDR instruction from Ir 4 if in ARM state LDR instruction from Ir 2 if in Thumb state 2 Ifthe instruction is the predefined breakpoint word for the current processor state and endianness Angel a halts execution of the application b transmits a message to the host to indicate the breakpoint status c executes a tight poll loop and waits for a reply from the host Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel If the instruction is not the predefined breakpoint word Angel a reports it to the debugger as an undefined instruction b executes a tight poll loop and waits for a reply from the host ARM breakpoints are detected in Thumb state When an ARM breakpoint is executed in Thumb state the undefined instruction vector is taken whether executing the instruction in the top or bottom half of the word In both cases these correspond to a Thumb undefined instruction and result in a branch to the Thumb undefined instruction handler Note Thumb breakpoints are not detected in ARM state 13 3 4 Angel task management All Angel operations are controlled by Angel task management Angel task management assigns task priorities and sc
80. a complex breakpoint You can set complex breakpoints on a line of code a function a low level symbol Follow these steps to set or edit a complex breakpoint on a line of code 1 Double click on the line where you want to set a breakpoint or on an existing breakpoint position The Set or Edit Breakpoint dialog is displayed 2 Enter or alter the details of the breakpoint 3 Click OK The breakpoint is displayed as a red marker in the left hand pane of the Execution Source File or Disassembly window If the line in which the breakpoint is set contains several functions the breakpoint is set on the function that you selected in step 1 Follow these steps to set or edit a complex breakpoint on a function 1 Display a list of function names in the Function Names window 2 Select Set or Edit Breakpoint from the Function Names window menu 3 The Set or Edit Breakpoint dialog is displayed Complete or alter the details of the breakpoint 4 Click OK Follow these steps to set or edit a breakpoint on a low level symbol 1 Display the Low Level Symbols window 2 Select Set or Edit Breakpoint from the window menu 3 Complete or alter the details of the breakpoint 4 Click OK Copyright 1997 1998 ARM Limited All rights reserved 3 31 ARM Debuggers for Windows and UNIX 3 4 4 Complex watchpoints When you set a complex watchpoint you specify additional conditions in the form of expressions entered in
81. a task ID that identifies a current task and signals the task that the event has occurred See the description of Angel_Wait for more information on event bits The task ID for the calling task is returned by the Angel_TaskID macro The task must write its task ID to a shared memory location if an external task is to signal it Angel_TaskiD This macro returns the task ID a small integer of the task that calls it There is no way to obtain the ID of another task unless the other task writes its task ID to a shared memory location Copyright 1997 1998 ARM Limited All rights reserved 13 37 Angel 13 3 5 Context switching 13 38 Angel maintains context blocks for each task under its control through the life of the task and saves the value of all current processor registers when a task switch occurs It uses two groups of register context save areas The Angel global register blocks These are used to store the CPU registers for a task when events such as interrupt and task deschedule events occur An array of available Task Queue Items TQI Each allocated TQI contains the information Angel requires to correctly schedule a task and to store the CPU registers for a task when required The global register blocks angel_GlobalRegBlock The Angel global register blocks are used by all the exception handlers and the special functions Angel_Yield and Angel_Wait Register blocks are defined as an array of seven element
82. a type of source file contributing its own project output to the current project file of a type unknown to APM When you add a source file to a project it is not copied or moved from its original location in the file system Its location is referenced from the project file Whenever possible APM refers to files relative to the project directory structure rather than absolutely You can set the variable DepthOfDotAPJBelowProjectRoot to increase the scope of the directories that are considered a part of the project Refer to Variables on page 2 26 for more information Note If you move a project you must keep the directory structure containing its files the same If you change the directory structure the files required to build the project will not be found Derived files are created as the result of a build step such as a compile or a link An object file A library fe AnARM executable image Creating a new project Follow these steps to create a new project 1 Select New from the File menu or click the New button The New dialog is displayed Figure 2 1 on page 2 6 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 5 ARM Project Manager 2 6 CiC source C C include tile Assembler source C SOuUICE x Cancel Figure 2 1 New dialog 2 Select Project from the scroll box 3 Click OK The New Project dialog is displayed Figure 2 2 New Project Template Descripti
83. al 0 ADC al al 0 Change the return type of function declaration for add 64 from void to int Revisiting the first implementation Although the first C implementation is inefficient it shows more about the APCS than the hand modified version You have already seen a4 and ip being used as non preserved temporary registers However here v1 and Ir are also used as temporary registers v1 is preserved by being stored together with Ir on entry Register Ir is corrupted but a copy is saved onto the stack and reloaded into pc when v1 is restored This means that there is still only a single exit instruction but now it is LDMIA sp v1 pc Copyright 1997 1998 ARM Limited All rights reserved 6 9 Using the Procedure Call Standards 6 2 3 6 10 A more detailed look at APCS register usage Although sb sl fp ip sp and Ir are dedicated registers the example in Example 6 2 on page 6 7 shows ip and Ir being used as temporary registers Sometimes these registers are not used for their APCS roles The details given below will enable you to write efficient and safe code that uses as many of the registers as possible and avoids unnecessary saving and restoring of registers ip lr sp sl fp sb Is used only during function calls so it is not preserved across function calls It is conventionally used as a local code generation temporary register At other times it can be used as a corruptible temporary register
84. all be locked down in one block within it This is important because FIQs are designed to service interrupts as quickly as possible The five extra FIQ mode banked registers enable status to be held between calls to the handler again increasing execution speed Note An interrupt handler should contain code to clear the source of the interrupt Simple interrupt handlers in C You can write simple C interrupt handlers by using the __irq function declaration keyword You can use the __irq keyword both for simple one level interrupt handlers and interrupt handlers that call subroutines However you cannot use the __irq keyword for reentrant interrupt handlers because it does not store all the required state In this context reentrant means that the handler re enables interrupts and may itself be interrupted Refer to Reentrant interrupt handlers on page 9 24 for more information The __irq keyword preserves all APCS corruptible registers preserves all other registers excluding the floating point registers used by the function exits the function by setting the program counter to lr 4 and restoring the CPSR to its original value If the function calls a subroutine __i rq preserves the link register for the interrupt mode in addition to preserving the other corruptible registers See Calling subroutines from interrupt handlers on page 9 23 for more information Copyright 1997 1998 ARM Limited All rights reser
85. almost the same initialization code interrupt handling and exception handling as full Angel The device driver architecture 1s the same and any Angel device driver that can be compiled as a raw device 1s fully supported The minimal library contains sufficient components to allow it to replace a full Angel system The main difference is that an image containing an application and the minimal library initializes and then immediately enters the application at the __entry symbol The minimal library is approximately one third to one fifth the size of full Angel The actual size depends on the device drivers that are included and on compile time debugging and assertion options Building and linking a minimal Angel library Separate build directories makefiles and APM project files are provided for minimal Angel The build directories for the PID Angel port are in angel source pid min There are separate subdirectories for Solaris HPUX and APM builds Within the Angel source code minimal Angel build specifics are controlled by the MINIMAL_ANGEL macro This is set to O for full Angel and to 1 for minimal Angel 13 24 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 2 6 Application communications ARM DUI 0040D Full Angel requires use of at least one device driver for its own communications requirements If you are using Angel on a board with more than one serial port such as the PID board you c
86. and Multi ICE are JTAG based debugging systems for ARM processors EmbeddedICE and Multi ICE provide the interface between a debugger and an ARM core embedded within an ASIC These systems provide real time address and data dependent breakpoints single stepping full access to and control of the ARM core full access to the ASIC system full memory access read and write full I O system access read and write EmbeddedICE and Multi ICE also enable the embedded microprocessor to access host system peripherals such as screen display keyboard input and disk drive storage See EmbeddedICE configuration on page 3 60 for information on configuration options Refer to the Multi ICE documentation for detailed information on Multi ICE Copyright 1997 1998 ARM Limited All rights reserved 3 5 ARM Debuggers for Windows and UNIX Angel Angel is a debug monitor that allows rapid development and debugging of applications running on ARM based hardware Angel can debug applications running in either ARM state or Thumb state on target hardware Angel runs alongside the application being debugged on the target platform You can use Angel to debug an application on an ARM Development Board or on your own custom hardware See Chapter 13 Angel for more information 3 1 4 Debugger concepts This section introduces some of the concepts of that you need to be aware when debugging program images Debug agent A debug agent i
87. and Prefetch abort handlers These handlers report the exception to the debugger suspend the application and pass control back to the debugger FIQ IRQ Angel installs IRQ and FIQ handlers that enable Angel communications to run off either or both types of interrupt If you have a choice you should use IRQ for Angel communications and FIQ for your own interrupt requirements You can chain your own exception handlers for your own purposes Refer to Chaining exception handlers on page 13 20 for more information Copyright 1997 1998 ARM Limited All rights reserved 13 5 Angel 13 1 2 Angel component overview The main components of an Angel system are shown in Figure 13 1 The following sections give a summary of the system components 13 6 Copyright 1997 1998 ARM Limited All rights reserved Debugger Debugger toolbox ADP Boot support support C Library support Channel manager Device drivers Channel manager Booting p Generic debug support and initialization Target dependent debug support Exceptions support Figure 13 1 A typical Angel system Angel C library SWI support C Library Application ARM DUI 0040D ARM DUI 0040D Angel Host system components summary The host system components are Debugger This is the ARM Debugger for Windows ADW the ARM Debugger for UNIX ADU the ARM command line debugger armsd or a third party debugger that supports the Angel Debug P
88. and they can take a significant length of time to process They can be treated as an APCS function call but they restore the registers they are called with before returning except for rO which contains the return status Copyright 1997 1998 ARM Limited All rights reserved 13 79 Table 13 3 gives a summary of the Angel semihosting SWIs Refer to the descriptions below for more detailed information Table 13 3 Angel semihosting SWIs SWI Page Description xxx SYS_OPEN 0x01 on page 13 81 Open a file on the host page 81 RK IS YS_CLOSE 0x02 on page 13 83 Close a file on the host page 83 kk SYS_WRITEC 0x03 on page 13 83 Write a character to the debug channel page 83 RE SYS_WRITEO 0x04 on page 13 83 Write a string to the debug channel page 83 RK ISYS_WRITE 0x05 on page 13 84 Write to a file on the host page 84 IS YS_READ 0x06 on page 13 85 Read the contents of a file into a buffer page 85 IS YS_READC 0x07 on page 13 86 Read a byte from the debug channel page 86 HK IS YS_ISERROR 0x08 page 13 86 Determine if a return code is an error on page 86 ISYS_ISTTY 0x09 on page 13 87 Check whether a file is connected to an interactive device page 87 HK SY S_ SEEK 0x0a on page 13 87 Seek to a position in a file page 87 HK SY S_FLEN 0x0c on page 13 88 Return the length of a file page 88 RR SY S
89. any of its elements details variables paths build steps implies editing a project template not editing one of the blank templates Creating a new template on page 2 45 describes how to create and edit new blank templates 2 4 4 Project hierarchy A typical project hierarchy defines the structure of a project as follows System Project my_proj Variant For example DebugRel Debug or Release Partition For example Target Dependencies or Source Source For example sub proj apj my_file c my_file o sub proj o When you build a project using different tool configurations or variable values project settings take precedence over system wide settings variant settings take precedence over project settings partition settings take precedence over variant settings and file settings take precedence over partition settings ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 25 ARM Project Manager 2 4 5 2 26 Variables A variable holds a value used either by APM or by a build step pattern to specify a changeable aspect of your project such as a filename or directory path A variable prefixed with is read only a variable prefixed with can affect the actions of APM A variable containing a such as path Debug has a standard purpose defined by APM You can set variables for any level of the project hierarchy The standard variables are DepthOfDotAPJBelowProjectRoot ProjectName
90. any special compile time or link time options The only requirement is that low level symbols must be included in the image These are inserted by the linker unless it is instructed otherwise by the Nodebug option Profiling data is collected by the ARM Debugger while the code is being executed The data is saved to a file It is then loaded into the ARM profiler which displays the results The profiler in turn generates a profile report 11 5 1 Availability of profiling Profiling is currently available only when you use the ARMulator or the Angel debug monitor on a target board such as the PID7T Profiling is an optional feature for Angel selectable at build time Refer to Chapter 13 Angel for more information The standard Angel image supplied with SDT 2 50 for the PID7T has profiling turned on It is not possible to use EmbeddedICE or Multi ICE for profiling When you select Options Profiling Toggle Profiling the debugger determines whether the target hardware can perform profiling If so profiling is enabled If not the message Target Processor can t do this is displayed 11 5 2 About armprof ARM DUI 0040D The ARM profiler armprof displays an execution profile of a program from a profile data file generated by a debugger The profiler displays one of two types of execution profile depending on the amount of information present in the profile data If only pc sampling information is present the profiler can displa
91. applications running on ARM based hardware Angel can debug applications running in either ARM state or Thumb state You can use Angel to evaluate existing application software on real hardware as opposed to hardware emulation develop new software applications on development hardware bring into operation new hardware that includes an ARM processor port operating systems to ARM based hardware These activities require you to have some understanding of how Angel components work together The more technically challenging ones such as porting operating systems require you to modify Angel itself A typical Angel system has two main components that communicate through a physical link such as a serial cable Debugger The debugger runs on the host computer It gives instructions to Angel and displays the results obtained from it All ARM debuggers support Angel and you can use any other debugging tool that supports the communications protocol used by Angel Angel Debug Monitor The Angel debug monitor runs alongside the application being debugged on the target platform There are two configurations of Angel a full version for use on development hardware a minimal version that you can use on production hardware See Figure 13 1 on page 13 6 for an overview of a typical Angel system The debugger on the host machine sends requests to Angel on the target system Angel interprets those requests and performs an oper
92. be considerably larger than expected because debug data was generated separately for each compilation unit The linker emitted all the debug areas because it was unable to identify multiple copies of debug data belonging to header files that were included more than once Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Introduction Impact Existing makefiles and APM projects generate smaller debug images and therefore the images load more quickly into the debugger This feature cannot be disabled New supported processors ARMulator models for the ARMOTDMI ARM940T ARM920T ARM710T ARM740T ARM7TDMI S ARM7TDI S and ARM7T S processors have been added to SDT 2 50 These are compatible with the memory model interfaces from the SDT 2 11a ARMulator These processor names and those of all other released ARM processors are now permitted as arguments to the processor command line option of the compilers and assembler ADW enhancements ADW has been enhanced to provide the following additional features Support for remote debug using Multi ICE Support for reading DWARF 2 debug tables The command line options supported by armsd that are suitable for a GUI debugger are now understood on the ADW command line This enables you for example always to start ADW in remote debug mode The available command line options are symbols li b1 armul adp linespeed bau
93. be a byte array and the offset is given in bytes Entry On entry rl contains a pointer to a two word data block word 1 is a handle for a seekable file object word 2 is the absolute byte position to be sought to Return On exit rO contains 0 if the request is successful A negative value if the request is not successful SYS_ERRNO can be used to read the value of the host errno variable describing the error Note The effect of seeking outside of the current extent of the file object is undefined Copyright 1997 1998 ARM Limited All rights reserved 13 87 Angel 13 7 12 SYS_FLEN 0x0c Returns the length of a specified file Entry On entry rl contains a pointer to a one word argument block word 1 is a handle for a previously opened seekable file object Return On exit rO contains the current length of the file object if the call is successful if an error occurs 13 7 13 SYS_TMPNAM 0x0d Returns a temporary name for a file identified by a system file identifier Entry On entry rl contains a pointer to a three word argument block word 1 is a pointer to a buffer word 2 is a target identifier for this filename word 3 contains the length of the buffer The length should be at least the value of L_tmpnam on the host system Return On exit rO contains 0 if the call is successful if an error occurs The buffer pointed to by rl contains the filename
94. been written with portability in mind all you may have to do is change a typedef or define to use int instead of short Where this is not the case you may have to make some functional changes to the code You may be able to establish the extent of code size increase resulting from using shorts by compiling the code with armcc Dshort int which preprocesses all instances of short to int Be aware that although it may compile and link correctly code created with this option may not function as expected Whatever your approach you need to weigh the change in code size against the opposite change in data size The program below illustrates the effect of using shorts integers and the ARM7T option on code and data size include lt stdio h gt typedef short number number array 2000 number loop int main Copyright 1997 1998 ARM Limited All rights reserved 11 17 Benchmarking Performance Analysis and Profiling 11 18 for loop 0 loop lt 2000 loop array loop loop return Q The results of compiling the program with all three options are shown in the following table Table 11 3 Object code and data sizes code _ inline inline const RW O init debug size data strings data data data data short 76 8 0 0 4 4000 64 short with hardware 60 8 0 0 4 4000 64 support see note int 44 8 0 0 4 8000 0 Note See Specifying the target processor and architecture on page 2 19 of the ARM So
95. bits 16 31 represent the icache protection register The first register value shown is for region 0 the second for region 1 and so on Copyright 1997 1998 ARM Limited All rights reserved 12 17 ARMulator The protection region base size register for region 0 is initialized to Ox3F marking the size of region O as 4GB and as enabled CP15 Register 6 CP15 Register 7 is a control register Reading from it is unpredictable At startup it shows a value of zero The programming lockdown registers are both initialized to zero CP15 Register 9 The first register value shown is for data lockdown control the second for instruction lockdown control CP15 Register 15 the Test Debug register is initialized to zero Only bits 2 and 3 have any effect in ARMulator These control whether the cache replacement algorithm is random or round robin 12 18 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 12 8 armflat ARMulator ARM flat armflat c provides a memory model of a zero wait state memory system The emulated memory size is not fixed so host memory is allocated in chunks of 64KB each time a new region of memory is accessed The memory size is limited by the host computer but in theory all 4GB of the address space is available ARMflat does not generate aborts 12 8 1 Selecting the ARMflat memory model ARM DUI 0040D You select the ARMflat model by setting Default Flat in the Memories se
96. configuration settings as required Profile Interval This is the time between pc sampling in microseconds It is applicable to ARMulator and Angel only Lower values have a higher performance overhead and slow down execution Higher values are not as accurate as lower values Source Tab Length This specifies the number of space characters used for tabs when displaying source files Endian Determines byte sex of the target Little low addresses have the least significant bytes Big high addresses have the least significant bytes Disable Allows you to turn off the following display features Splash screen When selected stops display of the splash screen the ARM Debugger startup box when the debugger is first loaded Copyright 1997 1998 ARM Limited All rights reserved 3 53 ARM Debuggers for Windows and UNIX 3 54 Remote Startup warning Turns on or off the warning that debugging is starting with Remote_A enabled If the warning is turned off and debugging is started without the necessary hardware attached there is a possibility that the ARM Debugger may hang If the warning is enabled you have the opportunity to start in ARMulate 3 Save or discard your changes click OK to save any changes and exit click Apply to save any changes click Cancel to ignore all changes not applied and exit Note When you make changes to the Debugger configuration the current execution is ended and your program is reloaded
97. construct your own You can modify a project template by adding tools and changing the way they are executed while building the project You can modify variables at any level in the project hierarchy to change the way specific files are handled You can also create additional variants Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager APM includes standard templates that you can copy and modify to suit your own needs If you have installed the ARM C Compiler you will have some additional templates that you can use see Using APM with C on page 2 52 A template can exist in two distinct forms A blank template as described in Blank templates supplied with APM on page 2 41 The standard templates supplied with APM are blank templates Each one contains the necessary project configuration information needed to create a particular type of project such as a Thumb executable image but has no source or output filenames assigned A project template A blank template becomes a project template when you create a new project based on the template and add files to it Normally you have one blank template for each type of project that you might want to create and you accumulate an increasing number of project templates Each project template is based on one of the blank templates but now uniquely defines the build steps for one particular project In most of this chapter editing a template or
98. file Defining the target macros in target s The GETSOURCE macro returns the current interrupt source These are target dependent and must correspond to the target peripherals The interrupt sources are defined in devconf h You must ensure that all interrupt sources used by Angel are supported by the GETSOURCE macro Refer to target s on page 13 58 for more information Writing the device drivers Writing device drivers for your hardware is the major part of the porting procedure and is completely target dependent Refer to Writing the device drivers on page 13 63 for information on writing device drivers Downloading Angel After you have completed your Angel port you must download it to your hardware There are a number of methods you can use to do this Refer to Downloading a new version of Angel on page 13 67 for more information 13 46 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel Debugging your Angel port At various stages throughout the porting process you will need to debug your Angel port Only the initial stages of development can be debugged under the ARMulator because the ARMulator environment does not support communications with peripheral devices Refer to Debugging your Angel port on page 13 68 for more information on debugging Angel 13 4 3 Modifying the UNIX makefile ARM DUI 0040D If you are using a command line UNIX system you must edit the appropriate makefile when you cop
99. for a summary of the different architecture versions 5 2 2 ARM and Thumb state Versions 4T and 4TxM of the ARM architecture define a 16 bit instruction set called the Thumb instruction set The functionality of the Thumb instruction set is a subset of the functionality of the 32 bit ARM instruction set The Thumb instruction set imposes some limitations on register access see Thumb instruction capabilities on page 5 9 does not allow conditional execution except for branch instructions see Conditional execution on page 5 17 does not allow access to the barrel shifter except as a separate instruction Refer to Thumb instruction set overview on page 5 8 for more information A processor that is executing Thumb instructions is said to be operating in Thumb state A Thumb capable processor that is executing ARM instructions is said to be operating in ARM state ARM processors always start in ARM state You must explicitly change to Thumb state using a BX Branch and exchange instruction set instruction 5 2 3 Address space All processors that implement version 3 or later of the ARM architecture have a 32 bit addressing range ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 3 Basic Assembly Language Programming 5 2 4 5 2 5 5 4 Processor mode Registers The ARM supports up to seven processor modes depending on the Architecture version These are User FIQ Fast Int
100. for interworking with the apcs interwork option In spite of the warning an interworking return veneer was inserted In SDT 2 50 the linker faults inter working calls to code that cannot return directly to the instruction set state of the caller and creates no executable image Impact Existing code that caused the interworking warning in SDT 2 1 1a is now faulted because the return veneers inserted by the SDT 2 1 1a linker can cause incorrect program behavior in obscure circumstances Deprecated PSR field specifications The assembler now warns about the use of the deprecated field specifiers CPSR CPSR_flg CPSR_ctl CPSR_all SPSR SPSR_flg SPSR_ctl and SPSR_all ORG no longer supported in the assembler The ORG directive is no longer supported in the assembler Its use conflicts with the scatter loading mechanism supported by the linker Impact Existing assembly language sources that use the ORG directive will no longer assemble The effect of the ORG directive can be obtained by using the scatter loading facility of the linker Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 2 ARM Project Manager This chapter describes the ARM Project Manager and contains the following sections About the ARM Project Manager on page 2 2 Getting started on page 2 4 The APM desktop on page 2 15 Additional APM functions on page 2 20 Setting preferences on page 2 31 Working with source fi
101. for more information Note If you are operating on a processor with separate instruction and data caches such as StrongARM or ARM94OT you must ensure that cache coherence problems do not prevent the new contents of the vectors from being used The data cache or at least the entries containing the modified vectors must be cleaned to ensure the new vector contents is written to main memory You must then flush the instruction cache to ensure that the new vector contents 1s read from main memory For details of cache clean and flush operations see the datasheet for your target processor Copyright 1997 1998 ARM Limited All rights reserved 9 13 Handling Processor Exceptions 9 4 SWI handlers When the SWI handler is entered it must establish which SWI is being called This information is usually stored in bits 0 23 of the instruction itself as shown in Figure 9 1 1 1 1 24 bit immediate comment field Figure 9 1 ARM SWI instruction The top level SWI handler typically accesses the link register and loads the SWI instruction from memory and therefore has to be written in assembly language The individual routines that implement each SWI handler can be written in C if required The handler must first load the SWI instruction that caused the exception into a register At this point Ir_SVC holds the address of the instruction that follows the SWI instruction so the SWI is loaded into the register in this case
102. gt r5 ASSERT rQ lt gt r4 ASSERT r0 lt gt r2 s Produce an error if the registers supplied are not all different These three only matter if Div is not null ratio MOV r2 r4 Put divisor in Temp CMP r2 r5 LSR 1 double it until 90 MOVLS r2 r2 LSL 1 So eZ S r5 CMP r2 r5 LSR 1 BLS b90 The b means search backwards MOV rO 0 Initialize quotient 91 CMP r5 r2 Can we subtract r2 SUBCS r5 r5 r2 If we can do so ADC ra r0 r0 Double r0 MOV r2 r2 LSR 1 Halve r2 CMP r2 r4 BHS b91 and loop until less than divisor ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 45 Basic Assembly Language Programming 5 9 5 9 1 consta constb X y string 5 46 MAP aii i i H Describing data structures with MAP and directives You can use the MAP and directives to describe data structures These directives are always used together Data structures defined using MAP and are easily maintainable can be used to describe multiple instances of the same structure make it easy to access data efficiently The MAP directive specifies the base address of the data structure See or MAP directive on page 5 35 of the ARM Software Development Toolkit Reference Guide The directive specifies the amount of memory required for a data item and can give the data item a label It is repeated for each data item in the structure See directive on pag
103. handler because the reset handler should execute your main code directly If the exception handler entry code uses the stack to store registers that must be preserved while it handles the exception it must return using a load multiple instruction with the qualifier For example if an exception handler stores all the work registers in use when the handler is invoked the link register modified to produce the same effect as the data processing instructions described below onto a full descending stack it can return in one instruction using LDMFD sp rQ r12 pc A The qualifier specifies that the CPSR is restored from the SPSR It must be used only from a privileged mode Refer to Implementing stacks with LDM and STM on page 5 36 for more general information on stack operations 9 2 3 The return address and return instruction The actual location pointed to by the program counter when an exception is taken depends on the exception type Because of the way in which the ARM processor fetches instructions when an exception is taken the program counter may or may not be updated to the next instruction to be fetched This means that the return address may not necessarily be the next instruction pointed to by the program counter ARM processors use a pipeline with at least a fetch a decode and an execute stage There is one instruction in each stage of the pipeline at any time The program counter points to the instruction cur
104. hardware platform operating system type and version a small stand alone sample of code that reproduces the problem a clear explanation of what you expected to happen and what actually happened the commands you used including any command line options sample output illustrating the problem the version string of the tool including the version number and date Copyright 1997 1998 ARM Limited All rights reserved xiii Preface XIV Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 1 Introduction ARM DUI 0040D This chapter introduces the ARM Software Development Toolkit version 2 50 and describes the changes that have been made since SDT version 2 1 1a It contains the following sections About the ARM Software Development Toolkit on page 1 2 Supported platforms on page 1 5 What is new on page 1 6 Copyright 1997 1998 ARM Limited All rights reserved 1 1 Introduction 1 1 About the ARM Software Development Toolkit The ARM Software Development Toolkit SDT consists of a suite of applications together with supporting documentation and examples that enable you to write and debug applications for the ARM family of RISC processors You can use the SDT to develop build and debug C C or ARM assembly language programs 1 1 1 Components of the SDT The ARM Software Development Toolkit consists of the following major components command line development tools
105. has changed a specified number of times stops when the variable is set to a specified value Note If you set a watchpoint on a local variable you lose the watchpoint as soon as you leave the function that uses the local variable Setting a simple watchpoint Follow these steps to set a simple watchpoint 1 Select the variable area of memory or register you want to watch 2 Set the watchpoint in any of the following ways select Toggle Watchpoint from the Execute menu select Toggle Watchpoint from the window specific menu click the Watchpoint button Select Watchpoints from the View menu to see all the watchpoints set in your executable image Removing a simple watchpoint Remove a simple watchpoint by using either of the following methods Method 1 1 Select Watchpoints from the View menu to display a list of watchpoints in the Watchpoint window 2 Select the watchpoint you want to remove 3 Remove the selected watchpoint in either of the following ways click the Toggle watchpoint button on the toolbar press the Delete key Copyright 1997 1998 ARM Limited All rights reserved 3 29 ARM Debuggers for Windows and UNIX Method 2 1 Position the cursor on a variable or register containing a watchpoint and right click 2 Select Toggle Watchpoint from the pop up menu Note If you set a watchpoint on a local variable you lose the watchpoint as soon as you leave the function that uses
106. highlighted in red in the Execution window 2 Click the Delete button in the dialog box that appears Method 2 1 Single click on a line containing a breakpoint highlighted in red in the Execution window 2 Right click on the line 3 Select Toggle breakpoint from the pop up menu that is displayed Method 3 1 Single click on a line containing a breakpoint highlighted in red in the Execution window 2 Click the Toggle breakpoint button in the toolbar or press the F9 key Method 4 1 Select Breakpoints from the View menu to display a list of breakpoints in the Breakpoint window 2 Select the breakpoint you want to remove 3 Click the Toggle breakpoint button or press the Delete key Method 5 1 Select Delete All Breakpoints from the Execute menu to delete all breakpoints that are set in the currently selected image Delete All Breakpoints is also available in relevant window menus Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 4 2 Simple watchpoints ARM DUI 0040D In its simplest form a watchpoint halts a program when a specified register or variable is changed The watchpoint halts the program at the next statement or machine instruction after the one that triggered the watchpoint There are two types of watchpoints a simple watchpoint that stops when a specified variable changes a complex watchpoint that stops when the variable
107. instruction set The inline assembler is a high level assembler Some low level features that are available to armasm such as branching by writing to pc are not supported Invoking the inline assembler The ARM C compilers support inline assembly language with the __asm specifier The ARM C compilers support the asm syntax proposed in the Draft C Standard with the restriction that the string literal must be a single string For example asm 1nstructionl instruction The asm syntax is supported by the C compilers when compiling both C and C The asm statement must be inside a C or C function Do not include comments in the string literal An asm statement can be used anywhere a C or C statement is expected In addition to the asm syntax ARM C supports the C compiler __asm syntax when used with both asm and __asm The inline assembler is invoked with the assembler specifier and is followed by a list of assembler instructions inside braces For example __asm instruction instruction Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Mixed Language Programming instruction If two instructions are on the same line you must separate them with a semicolon If an instruction is on multiple lines line continuation must be specified with the backslash character C or C comments may be used anywhere within an inline assembly language block String cop
108. loading and long distance branching ccceceeeeeeeeeeeeeeeeeeeeees 10 30 Converting ARM linker ELF output to binary ROM formats a000nnaan 10 32 Troubleshooting NIMS and tipS runnin a a 10 34 Benchmarking Performance Analysis and Profiling 11 1 About benchmarking and profiling cccccccseeeeeeceeeeeeeeceeseeeesseeeeesesaaees 11 2 11 2 Measuring code and data size 4 11 3 11 3 Performance benchmarking cccccsseeceecceeseeececeeeeeeeceuseeeceseueeeeesneeesesaaaes 11 6 11 4 Improving performance and code SIZE ccccceeeeecceeeeeeeeceeeeeeesaaeeeeesaaees 11 16 11 5 FOTIA cose ie Soe ieee a E Sec De 11 19 ARMulator 12 1 ADOUT THEA FIMIUIAION odr 12 2 12 2 AR Mulato Models rss scene immune nes 12 3 12 3 DES OS MR Steet attr nae ua tela ead a uviuewidue nea N 12 6 12 4 PONS reer EE a ete EAR N OEE Rte ener EE E EN E 12 12 12 5 WINdONS FHOUWJIAS O sacro mr een can a a aE 12 13 12 6 WateNpoINIS srini a a a nt 12 14 12 7 Fage table Manager SL EN aE 12 15 12 8 ALMA erns a a a ii 12 19 12 9 amaS e a E E ee cee ae 12 20 Teto ANAD een e a a 12 21 tat Dummy MMS sn ns a a ses nee 12 24 Copyright 1997 1998 ARM Limited All rights reserved V Contents vi Chapter 13 Appendix A 12 12 12 13 12 14 12 15 12 16 Angel 13 1 13 2 13 3 13 4 13 5 13 6 13 7 13 8 13 9 ANGE srra a 12 25 Controlling the ARMulator using the debugger ssssssssssnsssesrrrrrrrreerenn 12 27 Asample me
109. located at 0x0 during normal execution The changeover from the reset to the normal memory map is normally caused by writing to a memory mapped register Copyright 1997 1998 ARM Limited All rights reserved 10 3 Writing Code for ROM For example on reset an aliased copy of ROM is present at 0x0 but RAM is remapped to zero when code writes to the RPS REMAP register For more information refer to the ARM Reference Peripheral Specification Normal RESET Remapped D o rom O o rom OxOFOQ00000 gt OxOFOQ00000 gt ROM aliased to DRAM address 0x00000000 DRAM by system decoder 0x04000000 gt 0x04000000 gt 0x00000000 gt 0x00000000 gt Code writes to RPS REMAP register gt Figure 10 2 Example of a system with RAM at 0x0 Implementing RAM at 0x0 A sample sequence of events for implementing RAM at 0x0 is 1 Power on to fetch the RESET vector at 0x00000000 from the aliased copy of ROM 2 Execute the RESET vector LDR PC 0x0F000004 which jumps to the real address of the next ROM instruction 3 Write to the REMAP register Set REMAP 1 4 Complete the rest of the initialization code as described in Initializing the system on page 10 5 System decoder ROM can be aliased to address 0x00000000 by the system decoder case ADDR 31 24 is when 0x00 if REMAP 0 then select ROM else select SRAM when QxQF select ROM when 10 4 Copyrig
110. may be out of range of one or more LDR instructions in ARM state the offset from the pc to the constant must be less than 4KB in Thumb state the offset from the pc to the constant must be less than 1KB When an LDR Rd const pseudo instruction requires the constant to be placed in a literal pool the assembler Checks if the constant is available and addressable in any previous literal pools If so it addresses the existing constant Attempts to place the constant in the next literal pool if it is not already available Copyright 1997 1998 ARM Limited All rights reserved 5 25 Basic Assembly Language Programming If the next literal pool is out of range the assembler generates an error message In this case you must use the LTORG directive to place an additional literal pool in the code Place the LTORG directive after the failed LDR pseudo instruction and within 4KB ARM or 1KB Thumb Refer to Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide for a detailed description of the LTORG directive You must place literal pools where the processor does not attempt to execute them as instructions Place them after unconditional branch instructions or after the return instruction at the end of a subroutine Example 5 5 shows how this works in practice It is supplied as loadcon s in the examples asm subdirectory of the toolkit The instructions listed as comments are the ARM instructions that are
111. may obtain slightly different figures depending on the version of the compiler linker or library in use and the processor for which the ARMulator is configured 11 3 3 Real time simulation The ARMulator also provides facilities for real time simulation To carry out such a simulation you must specify the type and speed of the memory attached to the processor the speed of the processor Refer to Map files on page 11 9 for more information and examples While it is executing your program the ARMulator counts the total number of clock ticks taken This allows you to determine how long your application would take to execute on real hardware Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Benchmarking Performance Analysis and Profiling 11 3 4 Reading the simulated time 11 3 5 Map files ARM DUI 0040D When it performs a simulation the ARMulator keeps track of the total time elapsed This value may be read either by the simulated program or by the debugger Reading the simulated time from assembler To read the simulated clock from an assembly language program use the Angel SYS_CLOCK SWI Reading the simulated time from C From C use the standard C library function clock This function returns the number of elapsed centiseconds Reading the simulated time from the debugger The internal variable clock contains the number of microseconds since simulation started To display this value
112. not specified with the processor option will generate code that uses halfword loads and stores LDRH STRH where appropriate whereas such instructions would not previously have been generated Specifying arch 3 on the command line prevents the compilers from generating halfword loads and stores RDI 1 0 and RDI 1 5 support A new variant of the Remote Debug Interface RDI 1 5 is introduced in SDT 2 50 The version used in SDT 2 11a was 1 0 The debugger has been modified so that it will function with either RDI 1 0 or RDI 1 5 client DLLs Impact Third party DLLs written using RDI 1 0 will continue to work with the versions of ADW and armsd shipped with SDT 2 50 Register names permitted by the assembler In SDT 2 50 the assembler pre declares all PCS register names but also allows them to be declared explicitly through an RN directive In SDT 2 1 1a the procedure call standard PCS register names that the assembler would pre declare were restricted by the variant of the PCS chosen by the apcs option For example apcs noswst would disallow use of sl as a register name Impact Any source files that declared PCS register names explicitly will continue to assemble without fault despite the change to the default PCS Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Introduction 1 3 3 Obsolete and deprecated features ARM DUI 0040D The features listed below are either obsolete or deprecated Ob
113. number of bytes to be written from the buffer to the file Return On exit rO contains 0 if the call is successful the number of byte that are not written if there is an error Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 7 SYS READ 0x06 Read the contents of a file into a buffer The file position is specified either explicitly by a SYS_SEEK implicitly as one byte beyond the previous SYS_READ or SYS_WRITE request The file position is at the start of the file when the file is opened and is lost when the file is closed The file operation should be performed as a single action whenever possible That is a write of 16KB should not be split into four 4KB chunks unless there is no alternative Entry On entry rl contains a pointer to a four word data block word 1 contains a handle for a file previously opened with SYS_OPEN word 2 points to a buffer word 3 contains the number of bytes to read to the buffer from the file word 4 is an integer that specifies the file mode Table 13 4 on page 13 82 gives the valid values for the integer and their corresponding ANSI C fopen modes Return On exit rO contains 0 if the call is successful the number of bytes not read if there is an error If the handle is for an interactive device that is SYS_ISTTY returns 1 for this handle a non zero return from SYS_READ indicates that the line read did not fill the buffe
114. of pc 4 in Ir_ABT points to the second instruction beyond the address where the exception was generated When the MMU has loaded the appropriate address into physical memory the handler should return to the original aborted instruction so that a second attempt can be made to execute it The return address is therefore two words eight bytes less than that in Ir_ABT making the return instruction SUBS pc Ir 8 The handler entry and exit code to stack the return address and pop it on return is SUB Ir Ir 8 STMFD sp reglist Ir LDMFD sp reglist pc A Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 3 Installing an exception handler Any new exception handler must be installed in the vector table When installation is complete the new handler executes whenever the corresponding exception occurs Exception handlers can be installed in two ways Branch instruction This is the simplest method of reaching the exception handler Each entry in the vector table contains a branch to the required handler routine However this method does have a limitation Because the branch instruction only has a range of 32MB relative to the pc with some memory organizations the branch may be unable to reach the handler Load pc instruction With this method the program counter is forced directly to the handler address by 1 storing the absolute address of the handler in a
115. of files such as a program image or an object library ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 13 ARM Project Manager 2 14 The output is determined by one or more of the build step patterns in the project template A different version of the project output is created for each variant built For example output can be built for a debug and release version a debug version and a release version Using the project output When your project has been successfully built you can either execute or debug it to see how it works Use the ARM Debugger for Windows see ARM Debuggers for Windows and UNIX on page 3 1 for more information Executing an image Click the Execute button or select Execute project apj from the Project menu to load the image in to the ARM Debugger for Windows and commence execution If you execute the hello apj project Hello World appears in the Console Window Select Exit from the File menu when you have finished executing the image Debugging an image When you click the Debug button or select Debug project apj from the Project menu again the image is loaded into the ARM Debugger for Windows but the debugger is halted at the start of the program You can then debug the image as necessary using the features of the Debugger Note Whether you Execute or Debug your image if the project output is older than its source it is rebuilt before it is sent to the Debugger
116. or definitions Copyright 1997 1998 ARM Limited All rights reserved 13 59 Angel 13 60 To include your own C variables in the list contained in makelo c add lines in the format fprintf outfile Variable_Name t tEQU t d n Variable_Name for each variable or definition banner h This header file contains macros that define the text that is displayed when the host and target connect after initialization You can modify this file to suit your target and the build options you use Different ports can share components of this message by including the file configmacros h You should take care not to advertise a feature in the banner message that will not work correctly The banner message is limited to 204 characters devices c This file defines the base address in memory for each available device It enables C pointers to access the operational registers in each device It is helpful to use a structure or define offsets describing the peripheral register layout symbolically Symbolic definitions of bit fields can also be useful You must also define the interrupt handlers as the handler routine plus an optional parameter The parameter is used for handlers that service more than one source In the case of the PID the same handler is responsible for the two serial ports and the parallel port Serial drivers must conform to the generic function calls defined in devdriv h This ensures that generic calls from the deb
117. part of your program Use the Function Names window to display a selected function as source code set edit or remove a breakpoint on a function Locals Globals window The Locals window Figure 3 6 displays a list of variables currently in scope The Globals window displays a list of global variables The variable name is displayed in the left hand pane the value is displayed in the right hand pane Locals Figure 3 6 Locals window Use the Locals Globals window to change the content of a variable double click on it display the section of memory pointed to by a variable change the format of the values displayed by line or for the entire window if the format of a line is changed it is no longer affected by changing the format of the window set edit or remove a watchpoint on a variable double click on an item to expand a structure the details are displayed in another variable window As you step through the program the variable values are updated Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX For more information on displaying variable information see Working with variables on page 3 37 Low Level Symbols window The Low Level Symbols window displays a list of all the low level symbols in your program Use the Low Level Symbols window to display the memory pointed to by the selected symbol d
118. possible to access the entire data area with a single LDR pseudo instruction Example 5 24 shows how to do this Both speed and code size are improved Example 5 24 AREA data DATA StartOfData EQU 0x1000 EndOfData EQU 0x2000 DataAreaBase RN r11 MAP 0 DataAreaBase StartOfUsedData Q Integer 4 String MaxStrLen Array ArrayLen 8 BitMask 4 EndOfUsedData Q UsedDataLen EQU EndOfUsedData StartOfUsedData ASSERT UsedDataLen lt EndOfData StartOfData AREA code CODE LDR DataAreaBase StartOfData MOV rQ 1 STR rQ Integer MOV rQ 0 STRB rQ String MOV rQ 0xA000000A STRB rQ BitMask Note The MAP directive is MAP DataAreaBase not MAP StartOfData DataAreaBase The MAP and directives give the position of the data relative to the DataAreaBase register not the absolute position The LDR DataAreaBase StartOfData statement provides the absolute position of the entire data area Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Basic Assembly Language Programming If you use the same technique for an area of memory containing memory mapped I O or whose absolute addresses must not change for other reasons you must take care to keep the code maintainable One method is to add comments to the code warning maintainers to take care when modifying the definitions A better method is to use definitions of the absolute addresses to control the register based defini
119. program Subsequent instructions are Thumb r pointer to source block rl pointer to destination block r2 number of words to copy Number of four word multiples Less than four words to move Save some working registers Load 4 words from the source and put them at the destination Decrement the counter copy more Don t need these now restore originals Bottom two bits represent number of odd words left to copy No words left to copy load a word from the source and store it to the destination Decrement the counter copy more ange 1_SWIreason_ReportException ADP_Stopped_ApplicationExit Angel semihosting Thumb SWI 6 7 8 1 2 3 4 0 0 0 0 0 0 0 ARM DUI 0040D Basic Assembly Language Programming 5 8 Using macros A macro definition is a block of code enclosed between MACRO and MEND directives It defines a name that can be used instead of repeating the whole block of code This has two main uses to make it easier to follow the logic of the source code by replacing a block of code with a single meaningful name to avoid repeating a block of code several times See MACRO directive on page 5 72 of the ARM Software Development Toolkit Reference Guide for more details 5 8 1 Test and branch macro example ARM DUI 0040D A test and branch operation requires two ARM instructions to implement You can define a macro definition such as this MACRO label TestAndBranch dest reg cc label CMP
120. qualifed pathname to a log file When you have started the license server you can type cat log1le_name to see the output from the license server Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager A 5 Running your licensed software Before you run your licensed software for the first time you must set the environment variable ARMLMD_LICENSE_FILE to an appropriate value A 5 1 Setting the environment variable ARMLMD_LICENSE_FILE ARM DUI 0040D The required value depends on your circumstances as follows You have only one license server option 1 Assuming your license server is called enterprise goto the machine where the ARM Debugger is installed and type setenv ARMLMD_LICENSE_FILE enterprise You have only one license server option 2 Assuming your license file is called arm debugger 1lic and is in the directory home licenses type setenv ARMLMD_LICENSE_FILE home licenses You have only one license server and specified a TCP port option 1 Assuming your license server is called enterprise and you have specified TCP port 7117 in your license file goto the machine where your licensed software is installed and type setenv ARMLMD_LICENSE_FILE 7117 enterprise You have only one license server and specified a TCP port option 2 Assuming your license file is called mylicense txt and is in the directory ocal home license type setenv ARMLMD_LICENSE_FILE loca
121. rQ 0x18 0010 0x00008010 Oxe59F1000 qdr r1 0x00008018 0x00020026 0014 0x00008014 Oxef0000ab swi Qxab 0018 Ox00008018 Ox00020026 amp dcd Ox00020026 amp ThumbProg 0000 Ox0000801c Ox2102 MOV r1 2 0002 Ox0000801e 0x4770 pG bx r14 0004 0x00008020 Oxe59Fc00Q Idr r12 0x00008028 ThumbProg 0x1 0008 Ox00008024 Oxel2fffic bx r12 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb 000c Ox00008028 Ox0000801d andeq r8 r0 r13 1s1 rQ _edata 0000 Ox0000802c Oxe800e800 stmda r r11 r13 pc Figure 7 5 Example veneer You can see that the linker has added the required ARM to Thumb interworking veneer This is contained in locations 0x8020 to 0x8028 Location 0x8028 contains the address of the routine being branch exchanged to with bit O set Note The addresses may vary depending on the version of the toolkit you are using 7 4 2 C C and assembly language interworking using veneers ARM DUI 0040D C and C code compiled to run in one state can call assembly language code designed to run in the other state and vice versa To do this write the caller routine as any non interworking routine and if calling from assembly language use a BL instruction to make the call Then if the callee routine is in C compile it using apcs interwork if the callee routine is in assembly language set the INTERW
122. reg 0 B cc dest MEND The line after the MACRO directive is the macro prototype statement The macro prototype statement defines the name TestAndBranch you use to invoke the macro It also defines parameters label dest reg and cc You must give values to the parameters when you invoke the macro The assembler substitutes the values you give into the code This is an example of how this macro can be invoked test TestAndBranch NonZero rQ NE NonZero After substitution this becomes test CMP rO 0 BNE NonZero NonZero Copyright 1997 1998 ARM Limited All rights reserved 5 43 Basic Assembly Language Programming 5 8 2 Lab Lab 90 91 5 44 Unsigned integer division macro example Example 5 13 shows a macro that performs an unsigned integer division It takes four parameters Bot is the register that holds the divisor Top is the register that holds the dividend before the instructions are executed After the instructions are executed it holds the remainder Div is the register where the quotient of the division is placed It may be NULL if only the remainder is required Temp is a temporary register used during the calculation MACRO DivMod Div Top Bot Temp ASSERT Top lt gt Bot ASSERT Top lt gt Temp ASSERT Bot lt gt Temp IF Div lt gt ASSERT Div lt gt Top ASSERT Div lt gt Bot ASSERT Div lt gt Temp ENDIF MO
123. reserved ARM DUI 0040D Angel Heartbeat mechanism Heartbeats must be enabled for reliable packet transmission to work Heartbeats work only with the Software Development Toolkit version 2 1 1a Angel 1 04 EmbeddedICE 2 07 and later The remote_a heartbeat software writes packets using at least the heartbeat rate and uses heartbeat packets to ensure this It expects to see packets back using at least the packet timeout rate and signals a timeout error if this is violated 13 6 4 Device driver layer ARM DUI 0040D Angel supports polled and asynchronous interrupt driven devices and devices that start in an asynchronous mode and finish by polling the rest of a packet At the boundary of the device driver layer the interface offers asynchronous by callback read and write interfaces to Angel and a synchronous interface to the application Refer to Writing the device drivers on page 13 63 for more information on device drivers Support for callback across all devices This is primarily a channels layer issue but because the BOOT channel must listen on all Angel compatible devices the channels layer must determine how many devices to listen to for boot messages and which devices those are To provide this statically the devices layer exports the appropriate device table or tables together with the size of the tables Transmit queueing Because the core operating mode is asynchronous and more than one thread can use a device
124. s c ARM25 C1 objmacs s Copy these files to your working Angel source directory This step is optional You can rename the appropriate source and build directories for your own port For example you can rename working_directory Angel Sources pid and working_directory Angel Sources pid b as appropriate for your board You may need to do this if you have more than one project based on the PID port If you rename the pid and pid b directories you must make additional changes to the project so that it will find the appropriate source files Refer to Editing the APM project directory structure on page 13 52 for detailed instructions Copyright 1997 1998 ARM Limited All rights reserved 13 51 Angel If you have not renamed the directories you can perform a trial build Editing the APM project directory structure If you renamed the pid and pid b directories when you copied the Angel directory you must ensure that the new directory paths are used to compile assemble and link your sources Follow these steps to configure the project template 1 Open the APM project file for your project 2 Select Edit Project Template from the Project menu The Project Template Editor dialog is displayed Figure 13 7 Project Template Editor Select Build Step Pattern Figure 13 7 Project template editor 3 Select Assemble from the list of build step patterns and click on the Edit button The Edit Build Step Pattern dialo
125. same signed gt LE Z set N and V differ signed lt Examples ADD r rl r2 FO rl r2 don t update flags ADDS r rl r2 ADDEQS r0 rl r2 CMP r rl rO rl r2 and update flags If Z flag set then rQ rl r2 and update flags update flags based on rQ r1 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 43 Using conditional execution in ARM state ARM DUI 0040D You can use conditional execution of ARM instructions to reduce the number of branch instructions in your code Branch instructions are expensive in both code density and processor cycles Typically it takes three processor cycles to refill the processor pipeline each time a branch is taken The cost is less on ARM processors that have branch prediction hardware Example 5 4 Euclid s Greatest Common Divisor The following example uses two implementations of Euclid s Greatest Common Divisor algorithm to demonstrate how you can use conditional execution to improve code density and execution speed In pseudo code the algorithm can be expressed as function gcd integer a integer b result is integer while a lt gt b do if a gt b then a a b else b b a endif endwhi le result a You can implement the gcd function with conditional execution of branches only in the following way gcd CMP r rl BEQ end BLT less SUB r r0 rl B gcd less SUB rl rl r
126. source level debugging because the compiler automatically adds information to an AIF file to allow stack backtrace debugging 11 2 2 Calculating ROM and RAM requirements Calculate the ROM and RAM requirements for your system as follows ROM Code size inline data inline strings const data RW data RAM RW Data Q init data In addition you must allow some RAM for stacks and heaps In more complex systems you may require part or all of the code segment to be downloaded from ROM into RAM at runtime This increases the system RAM requirements but could be necessary if for example RAM access times are faster than ROM access times and the execution speed of the system is critical 11 2 3 Code and data sizes example Dhrystone The Dhrystone application is located in the examples subdirectory of the ARM Software Development Toolkit Copy the files into your working directory 11 4 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Benchmarking Performance Analysis and Profiling Using command line tools Compile the Dhrystone files without linking armcc c DMSC_CLOCK dhry_1 c dhry_2 c The compiler produces a number of warnings that you can either ignore or suppress using the w option The warnings are generated because the Dhrystone application is coded in Kernighan and Ritchie style C rather than ANSI C Perform the link with the info totals option to give a report on the total cod
127. source of the interrupt for the Tx case it passes bytes from the internal Tx buffer to the Serial Tx FIFO as long as there is space in the FIFO for the Rx case it passes the byte received at the Rx FIFO into the internal Rx buffer ready for Angel to unpack the message when the transfer is complete for the parallel case the parallel port is polled to pass the received data into the memory location requested Refer to Example of Angel processing a simple IRQ on page 13 40 for more information on how Angel handles interrupts Refer to Angel task management on page 13 33 for information on how Angel serializes communications tasks Note Other system drivers Ethernet DCC might not need the full operation functions described above They might need only a pure Rx Tx control Polled devices The registered read and write poll functions are called by the Angel_DeviceYield function Angel ensures this function is called whenever communication with the host is required On each call the device poll handler ensures that the device is serviced For a full Angel system a hardware timer must be available for polled devices to work because the timer interrupt is used to gain control of the processor and call Angel_DeviceYield This call must be inserted at the end of the timer interrupt handler for the port because the timer itself is part of the port For example See if it is time to call Angel_Yield yet if cal
128. specify the location of the files A search path points to a directory or set of directories that are used to locate files whose location is not referenced absolutely If you use the ARM command line tools to build your project you may need to edit the search paths for your image manually depending on the options you chose when you built it If you move the source files after building an image use the Search Paths window to change the search paths set up in the ARM Debugger see Search paths Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX To display source file search paths select Search Paths from the View menu The current search paths are displayed in the Search Paths window Follow these steps to add a source file search path 1 Select Add a Search Path from the Options menu The Browse for Folder dialog is displayed 2 Browse for the directory you want to add and highlight it 3 Click OK Follow these steps to delete a source file search path 1 Select Search Paths from the View menu The Search Paths window is displayed 2 Select the path to delete 3 Press the Delete key Listing source files Follow these steps to examine the source files of the current program 1 Display the list of source files by selecting Source Files from the View menu The Source Files List window is displayed 2 Select a source file to examine by double clicking on its name
129. step for the selected file type the menu item and the button are disabled For example if you have several source files in your hello project and select hello c from the Release variant the item on the Project menu would read Compile hello c Release Note Compile is a term specified withinthetemplate Any build type tool can be used to build an output file from a source file See Adding a build step pattern on page 2 51 for more information on assigning tools to a template Follow these steps to perform a build step on a single source file 1 Select hello c from the Project Window 2 Click the Perform Build Step button the tool tip reflects which build step is executed or select Compile hello c Release from the Project menu 3 The actions associated with the Compile build step are executed and the results are displayed in the build log pane Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 7 Viewing object and executable files You can view the contents of a binary file object library or image using one of the ARM decoders decaof decaxf or armlib For example to display the contents of hello o 1 Select hello o from the Project View 2 Select Contents hello o from the View menu The appropriate Viewing dialog for the translator is displayed Figure 2 18 Yiewing hello o x decaot Command Line Options i corce Figure 2 18 Viewing dia
130. symbol _printf in thumb o C code Error Unsupported call from Thumb code to ARM symbol arm_function in thumb o C code Error Unsupported call from Thumb code to ARM symbol _printf in thumb o C code Figure 7 4 Interworking errors These types of errors indicate that an ARM to Thumb or Thumb to ARM interworking call has been detected from the object module object to the routine symbol but the called routine has not been compiled for interworking You must recompile the module that contains the symbol and specify apcs interwork 7 16 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb 7 3 5 Using two copies of the same function You may wish to include two functions with the same name one compiled for ARM and the other for Thumb Duplicate definitions can be useful for example if you have a speed critical routine in a system with 16 bit and 32 bit memory where the overhead of the interworking veneer would degrade the performance too much The linker allows duplicate definitions provided that each definition is of a different type That is one definition defines a Thumb routine and the other defines an ARM routine The linker generates a warning message if there is a duplicate definition of a symbol Both ARM amp Thumb versions of symbol present in image This is a warning to advise you in case you accidentally include two copies of the same routine If that is what you i
131. the LM_LICENSE_FILE environment variable Now start Imgrd using the new license file Remember that you must use the latest version of Imgrd that is used by any of the products You can use the command Imgrd v or Imver Imgrd to find out the version of each Imgrd If the version of Imgrd is earlier than any of the vendor daemons you see error reports such as Vendor daemon cannot talk to Imgrd invalid data returned from license server Leave a symbolic link to the new license file in all the locations which held the original license files Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager A 8 2 All products use different license servers ARM DUI 0040D If all the products use different hosts to run the license managers then you must keep separate license files for each product Set the LM_LICENSE_FILE environment variable to point to the locations of all the license files for example setenv LM_LICENSE_FILE Jicense_filel license_file2 license_filen Note FlexLM version 6 0 allows each software vendor to have an individual environment variable for finding the license file for their products The environment variable name is xxX_LICENSE_FILE where xxx is the name of the vendor license daemon In the case of software from ARM Limited the vendor daemon is called ARMLMD therefore the environment variable for ARM software is ARMLMD_LICENSE_FILE FlexLM version 6 0 vendor daemons a
132. the Toggle breakpoint button on the toolbar Click the Go button to begin execution When prompted request at least two runs through Dhrystone When the breakpoint set at main is reached click Go again to begin execution of the main application When the breakpoint at Proc_5 is reached choose Debugger Internals from the View menu Double click on the statistics_inc field to display the detail for this variable Copyright 1997 1998 ARM Limited All rights reserved 11 7 Benchmarking Performance Analysis and Profiling 12 Click the Go button When the breakpoint at Proc_5 is reached again the contents of the statistics_inc_w field is updated to reflect the number of instructions and cycles consumed by one iteration of the loop Results The results are shown in the following table Table 11 2 Cycle counting results Instructions S cycles N cycles I cycles C cycles F cycles 358 427 188 64 0 0 S cycles Sequential cycles The CPU requests transfer to or from the same address or from an address that is a word or halfword after the preceding address N cycles Non sequential cycles The CPU requests transfer to or from an address that is unrelated to the address used in the preceding cycle I cycles Internal cycles The CPU does not require a transfer because it is performing an internal function or running from cache C cycles Coprocessor cycles F cycles Fast clock cycles for cached processors FCLK Note You
133. the debugger The default value is RUSPDAi fE An uppercase letter indicates an exception is intercepted normal interrupt request IRQ fast interrupt request FIQ R reset U undefined instruction S SWI P prefetch abort D data abort A address I F E unused Disassembly window The Disassembly window displays disassembled code interpreted from a specified area of memory Memory addresses are listed in the left hand pane and disassembled code is displayed in the right hand pane You can view ARM code Thumb code or both Use the Disassembly window to go to another area of memory change the disassembly mode to ARM Thumb or Mixed set edit or remove breakpoints Note More than one Disassembly window can be active at a time For details of displaying disassembled code see Displaying disassembled and interleaved code on page 3 40 Expression window The Expression window displays the values of selected variables and or registers Use the Expression window to change the format of selected items or all items Copyright 1997 1998 ARM Limited All rights reserved 3 21 ARM Debuggers for Windows and UNIX 3 22 edit or delete expressions display the section of memory pointed to by the contents of a variable For more information on displaying variable information see Working with variables on page 3 37 Function Names window The Function Names window lists the functions that are
134. the same as VirtualBase if it is unset This address should be aligned to a 1MB boundary on an MMU processor Size specifies the size of this region for an MMU This value is rounded down to the nearest megabyte on an MMU processor Cacheable controls the C bit in the translation table entry Bufferable controls the B bit in the translation table entry Updateable controls the U bit in the translation table entry Note that the U bit is only used for the ARM610 processor Domain specifies the domain field of the table entry AccessPermissions controls the AP field Translate controls whether accesses to this region causes translation faults Setting Translate No for a region causes an abort to occur whenever ARMulator reads from or writes to that region Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARMulator Pagetable model and protection units Core models such as the ARM740T and the ARM940T do not have an MMU and pagetables Instead they have a Protection Unit and protection regions If you use the PageTable model on a core that has a Protection Unit PU instead of initializing the MMU and setting up pagetables the PU is initialized With the above example the default set up initializes the first region that has the lowest priority such that the entire memory space 0 to 4GB is marked as read write cacheable and bufferable For the 740T the Protection Unit would be initializ
135. to the PCB of the next process to run is pointed to by r12 and the end of the list has a zero pointer Register r13 1s a pointer to the PCB and is preserved between time slices so that on entry it points to the PCB of the currently running process Example 9 17 STMIA r13 r0 r14 A Dump user registers above r13 MSR r SPSR Pick up the user status STMDB r13 r0 Ir and dump with return address below LDR r13 r12 4 Load next process info pointer CMP r13 0 gt If it is zero it is invalid LDMNEDB r13 rQ Ir gt Pick up status and return address MRSNE SPSR_csxf rQ Restore the status LDMNEIA r13 r0 r14 A Get the rest of the registers SUBNES pc r14 and return and restore CPSR Insert no next process code here ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 31 Handling Processor Exceptions 9 6 Reset handlers The operations carried out by the Reset handler depend on the system for which the software is being developed For example it may Set up exception vectors Refer to Installing an exception handler on page 9 9 for details Initialize stacks and registers Initialize the memory system if using an MMU Initialize any critical I O devices Enable interrupts Change processor mode and or state Initialize variables required by C Call the main application Refer to Chapter 10 Writing Code for ROM for more information 9
136. toolkit Because the Thumb LDM and STM instructions can access only the low registers the number of words copied per iteration is reduced from eight to four In addition the LDM STM instructions can be used to carry out the single word at a time copy because they update the base pointer after each access If LDR STR were used for this separate ADD instructions would be required to update each base pointer Copyright 1997 1998 ARM Limited All rights reserved 5 41 Basic Assembly Language Programming AREA EQU ENTRY header MOV ADR BX num CODE16 Start LDR LDR MOV blockcopy LSR BEQ PUSH quadcopy LDMIA STMIA SUB BNE POP copywords MOV AND BEQ wordcopy LDMIA STMIA SUB BNE MOV LDR SWI AREA DCD DCD END stop src dst 5 42 Tblock CODE READONLY 20 0x400 start 1 Sp rQ rQ rQ ri F2 src dst num r3 r2 2 copywords r4 r7 rQ r4 r7 rl r4 r7 r3 1 quadcopy r4 r7 r3 3 r2 r3 stop rQ r3 rl r3 r2 1 wordcopy rO 0x18 rl 0x20026 QxAB BlockData DATA READWRITE 1 2 3 4 5 6 7 0 1 2 3 5 0 0 0 0 0 0 0 0 0 0 0 0 0 Copyright 1997 1998 ARM Limited All rights reserved Example 5 12 Name this block of code Set number of words to be copied Mark first instruction to execute The first instruction to call Set up stack pointer r13 Processor starts in ARM state so small ARM code header used to call Thumb main
137. top 8 bits of halfword LDRH clears top 16 bits of word T_bit clear so load word ARM and clear top 8 bits of word Load address of the jump table Jump to the appropriate routine Restore the registers and return Copyright 1997 1998 ARM Limited All rights reserved 9 43 Handling Processor Exceptions 9 12 System mode Note This section only applies to processors that implement ARM Architectures 4 4T and later The ARM Architecture defines a User mode that has 15 general purpose registers a pc and a CPSR In addition to this mode there are five privileged processor modes each of which have an SPSR and a number of registers that replace some of the 15 User mode general purpose registers When a processor exception occurs the current program counter is copied into the link register for the exception mode and the CPSR is copied into the SPSR for the exception mode The CPSR is then altered in an exception dependent way and the program counter is set to an exception defined address to start the exception handler The ARM subroutine call instruction BL copies the return address into r14 before changing the program counter so the subroutine return instruction moves r14 to pc MOV pc Ir Together these actions imply that ARM modes that handle exceptions must ensure that they do not cause the same type of exceptions if they call subroutines because the subroutine return address will be overwritten with the excepti
138. typically at a breakpoint or watchpoint backtrace information is displayed in the Backtrace window to give you information about the procedures that are currently active The following example shows the backtrace information for a program compiled with debug information and linked with the C library DHRY_2 Proc_6 line 42 DHRY_1 Proc_1 line 315 DHRY_1 main line 170 PC Qx0000eb38 _main Ox5eQ PC Qx0Q00ae60 __entry 0x34 This backtrace provides you with the following information Lines 1 3 The first line indicates the function that is currently executing The second line indicates the source code line from which this function was called and the third line indicates the call to the second function Lines 4 5 Line 4 shows the position of the call to the C library in the main procedure of your program and the final line shows the entry point in your program made by the call to the C library Note A simple assembly language program assembled without debug information and not linked to a C library would show only the pc values ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 33 ARM Debuggers for Windows and UNIX 3 4 6 3 34 Stepping through an image To follow the execution of a program more closely than breakpoints or watchpoints allow you can step through the code in the following ways Step to the next line of code Step to the the next line of code in either of the following ways
139. updated Exit by restoring the pc to the interrupted address b If Angel is not active process as normal exiting by way of the scheduler if required Using Supervisor mode If you want your application to execute in Supervisor mode at any time you must set up your own Supervisor stack If you call an Angel SWI while in Supervisor mode Angel uses four words of your Supervisor stack when entering the SWI After entering the SWI Angel uses its own Supervisor stack not yours This means that if you set up your own Supervisor mode stack and call an Angel SWI the Supervisor stack pointer register sp_SVC must point to four words of a full descending stack in order to provide sufficient stack space for Angel to enter the SWI Chaining exception handlers Angel provides exception handlers for the Undefined SWI IRQ FIQ Data Abort and Prefetch Abort exceptions If you are working with exceptions you must ensure that any exception handler that you add is chained correctly with the Angel exception handlers Refer to Chapter 9 Handling Processor Exceptions for more information If you are chaining an interrupt handler and you know that the next handler in the chain is the Angel interrupt handler you can use the Angel interrupt table rather than the processor vector table You do not have to modify the processor vector table The Angel interrupt table is easier to manipulate because it contains the 32 bit address of the handler The processor
140. use the command Print clock if you are using armsd or select Debugger Internals from the View menu if you are using ADW or ADU Note The clock internal variable is unavailable if the processor clock frequency is set to 0 00 You must specify a processor clock frequency for ARMulator if you wish to read the clock variable Select Options Configure Debugger Target ARMulate Configure and use the ARMulator Configuration dialog The type and speed of memory in a simulated system is detailed in a map file This defines the number of regions of attached memory and for each region the address range to which that region is mapped the data bus width in bytes the access time for the memory region armsd expects the map file to be in the current working directory under the name armsd map Copyright 1997 1998 ARM Limited All rights reserved 11 9 Benchmarking Performance Analysis and Profiling ADW or ADU accept a map file of any name provided that it has the extension map See Real time simulation example Dhrystone on page 11 13 for details of how to associate a map file into an ADW or ADU session To calculate the number of wait states for each possible type of memory access the ARMulator uses the values supplied in the map file and the clock frequency See ARMulator configuration on page 3 57 for details of how the wait states are calculated Format of a map file The format of each li
141. will be faulted Demon debug monitor and libraries This feature is obsolete The Demon Debug monitor is now obsolete and support for it has been removed from the SDT There is no longer a remote_d d11 selectable as a remote debug connection in ADW and Demon C libraries are not supplied with SDT 2 50 Angel as a linkable library and ADP over JTAG This feature is obsolete Full Angel is no longer available as a library to be linked with a client application The version of Angel that runs on an EmbeddedICE and acts as an ADP debug monitor adpjtag rom is also no longer available Copyright 1997 1998 ARM Limited All rights reserved 1 17 Introduction ROOT ROOT DATA and OVERLAY keywords in scatter load description In the SDT 2 11 manuals use of the ROOT ROOT DATA and OVERLAY keywords in a scatter load description file was documented and a later Application Note warned against its use The linker now warns against use of these keywords Impact Any existing scatter load descriptions that use ROOT ROOT DATA or OVERLAY keywords will now generate a warning but the behavior will be as expected Future release In a future release of the linker use of ROOT ROOT DATA and OVERLAY will be faulted Automatically inserted ARM Thumb interworking veneers In SDT 2 1 1a the linker warned of calls made from ARM code to Thumb code or from Thumb code to ARM code interworking calls when the destination of the call was not compiled
142. you are using APM and have purchased the Angel Ethernet Kit separate project files are supplied to enable you to build Angel ROM Images with or without the Ethernet drivers Endianness is defined by the selected endianness of the APM environment Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel Copying the APM project When you have selected the Angel port that you want to base your own port on you must copy the required directories and files The following instructions assume that you are basing your port on the Angel PID port Follow these steps to copy the Angel template l Copy the entire Angel directory and all subdirectories to your working directory It is recommended that you do not work in the installation Angel directory by default c ARM250 Ange1 because this may cause problems if you reinstall the Software Development Toolkit In your working copy of the Angel directory select Edit variables for AngelPid apj from the Project menu The Edit Variable dialog is displayed Figure 13 6 Edit Yarables for AngelPid api Ed Projecth ame D epthO fo oth IB elowProyecth oot Projecth ame Value YouPod Figure 13 6 Edit variables Change the ProjectName variable to the name of your port The value given here is used by APM to name the build output binaries Angel requires two files from the SDT installation C library directory c ARM250 Cl h_la_obj
143. your development platform you build a stand alone application that runs next to Angel on your target hardware You must use one of the methods described in Downloading new application versions on page 13 27 to download the application to your development board At this stage you are highly reliant on Angel to debug your application In addition you must make design decisions about the final form of your application In particular you should decide whether the final application is stand alone or uses minimal Angel to provide initialization code interrupt handlers and device drivers If you are porting Angel to your own hardware you must also consider how you will debug your Angel port Refer to Debugging your Angel port on page 13 68 for more information If you are developing simple embedded applications you might want to move straight to building your application on a development board Stage 3 Building applications on a development board with little dependence on Angel As you proceed with your development project and your code becomes more stable you will rely less on Angel for debugging and support For example you might want to use your own initialization code and you might not require C library semihosting support You can switch off semihosting without building a special cut down version of Angel by setting the semihosting_enabled variable in the ARM debuggers In armsd semihosting_enabled 0 In ADW or ADU select De
144. your own C header files To include your own C header files you must wrap the include directive in an extern C statement You can do this in two ways When the file is included This is shown in Example 8 7 By adding the extern C statement to the header file This is shown in Example 8 8 Example 8 7 G code extern C include my headerl h include my header2 h i int main ae return Q Example 8 8 C header file ifdef __cplusplus Insert start of extern C construct extern C endif x Body of header file ifdef __cplusplus Insert end of extern C construct The C header file can now be endif included in either C or C code Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Mixed Language Programming 8 4 Calling between C C and ARM assembly language This section provides examples that may help you to call C and assembly language code from C and to call C code from C and assembly language It also describes calling conventions and data types You can mix calls between C and C and assembly language routines provided you follow the appropriate procedure call standard For more information on the APCS and TPCS see Chapter 6 Using the Procedure Call Standards Note The information in this section is implementation dependent and may change in future toolkit releases 8 4 1 General rules for calling bet
145. 0 0x18 LDR rl 0x20026 SWI Qx123456 LTORG func ADR rQ Start ADR rl DataArea ADR r2 DataArea 4300 ADRL r3 DataArea 4300 MOV pc Ir DataArea 8000 END 5 28 Copyright 1997 1998 ARM Limited All rights reserved Example 5 6 Y Mark first instruction to execute Branch to subroutine ange 1_SWIreason_ReportException ADP_Stopped_ApplicationExit Angel semihosting ARM SWI Create a literal pool gt SUB r0 PC offset to Start gt ADD r1 PC offset to DataArea This would fail because the offset cannot be expressed by operand2 of an ADD gt ADD r2 PC offsetl ADD r2 r2 offset2 Return Starting at the current location clears a 8000 byte area of memory to zero ARM DUI 0040D Basic Assembly Language Programming Implementing a jump table with ADR Example 5 7 shows ARM code that implements a jump table It is supplied as jump s in the examples asm subdirectory of the toolkit Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example The ADR pseudo instruction loads the address of the jump table In the example the function arithfunc takes three arguments and returns a result in r0 The first argument determines which operation is carried out on the second and third arguments argument1 0 argument1 1 argument1 gt 1 Result argument argument3 Result argument2 argument3 the same as argument1 0 The jump table is impl
146. 0 where the ROM is based and two data areas starting at address Ox 10000000 where the RAM is based Note The figures may differ depending on which version of the ARM Software Development Toolkit is being used 10 4 2 Output from info Sizes option object file code size init o 228 ex 0 184 Object totals 412 ARM DUI 0040D The output from the info Sizes option is shown in Example 10 3 Example 10 3 Sample output inline inline const RW Q Init debug data strings data data data data Q Q Q Q Q Q 28 356 16 4 320 Q 28 356 16 4 320 Q The required RAM size is the sum of the RW data 4 and the Init data 320 in this case 324 bytes The required ROM size is the sum of the code size 412 the inline data size 28 the inline strings 356 the const data 16 and the RW data 4 In this example the required ROM size is 816 bytes The RW data is included in both the ROM and the RAM counts This is because the ROM contains the initialization values for the RAM data Copyright 1997 1998 ARM Limited All rights reserved 10 11 Writing Code for ROM 10 4 3 Sample code Example 10 4 init s The AREA must have the attribute READONLY otherwise the linker will not place it in ROM The AREA must have the attribute CODE otherwise the assembler will not allow any code in this AREA gt Note the character is used to surround any symbols which contain non standard characters like AREA
147. 040D Chapter 11 Benchmarking Performance Analysis and Profiling This chapter describes various ways of measuring performance enabling you to improve any sections of code that are inefficient It contains the following sections About benchmarking and profiling on page 11 2 Measuring code and data size on page 11 3 Performance benchmarking on page 11 6 Improving performance and code size on page 11 16 Profiling on page 11 19 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 11 1 Benchmarking Performance Analysis and Profiling 11 1 About benchmarking and profiling This chapter explains how to run benchmarks on the ARM processor and shows you how to use the profiling facilities to help improve the size and performance of your code It makes extensive use of the example programs in the ARM Software Development Toolkit and contains a number of practical exercises for you to follow You should therefore have access to the examples directory of the toolkit and the ARM software tools themselves while working through it When developing application software or comparing the ARM with another processor it is often useful to measure code and data sizes overall execution time time spent in specific parts of an application Such information enables you to compare the ARM s performance against other processors in benchmark tests make decisions about the required clock spe
148. 040D Mixed Language Programming Constants The constant expression specifier is optional If it is used the expression following it must be constant Instruction expansion The constant in instructions with a constant operand is not limited to the values allowed by the instruction Instead such an instruction is translated into a sequence of instructions with the same effect For example ADD r0 r0 1023 may be translated into ADD r0 rO 1024 SUB r0 rQ 1 With the exception of coprocessor instructions all ARM and Thumb instructions with a constant operand support instruction expansion In addition the MUL instruction can be expanded into a sequence of adds and shifts when the third operand is a constant The effect of updating the CPSR by an expanded instruction is Arithmetic instructions set the NZCV flags correctly Logical instructions setthe NZ flags correctly donot change the V flag corrupt the C flag MRS sets the NZCV flags correctly Labels C and C labels can be used in inline assembler statements C and C labels can be branched to by branch instructions only in the form B cond label You cannot branch to labels using BL ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 8 5 Mixed Language Programming 8 1 3 Storage declarations All storage can be declared in C or C and passed to the inline assembler using variables Therefore the stor
149. 1 Pointers datamembers 8 18 member functions 8 18 Polled devices and Angel 13 66 POP instruction Thumb 5 41 Copyright 1997 1998 ARM Limited All rights reserved Index porting Angel 13 43 choosing an Angel template 13 45 Power up 9 2 Preferences in APM 2 31 Prefetch abort 9 2 and Angel 13 5 13 20 13 21 handler 9 34 9 41 returning from 9 7 Process control blocks 9 30 Processor exception vectors and Angel 13 71 Processor mode 5 4 and Angel stacks 13 39 13 62 Processor time analysis 3 43 Processors clock speeds 11 13 responding to exceptions 9 5 Profiler 11 19 12 12 cache misses 12 12 configuring under ARMulator 12 12 instruction counts 12 12 profiling interval 12 12 profiler c ARMulator model 12 3 file 12 12 Profiling 3 43 11 2 11 19 and Angel timers 13 61 call graph 11 19 collecting data 11 20 creating report 11 21 execution profile 11 19 flat 11 19 instruction tracing 11 26 interval setting 3 53 sorts example 11 22 Program counter 5 9 5 11 5 35 5 37 5 41 Program counter assembly 5 4 5 38 Program image reloading 3 11 stepping through 3 34 Program relative address 5 11 maps 5 49 Project adding files to 2 8 building 2 9 Index 9 Index editing source files 2 18 expanding collapsing view of 2 17 files 2 4 force building 2 11 format conversion 2 30 hierarchy 2 25 manager APM see APM naming 2 28 sub projects 2 4 templates 2 24 2 39 vari
150. 1 BNE gcd 3 1 1 CMP rQ r1 1 5 20 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Basic Assembly Language Programming Table 5 3 All instructions conditional continued r0 a ri b Instruction Cycles 1 1 SUBGT r0 r0 r1 1 Not executed 1 1 SUBLT r1 r1 r 1 Not executed 1 1 BNE gcd 1 Not executed Converting to Thumb Total 10 Because B is the only Thumb instruction that can be executed conditionally the Greatest Common Divisor algorithm in Example 5 4 on page 5 19 must be written with conditional branches in Thumb code Like the ARM conditional branch implementation the Thumb code requires seven instructions However because Thumb instructions are only 16 bits long the overall code size is 14 bytes compared to 16 bytes for the smaller ARM implementation In addition on a system using 16 bit memory the Thumb version runs faster than the second ARM implementation because only one memory access is required for each Thumb instruction whereas each ARM instruction requires two fetches Copyright 1997 1998 ARM Limited All rights reserved 5 21 Basic Assembly Language Programming 5 5 5 5 1 5 22 Loading constants into registers There is no single ARM instruction that can load an arbitrary 32 bit immediate constant into a register without performing a data load from memory This is because all ARM instructions are precisely 32 bits long and do not use the
151. 1 Main program code Main program code Janten FLASH Remap FLASH _ after RESET Boot code Initialized RW data or 0x04000000 gt Exception Handlers 2 S FLASH Exception Vectors Initialized RW data f i lt 0x00002000 gt A 4 4 1 1 Noe Exception Handlers SSRAM Main program code Exception Vectors Boot code lt 0x00000000 gt On RESET Load View Execution View 0x00000000 gt Figure 10 4 Memory map for example 5 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 8 2 Scatter load description file ARM DUI 0040D The scatter load description file shown in Example 10 10 defines one load region FLASH and three execution regions FLASH at 0x04000000 SSRAM at 0x0000 SRAM at 0x2000 On reset an aliased copy of FLASH is re mapped by hardware to address zero Following reset SRAM is mapped to address zero by the first few instructions in boot o The SSRAM area might be fast on chip internal 32 bit RAM and is typically used for the stack and code that must be executed quickly The exception vectors in vectors o and interrupt handler in C_int_handler o are relocated copied from FLASH to fast SSRAM at address 0x0000 for speed SRAM might be slower off chip external 16 bit DRAM or SRAM and is typically used for less frequently accessed RW variables and ZI data Here the RW vari
152. 10 19 Example 4 Simple scatter loading example on page 10 22 Example 5 Complex scatter load example on page 10 26 Scatter loading and long distance branching on page 10 30 Converting ARM linker ELF output to binary ROM formats on page 10 32 Troubleshooting hints and tips on page 10 34 Copyright 1997 1998 ARM Limited All rights reserved 10 1 Writing Code for ROM 10 1 About writing code for ROM This chapter describes how to write code for ROM and shows different methods for simple and complex images Sample initialization code is given as well as information on initializing data stack pointers interrupts and so on This chapter contains examples of using scatter loading to build complex images For detailed reference information on scatter loading refer to Chapter 6 Linker in the ARM Software Development Toolkit Reference Guide Two examples are given to illustrate the use of scatter loading a scatter loading application that runs under the ARMulator and also uses sprintf from the Embedded C library The example displays the linker generated scatter symbols on the screen a more complex scatter loading application that runs from Flash memory on an ARM Development Board PID7T 10 2 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 2 Memory map considerations 10 2 1 ROM at 0x0 10 2 2 RAM at 0x0 ARM DUI 0040D A major consideration in the design of a
153. 1024 1040 1056 4080 0x400 0xff0 16 Right by 28 bits 4096 4160 4224 16320 0x1000 0x3fc0 64 Right by 26 bits Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Basic Assembly Language Programming Table 5 4 ARM state immediate constants continued Equivalent Step Decimal values q between Rotate Hexadecimal values 64 x 224 65 x 224 255 x 224 Ox40000000 0xf 000000 224 Right by 8 bits 4 x 224 252 x 22443 0x4000000 0xfc000003 226 1 Right by 6 bits 16 x 224 240 x 224 15 0x10000000 0xf000000f 228 1 Right by 4 bits 64 x 224 192 x 224 63 0x40000000 0xc000003f 230 1 Right by 2 bits Using MOV and MVN You do not need to work out how to load a constant using MOV or MVN The assembler attempts to convert any constant value to an acceptable form This means that you can use MOV and MWN in two ways Convert the value to an 8 bit constant followed by the rotate right value For example MOV ro OxFF 30 r0 1020 Allow the assembler to do the work of converting the value If you specify the constant to be loaded the assembler converts it to an acceptable form if possible For example MOV rO 0x3FC r 1020 If the constant cannot be expressed as a right rotated 8 bit value or its bitwise complement the assembler reports an error Table 5 5 gives an example of how the assembler converts constants The left hand column lists th
154. 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Benchmarking Performance Analysis and Profiling 11 5 4 Saving profile data When collection is complete save the data to a file If you are using armsd enter the profwrite command profwrite data file If you are using ADW or ADU select Options Profiling Write to File 11 5 5 Generating the profile report The ARM profiler utility armprof generates the profile report using the data in the file The report is divided into sections each of which gives information about a single function in the program A section function called the current function is indicated by having its name start at the left hand edge of the Name column If call graph profiling is used information is also given about child and parent functions Functions listed below the current function are its children Those listed above the current function are the function parents it The columns in the report have the following meanings Name Displays the function names The current function in a section starts at the left hand edge of the column Parent and child functions are shown indented cum Shows the total percentage time spent in the current function plus the tme spent in any functions that it called It is only valid for the current function self Shows the percentage time spent in a function For the current function it shows the percentage time spent in this function
155. 1998 ARM Limited All rights reserved 2 21 ARM Project Manager 2 22 Making system wide configuration changes System wide configuration changes to a tool affect all projects that invoke the tool Follow these steps to make system wide configuration changes 1 Select Configure from the Tools menu and select the tool to configure You are given a warning message about the effects of such a configuration change 2 Confirm that you want to proceed The appropriate Tool Configuration dialog is displayed showing current settings 3 Make any required changes 4 Select one of the following click OK to save the changes and close the dialog click Apply to save the changes and keep the dialog open click Cancel to ignore all changes not applied and close the dialog Making project specific configuration changes Project specific configuration can affect an entire project or specific entities or scope within a project For example you can change how a particular source file is compiled or you can change how all the source for a specific partition is compiled The Project menu item Tool Configuration for reflects the scope that is affected by the change 1 Click on one or more entities such as the Debug variant in the Project window to specify the scope of a configuration change Hold down the Shift or Ctrl keys while clicking to select several entities or a range of entities 2 Select Tool Configuration for from the Proj
156. 24 view 2 19 watch window 3 66 watchpoints 3 25 winglass c ARMulator model 12 3 Writing code for ROM 10 1 attribute conflict in linker 10 35 C library 10 8 common problems 10 34 converting ELF output 10 32 critical I O devices 10 6 embedded C library 10 19 enabling interrupts 10 7 entry point 10 5 exception vectors 10 5 initialization 10 5 main function 10 8 memory for C code 10 7 MMU 10 6 processor mode 10 7 processor state 10 8 RAM at address O 10 3 RAM variables 10 6 ROM at address O 10 3 10 9 10 17 ROM at its base address 10 9 scatter loading 10 22 10 26 execution regions 10 24 10 28 variables 10 7 stack pointers 10 6 suitable output formats 10 33 SWISYS_WriteO 10 34 undefined symbols 10 34 undefined __ main 10 36 ARM DUI 0040D Z Zero wait state memory system 12 19 Numerics O init data 11 4 64 bit integer addition 6 6 multiplication result 6 16 Symbols directive 5 46 semihosting_enabled variable 13 4 13 16 top_of_memory debugger variable 13 93 vector_catch debugger variable 13 97 and indicators 3 43 Copyright 1997 1998 ARM Limited All rights reserved Index Index 13 Index Index 14 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D
157. 3 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 7 1 Interworking ARM and Thumb 7 1 About interworking You can mix ARM and Thumb code as you wish provided that the code conforms to the requirements of the ARM and Thumb Procedure Call Standards The ARM compilers always create code that conforms to these standards If you are writing ARM assembly language modules you must ensure that your code conforms See Chapter 6 Using the Procedure Call Standards for detailed information The ARM linker detects when ARM and Thumb code is being mixed and can generate small code segments called veneers These veneers perform an ARM Thumb state change on function entry and exit whenever an ARM function is called from Thumb state or a Thumb function is called from ARM state 7 1 1 When to use interworking When you write code for a Thumb capable ARM processor you will probably write most of your application to run in Thumb state because this provides the best possible code density and performance with 8 bit or 16 bit memory However you may want parts of your application to run in ARM state for reasons such as Speed Some parts of an application may be highly speed critical These sections may be more efficient running in ARM state than in Thumb state because in some circumstances a single ARM instruction can do more than the equivalent Thumb instruction Some systems include a small amount of fast 32 bit memory from whic
158. 3 Indicators and 3 43 Indirection 3 39 Initialization Angel 13 64 INITMMU macro 13 58 INITTIMER macro 13 58 13 70 init s initialization file 10 12 Inline assemblers 8 2 accessing structures 8 14 ADR pseudo instruction 8 6 ADRL pseudo instruction 8 6 ALU flags 8 5 8 8 BL instruction 8 6 branches 8 3 BX instruction 8 8 C global variables 8 14 C variables 8 4 8 8 commas 8 8 comments 8 3 complex expressions 8 4 ARM DUI 0040D constants 8 5 corrupted registers 8 3 CPSR 8 5 C C expressions 8 4 8 8 DC directives 8 6 examples 8 10 floating point instructions 8 8 instruction expansion 8 5 interrupts 8 10 invoking 8 2 labels 8 3 LDM instruction 8 8 long multiply 8 11 MUL instruction 8 5 multiple lines 8 3 operand expressions 8 4 physical registers 8 4 8 8 register corruption 8 6 8 8 restrictions 8 8 Saving registers 8 9 sign extension 8 4 stacking registers 8 9 STM instruction 8 8 storage declaration 8 6 subroutine parameters 8 6 SWI instruction 8 6 writing to pc 8 2 8 4 8 5 Inline strings 11 3 Installing FlexLM A 2 Instruction expansion 8 5 Instruction set ARM 5 6 Thumb 5 8 Instruction tracing 11 26 Instructions assembly language ADD 5 53 BL 5 15 8 6 BX 5 3 5 16 7 4 BX Thumb 5 8 LDM 5 34 5 49 LDM Thumb 5 41 LDR 5 46 MOV 5 22 5 48 MRS 5 7 MSR 5 7 MVN 5 22 POP Thumb 5 41 Copyright 1997 1998 ARM Limited All rights reserved Index PUS
159. 3 to write an image to the Flash memory chip on an ARM Development Board or any suitably equipped hardware Flash Download x Options Set Ethemet Address Figure 3 13 Flash Download dialog Set Ethernet Address Use the Set Ethernet Address option if necessary after writing an image to Flash memory You might do this for example if you are using Angel with ethernet support When you click OK you are prompted for the IP address and netmask for example 193 145 156 78 You do not need to use this option if you have built your own Angel port with a fixed ethernet address Arguments Image Specifies the arguments or image to write to Flash Use the Browse button to select the image For more information about writing to Flash memory including details of how to build your own Flash image refer to the Target Development System User Guide 3 48 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 6 Channel viewers Windows only The ARM Debugger for Windows supports the use of Channel Viewers to access debug communication channels An example channel viewer is supplied with ADW ThumbCV d11 or you can provide your own viewer Note The ARM Debugger for UNIX does not support the use of Channel Viewers 3 6 1 ThumbCV channel viewer ARM DUI 0040D To select a Channel Viewer when running the ARM Debugger for Windows L 2 Select Confi
160. 3 29 for an introduction to Angel operation Angel is designed to make porting to new hardware as easy as possible However there are many configurable features of Angel and you must modify Angel code to support your hardware The easiest way to port Angel is to select an existing Angel implementation as a template and modify it to suit your own hardware The ARM Software Development Toolkit provides a number of Angel ports in the Angel Source directory In addition there are Angel ports from other board manufacturers for their own development boards These are not distributed with the ARM Software Development Toolkit You should select an existing version of Angel that has been ported to hardware that is as similar as possible to your own If you are not basing your Angel port on a port from another board manufacturer it is recommended that you use the Angel PID port provided with the ARM Software Development Toolkit The most important hardware features to consider when making this decision include Device drivers Writing device drivers is a large part of the porting process If possible choose a version of Angel that supports the same or very similar communications hardware This makes it simpler to modify the device driver code Cache MMU The PID and ARM evaluation boards do not have a cache or MMU If you are porting to hardware that is based on a third party development board that includes a cache and MMU you should consider using t
161. 3 5 Addressing range 5 3 ADP 13 73 interrupt source for 13 61 adp h 13 97 ADP_Stopped_ApplicationExit 13 97 ADR pseudo instruction 5 27 5 53 ADR Thumb pseudo instruction 5 27 ADRL pseudo instruction 5 27 5 53 ADW ADU adding watches 3 70 adw exe 3 62 ARM DUI 0040D adw_cpp dll library 3 62 and Angel downloading 13 67 buttons 3 62 changing variables 3 70 class view 3 63 closing down 3 10 debug table formats 3 74 expression evaluation guidelines 3 71 expressions 3 70 formatting watch items 3 69 menus 3 62 starting 3 9 viewing code 3 64 watch window 3 66 watches recalculating 3 70 Agent debug 3 6 ALIGN directive 5 51 Alignment 5 51 ALU status flags 5 17 Analysis of processor time 3 43 AND operator 5 51 Angel 3 5 3 6 and ARMulator 13 15 13 68 and Ethernet 13 27 and exception handling 13 20 and RTOSes 13 19 APM project modifying 13 50 Board setup 13 61 Boot channel 13 73 boot support 13 74 breakpoint restrictions 13 32 breakpoint setting 13 22 buffer lifecycle 13 75 buffer management 13 74 build directories 13 44 building 13 24 13 45 C library support 13 21 C library support SWIs_ 13 79 channel restrictions 13 74 channel viewers 3 49 channels layer 13 74 channels packet format 13 76 communications layers 13 73 communications support 13 4 13 25 Copyright 1997 1998 ARM Limited All rights reserved Index 1 Index component summary 13 7 configuring 3 59 13 69 confi
162. 3 92 Thumb 5 41 SYS_GET_ELAPSED 13 94 Stopping SYS_GET_HEAPINFO 13 93 ADW ADU 3 10 SYS_ISERROR 13 86 APM 2 4 SYS_ISTTY 13 87 execution 3 34 SYS_OPEN 13 81 SYS_READ 13 85 Index SYS_READC 13 86 SYS_REMOVE 13 89 SYS_RENAME 13 89 SYS_SEEK 13 87 SYS_SYSTEM 13 91 SYS_TIME 13 90 SYS_TMPNAM 13 88 SYS_WRITE 13 84 SYS_WRITEC 13 83 SYS_WRITEO 13 83 T target s 13 46 13 57 13 70 13 71 13 100 Task management Angel 13 33 13 79 Task Queue Items 13 38 tasm 5 10 TDCC 13 61 13 73 Templates APM location of 2 52 blank 2 41 project 2 24 2 39 using APM 2 53 Terminology and concepts 3 7 this implicit 8 17 Thumb and scatter loading 10 31 and __irgq 9 23 Angel breakpoint instruction 13 32 Angel SWI number 13 72 APM template 2 41 breakpoint setting 3 31 BX instruction 5 16 7 4 C libraries 7 17 changing to Thumb state example 7 5 channel viewer 3 49 code for ROM applications 10 8 code interworking template 2 52 conditional execution 5 17 C APM template 2 52 data in code areas 7 11 debug communications channel 3 49 13 73 direct loading 5 24 disassembly mode 3 21 3 40 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved Index 1 1 Index example assembly language 5 16 exception handler 9 39 handling exceptions 9 39 inline assemblers 8 2 instruction set 5 8 instruction set overview 5 8 interworking libraries 7 17 interworking veneers and profiling restrictions 11 20 interworking with ARM 7 2 7
163. 3 levels of optimization 00 Turns off all optimization except some simple source transformations 01 Turns off structure splitting range splitting cross jumping and conditional execution optimizations Also no debug data for inline functions is generated 02 Full optimization The 00 option gives the best debug view but with the least optimized code The 01 option gives a satisfactory debug view with good code density By default no debug data is emitted for inline functions so they cannot be debugged With DWARF1 debug tables dwarf1 command line option variables local to a function are not visible and it is not possible to get a stack backtrace The 02 option emits fully optimized code that is still acceptable to the debugger However the correct values of variables are not always displayed and the mapping of object code to source code is not always clear because of code re ordering Copyright 1997 1998 ARM Limited All rights reserved 1 7 Introduction A new pragma has been introduced to specify that debug data is to be emitted for inline functions The pragma is pragma no debug_inlines You can use this pragma to bracket any number of inline functions It can be used regardless of the level of optimization chosen Impact Any existing makefiles or APM projects that use g gxo will now get the behavior defined by g 01 The SDT 2 1 1a option g gxr is still supported by SDT 2 50 and has the same f
164. 4 a4 a_hi b_hi m_hi al gt ip mmidl m_mid2 m_mid amp 10000 a4 m_h1 carry m_hi ip LSL 16 al ip LSR 16 a2 m_lo m_mid lt lt 16 m_hi m_mid gt gt 16 carry Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Using the Procedure Call Standards Note On processors with a fast multiply unit such as the ARM7TDMI and ARM7DMI this example can be recoded using the UMULL instructions Example 6 9 on page 6 16 is fine for use with assembly language modules but to use it from C you must tell the compiler that this routine returns its 64 bit result in registers You can do this by making the following declarations in a header file typedef struct int64_struct unsigned int lo unsigned int hi int64 __value_in_regs extern int64 mul64 unsigned a unsigned b The above assembly language code and declarations together with a test program are in the directory examples candasm as the files mu164 s mul64 h int64 h and multest c To compile assemble and link these to produce an executable image suitable for armsd copy them to your current directory and then execute the following commands armasm mul64 s o mul64 0 11 armcc c multest c 11 armlink mul64 0 multest o o multest where 1i can be omitted if armcc and armasm and armsd below have been configured with it as a default Follow these step to run multest under armsd 1 Enter arms
165. 4096 The assembler calculates constb 4096 for you However it is better to redesign the map description as in Example 5 16 Example 5 16 MAP Q consta 4 consta uses four bytes located at offset Q constb 4 constb uses four bytes located at offset 4 X 8 x uses eight bytes located at offset 8 y 8 y uses eight bytes located at offset 16 string 256 string 1s up to 256 bytes long starting at offset 24 Using the map in Example 5 16 you can access the data structure at the same location as before MOV r9 4096 LDR r4 r9 constb This program fragment assembles to exactly the same machine instructions as before The value of each label is 4096 less than before so the assembler does not need to subtract 4096 from each label to find the offset The labels are relative to the start of the data structure instead of being absolute The register used to hold the start address of the map r9 in this case is called the base register There are likely to be many LDR or STR instructions accessing data in this data structure You avoid typing 4096 repeatedly by using this method The code is also easier to follow This map does not contain the location of the data structure The location of the structure is determined by the value loaded into the base register at runtime ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 47 Basic Assembly Language Programming 5 9 3 consta constb X y
166. 5 Scatter load description file examples 10 23 10 27 Scatter loading assembly veneers 10 31 function pointers 10 30 long distance branching 10 30 range restrictions 10 30 Copyright 1997 1998 ARM Limited All rights reserved writing code for ROM 10 22 10 26 Scope 5 11 Search paths viewing 3 36 window 3 24 Searching for license file A 11 Semihosting 13 3 13 16 13 18 enabling and disabling 13 4 13 16 Semihosting SWIs_ 13 79 SYS_CLOCK 13 90 SYS_CLOSE 13 83 SYS_ELAPSED 13 94 SYS_ERRNO 13 91 SYS_FLEN 13 88 SYS_GET_ CMDLINE 13 92 SYS_HEAPINFO 13 93 SYS_ISERROR 13 86 SYS_ISTTY 13 87 SYS_OPEN 13 81 SYS_READ 13 85 SYS_READC 13 86 SYS_REMOVE 13 89 SYS_RENAME 13 89 SYS_SEEK 13 87 SYS_SYSTEM 13 91 SYS_TIME 13 90 SYS_TMPNAM 13 88 SYS_WRITE 13 84 SYS_WRITEC 13 83 SYS_WRITEO 13 83 serlasm s 13 35 serlock 13 35 Server for license management A 2 SERVER line in license file A 9 setjmp code speed 11 18 Setting breakpoints 3 26 environment variable A 7 profiling interval 3 53 simple breakpoint 3 27 simple watchpoint 3 29 Short integers to reduce code size 11 17 Simple breakpoint 3 26 3 27 watchpoint 3 29 Simulation real time 11 8 ARM DUI 0040D reducing time taken 11 15 Storage declaration inline assemblers Single stepping 3 5 8 6 Soft reset 9 2 STR instruction 5 46 Software String constants assembly language development toolkit SDT 3 1 5 12 licensed A 1 String copying software FPA emulator assembler 8 19
167. 5 1 illustrates some of the core constituents of an assembly language module The example is written in ARM assembly language It is supplied as armex s in the examples asm subdirectory of the toolkit Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example The constituent parts of this example are described in more detail in the following sections Example 5 1 ARMex CODE READONLY Name this block of code ARMex Mark first instruction to execute rQ 10 Set up parameters rl 3 r r0 rl r0 r0 r1 ro 0x18 angel_SwIreason_ReportException rl 0x20026 ADP_Stopped_ApplicationExit Qx123456 Angel semihosting ARM SWI Mark end of file The AREA directive ARM Object Format AOF areas are independent named indivisible sequences of code or data A single code area is the minimum required to produce an application The output of an assembly or compilation usually consists of two or more areas A code area This is usually a read only area A data area This is usually a read write area The linker places each area in a program image according to area placement rules Areas that are adjacent in source files are not necessarily adjacent in the application image Refer to Chapter 6 Linker in the ARM Software Development Toolkit Reference Guide for more information on how the linker places areas See also Chapter 10 Writing Code for ROM In an ARM assembly language sou
168. 5 18 conditional execution 5 17 constants 5 12 data structures 5 46 directives see Directives assembly entry point 5 14 examples 5 2 5 13 5 15 5 19 5 26 5 28 5 29 5 31 5 32 5 39 5 44 5 56 5 58 examples Thumb 5 16 5 21 5 30 5 33 5 41 execution speed 5 56 immediate constants ARM 5 22 inline armasm differences 8 6 instructions see Instructions assembly interrupt handlers 9 27 interworking ARM and Thumb 7 4 7 19 jump tables 5 29 labels 5 11 line format 5 10 line length 5 10 listing from debugger 4 3 4 9 literal pools 5 25 loading addresses 5 27 loading constants 5 22 local labels 5 11 macros 5 43 maintenance maps 5 46 multiple register transfers 5 34 see also STM LDM 5 51 Index 3 Index nesting subroutines 5 37 numeric constants 5 12 padding 5 51 pe 5 4 5 9 5 11 5 35 5 37 5 38 5 41 program counter 5 4 5 9 5 11 5 35 5 37 5 38 5 41 program relative 5 11 program relative maps 5 49 pseudo instructions see Pseudo instructions assembly register based maps 5 48 register relative address 5 11 relative maps 5 47 speed 5 56 stacks 5 36 string constants 5 12 subroutine return 5 5 subroutines 5 15 symbols 5 53 Thumb block copy 5 41 assembly language using the APCS 6 2 ASSERT directive 5 50 5 60 Assertions and Angel debugging 13 21 ASSERT_ENABLED macro 13 21 B B instruction Thumb 5 17 Backtrace window 3 18 3 33 Banked registers 9 3 banner h 13
169. 7 26 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D gt Interworking ARM and Thumb Click the General tab and ensure that the Search standard libraries check box is not selected Click the Listings tab and add any libraries you want to link with to the Extra command line arguments field Click OK to save the configuration As described in The C and C interworking libraries on page 7 17 you may sometimes need to force the inclusion of a specific module from a particular library Follow these steps to do this when using ARM Project Manager L 2 Select the project root Select Tool configuration for project apj armlink Set from the Project menu The Linker Configuration dialog is displayed Click the Listings tab and enter the library modules that you want to be forcibly included in the Extra command line arguments field For example to force the inclusion of strcpy and strcmp C ARM250 11b armlib 321 strcpy o C ARM250 11b armlib 321 strcmp o This can also be written within quotes to override the normal meaning of space as an argument separator Alternatively you can use a pattern for the name of the modules C ARM25Q l1b armlib 321 strcx Click OK to save the configuration Copyright 1997 1998 ARM Limited All rights reserved 7 27 Interworking ARM and Thumb 7 28 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 8 Mix
170. 9 43 44 calls From the cum column you can see in the main section that the program spent 96 04 percent of its time in main and its children Of this only 0 16 percent of the time is spent in main self column whereas 95 88 percent of the time is spent in functions called by main desc column The call count for main is O because it is the top level function and is not called by any other functions whereas the section for insert_sort shows that it made 243432 calls to strcmp and that this accounted for 59 44 percent of the time spent in strcmp the desc column shows 0 in this case because strcmp does not call any functions 11 5 6 Profiling example sorts The sorts application can be found in the Examples subdirectory of the ARM Software Development Toolkit Copy the files into your working directory PC sampling information If you are using the command line tools 1 Compile the sorts c example program armcc Otime o sorts sorts c 11 22 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Benchmarking Performance Analysis and Profiling Start armsd and load the executable armsd sorts Turn profiling on profon Run the program as normal go When execution completes write the profile data to a file using the ProfWrite command ProfWrite sortl prf Exit armsd Quit Generate the profile for the collected data by entering at the system prompt
171. ARM DUI 0040D Angel 13 5 Configuring Angel This section describes some of the major configuration changes that you can make to Angel All the configuration changes described in this section are static You must re compile Angel to implement these changes The changes you can make are described in the following sections Configuring the memory map Configuring timers and profiling on page 13 70 Configuring exception handlers on page 13 70 Configuring where Angel runs on page 13 70 Configuring SWI numbers on page 13 72 13 5 1 Configuring the memory map ARM DUI 0040D You can configure the Angel stack positions by editing the value of define Angel_StacksAreRelativeToTopOfMemory in devconf h By default the Angel stacks are configured relative to the top of memory This is the recommended option If Angel stacks are configured to start relative to the top of memory then the Angel code searches for the top of contiguous memory and the stack pointers are set at this location This means that you can add memory to your system without updating the memory map and rebuilding Angel Refer to devconf h on page 13 60 for more information You must define the memory map to allow the debugger to control illegal read writes using the checks in the PERMITTED macro These should reflect the permitted access of the system memory architecture You must take care with systems that have access to the full 4GB of memory because the hi
172. ARM DUI 0040D Angel Note Angel stack space is different from the application stack space However Angel uses four words of application stack when it returns to the application from an exception The download agent area The download agent area is a spare area of RAM to which new Angel images are downloaded The loadagent command writes the image to the download area When complete the agent is started with an ADP command It relocates itself to another area if it has been compiled to do so This enables the new Angel to overwrite the old Angel and release the download agent area The download agent can be in the same RAM as an application because the application and the download agent never run at the same time The Deviceldent structure The available devices must be defined in the DeviceIdent structure You must ensure that the order of the devices in this structure 1s the same as that defined in devices c because this enables access to the register base of the specified ports The IntHandlerID structure You must ensure that the order and number of entries in this structure is the same as defined in devices s because this is the basis for the jump table in suppasm s You must also place the labels in makelo c to ensure that they are available for suppasm s 13 4 6 Writing the device drivers ARM DUI 0040D Writing device drivers for your hardware 1s the main area of the porting operation and is completely applic
173. ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager resulting in a final value of Ic projdir mypro Outputs and command lines can refer to variables not used in an input pattern A typical example is lt tool gt o lt file gt o lt TOOLFLAGS gt If the variable lt TOOLFLAGS gt is defined within the project its value is used otherwise it is ignored A more typical output expression is lt file gt o A command line expression might be path lt path I gt lt path gt denoting the set of values accumulated from the expression discussed above Note The first variable on a command line is treated differently Its default value is its name APM insists that the name of a tool must be a variable So if you want to call armee you must enter lt armcc gt 2 9 2 Editing a build step pattern Note A build step pattern can use one or more tools process one or more input files and can produce one or more outputs Follow these steps to edit a build step pattern 1 Select the Build Step Pattern from the Project Template Editor dialog 2 Click Edit The Build Step Pattern dialog is displayed Figure 2 24 on page 2 50 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 49 ARM Project Manager Edit Build Step Pattern Xx Build Step Pattern Name Buia Input Partition Pattern SubProjects lt path gt lt s gt lt pri gt apl Delete Type in the box
174. ARM Software Development Toolkit Version 2 50 User Guide ARM Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Software Development Toolkit User Guide Copyright 1997 1998 ARM Limited All rights reserved Release Information The following changes have been made to this book Change History Date Issue Change Dec 1996 A Internal release Jan 1997 B First release for SDT 2 10 June 1997 C Updated for SDT 2 11 Nov 1998 D Updated for SDT 2 50 Proprietary Notice ARM Thumb StrongARM and the ARM Powered logo are registered trademarks of ARM Limited Angel ARMulator EmbeddedICE Multi ICE ARM7TDMI ARM9TDMI and TDMI are trademarks of ARM Limited All other products or services mentioned herein may be trademarks of their respective owners Neither the whole nor any part of the information contained in or the product described in this document may be adapted or reproduced in any material form except with the prior written permission of the copyright holder The product described in this document is subject to continuous developments and improvements All particulars of the product and its use contained in this document are given by ARM in good faith However all warranties implied or expressed including but not limited to implied warranties of merchantability or fitness for purpose are excluded This document is intended only to assist the reader in the use of the product
175. All rights reserved ARM DUI 0040D Angel 13 2 2 Minimal Angel Minimal Angel is a cut down version of Angel that provides board setup application launch device drivers Minimal Angel keeps the raw device drivers intact because your application might have been developed to use these Raw device drivers are device drivers that send and receive byte streams rather than ADP packets You can use minimal Angel in the final stages of development and on your production hardware Minimal Angel does not support features that are provided by full Angel such as debugging over ADP semihosting multiple channels on one device task management Minimal Angel is supplied in the following forms Prebuilt libraries There are separate big endian and little endian minimal Angel libraries Angel Images pid big angmin 11b Angel Images pid little angmin 1lib Full source code There is a separate build directory for minimal Angel PID port This is Angel Source pid min It contains UNIX makefiles and an ARM Project Manager project to build minimal Angel Refer to Porting Angel to new hardware on page 13 43 for more information ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 13 Angel 13 2 3 Overview of the development procedure This section gives an overview of the development process of an application using Angel from the evaluation stage to the final product The stages i
176. Angel components that provide this functionality Debug support Angel provides the following basic debug support reporting memory and processor status downloading applications to the target system setting breakpoints Refer to Angel debugger functions on page 13 31 for more information on how Angel performs these functions C library semihosting support Angel uses a software interrupt SWI mechanism to enable applications linked with the ARM C and C libraries to make semihosting requests Semihosting requests are requests such as open a file on the host or get the debugger command line that must be communicated to the host to be carried out These requests are referred to as semihosting because they rely on the C library of the host machine to carry out the request Copyright 1997 1998 ARM Limited All rights reserved 13 3 Angel 13 4 The ARM Software Development Toolkit provides prebuilt ANSI C libraries that you can link with your application The toolkit provides 26 prebuilt library variants that are targeted to Angel The libraries use the Angel SWI mechanism to request that specific C library functions such as input output are handled by the host system These libraries are used by default when you link code that calls ANSI C library functions Refer to Chapter 4 The C and C Libraries in the ARM Software Development Toolkit Reference Guide for more information Angel uses a single SWI to request semih
177. Angel rejects all but the first request returns a busy error message and leaves the user channels or the user application to retry later Angel interrupt handlers Angel Interrupt handlers are installed statically at link time The Angel Interrupt handler runs off either IRQ or FIQ It is recommended that it is run off IRQ The Angel interrupt is defined in devconf h Refer to devconf h on page 13 60 for more information Copyright 1997 1998 ARM Limited All rights reserved 13 77 Angel Control calls Angel device drivers provide a control entry point that supports the enable disable transmit receive commands so that Angel can control application devices at critical times Refer to Writing the device drivers on page 13 63 for more information 13 78 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 Angel C library support SWIs Angel uses a SWI mechanism to enable user applications linked with an ARM C library to make semihosting requests Semihosting requests are requests such as open a file on the host that must be communicated to the host to be carried out Refer to The ANSI C library on page 4 5 of the ARM Software Development Toolkit Reference Guide for more information on ARM C library support Angel uses a single SWI to request semihosting operations By default the Angel semihosting SWI is 0x123456 in ARM state Oxab in Thumb state You can configure the Angel SWI to a
178. C r14 r14 0x80 Clear the I bit use 0x40 for the F bit Write it back to re enable Interrupts and LDR PC PC r12 LSL 2 jump to the correct handler PC base address points to this Instruction 8 pad so the PC indexes this table Table of handler start addresses MSR CPSR_c r14 NOP DCD Priority Handler DCD PrioritylHandler DCD Priority2Handler Priority Handler STMFD sp r0 r11 Save other working registers Insert handler code here LDMFD sp r0 r11 Restore working registers not r12 Now read modify write the CPSR to disable interrupts MRS r12 CPSR Read the status register ORR r12 r12 0x80 Set the I bit use 0x40 for the F bit MSR CPSR_c r12 Write it back to disable interrupts Now that interrupt disabled can safely restore SPSR then return LDMFD sp r12 r14 Restore r12 and get SPSR MSR SPSR_csxf r14 Restore status register from r14 LDMFD sp pc A Return from handler PrioritylHandler 9 30 Context switch Example 9 17 on page 9 31 performs a context switch on the user mode process The code is based around a list of pointers to Process Control Blocks PCBs of processes that are ready to run Figure 9 3 on page 9 31 shows the layout of the PCBs that the example expects Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions User mode registers PCB pointer gt Figure 9 3 PCB layout The pointer
179. Configuration Dialog via filename Opens a file and reads additional command line options from it For example armcpp via input txt options source c The options specified in f7 ename are read at the same time as any other command line options are parsed If via is specified in the Extra command line arguments text box of the APM Compiler Configuration dialog the command line options are immediately read into the tool configuration settings You can nest via calls within via files latevia filename This option is similar to via In the case of latevia the file is read immediately before compilation begins not when other command line options are parsed If lateviais specified the command line options are not read in until the compiler is executed This means that files specified with the latevia option stay in the text box and can be changed more easily than files specified with the via option Calls to latevia files cannot be nested If latevia is specified within a latevia file it is ignored However you can nest via options within latevia files ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 23 ARM Project Manager 2 4 2 2 4 3 2 24 Partitions Partitions enable you to organize the various files that make up your project in a similar way to placing them in a directory structure Partitions exist only within APM as an organizational convenience Your files are not cop
180. Current Program Status Register cpsr changing from a lowercase t to an uppercase T 7 2 2 Implementing interworking assembly language subroutines ARM DUI 0040D To implement a simple subroutine call in assembly language you must store the return address in the link register branch to the address of the required subroutine In the case of non interworking subroutine calls you can carry out both operations in a single BL instruction In the interworking case where the subroutine is coded for the other state you must allow for state changes both when calling the subroutine and when returning from the subroutine To call the subroutine and change the processor state use a BX instruction as described in The Branch Exchange instruction on page 7 4 Unlike the BL instruction BX does not store the return address in the link register You must ensure that the link register 1s loaded with the return address before you use the BX instruction If the call is from Thumb code to ARM code you must also set bit 0 in the link register to ensure that the processor executes in Thumb state when the subroutine returns Copyright 1997 1998 ARM Limited All rights reserved 7 7 Interworking ARM and Thumb 7 8 Calling an ARM subroutine from Thumb The simplest way to carry out a Thumb to ARM interworking subroutine call is to BL to an intermediate Thumb code segment that executes the BX instruction The BL instruction loads the lin
181. D The RDI Log window displays the low level communication messages between the debugger and the target processor This facility is not normally enabled It must be specially turned on when the RDI is compiled To display remote debug information RDI select RDI Protocol Log from the View menu The RDI Log window 1s displayed Use the RDI Log Level dialog obtained by selecting Set RDI Log Level from the Options menu to select the information to be shown in the RDI Log window Bit 0 RDI level logging on off Bit 1 Device driver logging on off Warning The RDI log level is used internally within ARM to assist with debugging This level should be changed only if you have been requested to do so by ARM Copyright 1997 1998 ARM Limited All rights reserved 3 41 ARM Debuggers for Windows and UNIX 3 5 5 3 42 Using regular expressions Regular expressions are the means by which you specify and match strings A regular expression is either a single extended ASCII character other than the special characters described below a regular expression modified by one of the special characters You can include low level symbols or high level symbols in a regular expression see High level and low level symbols on page 3 43 for more information Pattern matching is done following the UNIX regexp 5 format but without the special symbols and The following special characters modify the meaning of the previous regu
182. EH Ee onan 4 Mogging c Se MoggingheS_ sendb s eaae _ Moggingsladpasm s Sane Le A Moggingslog552 c Senne E Mogging logadp c EE E A dogging slagterm c Senne E AMoggingspanicblk c Senne E Aoggingsrombos c E E A Amagbuild c E E Aparame c me Apid delay s PE Le A Mpid devices c D E aA Apid pomcia c PL Le A pids st 6662 c D Le A Apidstimer c Senne prof c a E OK AMC ee 4 serlasm s ee Le 4 serock c EE Le A Aserpkbc Pa Le LA WREITAI C ns E Oh A atackac ee 4 hstartlib s EE A ASUDpasm s ee Le LA MSUE C AOE Le A ABE E Sy IncludedFiles a Sy Objects ets Sy FomSre eee i Flan his sn Un I I Figure 13 11 Replacing target specific source files 14 The directory header in the APM window can be edited using the Edit Details button This is not required to build Angel Selecting build options The build variables for the APM project are the same as those defined in the UNIX makefile They are defined in either the project variables or as preprocessor definitions in the compiler configuration dialog Refer to Editing makefile build options on page 13 48 for a description of the build options 13 56 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 4 5 Modifying target specific files Target specific files are dependent on the target system you are porting Angel to You must modify these files for your system Overview of the target spe
183. File button The Open File dialog is displayed 2 Select the filename of the executable image you want to debug 3 Enter any command line arguments expected by your image Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 4 Click OK The program is displayed in the Execution window as disassembled code A breakpoint is automatically set at the entry point of the image usually the first line of source after the main function The current execution marker a green bar indicating the current line is located at the entry point of the program If you have recently loaded your required image your file appears as a recently used file on the File menu If you load your image from the recently used file list the ARM Debugger loads the image using the command line arguments you specified in the previous run Reloading an image After you have executed an image you must reload it before you can execute it again To reload an executable image select Reload Current image from the File menu or ER click the Reload button on the toolbar Executing an image To run your program in the ARM Debugger select Go from the Execute menu or click EN the Go button to execute the entire program Execution continues until a breakpoint halts the program at a specified point a watchpoint halts the program when a specified variable or register changes you stop the program by clicking
184. GEND link LK4 7 Power up the board and connect the debugger Make sure that the debugger is configured for big endian operation When you have a big endian Angel in Flash you can use a big endian version of the Flash downloader to program a new copy of Angel into the 16 bit device To do this 1 Switch on the board 2 Start the debugger 3 Insert the SEL8BIT link LK6 4 so that the target device is now the 16 bit Flash chip You must provide a 16 bit wide Flash device because one is not supplied with the board Refer to The Flash downloader on page 8 15 of the ARM Software Development Toolkit Reference Guide for more information on using the Flash download utility Note There is no performance gain from using a 16 bit wide device in this case because Angel copies itself to SRAM and executes from there Copyright 1997 1998 ARM Limited All rights reserved 13 23 Angel 13 2 5 Developing an application under minimal Angel The minimal Angel library is intended to support the later stages of debugging It does not include full Angel features such as debugging and packet organization through ADP reliable communications through ADP channels support semihosted C library support an Undefined exception handler the task serializer Minimal Angel is not suitable for use when you are in the development stage of your project Components of minimal Angel The minimal Angel library contains
185. H Thumb 5 41 STM 5 34 5 49 STM Thumb 5 41 STR 5 46 SWI 8 6 9 14 SWIs Thumb 9 42 integer like structures 6 14 Interrupt handlers 9 22 Angel 13 65 Interrupts and Angel 13 41 Angel Fusion stack 13 100 prioritization 9 29 ROM applications 10 7 source for Angel 13 61 interrupt s 13 59 Interval profiling 3 53 Interworking ARM and Thumb 2 52 7 1 APCS 7 2 7 12 7 21 APM template 2 52 7 23 assembly language 7 4 7 19 BX instruction 7 4 C 7 14 C and C 7 12 C and C libraries 7 15 7 17 C libraries 7 26 CODE16 directive 7 4 7 23 CODE32 directive 7 4 7 23 compatibility of options 7 12 compiler command line options 7 15 compiling code 7 12 CPSR 7 2 7 7 data in Thumb code 7 11 detecting calls 7 16 duplicate functions 7 17 examples 7 7 7 8 7 14 7 18 7 19 exceptions 7 2 function pointers 7 15 image template 7 23 indirect calls 7 15 leaf functions 7 12 mixed languages 7 19 7 21 modifying existing project 7 25 MOV pc lr 7 8 non Thumb processors 7 13 Index 7 Index procedure call standards 7 2 rules 7 15 SPSR 7 2 subroutines 7 7 TPCS 7 2 UNIX 7 18 veneers 7 2 7 12 7 13 7 14 7 19 16 assembler option 7 23 IntHandlerID structure 13 63 Introduction to debugging 3 2 IRQ 9 22 and Angel 13 9 13 19 Angel processing of 13 40 handler 9 7 9 41 IRQ exception 9 2 I O devices ROM applications 10 6 J JTAG 3 5 Jump table 9 15 9 42 Jump tables assembly 5 29 Jumps and code speed 11 18 K KickStar
186. I 0040D Angel Angel ISR 2 es Dev ISR yes Serialize Task Save Content 5 Create new task Select Next Angel Interrupt Complete Request New task highest priority no Angel Return Another task yes Queue callback End Rx_Proc Callback next no Another task Data specific callback Next task Select Next Task Appl Figure 13 4 Processing a simple IRQ The IRQ is handled as follows 1 The Interrupt exception is noticed by the processor The processor fetches the IRQ vector s enters Interrupt mode starts executing the Angel Interrupt Service Routine On entry to the IRQ handler FIQ interrupts are disabled if HANDLE_INTERRUPTS_ON_FIQ 1 the default is 0 FIQ interrupts enabled Interrupts are not re enabled until either Angel_SerialiseTask is called the interrupt completes ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 41 Angel 13 42 The Angel ISR saves the processor state in a register block uses the GETSOURCE macro to determine the interrupt source and jumps to the handler The processor state is saved because this data is required by Angel_SerialiseTask The interrupt handler determines the cause of the IRQ If the interrupt is not an Angel interrupt it returns immediately If the interrupt is an Angel interrupt and the driver uses polled input the handler call
187. Init CODE READONLY Now some standard definitions Mode_USR EQU 0x10 Mode_IRQ EQU 0x12 Mode_SVC EQU 0x13 I_Bit EQU 0x80 F_Bit EQU 0x40 Locations of various things in our memory system RAM_Base EQU 0x10000000 64k RAM at this base RAM_Limit EQU 0x10010000 IRQ_Stack EQU RAM_Limit 1K IRQ stack at top of memory SVC_Stack EQU RAM_Limit 1024 followed by SVC stack USR_Stack EQU SVC_Stack 1024 followed by USR stack gt Define entry point EXPORT __main defined to ensure that C runtime system __main is not linked in ENTRY gt Setup interrupt exception vectors IF DEF ROM_AT_ADDRESS_ZERO If the ROM is at address this is just a sequence of branches Reset_Handler Undefined_Handler SWI_Handler Prefetch_Handler Abort_Handler OP Reserved vector IRQ Handler FIQ_ Handler Z ww ELSE Otherwise copy a sequence of LDR PC instructions over the vectors Note Copy LDR PC instructions because branch instructions could not simply be copied the offset in the branch instruction would have to be modified so that it branched into ROM Also a branch instructions might not reach if the ROM is at an address gt 32M 10 12 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D MOV R8 0 ADR R9 Vector_Init_Block LDMIA R9 RQ R7 STMIA R8 RQ R7 LDMIA R9 RQ R7 STMIA R8 RQ R7 Now fall into the LDR PC Reset_Addr instruction which will continu
188. N WHere Backtrace Laym LEt Arguments Type Call WA le LOG RELoad REAdSsyms GEtrile LoCalvar COMment sPlecteonfig LISTConftig LOAD Agent PROFClear PROFWrite Cin PROCessar nis ELF gives helps on all available commands To print the HE command ta record the heln output into a file amp print the fi Ha Figure 3 5 Command window See Using command line debugger instructions on page 3 46 for further details about the use of the Command window Type help at the Debug prompt for information on the available commands or refer to Chapter 7 ARM Symbolic Debugger in the ARM Software Development Toolkit Reference Guide ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 17 ARM Debuggers for Windows and UNIX 3 3 2 Optional windows The windows described in this section are all available by selecting appropriate options in the View menu Backtrace window The Backtrace window displays current backtrace information about your program Use the Backtrace window to show disassembled code for the current procedure show a list of local variables for the current procedure set or remove breakpoints Breakpoints window The Breakpoints window displays a list of all breakpoints set in your image The actual breakpoint is displayed in the right hand pane If the breakpoint is on a line of code the relevant source file is shown in the left hand pane Use the Breakpoints window to show source disassem
189. NIX Read this chapter for a description of the ARM graphical user interface debuggers for Windows and UNIX Chapter 4 Command Line Development Read this chapter for a brief overview of developing programs in a command line environment Chapter 5 Basic Assembly Language Programming Read this chapter for tutorial information on writing ARM assembly language including information about effectively using the directives and pseudo instructions provided by the assembler Chapter 6 Using the Procedure Call Standards Read this chapter for a description of how to use the ARM and Thumb procedure call standards when writing mixed assembly language and C or C Chapter 7 Interworking ARM and Thumb Read this chapter for information on how to interwork code developed to run in Thumb state and code developed to run in ARM state Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Preface Chapter 8 Mixed Language Programming Read this chapter for information on developing mixed C C and ARM assembly language programs and for information on writing inline assembly language code within your C or C program Chapter 9 Handling Processor Exceptions Read this chapter for instructions on how to write exception handlers for the ARM processor exceptions Chapter 10 Writing Code for ROM Read this chapter for tutorial information on writing code that is designed to run from ROM This chapter includes information o
190. ORK attribute and return using BX Ir Note Any assembly language code used in this manner must conform to the APCS where appropriate Example 7 6 thumb c include lt stdio h gt extern int arm_function int int main void int 1 1 printf 1 d n 1 printf And now 1 d n arm_function 1 return Q Copyright 1997 1998 ARM Limited All rights reserved 7 21 Interworking ARM and Thumb ale als ale ale ale j ww 29 29 29 2 arm s AREA Arm CODE READONLY INTERWORK Name this block of code EXPORT arm_function arm_function ADD rQ rQ 4 Add 4 to first parameter BX LR Return END Follow these steps to build and link the modules 1 Type tcc c thumb c to compile the thumb code 2 Type armasm arm s to assemble the arm code 3 Type armlink arm o thumb o o add to link the two object files 7 22 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb 7 5 ARM Thumb interworking with the ARM Project Manager The ARM Project Manager see Chapter 2 ARM Project Manager uses templates to define the tools and command line options that are used to build a project All templates supplied with APM that build executable images can support interworking The Thumb ARM Interworking Image template specifically allows an interworking application to be created It assumes that armasm 16 is used for all assembly language sources and that the assem
191. Overview of the ARM architecture on page 5 3 Structure of assembly language modules on page 5 10 Conditional execution on page 5 17 Loading constants into registers on page 5 22 Loading addresses into registers on page 5 27 Load and store multiple register instructions on page 5 34 Using macros on page 5 43 Describing data structures with MAP and directives on page 5 46 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 1 Basic Assembly Language Programming 5 1 5 1 1 5 2 Introduction This chapter gives a basic practical understanding of how to write ARM and Thumb assembly language modules It also gives information on the facilities provided by the ARM assembler armasm For additional details about armasm see Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide This chapter does not provide a detailed description of either the ARM instruction set or the Thumb instruction set This information can be found in the ARM Architectural Reference Manual or in an appropriate ARM data sheet Code examples There are a number of code examples in this chapter Many of them are supplied in the examples asm directory of the Software Development Toolkit Follow these steps to build link and execute an assembly language file 1 Type armasm g filename s at the command prompt to assemble the file and generate debug tables 2 Type armlink filename o o fil
192. Q 2 STR rQ Point_y MOV rQ 3 STR rQ Point_z is equivalent to the C code origin x Q origin y 2 origin z 3 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming Making faster access possible To gain faster access to an area of memory 1 Describe the memory area as a structure 2 Use a register to address the structure For example consider the definitions in Example 5 22 Example 5 22 StartOfData EQU 0x1000 EndOfData EQU 0x2000 MAP StartOfData Integer 4 String MaxStrLen Array ArrayLen 8 BitMask 4 EndOfUsedData Q ASSERT EndOfUsedData lt EndOfData If you want the equivalent of the C code Integer 1 String BitMask QxAQQQQ0Q0A With the definitions as above the assembly language code could be as in Example 5 23 Example 5 23 MOV rQ 1 LDR r1 Integer STR rQ r1 MOV rQ 0 LDR r1 String STRB rQ r1 MOV r0 0xA000000A LDR r1 BitMask STRB rQ r1 Example 5 23 uses LDR pseudo instructions See Loading with LDR Rd const on page 5 25 for an explanation of these ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 55 Basic Assembly Language Programming 5 56 Example 5 23 on page 5 55 contains separate LDR pseudo instructions to load the address of each of the data items Each LDR pseudo instruction is converted to a separate instruction by the assembler However it is
193. RCDIR1 armdefs h example o SRCDIR1 rdi_hif h CC CFLAGS CFLexample o example o SRCDIR1 example c In directory build type make For the Solaris gcc target this produces the following output Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator Example 12 1 Sample output gcc c ansi pedantic W Wformat Wimplicit Wmissing prototypes Wchar subscripts Wunused Wuninitialized Wreturn type Wpointer arith Wcast qual Wstrict prototypes Wcomment Dunix g 02 DARM_RELEASE unreleased Iderived I armsd source I armsd source I armsd obj I armsd obj I armsd obj I armsd obj I armsd obj I armsd obj I armsd ob I armsd obj I armsd obj I armsd obj I armsd ob I armsd obj I armsd obj I armsd obj o example o armsd source example c armsd source example c 44 warning pointer targets in initialization differ in signedness gcc o armsd Im Isocket Insl main o angel o armfast o armflat o armmap o armpie o bytelane o dummymmu o ebsa110 0 errors o models o pagetab o profiler o tracer o trickbox o validate o watchpnt o winglass o example o armsd obj gccsolrs angsd o armsd obj gccsolrs sarmul a armsd obj gccsolrs iarm a armsd obj gccsolrs armul920 a_ armsd obj gccsolrs armul940 a armsd obj gccsolrs armulib a armsd obj gccsolrs asdlib a a
194. RITEQ used by the examples in this chapter to print to the debugger console Upgrade to the latest ICEagent currently 2 07 to remedy this problem It is possible to make a temporary workaround to this problem by using the following code to replace the Write0 SWI call though the recommended fix is to upgrade to ICEA gent 2 07 x Write a character __swi SemiSWI void _WriteC unsigned op char C define WriteC c _WriteC 0x3 c void WriteQ char string int pos 0 while string pos WriteC amp string pos 10 11 2 Linker errors These are common linker errors Undefined symbols _ rt_ or _16 rt_ The linker reports a number of undefined symbols of the form __rt_ or __16__rt_ Cause These are runtime support functions called by compiler generated code to perform tasks that cannot be performed simply in ARM or Thumb code for example integer division or floating point operations For example the following code generates a call to runtime support function __rt_sdiv to perform a division int test int a int b return a b 10 34 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Writing Code for ROM Solution Link with a C library so that these functions are defined Undefined symbols __rt_stkovf_split_big or __rt_stkovf_split_ small The linker reports one of the symbols _rt_stkovf_split_big or __rt_stkovf_split_small as being undefine
195. RM DCC instructions to the processor No other extra channels are supported 13 26 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 2 7 Downloading new application versions There are a number of techniques you can use to move successive versions of your application onto a development board Each technique has advantages and disadvantages Using Angel with a serial port This gives slow downloading but has the advantage that it requires only a simple UART on the development board If your board supports Flash download you can use this method to fix your image in Flash Using Angel with serial and parallel ports This provides medium speed downloading but requires a serial and a parallel port on the development board If your board supports Flash download you can use this method to fix your image in Flash Using Angel with an Ethernet connection This provides fast downloading but requires Ethernet hardware on the development board and a considerable amount of Ethernet support software to run on the development board If your board supports Flash download you can use this method to fix your image in Flash Flash download This provides slow to fast downloading depending on the type of connection you are using This method is only available on boards that have Flash memory and are supported by the Flash download program It has the advantage that after the Flash is set the image is fixed in mem
196. RM Project Manager _ Note To build from a single source file you must access the file as part of a project because APM uses the project template to determine how to process the file 2 3 4 View window The View window is used to display the contents of a binary file such as an object library or image file using a utility such as decaof decaxf or armlib Figure 2 8 shows an example of the View window fm C examples DebugRel hello o Header file C examples Debughel hello o AOF file type Little endian Relocatable object code AOF Version 311 Ho of areas 12 No of symbols 11 Area 0 CSScode Alignment 4 Size 32 0z0020 1 relocations Attributes Code a2bit NosWotackCheck Read only EXPORT main main Ox000000 ef2d4000 STMDB ria ri4 OxQU0004 e2zerord2e ADD rO poe 6 0x14 Ox000008 ebrfrrfre BL _printf 0z00000e ezanit MOV r 0 0z000010 esbd8000 LDMIA ris pe Sole ESlitpoolso OxQ00014 6c6c6546 eICVSL ps c6 r12 0x120 OxO00018 6f57206f gt owls 0z57206f ESlitpool eS0 Oz3 NANNI MNA dr 7 RSRF rA r r BOP rl Figure 2 8 View window ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 19 ARM Project Manager 2 4 Additional APM functions This section describes configuring tools force building a project adding a new variant to a project building selected variants changing the name of a project
197. SET 32bitRAM is at 0x00000000 to hold the exception vectors 16bitRAM is at 0x02080000 for the storage of program variables To Fos Initialized RW data FLASH Exception vectors ry A Main program code Remap FLASH after RESET Boot code 0x04000000 a T 16bitRAM 16bitRAM Initialized RW data TN 0x00000000 gt 32bitRAM On RESET Load View Execution View Boot code L 0x00000000 Figure 10 3 Memory map for example 4 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 7 2 Scatter load description file ARM DUI 0040D The scatter load description file shown in Example 10 9 defines one load region FLASH three execution regions FLASH at 0x04000000 32bitRAM at 0x0 16bitRAM at 0x02080000 On reset an aliased copy of FLASH is re mapped by hardware to address zero as described in Memory map considerations on page 10 3 Following reset 32bitRAM is mapped to address zero by the first few instructions in boot o The 32bitRAM region might be fast on chip internal RAM and is typically used for code that must be executed quickly Here the exception vectors of vectors o get relocated copied from FLASH to 32bitRAM It can also be advantageous to locate the stack here if enough memory is available The 16bitRAM region might be slower off chip external DRAM and is typically used for less frequently accessed
198. SVC see The processor response to an exception on page 9 5 If the processor is already in supervisor mode Ir_SVC and spsr_SVC are corrupted If you call a SWI while in supervisor mode you must store Ir_SVC and spsr_SVC to ensure that the original values of the link register and the SPSR are not lost For example if the handler routine for a particular SWI number calls another SWI you must ensure that the handler routine stores both Ir_SVC and spsr_SVC on the stack This ensures that each invocation of the handler saves the information needed to return to the instruction following the SWI that invoked it Example 9 8 on page 9 18 shows how to do this ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 17 Handling Processor Exceptions STMFD LDR BIC MOV MRS STMFD BL LDMFD MSR LDMFD END sp rQ r3 Ir r0 Ir 4 r0 r0 0xfF000000 rl sp r2 spsr sp r2 C_SWI_Handler sp r2 spsr r2 sp r0 r3 pc Example 9 8 SWI Handler Store registers Calculate address of SWI instruction and load it into rQ Mask off top 8 bits of Instruction to give SWI number Second parameter to C routine 1S pointer to register values Move the spsr into a general purpose register Store spsr onto stack This is only really needed in case of nested SWIs Call C routine to handle the SWI Restore spsr from stack into r2 and restore it int
199. Stack Stack operations are very useful at subroutine entry and exit At the start of a subroutine any working registers required can be stored on the stack and at exit they can be popped off again In addition if the link register is pushed onto the stack at entry additional subroutine calls can safely be made without causing the return address to be lost You can return from a subroutine by popping the pc off the stack at exit rather than by popping lr and then moving that value into the pc For example Subroutine STMFD code BL ARM DUI 0040D code LDMFD sp r5 r7 Ir Push work registers and Ir somewhere_else sp r5 r7 pc Pop work registers and pc Copyright 1997 1998 ARM Limited All rights reserved 5 37 Basic Assembly Language Programming Warning Use this with care in mixed ARM Thumb systems You cannot return to Thumb code by popping directly into the program counter 5 38 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 5 7 4 num Start wordcopy stop Src dst Basic Assembly Language Programming Block copy with LDM and STM AREA EQU ENTRY LDR LDR MOV LDR STR SUBS BNE MOV LDR SWI AREA DCD DCD END ARM DUI 0040D Example 5 10 is an ARM code routine that copies a set of words from a source location to a destination by copying a single word at a time It is supplied as word s in the examples asm subdirectory of the toolkit
200. T v2 50 Program folder if you are running Windows NT4 double click on the ARM Debugger for Windows icon in the ARM SDT v2 50 Program group or select Start Programs ARM SDT v2 50 ARM Debugger for Windows if you are working in the ARM Program Manager click the ARM Debugger button or select Debug project from the Project menu launch ADW from the DOS command line optionally with arguments Start the ARM Debugger for UNIX ADU in either of the following ways from any directory type the full path and name of the debugger for example opt arm adu change to the directory containing the debugger and type its name for example adu The possible arguments which must be in lower case for both ADW and ADU are debug ImageName Load ImageName for debugging exec ImageName Load and run ImageName reset Reset the registry settings to defaults nologo Do not display the splash screen on startup nowarn Do not display the warning when starting remote debugging nomainbreak Do not set a breakpoint on main on loading image script ScriptName Obey the ScriptName on startup This is the equivalent of typing obey ScriptName as soon as the debugger starts up symbols Load only the symbols of the specified image This is equivalent to selecting Load Symbols only from the File menu Copyright 1997 1998 ARM Limited All rights reserved 3 9 ARM Debuggers for Windows and UNIX 3 2 3 3
201. The ARMulator is supplied with the following models Basic models Memory models Coprocessor models Operating system models Basic models The following source files are provided for the basic models tracer c The tracer module can trace instruction execution and events from within the ARMulator profiler c The profiler module provides the profiling functionality This includes basic instruction sampling and more advanced use such as profiling cache misses winglass c This module is used only with the ARM Debugger for Windows pagetab c This module sets up the MMU cache and associated pagetables inside the ARMulator on reset Memory models The following source files are provided for memory models armflat c This memory model implements a flat model of 4GB RAM armfast c This memory model implements a flat model of 2MB RAM Copyright 1997 1998 ARM Limited All rights reserved 12 3 ARMulator 12 4 armmap c bytelane c trickbox c tracer c armpie c example c This is another memory model that allows you to have an armsd map file specifying memory layout This slows down emulation speed so when no armsd map file is present ARMulator uses the faster armflat c model in preference This is an example of a memory model veneer A veneer is a model that sits between the processor and the real memory model This model converts the accesses from the core into byte lane also known as byte strob
202. This can be a very useful debugging tool Reading the memory statistics To read the memory statistics use the command Print memory_statistics The statistics are reported in the following form 11 12 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D address name 00000000 Dummy 7FFF8000 Stack 00010000 DRAM 00008000 ROM 00000000 SRAM Benchmarking Performance Analysis and Profiling Example 11 1 w acc R N S W N S reads N S writes N S time ns 4 1 1 1 1 0 0 0 0 Q 2 rw 150 100 150 100 0 0 0 0 Q 2 rw 150 100 150 100 0 0 0 0 Q 2 r 100 100 100 100 0 0 0 0 Q 4 rw 1 1 1 1 0 0 0 0 Q Print memstats is a Shorthand version of Print memory_statistics Processor clock speed You must specify the clock speed of the processor being simulated in the debugger In armsd this is set by the command line option clock value The value is presumed to be in Hz unless MHz is specified In ADW or ADU the clock speed is set in the Debugger Configuration dialog To display this dialog 1 Select Options Configure Debugger Target ARMulate Configure 2 Enter a value and click OK See ARMulator configuration on page 3 57 for more information 11 3 6 Real time simulation example Dhrystone ARM DUI 0040D To work through this example you must create a map file If a map file is included in the files you copied from the toolkit directory edit it to match the one shown here Call it a
203. UBLES pc Ir 4 ARM DUI 0040D Reached the end No so return Insert transfer complete code here Byte transfers can be made by replacing the load instructions with load byte instructions Transfers from memory to an I O device are made by swapping the addressing modes between the load instruction and the store instruction Dual channel DMA transfer Example 9 15 on page 9 28 is similar to Example 9 14 except that there are two channels being handled which may be the input and output side of the same channel The code is an FIQ handler It uses the banked FIQ registers to maintain state between interrupts It is best situated at location OxIc Copyright 1997 1998 ARM Limited All rights reserved 9 27 Handling Processor Exceptions LDR TST LDREQ LDRNE STREQ STRNE CMP CMPLE SUBNES In the example code rs Points to the base address of the I O device from which data is read IOStat Is the offset from the base address to a register indicating which of two ports caused the interrupt 1OPort1Active Is a bit mask indicating if the first port caused the interrupt otherwise it is assumed that the second port caused the interrupt 1OPort1 OPort2 Are offsets to the two data registers to be read Reading a data register clears the interrupt for the corresponding port r9 Points to the memory location to which data from the first port is being transferred r10 Points to the memory location to which data from t
204. URCE Cancel CiC include file Assembler source C SOUTCE Figure 2 25 The APM New dialog 2 Select Project from the list of options and click OK The New Project dialog is displayed Figure 2 26 on page 2 54 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 53 ARM Project Manager New Project Ed Template Description OK Build and debug an ARM executable image made from C C and ARM Assembly Cancel Language source files and ARM Object Libraries The DebugRel variant compiles smaller faster code that can be debugged tested and released unchanged ou can build your object libraries using sub projects ARM C Executable Image Project Name project Project Directory examples Browse Figure 2 26 The APM New Project dialog 3 Select the type of project you want to create In addition to the standard options available in SDT 2 50 you can create a project based on the new C templates These are ARM C Executable Image Thumb C Executable Image ARM C Object Library Thumb C Object Library Thumb ARM C Interworking Image 4 Enter a project name and project directory for the new project 5 Click OK A new project is created for the type of image or library you have chosen 2 54 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 3 ARM Debuggers for Windows and UNIX This chapter describes the ARM Debu
205. V Temp Bot CMP Temp Top LSR 1 MOVLS Temp Temp LSL 1 CMP Temp Top LSR 1 BLS b90 IF Div lt gt MOV Div 0 ENDIF CMP Top Temp SUBCS Top Top Temp IF Div lt gt ADC Div Div Div ENDIF MOV Temp Temp LSR 1 CMP Temp Bot BHS b91 MEND Example 5 13 Produce an error message if the registers supplied are not all different These three only matter if Div gt 1S not null Put divisor in Temp double it until gt 2 Temp gt Top The b means search backwards Omit next instruction if Div is null gt Initialize quotient Can we subtract Temp If we can do so Omit next instruction if Div is null Double Div Halve Temp gt and loop until less than divisor The macro checks that no two parameters use the same register It also optimizes the code produced if only the remainder is required Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming To avoid multiple definitions of labels if DivMod is used more than once in the assembler source the macro uses local labels 90 91 See Local labels on page 5 28 of the ARM Software Development Toolkit Reference Guide Example 5 14 shows the code that this macro produces if it is invoked as follows ratio DivMod rQ r5 r4 r2 Example 5 14 ASSERT r5 lt gt r4 ASSERT r5 lt gt r2 ASSERT r4 lt gt r2 ASSERT r lt
206. YS_WRITEC 0x03 Writes a character byte pointed to by rl to the debug channel When executed under an ARM debugger the character appears on the display device connected to the debugger Entry On entry rl contains a pointer to the character Return None Register rO is corrupted 13 7 5 SYS WRITEO 0x04 ARM DUI 0040D Writes a null terminated string to the debug channel When executed under an ARM debugger the characters appear on the display device connected to the debugger Entry On entry rl contains a pointer to the first byte of the string Return None Register rO is corrupted Copyright 1997 1998 ARM Limited All rights reserved 13 83 Angel 13 7 6 SYS WRITE 0x05 13 84 Writes the contents of a buffer to a specified file at the current file position The file position is specified either explicitly by a SYS_SEEK implicitly as one byte beyond the previous SYS_READ or SYS_WRITE request The file position is at the start of the file when the file is opened and is lost when the file is closed The file operation should be performed as a single action whenever possible That is a write of 16KB should not be split into four 4KB chunks unless there is no alternative Entry On entry rl contains a pointer to a three word data block word 1 contains a handle for a file previously opened with SYS_OPEN word 2 points to the memory containing the data to be written word 3 contains the
207. You can use the Retain partition selection settings on the APM Preferences dialog to keep the default partition set to the one last used Project templates supplied with APM have a Miscellanea partition where files of types not associated with other partitions are placed If the Miscellanea partition does not exist when you add a file not associated with a partition the Unable to Add Files message box appears To add the file to the project you must associate the file type with a partition If you have a file type that is associated with more that one partition you can select the partition to receive the file before you add the file to the project Follow these steps to select the partition 1 Select the partition from the project view Copyright 1997 1998 ARM Limited All rights reserved 2 35 ARM Project Manager 2 6 3 2 36 2 Select Add Files to partition from the Project menu 3 Select the files to be added to the project using the Add Files to partition dialog 4 Click OK Performing a single build step You can process and generate output from a single file if it is associated with a project and if the file has been opened as a part of that project If a build step can be performed on the file if it can be compiled or assembled for example the appropriate menu item in the Project menu is enabled and labeled with the name of the build step pattern for the build step If the project template does not define a build
208. _SWI_THUMB OxAB Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 6 Angel communications architecture This section gives an overview of the Angel communications architecture It describes how the various parts of the architecture fit together and how debugging messages are transmitted and processed by Angel For full details of the Angel Debug Protocol refer to the ADP specification document in c ARM25 PDF specs 13 6 1 Overview of the Angel communications layers ARM DUI 0040D Figure 13 12 shows a conceptual model of the communication layers for Angel In practice some layers might be combined BOOT TDCC CLIB Reliable comms and buffer management Device driver with error detection Raw device driver Figure 13 12 Communications layers for Angel The channels layer includes ADP The Angel Debug Protocol channel This consists of the Host ADP channel HADP and Target ADP channel TADP BOOT The boot channel TDCC The Thumb debug communications channel CLIB C library support At the top level on the target the Angel agent communicates with the debugger host and the user application can make use of semihosting support CLIB All communications for debugging ADP BOOT TDCC CLIB require a Reliable channel between the target and the host The Reliable communications and buffer management layer is responsible for providing reliability retransmissions and multiplexing d
209. _TMPNAM 0x0d page 13 88 Return a temporary name for a file on page 88 xk SYS REMOVE 0x0e page 13 89 Remove a file from the host on page 89 RK SYS RENAME Oxf on page 13 89 Rename a file on the host page 89 SYS_CLOCK 0x10 on page 13 90 Number of centiseconds since support code started page 90 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel Table 13 3 Angel semihosting SWIs continued SWI Page Description SY S_TIME 0x11 on page 13 90 Number of seconds since Jan 1 1970 page 90 RE SYS SYSTEM 0x12 page 13 91 Pass a command to the host command line interpreter on page 91 SYS ERRNO 0x13 on page 13 91 Get the value of the C library errno variable page 91 RE SYS _ GET_CMDLINE page 13 92 Get the command line used to call the executable Ox15 on page 92 SYS_HEAPINFO 0x16 page 13 93 Get the system heap parameters on page 93 RK IS YS_ELAPSED 0x30 page 13 94 Get the number of target ticks since support code started on page 94 RK ISYS_TICKFREQ 0x31 page 13 94 Define a tick frequency on page 94 13 7 2 SYS_OPEN 0x01 Open a file on the host system The file path is specified either as relative to the current directory of the host process or absolutely using the path conventions of the host operating system The ARM debuggers interpret the special path name tt as meaning the cons
210. _func o info totals info sizes scatter scat txt list out txt map symbols xref c ARM250 1ib embedded armlib_cn 321 0 scatter axf fromelf nozeropad scatter axf bin scatter bin This creates ARM DUI 0040D an ELF debug image scatter axf for loading into a debugger ADW ADU or armsd a binary ROM image scatter bin suitable for downloading into the Flash memory of a PID board Copyright 1997 1998 ARM Limited All rights reserved 10 25 Writing Code for ROM 10 8 Example 5 Complex scatter load example 10 8 1 10 26 This example shows a more complex scatter loading application that runs from the Flash memory on an ARM Development Board PID7T It reads the switches S3 connected to the Parallel Port and flashes LEDs It requires the link LK8 to be closed and the LK11 link field to be correctly configured Refer to the documentation for the ARM Development Board for more information The code for this example is in Examples rom PID_Scatter in your SDT installation directory normally c ARM250 Examples rom PID_Scatter Note This code is a modified version of the code provided in the sample code suite of the ARM Development Board Memory map This example shows FLASH is 0 on RESET and is remapped to 0x04000000 after RESET Fast SSRAM is at 0x0000 to hold the exception vectors and the exception handlers SRAM is at 0x02000 for the storage of program variables 0x08000000 gt
211. a jump table holding the individual Angel Interrupt source handler function pointers The PID board has the following possible interrupt sources TIMER For polled device support and profiling PARALLEL For parallel code download if this option is selected at compile time PCMCIA CARD A Used by the Olicom Ethernet driver if selected at compile time PCMCIA CARD B Used by the Olicom Ethernet driver if selected at compile time SERIAL A This is the default for debug communications SERIAL B This is optional for debug communications CACHE_IBR This macro is called by Angel support routines in suppasm s to set an Instruction Barrier Range This is an option on the SA1100 processor There is no code included in this macro for the PID example makelo c This file enables you to share variables and definitions between C and assembly language sources The makelo c source file is compiled with armcc and executed under armsd as part of the Angel build process When executed it reads the contents of the C header files included at the start of makelo c and produces an assembler header file named lolevel s The assembler header file mirrors the C definitions in the included C header files For example the processor mode defined in arm h such as define USRmode 0 produce equivalent assembler EQU directives such as USRmode EQU Use a GET directive to include lolevel s in any assembly language file that requires access to C variables
212. ables 2 26 variants 2 27 viewing 2 8 window 2 15 Properties of variables 3 39 Prototype statement 5 43 Pseudo instructions assembly language ADR 5 27 5 53 ADR Thumb 5 27 ADRL 5 27 5 53 LDR 5 22 5 25 5 30 LDR literal pools 5 25 PUSH instruction Thumb 5 41 Q Quitting ADW ADU 3 10 APM 2 4 R RAM at address O 10 3 measuring requirements 11 4 RB_ Angel register blocks 13 38 RDI Remote Debug Interface 3 6 log window 3 24 3 41 Real time addresses 3 5 Real time simulation 11 8 References 8 18 RegionInit macro scatter loading 10 24 10 28 Register access Thumb 5 9 Register banks 5 4 Register based symbols 5 53 Index 10 Register based maps 5 48 Register relative address 5 11 Registers 5 4 displaying contents 4 3 halting if changed 3 29 REMAP 10 4 usage 6 10 window 3 23 Regular expressions 3 42 Relative maps 5 47 Reloading an image 3 11 REMAP register 10 4 Remote debug information 3 41 Remote_A 3 6 configuring 3 59 Reset exception 9 2 handler 9 32 RESET vector 10 4 Return address 9 6 Return instruction 9 6 returning structures 6 13 ROADDR Angel 13 29 13 48 13 70 13 71 ROM at address O 10 3 measuring requirements 11 4 writing code for 10 1 ROMBase macro 13 71 ROMulator 13 68 ROUT directive 5 11 RTOS and Angel 13 19 and context switching 13 38 Run to cursor 3 34 Running licensed software A 7 RWADDR Angel 13 29 13 48 13 70 13 71 S Saved program status register 5
213. ables and ZI data of the main program code in C_main c get copied initialized in SRAM at address 0x2000 All other read only code R0 for example region initialization and library code is executed from FLASH by using a wildcard in the description file Example 10 10 scat txt FLASH 0x04000000 0x04000000 FLASH 0x04000000 boot o Boot First RO SSRAM 0x0000 vectors o Vect FIRST C_int_handler o RO SRAM Ox2000 C_main o RW ZI Copyright 1997 1998 ARM Limited All rights reserved 10 27 Writing Code for ROM 10 8 3 10 8 4 Initialization code This example illustrates the use of boot code boot s as described in nitialization code on page 10 24 Note The initialization code should move all the execution regions from their load addresses to their execution addresses before creating any zero initialized areas This ensures that the creation of a zero initialized area does not overwrite any execution region contents before they are moved from their load address to their execution address Failure to do so may produce unpredictable results when the image executes Initializing execution regions This example uses region initialization code regioninit s as in Initializing execution regions on page 10 24 but changes the macro invocations in the scatter load description file macro_RegionInit SSRAM macro_RegionInit SRAM 10 8 5 Building the example 10 28 To b
214. abort Three types of instruction can cause this abort Single Register Load or Store The response depends on the processor type If the abort takes place on an ARM6 based processor If the processor is in early abort mode and writeback was requested the address register will not have been updated If the processor is in late abort mode and writeback was requested the address register will have been updated The change must be undone If the abort takes place on an ARM 7 based processor including the ARM7TDMI the address register will have been updated and the change must be undone If the abort takes place on an ARMOTDMI or StrongARM based processor the address is restored by the processor to the value it had before the instruction started No further action is required to undo the change Swap There is no address register update involved with this instruction Load Store Multiple The response depends on the processor type If the abort takes place on an ARM6 based processor or ARM 7 based processor and writeback is enabled the base register will have been updated as if the whole transfer had taken place In the case of an LDM with the base register in the register list the processor replaces the overwritten value with the modified base value so that recovery is possible The original base address can then be recalculated using the number of registers involved If the abort takes place on an ARMOTDMI or
215. ach exception If the ROM is located elsewhere the vectors must be dynamically initialized by the initialization code Some standard code for doing this is shown in Example 2 Building a ROM to be entered at its base address on page 10 17 Copyright 1997 1998 ARM Limited All rights reserved 10 5 Writing Code for ROM 10 3 3 Initializing the memory system If your system has a Memory Management or Protection Unit you must make sure that it is initialized before interrupts are enabled before any code is called that might rely on RAM being accessible at a particular address either explicitly or implicitly through the use of stack 10 3 4 Initializing the stack pointers The initialization code initializes the stack pointer registers You may need to initialize some or all of the following stack pointers depending on which interrupts and exceptions you use sp_SVC must always be initialized sp_IRQ must be initialized if IRQ interrupts are used It must be initialized before interrupts are enabled sp_FIQ must be initialized if FIQ interrupts are used It must be initialized before interrupts are enabled sp_ABT must be initialized for data and prefetch abort handling sp_UND must be initialized for undefined instruction handling Generally sp_ABT and sp_UND are not used in a simple embedded system However you may wish to initialize them for debugging purposes Note You can set up the stack pointer sp_USR w
216. ag from the low word addition in the high word addition However in C there is no way of specifying the Carry flag Example 6 1 shows a workaround Example 6 1 void add_64 int64 dest int64 srcl int64 src2 unsigned hibitl srcl gt lo gt gt 31 hibit2 src2 gt lo gt gt 31 hibit3 dest gt lo srcl gt lo src2 gt 1l0 hibit3 dest gt lo gt gt 31 dest gt hi srcl gt hi src2 gt hi hibitl amp hibit2 hibitl hibit3 return The highest bits of the low words in the two operands are calculated shifting them into bit 0 while clearing the rest of the register These bits are then used to determine the value of the carry bit in the same way as the ARM itself does Examining the compiler output If the addition routine were to be used a great deal an implementation such as this would probably be inadequate To consider the quality of the implementation examine the code produced by the compiler Follow these steps to produce an assembly language listing 1 Copy file examples candasm add64_1 c to your current working directory This file contains the C code in Example 6 1 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D 2 Compile it to ARM assembly language source as follows armcc l1 S add64_1 c Using the Procedure Call Standards The S flag tells the compiler to produce ARM assembly language source suitable for armasm instead of object code E
217. age This template builds an ARM Thumb C interworking image from Thumb C and C source files ARM C and C source files Thumb ARM assembly language source files Thumb object libraries 2 52 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager ARM object libraries 2 10 2 Using the ARM Project Manager C Templates The APM C templates provide a number of options for creating C source files header files and projects This section describes how to create new projects based on the C project templates The following general points apply to the templates All templates that produce ARM executable images or ARM object libraries are configured to use armcpp to compile C source files All templates that produce Thumb executable images or Thumb object libraries are configured to use tcpp to compile C source files All templates that produce executable images use the ARM Debugger for Windows ADW as their debugger You can convert a non interworking project to an interworking project by following the instructions in ARM Thumb interworking with the ARM Project Manager on page 7 23 Substitute armcpp for armcc and tcpp for tcc e Libraries must contain either ARM code only or Thumb code only Creating new projects Follow these steps to create a new C project 1 Select New from the File menu The New dialog is displayed Figure 2 25 CiC SO
218. age Programming TAG return cfunc amp t In C struct T extern int f__1TFi struct T int create an object of type T the mangled name of the C function to be called int cfunc struct Tx t x C x like 3 t gt f 2 return 3 f__1TFi t 2 7 Definition of the C function to be called from ala r0 already contains the object pointer multiply by 3 Example 8 16 Passing a reference between C and C functions Or implementing cfunc in ARM assembly language EXPORT cfunc AREA cfunc CODE IMPORT f__1TFi STMDB sp Ir MOV ri 2 BL f__1TFi ADD r r0 r0 LSL 1 LDMIA sp pc END In C extern C int cfunc const int amp extern C int cppfunc const int amp r return 7 x r int f int 1 3 return cfunc 1 f In C 8 24 passes a pointer to 1 Copyright 1997 1998 ARM Limited All rights reserved Declaration of the C function to be called from C Definition of the C to be called from C ARM DUI 0040D Mixed Language Programming declaration of the C to be called from C definition of the C function to be called x from C extern int cppfunc const int int cfunc const ints p int k p 4 return cppfunc amp k ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 8 25 Mixed Language P
219. age declarations that are supported by armasm are not implemented SWI and BL instructions SWIs and branch link instructions must specify exactly which calling standard is used Three optional register lists follow the normal instruction fields The register lists specify the registers that are the input parameters the registers that are output parameters after return the registers that are corrupted by the called function For example SWI cond swi_num input_regs output_regs corrupted_regs BL cond function input_regs output_regs corrupted_regs An omitted list is assumed to be empty except for BL which always corrupts r0 r3 ip and Ir The register lists have the same syntax as LDM and STM register lists If the NZCV flags are modified you must specify PSR in the corrupted register list Differences between the inline assemblers and armasm There are a number of differences between the assembly language accepted by the inline assemblers and the assembly language accepted by the ARM assembler For the inline assemblers You cannot get the address of the current instruction using dot notation or PC The LDR Rn expression pseudo instruction is not supported Use MOV Rn expression instead this may generate a load from a literal pool Label expressions are not supported The ADR and ADRL pseudo instructions are not supported The amp operator cannot be used to denote hexa
220. aken by the veneers The interworking veneers are included in the const data column of the object totals See Figure 7 1 on page 7 14 for an example code inline inline const RW Q Init debug size data strings data data data data Object totals 32 Q 92 20 Q Q Q Library totals 6924 1516 532 4 264 1104 2224 Grand totals 6956 1516 624 24 264 1104 2224 Debug Area Optimization Statistics Copyright 1997 1998 ARM Limited All rights reserved 7 13 Interworking ARM and Thumb Input debug total excluding low level debug areas 2224 2 17Kb Output debug total 2224 2 17Kb reduction 0 00 Figure 7 1 Total code sizes Use the armlink info size option to see more detail The space taken by the veneers is displayed as an lt anon gt row entry at the top of the table See Figure 7 2 for an example object file code inline inline const RW Q Init debug size data strings data data data data arm o 8 Q 36 Q Q Q Q thumb o 24 Q 56 Q Q Q Q lt anon gt Q Q Q 20 Q Q Q Figure 7 2 Interworking veneer sizes Simple C interworking example The two modules in Example 7 4 can be built to produce an application where main is a Thumb routine that carries out an interworking call to an ARM subroutine The subroutine call itself makes an interworking call to the Thumb library routine printf Example 7 4 thumb c include lt stdio h gt extern void arm_function void int main void printf Hello from Thumb World n
221. all standard for the ARM not Thumb compiler in SDT 2 11a was apcs 3 32 fp swst wide softfp The default procedure call standard for the ARM not Thumb assembler in SDT 2 1 1a was apcs 3 32 fp swst Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Introduction Impact Existing makefiles and APM project files where the PCS was not specified will generate code that does not perform software stack checking and does not use a frame pointer register This will result in smaller and faster code because the default for previous compilers was to emit function entry code that checked for stack overflow and set up a frame pointer register Default debug table format In SDT 2 50 and C 1 10 the default debug table format is DWARF 2 DWARE 2 is required to support debugging C and to support the improvements in debugging optimized code The default debug table format emitted by the SDT 2 1 1a compilers and assemblers was ASD If DWARF debug table format was chosen the SDT 2 1 1a compilers and assemblers emitted DWARF 1 0 3 Impact Existing makefiles and APM project files where debugging information was requested will now result in DWARF 2 debug data being included in the executable image file Previous behavior can be obtained from the command line by specifying g asd or g dwarf1 or by choosing these from the appropriate Tool Configuration dialog boxes in APM Default image file format
222. am execution is directed to the __main entry point At this point the initialization procedure is different for full Angel and minimal Angel For minimal Angel a The device drivers are set up for transmission of raw data only The ADP packet protocol and communications channels are not used b The application entry point is called by a branch with link BL instruction to an __entry label You must use this label as your application entry point to ensure that the application is launched For full Angel a The communications channels are initialized for ADP Any raw data channels installed for the application are set up if you are using extra channels The application can set this up itself Refer to the Angel source code for details c Full Angel transmits its boot message through the boot task and waits for communication from the debugger 13 3 2 Waiting for debug communications 13 30 After initialization full Angel enters the idle loop and continually calls the device polling function This ensures that any polled communications device is serviced regularly When input is detected it is placed into a buffer and decoded into packet form to determine which operation has been requested If an acknowledgment or reply is required it is constructed in an output buffer ready for transmission All Angel operations are controlled by Angel task management Refer to Angel task management on page 13 33 and Example of Angel proces
223. ames and source code Denotes a permitted abbreviation for a command or option The underlined text may be entered instead of the full command or option name typewriter italic italic bold Denotes arguments to commands and functions where the argument is to be replaced by a specific value Highlights important notes introduces special terminology denotes internal cross references and citations Highlights interface elements such as menu names Also used for emphasis in descriptive lists where appropriate and for ARM processor signal names typewriter bold Denotes language keywords when used outside example code Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Feedback Feedback on this book Preface ARM Limited welcomes feedback on both the Software Development Toolkit and the documentation If you have any comments on this book please send email to errata arm com giving the document title the document number the page number s to which you comments apply a concise explanation of your comments General suggestions for additions and improvements are also welcome Feedback on the ARM Software Development Toolkit ARM DUI 0040D If you have any problems with the ARM Software Development Kit please contact your supplier To help us provide a rapid and useful response please give details of the release you are using details of the platform you are running on such as the
224. amples assume a no software stack checking and no frame pointer APCS variant Example 8 9 shows a C program that uses a call to an assembly language subroutine to copy one string over the top of another string Example 8 9 Calling assembly language from C include lt stdio h gt extern void strcopy char d char xs int main char srcstr First string source char dststr Second string destination printf Before copying n printf s n s n srcstr dststr strcopy dststr srcstr printf After copying n printf s n s n srcstr dststr return 0 The ARM assembly language module that implements the string copy subroutine AREA SCopy CODE READONLY EXPORT strcopy strcopy Copyright 1997 1998 ARM Limited All rights reserved 8 19 Mixed Language Programming r points to destination string rl points to source string LDRB r2 r1 1 Load byte and update address STRB r2 rQ 1 Store byte and update address CMP r2 0 Check for zero terminator BNE strcopy Keep going if not MOV pc Ir Return END Example 8 9 on page 8 19 is located in the examples asm subdirectory of your installation directory as strtest c and scopy s Follow these steps to build the example 1 Type armasm scopy s at the command line to build the assembly language source 2 Type armcc c strtest c to build the C source 3 Type armlink strtest o scopy o o strtest to link the objec
225. an either use Angel on one serial port and your own device on the other use minimal Angel which requires no serial port and use either or both of the serial ports for your application The PID Angel port provides examples of raw serial drivers Refer to the Angel source code for details of how these are implemented If you want to use Angel with your own hardware you must write your own device drivers Refer to Writing the device drivers on page 13 63 for more information Angel serial drivers Figure 13 3 on page 13 26 gives an overview of the Angel serial device architecture Copyright 1997 1998 ARM Limited All rights reserved 13 25 Angel D g lt I bj Minimal Angel lt g a g Application 3 p R wit Swisher serraw c Byte Serial Devices Packet Packet I F Write Send layer serpkt c Devclnt c Device Channels Switcher layer 7 z Packet Packet ee Read Read T unreliable channel reliable T unordered ordered simplex multiple T uses Rx Tx Develnt c streams streams code be ee Angel Poll Device Call sms a ee ge ess ee ee ee iy aa i a a i a ae en on Ven Am ie pee nn ee the a es Angel meme Sons Figure 13 3 Angel raw serial device Using the Thumb Debug Communication Channel You can use cin and cout in armsd and the channel viewer interface to access the TDCC from the host You can use the TDCC channel to send A
226. and directives 5 46 Using the Procedure Call Standards 6 1 About the procedure Call standards cccccccseecceeeeceeeeceeeeceeeeseeeeseeeaees 6 2 6 2 Using the ARM Procedure Call Standard cccccsseeceeeceeeeeeeeeeeeeeeeaneees 6 3 6 3 Using the Thumb Procedure Call Standard cccccssseeeceeeeeeeeeeeeeeeees 6 11 6 4 Passing and returning structures cc eceeecceceeseeeeeeensereeeeaneeteeseueeeeenas 6 13 Interworking ARM and Thumb 7 1 Abou tinterWorkingi sssacisien Seite cata dudit te a E 7 2 7 2 Basic assembly language interworking ccceeeeeeeeeeeeeeeeeeaeeeeeeeeeeeeeeaaes 7 4 7 3 C and C interworking and veneers cccccseeeeecceeeeeeeeeceeeeeeeeneeeeeeesaaees 7 12 7 4 Assembly language interworking USING veneers cccceeeeeeeeeeeeeeeeeeeees 7 19 7 5 ARM Thumb interworking with the ARM Project Manager saensnnaannn 7 23 Mixed Language Programming 8 1 Using the inline assemblers ss 8 2 8 2 Accessing C global variables from assembly code 8 14 8 3 Using C header files from C ceccccccseeeeeeceeeeeeeeceeeeecaeeeeeeeeaeeeeeseaneeeeeas 8 15 8 4 Calling between C C and ARM assembly language 8 17 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 9 Chapter 10 Chapter 11 Chapter 12 ARM DUI 0040D Contents Handlin
227. andlers You can chain your own exception handlers to the Angel exception handlers Refer to Chaining exception handlers on page 13 20 for more information 13 5 4 Configuring where Angel runs This section describes how to configure Angel to run from ROM ROM mapped to address zero RAM the default Link addresses The makefile for angel rom contains two makefile macros that control the addresses where Angel is linked RWADDR This defines the base address for read write areas such as dataseg and bss zero initialized areas along with some assembler areas Angel requires approximately 24KB of free RAM for its read write areas ROADDR This defines the base address for read only areas In general read only areas are code areas Angel requires between 50 and 100KB of RAM for its read only areas 13 70 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel The target specific configuration file devconf h contains a number of macros that define the memory layout of the target board It also contains checks to ensure that the values of RWADDR and ROADDR are sensible Most of these macros are only used within devconf h for the sanity checks in the READ WRITE_PERMITTED macros and for defining application stack and heap areas In addition the macro ROMBase is used during startup to calculate the offset between the code currently executing in ROM and its eventual ROADDR destination
228. ar into rl from literal pool LDR rQ r1 ADD r0 rO 2 STR rQ r1 MOV pc Ir END 8 14 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Mixed Language Programming 8 3 Using C header files from C This section describes how to use C header files from your C code C header files must be wrapped in extern C directives before they are called from C 8 3 1 Including system C header files To include standard system C header files such as stdio h you need do nothing special The standard C header files already contain the appropriate extern C directives For example C code include lt stdio h gt int main he return Q The C standard specifies that the functionality of the C header files is available through C specific header files These files are installed in c ARM250 include together with the standard C header files and may be referenced in the usual way For example C code include lt cstdio gt int main VE MER return Q In ARM C these headers simply include the C headers Note Both the C and C standard header files are available as precompiled headers in the compilers in memory file system Refer to Chapter 2 The ARM Compilers in the ARM Software Development Toolkit Reference Guide for more information ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 8 15 Mixed Language Programming 8 3 2 Including
229. are optionally returned in r0 r3 as described earlier The operation number passed in r12 could be but need not be the number of the SWI to be called by the generic SWI Example 9 10 on page 9 21 shows a C fragment that uses a generic or indirect SWI Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions Example 9 10 __swi_indirect 0x80 unsigned SWI_ManipulateObject unsigned operationNumber unsigned object unsigned parameter unsigned DoSelectedManipulation unsigned object unsigned parameter unsigned operation return SWI_ManipulateObject operation object parameter This produces the following code EXPORT DoSelectedManipulation DoSelectedManipulation Qx000000 ela c0Q2 MOV r12 r2 Qx000004 efQ00080 SWI 0x80 0x000008 ela0f0 e MOV pc r14 It is also possible to pass the SWI number in r0 from C using the __swi mechanism For example if SWI 0x0 is used as the generic SWI and operation 0 is a character read and operation a character write the following can be set up __swi char __ReadCharacter unsigned op __swi void __WriteCharacter unsigned op char c These can be used in a more reader friendly fashion by defining the following define ReadCharacter __ReadCharacter 0 define WriteCharacter c __WriteCharacter 1 c However using r0 in this way means that only three registers are available for passing paramete
230. ary By default a read from or write to memory in armsd ADW or ADU transfers a word value For example let 0x8000 0x01 transfers 4 bytes to memory starting at address 0x8000 In this example the bytes at Ox8001 0x8002 and 0x8003 are all zero filled To write a single byte to memory use an instruction of the form let char xaddress value and to read a single byte from memory use an instruction of the form print x char Oxaddress where x means display in hexadecimal You can also read and write halfword short values in a similar way for example let short xaddress value print x short xaddress You can also select View Variables Expression to open the View Expression window and use that to specify bytes or shorts for displaying memory For example for bytes enter char xaddress in the View Expression box and for shorts enter short xaddress in the View Expression box To display in hexadecimal click the right mouse button on the Expression window select Change Window Format and enter x Note Changes to window formats are saved Changes to line formats are not saved If you select Change Window Format and leave the format field blank the setting defaults to the original setting ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 47 ARM Debuggers for Windows and UNIX 3 5 12 Flash download Use the Flash Download dialog Figure 3 1
231. ary functionality Use the ARM C library for early prototyping only and replace it with your own C library targeted at your hardware and operating system environment Support Angel SWIs in your own application or operating system and use the ARM C libraries as provided Port the ARM C library to your own environment The ARM C libraries are supplied as full source code so that you can retarget them to your own system Refer to Retargeting the ANSI C library on page 4 6 of the ARM Software Development Toolkit Reference Guide for more information Use the embedded C library with your own startup code The embedded C library does not rely on underlying Angel or operating system functionality Refer to The embedded C library on page 4 18 of the ARM Software Development Toolkit Reference Guide for more information Using assertions when debugging To speed up debugging Angel includes runtime assertion code that checks that the state of Angel is as expected The Angel code defines the ASSERT_ENABLED option to enable and disable assertions Copyright 1997 1998 ARM Limited All rights reserved 13 21 Angel If you use assertions in your code you should wrap them in the protection of ASSERT_ENABLED macros so that you can disable them in the final version if required 1f ASSERT_ENABLED endif Angel uses such assertions wherever possible For example assertions are made when it is assumed that a stack is empty or that the
232. as been created or you can create your own blank templates After creating a project you can add new tools remove unused tools and edit the build step patterns to suit your needs These changes have a global effect across your project but do not affect the blank template you used when you created your project If you need finer control for example to compile a subset of your sources in a particular way you can use tool configuration settings and or variables to change the handling of a single source or a group of sources For example you could create an additional source partition You could then configure the tool used on source files differently depending on the partition used You could even use a different compiler Finally to create a number of projects that require a framework that is not supported by the supplied blank templates you can create your own blanks To create a blank template take an existing blank template save it to a new file in the Templates directory then make the required changes The new template appears in the list presented when you create a new project Note You are advised to create new templates based on the current APM templates rather than modifying the blank templates supplied with APM 2 40 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 8 2 Blank templates supplied with APM You can use the following APM templates to create both executable ima
233. assembler from C 8 17 C from assembly language 8 17 C from C 8 17 8 19 C from assembler 8 22 C from assembly language 8 17 language conventions 8 17 Calling SWIs 9 19 Case rules assembly 5 10 Chaining exception handlers 9 37 and Angel 13 20 Changing debugger variables 3 12 Channel viewers activating 3 49 Channels Angel channel restrictions 13 74 Characters special 3 42 Class view window 3 63 Clock speeds 11 13 Closing ADW ADU 3 10 APM 2 4 Code ARM Thumb 3 40 density and interworking 7 2 size 5 19 5 56 speed and setymp 11 18 Code size Dhrystone example 11 4 measuring 11 3 reducing 11 16 reducing with short integers 11 17 CODE16 directive 5 16 7 4 CODE32 directive 5 16 7 4 Collapsing project view 2 17 Command line arguments 3 46 debugger instructions 3 46 Command window 3 16 Command line examples 4 2 tools 4 1 Comments assembly language 5 11 inline assemblers 8 3 Communications Angel communications architecture 13 73 ARM DUI 0040D Compiler options latevia 2 23 MD 2 9 reading froma file 2 23 via 2 23 Compiler using 4 2 Complex breakpoint 3 26 watchpoint 3 29 Concepts and terminology 3 7 Condition code suffixes 5 18 Conditional execution Thumb 5 8 5 9 Conditional execution assembly 5 17 5 19 Configuring Angel 13 69 Angel run address 13 70 ARMulator 3 57 EmbeddedICE 3 60 Remote_A 3 59 tools in APM 2 20 Console window 3 15 Constants assembly 5 12 Constants
234. ast region from 0 to 0x7fff with a 32 bit data bus A slower region from 0x8000 to Oxffff with a 16 bit data bus This is labelled ROM and contains the image code and is therefore marked as read only A region of RAM from 0x10000 to 0x17fff that is used for image data A region of RAM from 0x7ff 8000 to 0x7fffffff that is used for stack data the stack pointer is initialized to 0x80000000 In the final hardware the two distinct regions of the external DRAM would be combined This does not make any difference to the accuracy of the simulation The SRAM region is given access times of Ins In effect this means that each access takes 1 clock cycle because ARMulator rounds this up to the nearest clock cycle However specifying it as Ins allows the same map file to be used for a number of simulations with differing clock speeds Note To ensure accurate simulations take care that all areas of memory likely to be accessed by the image you are simulating are described in the memory map To ensure that you have described all areas of memory you think the image should access you can define a single memory region that covers the entire address range as the last line of the map file For example you could add the following line to the above description 00000000 80000000 Dummy 4 1 1 1 1 You can then detect if any reads or writes are occurring outside the regions of memory you expect using the print memory_statistics command
235. ate the value stored in Ir_mode is pc 4 as described in The return address and return instruction on page 9 6 However if the exception occurs in Thumb state the processor automatically stores a different value for each of the exception types This adjustment is required because Thumb instructions take up only a halfword rather than the full word that ARM instructions occupy If this correction were not made by the processor the handler would have to determine the original state of the processor and use a different instruction to return to Thumb code rather than ARM code By making this adjustment however the processor allows the handler to have a single return instruction that will return correctly regardless of the processor state ARM or Thumb at the time the exception occurred The following sections give a summary of the values to which the processor sets Ir_mode if an exception occurs when the processor is in Thumb state SWI and Undefined instruction handlers The handler s return instruction MOVS pc 1r changes the program counter to the address of the next instruction to execute This is at pc 2 so the value stored by the processor in lr_mode is pc 2 FIQ and IRQ handlers The handler s return instruction SUBS pc 1r 4 changes the program counter to the address of the next instruction to execute Because the program counter is updated before the exception is taken the next instruction is at pc 4 T
236. ation dependent The device drivers provided with the PID Angel port can provide a starting point but in many cases you must completely recode the source files The simplest approach is to use the main functions defined in the PID code and rewrite the underlying functionality For example the Angel PID port controls the device through function pointers defined between devcint h and devdriv h The main controlling functions are the angel_DeviceControlFn Transmit Control ControlTx Receive Control ControlRx Copyright 1997 1998 ARM Limited All rights reserved 13 63 Angel 13 64 Transmit Kick Start KickStartFn The interrupt handler These are discussed in more detail in the following sections To implement a device driver you must Write the initialization code for your device Write either an interrupt service routine or a poll function that does input output Provide ring buffers that allow you to communicate with the rest of the code You must provide one transmit and one receive ring buffer Write a control routine similar to the angel_DeviceControlFn Angel device drivers provide control calls for disabling and enabling the reception of raw data disabling and enabling packet interpretation of the data stream initializing the device resetting the device to its default state setting the device configuration to a set of specified parameters Your device drive
237. ation such as inserting an undefined instruction where a breakpoint is required or reading a portion of memory and sending back a response to the host Angel uses a debugging protocol called the Angel Debug Protocol ADP to communicate between the host system and the target system ADP supports multiple channels and provides an error correcting communications protocol Refer to the Angel Debug Protocol specification in Arm25 PDF specs for more information on ADP Angel is supplied as a stand alone form that is built into the Flash and or ROM of ARM evaluation and development boards and other third party boards Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel prebuilt images that you can program into ROM or download to Flash a minimal library that you can link with your application In addition full Angel source is provided so that you can port Angel to your own ARM based hardware ANSI C and C libraries that support Angel are supplied with the ARM Software Development Toolkit Refer to Chapter 4 The C and C Libraries in the ARM Software Development Toolkit Reference Guide for more information 13 1 1 Angel system features ARM DUI 0040D Angel provides the following functionality basic debug support C library support communications support task management exception handling These features are described below See Figure 13 1 on page 13 6 for an overview of the
238. ault address register 9 36 FEATURE line in license file A 9 File formats Intel 32 bit hex 10 33 Intellec hex 10 33 Motorola 32 bit hex 10 33 Files adding to project 2 8 armsd map 11 9 12 28 armul cnf 12 6 12 28 12 34 boot s 10 24 init s 10 12 memory map 3 55 models h 12 5 profiler c 12 12 project 2 4 Finding a license file A 11 FIQ 9 2 9 22 and Angel 13 9 13 19 handler 9 7 9 22 9 41 registers 9 22 Flash download 3 48 13 67 and Angel 13 27 Flat profile 11 19 FlexLM license management A 2 installing A 2 multiple licenses A 12 versions A 12 Force building a project 2 11 Formatting displayed variables 3 38 FPA undefined instruction handlers Functions call graph count 11 20 names window 3 22 3 43 stepping into 3 34 stepping out of 3 34 Fusion IP stack 13 99 9 33 G GETSOURCE macro 13 42 13 46 13 57 13 59 13 100 Global hierarchy in ADW ADU 3 63 Global memory map file 3 55 Globals window 3 22 ARM DUI 0040D H Halfwords in load and store instructions 5 6 reading and writing in ADW ADU 3 47 to reduce code size 11 17 HANDLE_INTERRUPTS_ON_FIQ 13 41 13 62 HANDLE_INTERRUPTS_ON_IRQ 13 61 Heartbeats Angel 13 77 Help online 2 2 3 2 Hierarchy project 2 25 High level symbols 3 43 Host peripherals accessing 3 5 Illegal address 9 2 Image reducing size of 11 16 reloading 3 11 stepping through 3 34 Immediate constants ARM 5 22 implicit this 8 17 IMPORT directive 8 14 INDEX operator 5 5
239. ause the control bits of the cpsr and spsr cannot be changed while in User mode __inline void enable_IRQ void int tmp __asm MRS tmp CPSR BIC tmp tmp 0x80 MSR CPSR_c tmp j j __inline void disable_IRQ void int tmp __asm MRS tmp CPSR ORR tmp tmp 0x80 MSR CPSR_c tmp int main void disable_IRQ enable_IRQ Copyright 1997 1998 ARM Limited All rights reserved Example 8 2 ARM DUI 0040D Mixed Language Programming Dot product Example 8 3 calculates the dot product of two integer arrays It demonstrates how inline assembly language can interwork with C or C expressions and data types that are not directly supported by the inline assembler The inline function mlal is optimized to a single SMLAL instruction Use the S fs compiler option to view the assembly language code generated by the compiler Example 8 3 include lt stdio h gt define 1064 a unsigned amp a low 32 bits of a long long define hi64 a int amp a 1 high 32 bits of a long long __inline __int64 mlal __int64 sum int a int b 1f defined __thumb amp amp defined __TARGET_FEATURE_MULTIPLY __asm SMLAL 1064 sum hi64 sum a b i else sum __1nt64 a __int64 b endif return sum __1nt64 dotprod int a int b unsigned n __1nt64 sum Q do sum mlal sum a b while n 0 return sum int a 10 1 2 3 4 5 6 7 8 9 10
240. available for any later Find operations Select Using Help from the Help menu to display a guide to the use of on screen help Hypertext links Most pages of online help include highlighted text that you can click on to display other relevant online help Clicking on highlighted text underscored with a broken line displays a popup box Clicking on highlighted text underscored with a solid line jumps to another page of help Browse buttons Most pages of online help include a pair of browse buttons that enable you to step through a sequence of related help pages ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 3 ARM Project Manager 2 2 Getting started This section explains various APM concepts and offers you some hands on experience creating a simple project In doing so you make use of some APM features that are described more fully in later sections of this chapter This section covers starting and stopping APM projects and sub projects building a project correcting problems project output 2 2 1 Starting and stopping APM Start APM in any of the following ways if you are running Windows 95 or Windows 98 click on the ARM Project Manager icon in the ARM SDT v2 50 Program folder or select ARM Program Manager from the program menu if you are running Windows NT4 double click on the ARM Project Manager icon in the ARM SDT V2 50 Program group or select Start Programs
241. ayed again the next time you start the Debugger The following sections describe the purpose of each window 3 14 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 3 1 Main windows ARM DUI 0040D This section describes the Execution Console and Command windows Execution window The Execution window Figure 3 3 displays the source code of the program that is currently executing ar ARM Execution Window OxO00080e4 ro 0 Ox 000080e8 Pio rt Faber Ox000080ec Ox00011450 0 r3 r Fire r ri riz r r2 0 ro 0 pe rl4 ri3 r4 r5 ri4 r1i4 ru P42 0 ra rl4 r4 1lsl 2 rO rl4 r4 1lsl 2 rlz rl rd4 lsl 2 ro rl2 4 r rl rd4 lsl 2 r4 r0 0z76 ro r4 ro r4 1 gig pe aa Oxo1l46 Proc_6 OD Oz61l5c Proc_6 Om Ox00008140 ar Figure 3 3 Execution window Use the Execution window to execute the entire program or step through the program line by line change the display mode to show disassembled machine code interleaved with high level C or C source code display another area of the code by address set edit or remove breakpoints Console window The Console window Figure 3 4 on page 3 16 allows you to interact with the executing program Anything printed by the program for example a prompt for user input is displayed in this window and any input required by the program must be entered here Copyright
242. be used including setting watchpoints and breakpoints and evaluating expressions in the Watch window ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 71 ARM Debuggers for Windows and UNIX 3 72 The following rules apply to expression evaluation for C Member functions of C classes cannot be used in expressions Overloaded functions cannot be used in expressions Only C operators can be used in constructing expressions Any operators defined in a C class that also have a meaning in C such as will not work correctly because ADW and AU use the C operator instead Specific C operators such as the scope operator are not recognized Member variables of a class cannot be accessed from the Evaluate Expression window in a C manner as if they were local variables To use a member variable in an expression you must use one of this gt member this Q member x this member If the member variable is defined in a base class then this gt member will return the correct results In the Expression Evaluation window and only there you can access variables of aclass by name This means that member gives the same result as this gt member However if you have more complex expressions such as this gt memberl this gt member2 you cannot use member1 member2 Base classes cannot be accessed in standard C notation For example class Base char name char x
243. bled If not olicom_process re queues itself and then exits in case another device is waiting for the serializer lock Additionally the Fusion stack can make calls to olicom_start to queue a new packet for transmission 01icom_ioct1 and olicom_updown in response to socket calls from the Angel Ethernet driver or as a result of packet processing Copyright 1997 1998 ARM Limited All rights reserved 13 101 Angel 13 102 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Appendix A FlexLM License Manager ARM DUI 0040D This appendix describes the use made by ARM Limited of FlexLM license management software You need to read this appendix and use FlexLM software only if you intend to run any ARM licensed software which at present is confined to UNIX based products This appendix contains the following sections About license management on page A 2 Obtaining your license file on page A 4 What to do with your license file on page A 5 Starting the server software on page A 6 Running your licensed software on page A 7 Customizing your license file on page A 9 Finding a license on page A 11 Using FlexLM with more than one product on page A 12 FlexLM license management utilities on page A 14 Frequently asked questions about licensing on page A 18 Copyright 1997 1998 ARM Limited All rights reserved A 1 FlexLM License Manager A 1 About license management FlexLM is a software licens
244. bled code set edit or remove breakpoints Debugger Internals window The Debugger Internals window displays some of the internal variables used by the ARM Debugger You can use this window to examine the values of the following variables and to change the values of those not marked read only clock Contains the number of microseconds elapsed since the application program began execution This value is based on the ARMulator clock speed setting and is unavailable if that speed is set to 0 00 see also ARMulator configuration on page 3 57 This variable is read only cmdline Contains the argument string for the image being debugged echo Non zero if commands from obeyed files should be echoed initially set to 0 Obeyed files are text files that contain lists of armsd commands Refer to the description of the obey command in Chapter 7 ARM Symbolic Debugger in the ARM Software Development Toolkit Reference Guide for more information Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX examine_lines Contains the default number of lines for the examine command initially set to 8 int_format Contains the default format for displaying integer values uint_format Contains the default format for displaying unsigned integer values float_format Contains the default format for displaying floating point values sbyte_format Contains the default format for d
245. bler directives CODE16 and CODE32 are used to switch between Thumb and ARM instruction sets C and C sources are compiled using the appropriate ARM or Thumb compiler Additionally projects created from either the ARM Executable Image template or Thumb Executable Image template may be easily modified to support interworking with Thumb or ARM code respectively For example an ARM only application can easily be made into an ARM mostly project and a Thumb only project can easily be made into a Thumb mostly project A Thumb application written only in C that must implement exception handlers will by architectural necessity have these in ARM assembly code and should probably be created using the Thumb Executable Image template 7 5 1 Choosing a template Follow these steps to choose a template 1 Within APM select New from the File menu 2 In the New dialog select Project and click OK The New Project dialog is displayed 3 Select a template from the Type box A descriptions of the template is displayed in the field Template description when you make a selection For interworking it is best to choose the Thumb ARM interworking image or the Thumb ARM C Interworking image and follow the instructions in Using the Thumb ARM interworking image project on page 7 24 Refer to Modifying a project to support interworking on page 7 25 for information on converting an existing Thumb or ARM project to an interworking project 4 Enter a Project
246. bugger Internals from the View menu to view and edit the variable Refer to on page 3 1 for more information You can build an application that links with the minimal Angel library This can be blown into a ROM soft loaded into Flash by the ARM debuggers or installed using a ROM emulator Multi ICE or EmbeddedICE Minimal Angel provides the same initialization code raw device drivers and interrupt support as full Angel Moving from full Angel to minimal Angel on your development hardware is straightforward See Developing an application under minimal Angel on page 13 24 for a description of minimal Angel This is conceptually a step closer to the final product compared with using the debugger to download an image You can choose either to keep minimal Angel in your production system or remove it for final production If you need to debug a minimal Angel application and your hardware supports JTAG you can use EmbeddedICE or Multi ICE These do not require any resource on the target Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel Stage 4 Moving an application to final production hardware When you are ready to move the application onto final production hardware you have a different set of requirements For example Production hardware might not have as many communications links as your development board You might not be able to communicate with the debugger RAM and ROM might be limited
247. by simulating the ARM instructions In software Cancel Apply Help Figure 3 15 Configuration of target environment 2 Change the following configuration options as required Target Environment The target environment for the image being debugged Add Display an Open dialog to add a new environment to the debugger configuration Remove Remove a target environment Configure Display a configuration dialog for the selected environment Display a more detailed description of the selected environment 3 Save or discard your changes click OK to save any changes and exit click Apply to save any changes click Cancel to ignore all changes not applied and exit Note Apply is disabled for the Target page because a successful RDI connection must be made first When you click OK an attempt is made to make your selected RDI connection If this does not succeed the ARMulate setting is restored Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX Debugger Follow these steps to change the configuration used by the debugger Click the Debugger tab of the Debugger Configuration dialog Figure 3 16 Target Debugger Memory Maps Endian Profile Interval 100 Little Source Tab Length fe C Big Disable M Splash screen PF Remote Startup warning Figure 3 16 Configuration of debugger Change the following
248. call the appropriate code In this case you are modifying the source code for the exception handler Angel has been written to make this approach simple Angel decodes SWIs and undefined instructions and the Angel exception handlers can be extended to deal with non Angel SWIs and undefined instructions However this approach is only useful if all the sources of an exception are known when the single exception handler is written 9 10 2 Several chained handlers ARM DUI 0040D Some circumstances require more than a single handler Consider the situation in which a standard Angel debugger is executing and a standalone user application or RTOS which wants to support some additional SWIs is then downloaded The newly loaded application may well have its own entirely independent exception handler that it wants to install but which cannot simply replace the Angel handler In this case the address of the old handler must be noted so that the new handler is able to call the old handler if it discovers that the source of the exception is not a source it can deal with For example an RTOS SWI handler would call the Angel SWI handler on discovering that the SWI was not an RTOS SWI so that the Angel SWI handler gets a chance to process it Copyright 1997 1998 ARM Limited All rights reserved 9 37 Handling Processor Exceptions 9 38 This approach can be extended to any number of levels to build a chain of handlers Note that although
249. ccurs FIQs are disabled when a FIQ occurs and on reset Sets Ir_mode to the return address as defined in The return address and return instruction on page 9 6 Sets the program counter to the vector address for the exception This forces a branch to the appropriate exception handler Note If the application is running on a Thumb capable processor the processor response is slightly different See Handling exceptions on Thumb capable processors on page 9 39 for more details 9 2 2 Returning from an exception handler ARM DUI 0040D The method used to return from an exception depends on whether the exception handler uses stack operations or not In both cases to return execution to the place where the exception occurred an exception handler must restore the CPSR from spsr_mode restore the program counter using the return address stored in lr_mode Copyright 1997 1998 ARM Limited All rights reserved 9 5 Handling Processor Exceptions For a simple return that does not require the destination mode registers to be restored from the stack the exception handler carries out these two operations by performing a data processing instruction with the S flag set the program counter as the destination register The return instruction required depends on the type of exception Refer to the following section for instructions on how to return from each exception type Note You do not need to return from the reset
250. changes not yet applied and exit Copyright 1997 1998 ARM Limited All rights reserved 2 43 ARM Project Manager Note Do not edit paths if your tools are on your Windows search path Editing paths can make your project difficult to use on another machine or with other versions of the software The Windows search path is the preferred method for locating tool DLLs The primary reason to edit a path is to experiment with a different version of a tool DLL 2 8 5 Editing a project template 2 44 When you edit a project template you change the options used by APM when it builds the project Follow these steps to edit a project template 1 Select Edit Project Template from the Project menu The Project Template Editor dialog is displayed Figure 2 22 Project Template Editor select Build step Pattern Figure 2 22 Project Template Editor dialog 2 You can now do one or more of the following select a build step pattern and click Edit to modify it see Editing a build step pattern on page 2 49 or Delete to remove it click New to add a new build step pattern see Adding a build step pattern on page 2 51 click Edit Details to change the title and or description of the template see Editing project template details on page 2 46 3 Click Close to close the dialog Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 8 6 Creating a new template If you hav
251. chine a remote machine or three machines To use your local machine machine as the license server fill in the license request form with the hostname and hostID of your machine To use a remote machine as the license server fill in the license request form with the hostname and hostID of the remote machine Sometimes an organization will designate one machine as the machine to run all license servers so find out if this is what happens in your company To specify three separate machines as license servers fill in the hostname and hostIDs of all three machines on the license request form Return the form to ARM Limited as follows if you have email available paste the completed form into your email composition tool and send it using the email address contained within the template if you do not have email available print out the completed form and send a facsimile using the Fax number contained within the template A license file will be returned to you shortly Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager A 3 What to do with your license file ARM DUI 0040D Make a copy of the license file on each of your license servers as follows l J If you receive the license file by email you can either copy the license file section out of the message or save the entire message to disk The license server ignores all lines except those start with SERVER VENDOR o
252. cific sources Most of the work in porting is carried out on the code in the target specific source directory to set up the target and provide device drivers The target specific files are target s This file provides important startup macros specific to the hardware You must check each macro in this file and change them for your board if necessary This file also contains the GETSOURCE macro GETSOURCE is used to identify which interrupt source has caused an interrupt You must modify this macro to suit the interrupt driven devices and interrupt scheme used by your hardware Refer to target s on page 13 58 for details makelo c This is part of the Angel build environment When built makelo includes a number of Angel header files and produces an assembly language s file that defines globals shared between C and assembly language routines This enables assembly language and C modules to access global constants without requiring separate copies for assembler use and for C compiler use If you introduce new constants that need to be shared by C and assembly language routines you must add them to makelo c Refer to makelo c on page 13 59 for details banner h This declares what board Angel is running on and with what options Refer to bannerh on page 13 60 for details devices c This file includes the headers for device drivers for the system You must modify this file if you add remove or rename any device drivers Refer to device
253. cks for the presence of an MMU If an MMU is present it can be initialized after switching to Supervisor mode 2 Angel sets the code execution and vector location depending on the compilation addresses generated by the values of ROADDR and RWADDR Refer to Configuring where Angel runs on page 13 70 for more information 3 Code and data segments for Angel are copied to their execution addresses 4 Ifthe application is to be executed then the runtime system setup code and the application itself are copied to their execution addresses If the system has ROM at address 0 and the code is to be run from ROM only the Data and Zero Initialization areas are copied 5 The stack pointers are set up for each processor mode in which Angel operates Angel maintains control of its own stacks separately from any application stacks You can configure the location of Angel stacks Refer to Configuring the memory map on page 13 69 for more information 6 Target specific functions such as MMU or Profiling Timer are initialized if they are included in the system 7 The Angel serializer is set up Refer to the Angel task management on page 13 33 for more information on the Angel serializer 8 The processor is switched to User mode and program execution is passed to the high level initialization code for the C library and Angel C functions Copyright 1997 1998 ARM Limited All rights reserved 13 29 Angel When initialization is complete progr
254. class Derived public class Base char name char xB void do_sth If you are in method do_sth you can access the member variables A name and B through the this pointer For example this gt name returns the name defined in class Derived To access name in class Base the standard C notation is Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX void Derived do_sth Base name value sets name in the base class to value However the expression evaluation window does not accept this gt Base name because ADW and ADU do not understand the scope operator You can access this value with this gt Base name Though it is possible to call member functions in the form Class Member this will give undefined results private public and protected attributes are not recognized by the ADW or ADU Evaluate Expression window This means that private and protected member variables can be accessed in the Evaluate Expression window because ADW and ADU treat them as public Copyright 1997 1998 ARM Limited All rights reserved 3 73 ARM Debuggers for Windows and UNIX 3 8 6 Debug Format Considerations This section provides information about the debug table formats that can be generated by the ARM C compilers It also describes how to change the format of the debug tables generated The debug table format T
255. code that takes this approach allows each handler to be entirely independent it is less efficient than code that uses a single handler or at least it becomes less efficient the further down the chain of handlers it has to go Both routines given in Installing the handlers from C on page 9 11 return the old contents of the vector This value can be decoded to give The offset for a branch instruction This can be used to calculate the location of the original handler and allow a new branch instruction to be constructed and stored at a suitable place in memory If the replacement handler fails to handle the exception it can branch to the constructed branch instruction which in turn will branch to the original handler The location used to store the address of the original handler If the application handler failed to handle the exception it would then need to load the program counter from that location In most cases such calculations may not be necessary because information on the debug monitor or RTOS handlers should be available to you If so the instructions required to chain in the next handler can be hard coded into the application The last section of the handler must check that the cause of the exception has been handled If it has the handler can return to the application If not it must call the next handler in the chain Note When chaining in a handler before a debug monitor handler you must remove the chain when the mo
256. collected by the debugger and processed by armprof in exactly the same way using the same commands and menus Instruction tracing with the Tracer module At the cost of a significant runtime overhead the Tracer module can generate a continuous trace stream of executing instructions and memory accesses Both modules are supplied in source form and you can modify them as you want This enables profiling and tracing to be customized to your specific needs For help with understanding the contents of a trace file see Interpreting trace file output on page 12 8 For more information on the ARMulator refer to Chapter 12 ARMulator Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 12 ARMulator ARM DUI 0040D This chapter describes the ARMulator a collection of programs that provide software emulation of ARM processors It contains the following sections About the ARMulator on page 12 2 ARMulator models on page 12 3 Tracer on page 12 6 Profiler on page 12 12 Windows Hourglass on page 12 13 Watchpoints on page 12 14 Page table manager on page 12 15 armflat on page 12 19 armfast on page 12 20 armmap on page 12 21 Dummy MMU on page 12 24 Angel on page 12 25 Controlling the ARMulator using the debugger on page 12 27 A sample memory model on page 12 29 Rebuilding the ARMulator on page 12 32 Configuring ARMulator to use the example on page 12 34
257. ct Template Editor dialog Note If you do not click Add Replace or Delete in step 3 you are prompted to save or cancel your changes before exiting this dialog You can have more than one Edit Build Step Pattern dialog open at one time so that you can copy from one build step pattern to another easily using Ctrl Insert to copy text and Shift Insert to paste text 2 9 3 Adding a build step pattern ARM DUI 0040D Follow these steps to add a new build step pattern 1 Select Edit Project Template from the Project menu 2 Click New 3 Enter the name of the new build step pattern 4 Click OK The Edit Build Step Pattern dialog is displayed see Edit Build Step Pattern dialog on page 2 50 5 Specify Input and Output Partition information 6 Enter a Partition name If the partition does not exist it is created 7 Enter the Pattern 8 Click Add 9 Enter a command line in the Command Lines edit box 10 Click OK 11 Click Close to close the Project Template Editor dialog If you are debugging with ADW or ADU you can use the args option in a command line to introduce any arguments you may want to supply to the program you are about to debug For example launch lt adw gt exec lt any gt asf args exQ eqn See Chapter 10 Writing Code for ROM for an example showing how to add a FromELF build step pattern Copyright 1997 1998 ARM Limited All rights reserved 2 51 ARM Project Manager 2 10 Using APM wit
258. ction of the armul cnf file Memories Default memory model is the Flat model or the MapFile gt model if there is an armsd map file to load Validation suite uses the trickbox if Validate Default TrickBox endif gt If there s a memory mapfile use that 1f MemConfigToLoad amp amp MEMORY_MapFi le Default MapFi le endif gt Default default is the flat memory map Default Flat Copyright 1997 1998 ARM Limited All rights reserved 12 19 ARMulator 12 9 12 9 1 12 20 armfast ARM fast armfast c provides a flat memory model of 2MB of RAM Emulation using ARMfast is typically 17 faster than for ARMflat This performance increase is partly achieved by not counting cycles so cycle counts in statistics will be zero This model is intended for use by software developers who want maximum emulation speed and are not interested in cycle counts or execution time The memory size is limited to 2MB You can change this by editing armfast c and rebuilding ARMulator as described in Rebuilding the ARMulator on page 12 32 ARM fast does not generate aborts Selecting the ARMfast memory model You select ARMfast by setting Default Fast in the Memories section of the armul cnf file Memories Default memory model is the Flat model or the MapFile gt model if there is an armsd map file to load Validation suite uses the trickbox if Validate Default TrickBox endif gt If t
259. d 8 1 5 Usage The following points apply to using inline assembly language Comma is used as a separator in assembly language so C expressions with the comma operator must be enclosed in parentheses to distinguish them _ asm ADD x y FO z If you are using physical registers you must ensure that the compiler does not corrupt them when evaluating expressions For example __asm MOV r0 x ADD y r0 x y x y overwrites rQ with the result Because the compiler uses a function call to evaluate x y it corrupts r2 r3 ip and Ir updates the NZCV flags in the cpsr alters rO and rl with the divident and modulo The value in rO is lost You can work around this by using a C variable instead of r0 8 8 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Mixed Language Programming mov var x add y var x y The compiler can detect the corruption in many cases for example when it needs a temporary register and the register 1s already in use __asm MOV ip 3 ADDS x x 0x12345678 this instruction 1s expanded ORR x x ip The compiler uses ip as a temporary register when it expands the ADD instruction and corrupts the value 3 in ip An error message is issued Do not use physical registers to address variables even when it seems obvious that a specific variable is mapped onto a specific register If the compiler detects this it either gen
260. d Cause You have compiled your C code with software stack checking enabled The C compiler generates code that calls one of the above functions when stack overflow is detected Solutions Recompile your C code with stack checking disabled Stack checking is disabled by default Link with a C library that provides support for stack limit checking This is usually possible only in an application environment because C library stack overflow handling code relies heavily on the application environment Write a pair of functions __rt_stkovf_split_big and __rt_stkovf_split_small the code for which usually generates an error for debugging purposes This effectively means that the application has a fixed size stack The code might look similar to the following EXPORT __rt_stkovf_split_big EXPORT __rt_stkovf_split_smal __rt_stkovf_split_big __rt_stkovf_split_small ADR RO stack_overflow_message SWI Debug_Message System dependent SWI to write a debugging forever message and loop forever B forever stack_overflow_ message DCB Stack overflow Q Attribute conflict in the linker The linker generates an error similar to the following ARM Linker Warning Attribute conflict between AREA test2 0 C code and image code ARM Linker attribute difference NO_SW_STACK_CHECK Copyright 1997 1998 ARM Limited All rights reserved 10 35 Writing Code for ROM 10 36 Cause Parts of your code have been comp
261. d 3 63 ARM Debuggers for Windows and UNIX You can also use the Class View window to view function code and set breakpoints for a class Displaying the Class View window Follow these steps to open the Class View window 1 Select View Classes from the C menu or click on the View Classes button in the toolbar A Class View window is displayed that shows the class hierarchy of your C program Figure 3 22 shows an example of the Class View window Class View x Func_2lchar tr 1_Par_Refchar str Func_3 Enumeration Enum_Par_Yall Li maint Proc_ Rec_Painter Atr_Yal_Par Proc_e One_Fitty Int_Par_Ref Proc_3 Rec_Pointer PtrRet_Par Proca Proc 5 Proc_6 Enumeration Enum_Yal_ParE Proc_ One_Fifty Int 1_Par_ValOne_ amp Proc_Bfint An_1_Par_Retint Arn_2_F Figure 3 22 The Class View window Viewing code from the Class View window Follow these steps to view the source code for a class 1 Display the Class View window 2 Click the right mouse button on a member function A Class View window menu is displayed Figure 3 23 on page 3 65 3 64 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX Class View x J dhry a d classes ce Global vs Proc_a Rec_Painter Ftr_Ret_Par an Froc_4f Proc 5i vs Proc_6 Enumeration Enum_Yal_ParE ft Proc_ Cne_Fift
262. d from the ARM C compiler if they have no base classes or virtual functions If such a struct has neither a user defined copy assignment operator or a user defined destructor it is a plain old data POD structure References are represented as pointers Pointers to data members and pointers to member functions occupy four bytes They have the same null pointer representation as normal pointers No distinction is made between pointers to C functions and pointers to C non member functions 8 18 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 8 4 3 Examples ARM DUI 0040D Mixed Language Programming Symbol name mangling ARM C mangles external names of functions and static data members in a manner similar to that described in section 7 2c of Ellis M A and Stroustrup B The Annotated C Reference Manual 1990 The linker decaof and decaxf unmangle symbols C names must be declared as extern C in C programs This is done already for the ARM ANSI C headers Refer to Using C header files from C on page 8 15 for more information The following code examples demonstrate how to call assembly language from C call C from assembly language call C and assembly language functions from C call C functions from C and assembly language call a non static non virtual C member function from C or assembly language pass references between C and C functions The ex
263. d li multest to load the image into armsd The armsd prompt is displayed armsd 2 Type go at the armsd prompt to run the program The following line is displayed Enter two unsigned 32 bit numbers in hex eg 100 FF43D 3 Type 12345678 10000001 The following lines are displayed Least significant word of result is 92345678 Most significant word of result is 1234567 Program terminated normally at PC 0x00008418 Qx00008418 OxefQ0Q011 gt swi Angel armsd Copyright 1997 1998 ARM Limited All rights reserved 6 17 Using the Procedure Call Standards 4 Type quit at the armsd prompt to exit armsd To confirm that _ value_in_regs is being used remove it from mul164 h recompile multest c relink multest and rerun armsd This time the answers returned will be incorrect because the result is no longer being returned in registers but in a block of memory 6 18 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 7 Interworking ARM and Thumb This chapter explains how to change between ARM state and Thumb state when writing code for processors that implement the Thumb instruction set It contains the following sections About interworking on page 7 2 Basic assembly language interworking on page 7 4 C and C interworking and veneers on page 7 12 Assembly language interworking using veneers on page 7 19 ARM Thumb interworking with the ARM Project Manager on page 7 2
264. d processor the clock speeds are set in the configuration file see Using the armul cnf configuration file on page 12 28 and also Application Note 52 The ARMulator Configuration File ARM DAI 0052A the memory map The debugger reads the armsd map file and tells ARMulator its contents Individual memory models have to support this information 1f they are to use the armsd map file One such model armmap c is supplied with the ARMulator as an example Other information is sent over the RDI Models can intercept the UnkRDIInfoUpcal1 to receive this data Some of the sample models do this for example armmap C intercepts the memory map information coming from the debugger See The armsd map File on page 12 28 angel c intercepts RDIErrorP RDISet_Cmdline and RDIVector_Catch RDI_Semihosting_SETARMSWI and RDI_Semihosting_SETThumbSWI dummymmu c responds to the debugger s request about the emulated MMU profiler c intercepts the profiling calls from the debugger to set up information such as profiling maps enable profiling and write back profiling data watchpnt c responds to the RDIInfo_Points call from the debugger responding that watchpoints are available Note It is not possible to add further control of the ARMulator from the debugger by for example the addition of extra commands or pseudo variables Copyright 1997 1998 ARM Limited All rights reserved 12 27 ARMulator 12 13 2 Using the armul cnf confi
265. d after the call it should be pushed onto the stack before the call and popped afterwards as for a BL function call 13 96 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 8 2 angel_SWlireason_ReportException 0x18 This SWI can be called by an application to report an exception to the debugger directly The most common use is to report that execution has completed using ADP_Stopped_ApplicationExit Entry On entry rO is set to Angel_SWIreason_ReportException and rl is set to one of the values listed in Table 13 5 and Table 13 6 on page 13 98 These values are defined in adp h The values marked with a are not supported by the ARM debuggers The debugger reports an Unhandled ADP_Stopped exception for these values ADP_UserInterruption is generated by Angel if the debugger sends an ADP_InterruptRequest to stop the application ADP_Breakpoint is generated when Angel detects attempted execution of a breakpoint instruction Angel does not implement watchpoints although other debug agents do The hardware exceptions are generated if the debugger variable vector_catch is set to catch that exception type and the debug agent is capable of reporting that exception type Angel cannot report exceptions for interrupts on the vector it uses itself Table 13 5 Hardware vector reason codes Name defined in adp h Hexadecimal value ADP_Stopped_BranchThroughZero 0x20000 ADP_Stopped_Undefin
266. d be returned in the argument registers al a4 by using the keyword __value_in_regs This is only useful for returning structures that are no larger than four words Returning a 64 bit result To illustrate how to use __value_in_regs consider a function that multiplies two 32 bit integers together and returns a 64 bit result To make such a function work you must split the two 32 bit numbers a b into high and low 16 bit parts a_hi a_lo b_hi b_lo You then perform the four multiplications a_lo b_lo a_hi b_lo a_lo b_hi a_hi b_lo and add the results together taking care to deal with carry correctly Since the problem involves manipulation of the Carry flag writing this function in C does not produce optimal code see An example of APCS register usage 64 bit integer addition on page 6 6 Therefore you must code the function in ARM assembly language Example 6 9 shows code that implements the algorithm Example 6 9 On entry al and a2 contain the 32 bit integers to be multiplied a b On exit al and a2 contain the result al bits 0 31 a2 bits 32 63 mu 164 MOV MOV BIC BIC MUL MUL MUL MUL ADDS ADDCS ADDS ADC MOV ip a4 al a2 a3 a2 al al a2 al a2 al ip a4 ip a2 a4 a3 a4 Ir LSR 16 ip a_hi LSR 16 gt a4 b_hi 1p LSL 16 al a_lo a4 LSL 16 a2 b_lo a2 a3 a_lo b_lo m_lo a2 a2 a_hi b_lo m_mid1 al al a_lo b_hi m_mid2 a
267. d is provided by an Olicom EtherCom PCMCIA Ethernet card installed in either PCMCIA slot The Olicom card uses an Intel 182595 Ethernet controller The UDP IP stack is the Pacific Softworks Fusion product ported to ARM and the Angel environment The drivers for PCMCIA and the Ethernet card have been implemented as has the Angel device driver to make the whole stack appear as an Angel device Figure 13 14 shows how the components fit together Fusion sockets library pcmcia manager Ethernet Figure 13 14 Angel Fusion and PID hardware ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 99 Angel 13 100 Initialization The stack is initialized in the following sequence l devclnt c angel_InitialiseDevices calls ethernet c ethernet_init toopena socket 2 fusion socket notices that the fusion stack has not been initialized Fusion stack initialization calls a olicom c olicom_init calls b pcmcia c pcmcia_setup detects Olicom card and calls Cc olicom c olicom_card_handler with a card insertion event and then d olicom c read_card_params to register olicom_isr with pcmcia c 3 Fusion stack initialization calls olicom c olicom_updown and through olicom_state 82595 c 1595_bringup to complete the initialization sequence Angel Ethernet device driver After initialization the Angel side of the driver is implemented as a polling device At every call to Angel_Yi
268. d of this file Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb 7 2 3 Data in Thumb code areas ARM DUI 0040D You must use the DATA directive when you define data within a Thumb code area When the linker relocates a label in a Thumb code area it assumes that the label represents the address of a Thumb code routine Consequently it sets bit O of the label so that the processor is switched to Thumb state if the routine is called with a BX instruction The linker cannot distinguish between code and data within a code area If the label represents a data item rather than an address the linker adds 1 to the value of the data item The DATA directive marks a label as pointing to data within a code area and the linker does not add 1 to its value For example AREA code CODE Thumb_fn MOV pc Ir Thumb_Data DATA DCB 1 3 4 Note that the DATA directive must be on the same line as the symbol Refer to the description of the DATA directive in the ARM Software Development Toolkit Reference Guide for more information Copyright 1997 1998 ARM Limited All rights reserved 7 11 Interworking ARM and Thumb 1 3 7 3 1 7 3 2 7 12 C and C interworking and veneers You can freely mix C and C code compiled for ARM and Thumb but small code segments called veneers are needed between the ARM and Thumb code to carry out state changes The ARM linker generates these in
269. d should allow access to the full Data bus and Address bus In addition general purpose outputs such as programmable LEDs can be useful for debug purposes You can use the following debug methods ARMulator You can debug the early stages of your Angel port under ARMulator Only the initial stages of the code can be debugged in ARMulator because the ARMulator environment has no means of receiving responses from peripherals You can use programmable LEDs to assist you in debugging under ARMulator Multi ICE EmbeddedICE and Multi ICE are valuable tools for debugging Angel because they can operate before the basic Angel functionality is working For example they can operate before your Angel device drivers are functional These are the preferred option if your board uses an appropriate ARM processor such as the ARM7TDMI Your processor must support the DI debug extensions to work with an ICE solution ROM emulators and Logic Analyzers If your ARM processor does not support debugging under Multi ICE or EmbeddedICE you can use ROM emulators or logic analyzers to help you debug your Angel port The Angel sources include source files to help you use the E5 ROM Emulator from Crash Barrier Ltd the neXus ROMulator from neXus Ltd The support files for these are located in the Angel Source logging directory Note Specify DEBUG 1 to build a debugging version of Angel Copyright 1997 1998 ARM Limited All rights reserved
270. d the result placed in r0 Application termination After executing the main code the application terminates by returning control to the debugger This is done using the Angel semihosting SWI by default this is 0x123456 in ARM state with the following parameters rO equal to angel_SWIreason_ReportException by default 0x18 rl equal to ADP_Stopped_ApplicationExit by default 0x20026 For additional information on this see Chapter 13 Angel The END directive This directive instructs the assembler to stop processing this source file Every assembly language source module must finish with an END directive on a line by itself 5 14 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 3 3 Calling Subroutines To call subroutines in assembly language use a Branch Link instruction The syntax is BL label where label is usually the label on the first instruction of the subroutine It could alternatively be a program relative or register relative expression see Register relative and program relative expressions on page 5 89 of the ARM Software Development Toolkit Reference Guide The BL instruction places the return address in the link register lr sets pc to the address of the subroutine After the subroutine code is executed you can use a MOV pc Ir instruction to return By convention registers r0 r3 are used to pass parameters to subroutines and to pass
271. data source This is one of TRUE Bus between processor and memory FALSE Core between core and cache if present Disassemble disassembles instructions Enabling disassembly will greatly affect emulation speed Other tracing controls You can also control tracing using Range ow address high address Tracing is carried out only within the specified address range Sample n Only every nth trace entry is sent to the trace file Copyright 1997 1998 ARM Limited All rights reserved 12 7 ARMulator Tracing events When tracing events you can select the events to be traced using EventMask mask value Only those events whose number when masked bitwise AND with mask equals value are traced Event number Only number is traced This is equivalent to EventMask OxfffffffFf number For example the following traces only MMU cache events EventMask Oxffff0000 0x00010000 See Events on page 12 87 of the ARM Software Development Toolkit Reference Guide for more information on events 12 3 2 Debugger support for tracing 12 3 3 12 8 There is no direct debugger support for tracing Instead the tracer uses bit 4 of the RDI Logging Level rdi_log variable to enable or disable tracing Using the ARM Debugger for Windows ADW Select Set RDI Log Level from the Options menu To enable tracing set the RDI Log Level to 16 To disable tracing set the RDI Log Level to 0 Using armsd To enable tracing
272. de info Sizes tell the linker to print information on the code and data sizes of each object file along with the totals for each type of code or data The output generated is shown in Output from info Sizes option on page 10 11 4 Run the fromELF utility to produce a plain binary version of the image fromelf nozeropad rom axf bin rom bin ARM fromelf nozeropad trom axf bin trom bin Thumb where nozeropad tells the linker not to pad the end of the image with zeros to make space for variables This option should always be used when building ROM images bin specifies a binary output image with no header 5 Load and execute the ROM image under ARMulator by starting armsd ADW or ADU then type the following on the command line getfile rom bin ARM getfile trom bin 0 Thumb pc 0 go Area listing for the code Example 10 2 on page 10 11 shows the map area listing for the sample code Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Base Size 0x00000000 e4 0x000000 e4 238 0x0000031c 10 0x10000000 4 0x10000004 140 Writing Code for ROM Example 10 2 Area listing Type RO Name CODE RO I I from object file init o CODE RO C code from object file ex o CODE RO C constdata from object file ex o DATA RW C data from object file ex o ZERO RW C zidata from object file ex o This shows that the linker places three code areas at successive locations starting from 0x000000
273. decimal constants Use the 0x prefix instead For example __asm AND x y QxFQQ Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Mixed Language Programming The notation to specify the actual rotate of an 8 bit constant is not available in inline assembly language This means that where an 8 bit shifted constant is used the C flag should be regarded as corrupted if the NZCV flags are updated Copyright 1997 1998 ARM Limited All rights reserved 8 7 Mixed Language Programming 8 1 4 Restrictions The following restrictions apply to the use of the inline assemblers Physical registers such as r0 r3 ip lr and the NZCV flags in the cpsr must be used with caution If you use C or C expressions these may be used as temporary registers and NZCV flags may be corrupted by the compiler when evaluating the expression LDM and STM instructions only allow physical registers to be specified in the register list The BX instruction is not implemented You can change processor modes alter the APCS registers fp sl and sb or alter the state of coprocessors but the compiler is unaware of the change If you change processor mode you must not use C or C expressions until you change back to the original mode Similarly if you change the state of an FP coprocessor by executing FP instructions you must not use floating point expressions until the original state has been restore
274. ded during the current debug session A box allows you to enter a filename or to select a filename from a pull down list Use this box to add new map files to the list or select a map file from the list When you have selected a map file the debugger checks that the file exists and is of a valid format Any file that fails these checks is removed from the list The dialog remains however so you can correct an error or select another map file if necessary Use the Remove button to remove the currently selected file from the list The browse button allows you to select a memory map file using a dialog Local Map File Select this option to use a memory map file that is local to a project If a local memory map file is required when the debugger is initialized the current working directory is searched If a re initialization occurs after the debugger has started and loaded an image the directory containing the image is searched ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 55 ARM Debuggers for Windows and UNIX 3 56 l A box allows you to enter a filename or to select a filename from a pull down list Use this box to add new map files to the list or select a map file from the list You must not specify an absolute path name but you can specify a memory map file relative to the current image path The browse button allows you to select a memory map file using a dialog When you have selected a f
275. defined in Project files on page 2 4 Phin sy partition You can use the project view to examine various aspects of your project and select elements for action For example you can select a partition in which you want to add a file or select a source file for a build Build log The build log occupies the lower pane and is displayed each time you perform a build The build log contains messages from the tools used to build your project You can double click on many of these messages to display the line where an error was detected The following symbols in the build log indicate the type of diagnostic message i Informational blue I Warning blue l Error red gy Serious Error odaia Fatal Error black Status area The status area at the bottom of the Project window displays a button for starting or stopping a build a progress display a status bar that displays the current status information or describes the currently selected user interface component such as a menu option Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 3 2 Changing the way a project is displayed You can change the level of detail displayed in the Project Window in several ways te e Click the View Dependencies button to show or hide the lower level dependency files These are indicated by a plus sign next to the source filename Click the View Build Log button to toggle the display of
276. definitions in the code generated by the compilers If you specify a library explicitly on the linker command line you must ensure that it is an appropriate interworking library The library should match the state in which the main function executes Refer to The C and C interworking libraries on page 7 17 for further details These rules are summarized in Figure 7 3 on page 7 16 Note You must take great care when using function pointers in applications that contain both ARM and Thumb code The linker cannot generate warnings about illegal indirect calls and the code will fail at runtime ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 7 15 Interworking ARM and Thumb No calls possible Non interworking Non interworking Thumb code ARM code Non interworking to Thumb Thumb calls interworking ARM ARM calls permitted ARM Thumb calls permitted N Interworking ARM Thumb Calls Interworking Thumb code permitted ARM code Figure 7 3 Interworking using direct calls 7 3 4 Detecting interworking calls The linker generates an error 1f it detects a direct ARM Thumb interworking call where the called routine is not compiled for interworking You must recompile the called routine for interworking For example Figure 7 4 shows the errors that are produced if the ARM routine in Example 7 2 on page 7 9 is compiled without the apcs interwork option Error Unsupported call from Thumb code to ARM
277. drate port s serzal_port p parallel_port e ethernet_address A delete all breakpoints facility Save and restore all window formats Windows retain the format they were given Breakpoints can be set as 16 bit or 32 bit The dialog box for setting a breakpoint has been modified to enable breakpoints to be set either as ARM or Thumb breakpoints or for the choice to be left to the debugger The display of low level symbols can be sorted either alphabetically or by address order sorting was by address order only in SDT 2 11a You can choose the order that is used Copyright 1997 1998 ARM Limited All rights reserved 1 9 Introduction Locals Globals and Debugger Internals windows format is now controlled by int_format uint_format float_format sbyte_format ubyte_format string_format complex_format These formats are available by selecting Change Default Display Formats from the Options menu The Memory window now has halfword and byte added to its display formats Value fields in editable windows for example Variable windows and Memory windows are now edit in place rather than using a separate dialog box for entering new values A copy of ADW is also supplied in a file named MDW exe to maintain backwards compatibility with the Multi ICE release Interleaved source and assembly language output The compilers in SDT 2 50 and C 1 10 have been enhanced to provide an assembly language
278. e This book is not intended to be an introduction to the C or C programming languages It does not try to teach programming in or C and it is not a reference manual for the C or C standards The following texts provide general information ARM architecture Furber S ARM System Architecture 1996 Addison Wesley Longman Harlow England ISBN 0 201 40352 8 ISO IEC C reference ISO IEC JTC1 SC22 Final CD FCD Ballot for CD 14882 Information Technology Programming languages their environments and system software interfaces Programming Language C This is the December 1996 version of the draft ISO IEC standard for C It is referred to hereafter as the Draft Standard C programming guides The following books provide general C programming information Ellis M A and Stroustrup B The Annotated C Reference Manual 1990 Addison Wesley Publishing Company Reading Massachusetts ISBN 0 201 51459 1 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Preface This is a reference guide to C Stroustrup B The Design and Evolution of C 1994 Addison Wesley Publishing Company Reading Massachusetts ISBN 0 201 54330 3 This book explains how C evolved from its first design to the language in use today Meyers S Effective C 1992 Addison Wesley Publishing Company Reading Massachusetts ISBN 0 201 56364 9 This provides short specific guidelines fo
279. e execution at Reset_Handler Vector_Init_Block LDR PC Reset_Addr LDR PC Undefined_Addr LDR PC SWI_Addr LDR PC Prefetch_Addr LDR PC Abort_Addr NOP LDR PC IRQ_Addr LDR PC FIQ_Addr Reset_Addr DCD Reset_Handler Undefined_Addr DCD Undefined_Handler SWI_Addr DCD SWI_Handler Prefetch_Addr DCD Prefetch_Handler Abort_Addr DCD Abort_Handler DCD Q Reserved vector IRQ_Addr DCD IRQ_ Handler FIQ_Addr DCD FIQ_Handler ENDIF The following handlers do not do anything useful in this example ndet ned Handle B Undefined_Handler SWI_Handler B SWI_Handler Prefetch_Handler B Prefetch_Handler Abort_Handler B Abort_Handler TRQ_Handler B TRQ_Handler FIQ_Handler B FIQ_ Handler The RESET entry point Reset_Handler gt Initialize stack pointer registers Enter IRQ mode and set up the IRQ stack pointer MOV RO Mode_IRQ 0R I_Bit OR F_Bit No interrupts MSR CPSR_c RQ LDR R13 IRQ_Stack Set up other stack pointers if necessary Set up the SVC stack pointer last and return to SVC mode ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved Writing Code for ROM 10 13 Writing Code for ROM MOV RQ Mode_SVC 0R I_Bit OR F_Bit No interrupts MSR CPSR_c RQ LDR R13 SVC_Stack Initialize memory system Initialize critical IO devices gt Initialize interrupt system variables here Initialize memory required by C code IMPORT Image RO Limi
280. e accesses This is a memory model of a system that shows how accessing various addresses causes events such as aborts and interrupts to occur As well as being a basic model the tracer module provides a veneer memory model that can log memory accesses This is a model of the ARM PIE card UNIX only This memory model is the example described in A sample memory model on page 12 29 Coprocessor models dummymmu C validate c This is a cut down model of coprocessor 15 the system coprocessor This is a small coprocessor that is used to validate the behavior of the ARM emulator It can cause interrupts and busy waits for example It is supplied as an example Operating system models angel c noos c This is an implementation of the Software Interrupts SWIs and environment required for running programs linked with the Angel semihosted C library on AR Mulator This is a dummy operating system model where no SWIs are intercepted Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 2 2 Model stub exports ARM DUI 0040D Each of these models exports a stub see the ARM Software Development Toolkit Reference Guide You declare stubs in models h using sets of macros For example MEMORY ARMu1_F lat COPROCESSOR ARMu 1 _DummyMMU OSMODEL ARMul_Angel MODEL ARMul_Profiler There are no trailing semicolons on these lines You can also add new user supplied models t
281. e added 3 Select the required file or files and click Open The files are added to the selected partition After adding files you may have to expand branches of the tree to make them visible Branches containing subtrees have a button If you added assembly language files to the ASM Source partition that do not contain CODE32 directives perform the steps listed in Configuring the assembler to read ARM assembly source below Configuring the assembler to read ARM assembly source By default the interworking templates call the assembler with the 16 option to instruct the assembler to assemble Thumb code The templates assume that assembly language source uses CODE16 and CODE32 directives to switch between Thumb and ARM assembly where required Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb If you have ARM assembly language files that do not use CODE32 directives you can configure the assembler to avoid changing the assembly language source Follow these steps to change the assembler configuration for an individual source file l In the Project View expand the ASM Sources partition and select the ARM assembler source for example armer_kerl s Choose Tool configuration for armer_Kerl s asm Set from the Project menu The Compiler Configuration dialog is displayed Click the Target tab and select the ARM radio button in the Initial state group Select the Call Standa
282. e at present confined to UNIX based products The following list shows the platforms supported and the subdirectory containing the appropriate software for each Solaris 2 5 flexlm solaris SunOS 4 1 x flexlm sunos HP UX 9 x flexim hpux Each directory contains the software in TAR file format in a file called flex1m tar A 2 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager Before applying for a license file you must install the FlexLM license management software as follows 1 Copy the TAR file from the appropriate directory onto each license server machine 2 On each license server machine unTAR the file using the command tar xvf flexim tar 3 When you have un TARed the software you need to run the makelinks sh script Change into the directory containing the unTARed software and type makelinks sh 4 This creates numerous hard links one of which is Imhostid You need Imhostid when you complete your license request form ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved A 3 FlexLM License Manager A 2 A 4 Obtaining your license file The installation directory contains a file called 1icense_request_form txt To obtain your license file L 2 Open this text file with the editor of your choice Complete the form following any instructions that are in the file You must decide whether your license server 1s to be your local ma
283. e but you cannot open more than one window for each processor mode For example you can open no more than one FIQ register window at a time RDI Log window The RDI Log window displays the low level communication messages between the ARM Debugger and the target processor Note This facility is not normally enabled It must be specifically enabled when the RDI is compiled In addition the debugger internal variable rdi_log must be non zero For more information on RDI see Remote debug information on page 3 41 Search Paths window The Search Paths window displays the search paths of the image currently being debugged You can remove a search path from this window using the Delete key Source Files List window The Source Files List window displays a list of all source files that are part of the loaded image Use the Source Files List window to select a source file that is displayed in its own Source File window Source File window The Source File window displays the contents of the source file named at the top of the window Line numbers are displayed in the left hand pane code in the right hand pane Use the Source File window to search for a line of code by line number set edit or remove breakpoints on a line of code toggle the interleaving of source and disassembly For more information on displaying source files see Working with source files on page 3 36 Copyright 1997 1998 ARM Limited All ri
284. e line that was being processed when the error was detected highlighted 2 Inthis case the error is due to the missing semicolon at the end of the previous line printf Hello World n should read printf Hello World n Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager Note Often an error in a line is detected only when the next line is being processed 3 Correct the error and click the Build button When you rebuild the project APM prompts you to save the file if you have not already done so the Project window becomes the current window the build takes place and messages are written to the build log Figure 2 5 shows the APM Desktop when the build is complete Blue checkmarks appear by all three files and an informational message in the x build log shows that the project is up to date This means that the project was built successfully and that the output of every project build step involved was created after the most recent change to any of its inputs You can now execute or debug your project fa C examples hello apj oo iy ARM Executable Image Je DebugRel SubProjects Libraries armlink 4 reduction 0 00 i Information C examples hello apj Project is up to date 0 Warnings 9 Errors Duos DebugRel Figure 2 5 Successful project build 2 2 5 Project output The output of a project is typically a single file or a closely related group
285. e link and execute the example Example 5 3 AREA ThumbSub CODE READONLY Name this block of code ENTRY CODE32 ADR BX CODE16 MOV MOV BL MOV LDR SWI ADD MOV END Mark first instruction to execute Subsequent instructions are ARM r0 start 1 Processor starts in ARM state rQ so small ARM code header used to call Thumb main program Subsequent instructions are Thumb r0 10 Set up parameters rl 3 doadd Call subroutine rQ 0x18 angel_SwIreason_ReportException rl 0x20026 ADP_Stopped_ApplicationExit QxAB Angel semihosting Thumb SWI r r0 rl Subroutine code pc Ir Return from subroutine Mark end of file CODE32 and CODE16 directives These directives instruct the assembler to assemble subsequent instructions as ARM CODE32 or Thumb CODE16 instructions They do not assemble to an instruction to change the processor state at runtime They only change the assembler state The ARM assembler armasm assembles ARM instructions until it reaches a CODE16 directive unless the 16 option is used in the command line BX instruction This instruction is a branch that can change processor state at runtime The least significant bit of the target address specifies whether it is an ARM instruction clear or a Thumb instruction set In this example the ADR pseudo instruction sets this bit so start is a label to a Thumb instruction Copyright 1997 1998 ARM Limited All rig
286. e 5 31 of the ARM Software Development Toolkit Reference Guide Note No space in memory is allocated when a map is defined Use Define Constant DC directives to allocate space in memory Absolute maps Example 5 15 shows a data structure described using MAP and It is located at an absolute fixed address 4096 0x1000 in this case Example 5 15 consta uses four bytes and is located at 4096 constb uses four bytes and is located at 5000 x uses eight bytes and is located at 5004 y uses eight bytes and is located at 5012 gt String can be up to 256 bytes long starting at 5020 You can access data at these locations with LDR or STR instructions such as LDR r4 constb You can only do this if each instruction is within 4KB in either direction of the data item it accesses See the ARM Architectural Reference Manual for details of the LDR and STR instructions Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 9 2 Relative maps If you need to access data from more than 4KB away you can use a register relative instruction such as LDR r4 r9 offset offset is limited to 4096 so r9 must already contain a value within 4KB of the address of the data You can access data in the structure described in Example 5 15 on page 5 46 from an instruction at any address This program fragment shows how MOV r9 4096 or 0x1000 LDR r4 r9 constb
287. e ARM instructions input to the assembler The right hand column shows the instruction generated by the assembler Table 5 5 Assembler generated constants Input instruction Assembled equivalent MOV r0 0 MOV rO 0 MOV r1 0xFF000000 MOV r1 0xFF 8 MOV r2 0xFFFFFFFF MVN r2 0 Copyright 1997 1998 ARM Limited All rights reserved 5 23 Basic Assembly Language Programming 5 24 Input instruction MVN r3 1 Table 5 5 Assembler generated constants continued Assembled equivalent MVN r3 1 MOV r4 0xFC000003 MOV r4 0xFF 6 MOV r5 0x03FFFFFC MVN r5 0xFF 6 MOV r6 0x55555555 Error cannot be constructed Direct loading with MOV in Thumb state In Thumb state you can use the MOV instruction to load constants in the range 0 255 You cannot generate constants outside this range because The Thumb MOV instruction does not provide inline access to the barrel shifter Constants cannot be right rotated as they can in ARM state The Thumb MWN instruction can act only on registers and not on constant values Bitwise complements cannot be directly loaded as they can in ARM state If you attempt to use a MOV instruction with a value outside the range 0 255 the assembler generates an error message Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 5 2 Loading with LDR Rd const ARM DUI 0040D The LDR Rd cons
288. e Call Standard on page 6 3 Using the Thumb Procedure Call Standard on page 6 11 Passing and returning structures on page 6 13 Refer to the ARM Software Development Toolkit Reference Guide for a complete description of the procedure call standards ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 6 1 Using the Procedure Call Standards 6 1 6 2 About the procedure call standards Sometimes you will find it necessary to combine C or C and assembly language in the same program For example you may wish to hand code performance critical routines in assembly language so that they run at optimum speed The ARM Software Development Toolkit enables you to generate object files from C C and assembly language source and then link them with one or more libraries to produce an executable file as shown in Figure 6 1 S ASM source module s JE C library C source module s EAS O armlink executable Figure 6 1 Mixing C or C and assembly language Irrespective of the language in which they are written routines that make calls to other modules must observe a common convention of argument and result passing For the ARM and Thumb instruction sets these are the ARM Procedure Call Standard APCS the Thumb Procedure Call Standard TPCS This chapter introduces these standards and discusses their role in ARM assembly language for passing and returning values and pointers to str
289. e Watch window L 2 Display the Watch window Either click the right mouse button in the Watch window to display the Watch window menu and select Add Item from the Watch window menu press the Insert key A Watch Control window is displayed Figure 3 26 on page 3 69 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Watch Control Enter the expression that you wish to be evaluated ay Cancel Figure 3 26 The Watch Control window 3 Enter an expression to add to the Watch window and click OK Refer to Evaluating expressions and adding watches on page 3 71 for more information on the types of expression you can add to the Watch window Note You can also add an expression to the Watch window directly from the Evaluate Expression window Refer to Evaluating expressions and adding watches on page 3 71 for more information Formatting watch items Follow these steps to change the formatting of values displayed in the Watch window 1 Display the Watch window 2 Click the right mouse button in the Watch window to display the Watch window menu 3 Select Format Window to format all items in the window The Display Format window is displayed Figure 3 27 Display Format x Please set format string for ch Cancel Figure 3 27 The Display Format window ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 69
290. e a number of similar project outputs to produce that do not fit the templates provided with the ARM Project Manager you can create your own blank template to use as a basis for new project templates You can use an existing blank template or project template as a basis for your new blank template Follow these steps to create a new blank template L g 10 Select a suitable model in one of the following ways create a new project see Creating a new project on page 2 5 selecting a suitable blank template open a suitable existing project Select Edit Project Template from the Project menu Click the Edit Details button and modify the Title and the Description of the template see Editing project template details on page 2 46 Select Save as Template from the File menu The Save As dialog is displayed Locate the file in the directory specified in the APM Preferences dialog Setting preferences on page 2 31 and give it a unique name Click Save The new project has now been created and is the currently active project Modify the build step patterns listed for the template adding or deleting build step patterns as necessary see Editing a build step pattern on page 2 49 Edit any variables as necessary see Editing a variable on page 2 42 Edit any tool paths as necessary see Editing a path on page 2 43 Save the project The new template is displayed sorted by filename in the Type list of the New Proj
291. e and data sizes in the image broken into separate totals for the object files and library files armlink info totals dhry_1 0o dhry_2 0 o dhry Using the Windows tools You can use this easier method if you use ADW and are running APM Load the Dhrystone project file dhry apj into the ARM Project Manager APM Change the project setting to produce a release build with a little endian memory model using the ARM tools instead of the Thumb tools see Configuring tools on page 2 20 Click the Force Build button This compiles and links the project automatically generating a summary of the total code and data sizes in the image Results Table 11 1 Code and data sizes results code inline les const RW O init debug size data g data data data data Object totals 2136 28 1536 0 48 10200 0 Library totals 33888 528 616 24 396 1132 0 Grand totals 36024 556 2152 24 444 11332 0 Your figures may differ depending on the version of the compiler linker and library Copyright 1997 1998 ARM Limited All rights reserved Benchmarking Performance Analysis and Profiling 11 3 Performance benchmarking 11 3 1 The basis for improving performance is to minimize the number of machine cycles required to perform a task a specific number of times Measuring performance There are two debugger internal variables that contain the cycle counts These can be displayed using the armsd print command or by selecting Debugger Internals from t
292. e button and select the map file you created The association is now set up and you can run the program L If you use ADW and are running APM then click on the Debug button to start ADW and load the project If you use ADU then start ADU and select Load Image from the File menu to load the project If a dialog box prompts you to save the changes to the project file click Yes To set up the debugger to run at the required clock speed Select Configure Debugger from the Options menu b Select ARMulator from the Target Environment box on Target page of the Debugger Configuration dialog C Click the Configure button d Ensure the Emulated radio button is selected set the Clock Speed to 20MHz and click OK e Click OK on the Debugger Configuration dialog The image is reloaded Click the Go button to begin execution and again when the breakpoint on main is reached Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Benchmarking Performance Analysis and Profiling 4 When requested for the number of Dhrystones enter 30000 5 When the application completes record the number of Dhrystones per second reported This is your performance figure When the debugger is configured to emulate a processor of the required clock speed in this case 20MHz you can repeat the simulation by clicking on Execute rather than Debug in APM Note You may obtain slightly different figures depending on the ver
293. e expiration date of the license a year of 0 means the license never expires the number of concurrent licenses available and the license key A 10 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager A 7 Finding a license ARM DUI 0040D Figure A 1 shows the rules followed by licensed software when it searches for a license authorizing it to run START environment variable ARMLMD LICENSE FILE set License found Search for license Is environment variable Let LICENSE FILE set License found Search for license License found Open any lic files found in Cearch for license foptfarm licenses directory License found Open default license file license dat in directory search for license fusrlocalfleaximnvlican ses 10 License Is Process Unavailable license SEARCH FOR LICENSE Environment variables can contain multiple filenames and or directory names separated by colons They can also contain a hostname or hostname and TCP port number Examine each name in turn until you find the file that contains the license you require search the directory for _ Is this all files with a lic a file name or filename extension ee Examine each such license file in turn Is this a hostname or hostname and port no Yes Connect to hostto get license search the license file for the requir
294. e multiplexing for these channels This layer must also handle buffer management because reliability requires retransmission after errors have occurred Copyright 1997 1998 ARM Limited All rights reserved 13 73 Angel The device driver layer detects and rejects bad packets but does not offer reliability itself 13 6 2 Boot support If there are two or more debug devices for example serial and serial parallel the boot agent must be able to receive messages on any device and then ensure that further messages that come through the channels layer are sent to the correct new device When the debug agent detects a Reboot or Reset message it listens to the other channels using the device that received the message All debug channels switch to use the newly selected debug device During debugging each channel is connected through the same device to one host Initially Angel listens on all Angel aware devices for an incoming boot packet and when one is received the corresponding device is selected for further Angel use Angel listens for a reset message throughout a debugging session so that it can respond to host end problems or restarts To support this the channels layer provides a function to register a read callback across all Angel aware devices and a function to set the default device for all other channel operations 13 6 3 Channels layer and buffer management The channels layer is responsible for multiplexing the va
295. e number of elapsed ticks The first word is the least significant word The last word is the most significant word This follows the convention used by the ARM compilers for the long long data type Return If the double word pointed to by rl low order word first does not contain the number of elapsed ticks rl is set to 1 13 7 23 SYS_TICKFREQ 0x31 13 94 Defines a tick frequency Entry On entry rO contains the reason code 0x31 Exit On exit rO contains either the ticks per second 1 if the target does not know the value of one tick Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 8 Angel debug agent interaction SWIs In addition to the C library support SWIs described in Angel C library support SWIs on page 13 79 Angel provides the following SWIs to support interaction with the debug agent The ReportException SWI This SWI is used by the semihosting support code as a way to report an exception to the debugger It can be considered as a breakpoint that starts in Supervisor mode rather than Undefined mode The EnterS VC SWI This SWI sets the processor to Supervisor mode These are described below 13 8 1 angel_SWlreason_EnterSVC 0x17 ARM DUI 0040D Sets the processor to Supervisor SVC mode and disables all interrupts by setting both interrupt mask bits in the new CPSR Under Angel the user stack pointer r13_USR is copied to the Supervisor stac
296. e parameters are passed to the SWI as if the SWI were a real function call However if there are between two and four return values you must tell the compiler that the return values are being returned in a structure and use the __value_in_regs directive This is because a struct valued function is usually treated as if it were a void function whose first argument is the address where the result structure should be placed Example 9 9 shows a SWI handler that provides SWI numbers 0x0 and 0x1 SWI 0x0 takes four integer parameters and returns a single result SWI Ox takes a single parameter and returns four results Example 9 9 struct four int a b c d __sw1 0x0 int calc_one int int int int __swi 0x1 __value_in_regs struct four calc_four int You can call the SWIs in the following manner void func void struct four result int single resl res2 res3 res4 single calc_one vall val2 val3 val4 result calc_four val5 resl result a res2 result b Copyright 1997 1998 ARM Limited All rights reserved 9 19 Handling Processor Exceptions 9 4 5 9 20 res3 result c res4 result d Calling SWIs dynamically from an application In some circumstances it may be necessary to call a SWI whose number is not known until runtime This situation can occur for example when there are a number of related operations that can be performed on an object and each operation has its own SWI In suc
297. e pointed to by Ir_mode The address to continue from is one word four bytes less than that in Ir_mode so the return instruction is SUBS pc Ir 4 The handler entry and exit code to stack the return address and pop it on return is SUB Ir Ir 4 STMFD sp reglist Ir LDMFD sp reglist pc A Returning from prefetch abort If the processor attempts to fetch an instruction from an illegal address the instruction is flagged as invalid Instructions already in the pipeline continue to execute until the invalid instruction is reached at which point a prefetch abort is generated Copyright 1997 1998 ARM Limited All rights reserved 9 7 Handling Processor Exceptions The exception handler invokes the MMU to load the appropriate virtual memory locations into physical memory It must then return to the address that caused the exception and reload the instruction The instruction should now load and execute correctly Because the program counter is not updated at the time the prefetch abort is issued Ir_ABT points to the instruction following the one that caused the exception The handler must return to lr_ABT 4 with SUBS pc Ir 4 The handler entry and exit code to stack the return address and pop it on return is SUB Ir Ir 4 STMFD sp reglist Ir LDMFD sp reglist pc A Returning from data abort When a load or store instruction tries to access memory the program counter has been updated A stored value
298. e the compile and link stages L 2 Quit the debugger if it is running Enter armcc c hello c to recompile hello c into an object file No executable file is produced Enter armlink hello o o hel1o3 to link the object file with a library and generate an executable program Enter armsd hello3 to load the program into the debugger hello3 contains no C source level debugging information because hello o was compiled without the g option so you cannot view the source statements with the type command However you can refer to program locations and set breakpoints on them by using the character to reference the low level symbols For example to set a breakpoint on the first location in main type break main Generating interleaved C and assembly language Follow these steps to generate interleaved C and assembly language 1 2 Quit the debugger if it is running Enter armcc S fs hello c at the system prompt The S option instructs armcc to write out an assembly language listing of the instructions that would usually be compiled into executable code The fs option instructs the compiler to interleave C and the generated assembly language By default the output file will have the same name as the C source file but with the extension s Display the file hello s on screen using the appropriate operating system command or load it into a text editor Example 4 1 on page 4 5 shows the assembly language generat
299. e to read data 1 Packet buffers not requested Writing to the ring buffer is allowed Q Normal operation n deliver n good packets then behave as RX_PACKET_FLOW Q Transmit Control ControlTx When in operation Angel defaults to the receive active state in order to enable quick response to host messages This function controls the transmit channel of the serial driver switching it on or off depending on the flag status set up in the calling routine Receive Control ControlRx This function is similar to ControlTx It controls the receive channel Transmit Kick Start KickStartFn Transmission must be initiated by this function because Angel generally operates in receive active mode The Angel packet construction code sets up the bytes to be transmitted for a message to the host in a transmit buffer and calls the KickStartFn function to initiate the transfer The KickStartFn takes the first character from the transmit buffer and passes it to the serial Tx register This causes a Tx interrupt from which the interrupt handler passes the remainder of the buffer as each character 1s transmitted Interrupt handlers The interrupt handlers are generic for each peripheral In the case of the PID board the interrupt handler controls interrupts from each serial driver Tx and Rx in addition to the parallel reads Copyright 1997 1998 ARM Limited All rights reserved 13 65 Angel 13 66 The interrupt handler determines the
300. e two options for changing the name of a project changing the name of the project output only changing the names of both the project file and the project output In both cases the original files remain Changing the name of the project output only Follow these steps to change the name of the project output only 1 Select Edit Variables for projectname apj from the Project menu The Edit Variables dialog is displayed Figure 2 12 on page 2 29 2 28 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager Edit Variables for hello apj x Name OK oulld_target Delete Cancel Help Apply elle Value sprojectname gt ax Figure 2 12 Edit Variables dialog 2 Select the variable ProjectName 3 Enter the new name in the Value text box 4 Click the OK button Changing the names of both the project file and the project output Follow these steps to change the name of both the project file and the project output 1 Select Save As from the File menu The Save As dialog is displayed 2 Save the file with the new name 3 Rebuild the project Note The value of ProjectName must be stored in that variable otherwise the project output retains the name The value of projectname is updated by APM See Variables on page 2 26 for more information on variables ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 29 ARM Project Ma
301. ecified in the makefile or APM project file The value of DEBUG_METHOD defines the channel that is used to pass debug messages Some options require specific equipment or software for example pidulate rombox and e5 see also Debugging your Angel port on page 13 47 The logadp option should not be used In general the safest option is panicblk The most useful option is logterm but this requires a spare serial port Use the defines NO_LOG_INFO and NO_LOG_WARNING to increase execution speed and reduce the size of images created with debug enabled when some or all debug messages are not required Interrupt source for ADP You can select the interrupt source that is used to drive ADP channel communications and timer interrupts You can select either or both of HANDLE_INTERRUPTS_ON_IRQ Angel interrupt handlers will handle interrupts on IRQ ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 61 Angel HANDLE_INTERRUPTS_ON_FIQ Angel interrupt handlers will handle interrupts on FIQ The recommended option is to use IRQ because Angel interrupt operation is not time critical you can use FIQ for your application the Angel FIQ handler is slower than the IRQ handler Device Data Control Device data control is dependent on the build options minimal or not and the number of ports controlled by Angel The default options for full debug operation Angel on the PID board are serial port A fo
302. eck mark the Build also builds sub projects option Force Build also builds any associated sub projects see APM preferences on page 2 31 Force build a project in either of the following ways select Force Build projectname apj variant from the Project menu click the Force Build button Note If you move your project to a new location you must rebuild it using Force Build Building variants When you build a project only the selected variant is built To build all variants of your project select Build Variants from the Project menu Build steps A build step is a step in the build process that contributes to the project output Usually a build step generates one file or a group of related files The actions performed in a build step are defined by a build step pattern within the project template The build step pattern also defines what type of source file each build step acts upon Typical build steps include compiling or assembling source files linking object files and libraries building sub projects Copyright 1997 1998 ARM Limited All rights reserved 2 11 ARM Project Manager 2 2 4 2 12 Build step patterns A build step pattern associates a tool or tools such as armec or armlink with a build step within a project template defines the inputs and outputs associated with a build step associates the file types conventionally used and generated by a tool with the partition
303. ect dialog the next time you create a new project ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 45 ARM Project Manager 2 8 7 Editing project template details Project template details consist of a short project name for example ARM Executable Image and a description providing more details of the project Follow these steps to edit the details of a template 1 Select Edit Project Template from the Project menu The Project Template Editor 1s displayed 2 Click Edit Details The Edit Template Details dialog is displayed Figure 2 23 Edit Template Details Description Build and debug an ARM executable Image made from Cand ARM Assembly Language source files and ARM Object Libraries The DebugRel variant compiles smaller faster code that can be debugged tested and released unchanged You can build your abject libraries using sub projects Cancel Help Figure 2 23 Edit Template Details dialog 3 Change the Title and or Description as needed 4 Click OK 5 Click Close to close the Project Template Editor dialog 2 46 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 9 Build step patterns This section explains how to specify input and output patterns in a build step edit a build step pattern add a new build step pattern 2 9 1 Specifying input and output patterns in a build step pattern ARM DUI 0040D A bui
304. ect menu to display a submenu of the tools used 3 Select the tool you want to configure The Tool Configuration submenu is displayed 4 Click Set The appropriate Tool Configuration dialog is displayed showing current settings and allowing you to make changes 5 Make any required changes 6 Select one of the following click OK to save the changes and close the dialog click Apply to save the changes and keep the dialog open click Cancel to ignore all changes not applied and close the dialog Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager Resetting tool configuration You can return the configuration of a tool to the settings of its parent see Project hierarchy on page 2 25 as follows 1 Click on one or more entities for example the Debug variant in the Project window to select the scope for the configuration change 2 Select Tool Configuration for from the Project menu then select the tool to be configured The Tool Configuration submenu is displayed If there is a configuration setting for the selected scope the Unset menu item is enabled 3 Select Unset to reset the configuration to the settings of that tool at the next higher level of hierarchy Reading compiler options from a file There are two options that allow you to read additional command line options from a file These options must be specified on the Extra command line arguments text box of the
305. ed All rights reserved 2 7 ARM Project Manager 2 8 Release This variant is designed for projects where you intend to have separate debug and release builds of your code It contains the release version of your project It provides maximum optimization at the expense of debug information This variant turns off debug table generation and sets the optimization command line option to 02 Adding files to a project Follow these steps to add the newly created file to your project 1 Select the hello project as the current project 2 Select Add Files to Project from the Project menu The Open File dialog box is displayed 3 Move to the correct directory if necessary and select hello c 4 Click Open The file is added to the project Note If the project directory is still your current directory that is where the source file is stored by default You can however store source files in any accessible directory and add source files from any directory to a project Viewing the project When you have added files to your project you may want to view the project in more detail To expand a level of the project hierarchy click on the plus symbol next to that level Figure 2 3 on page 2 9 shows how the Project View looks if you expand the first three levels of hello apj Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 2 2 3 Build ARM DUI 0040D ARM Project Manager i C examples hello ap
306. ed Language Programming This chapter describes how to write mixed C C and ARM assembly language code It also describes how to use the ARM inline assemblers from C and C It contains the following sections Using the inline assemblers on page 8 2 Accessing C global variables from assembly code on page 8 14 Using C header files from C on page 8 15 Calling between C C and ARM assembly language on page 8 17 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 8 1 Mixed Language Programming 8 1 8 1 1 8 2 Using the inline assemblers The inline assemblers enable you to use most ARM assembly language instructions within a C or C program You can use the inline assembler to use features of the target processor that cannot be accessed from C achieve more efficient code The inline assembler supports very flexible interworking with C and C Any register operand may be an arbitrary C or C expression The inline assembler also expands complex instructions and optimizes the assembly language code Note Inline assembly language is subject to optimization by the compiler if optimization is enabled either by default or with the 01 or 02 compiler options The armcc and armcpp inline assemblers implement the full ARM instruction set including generic coprocessor instructions halfword instructions and long multiply The tcc and tcpp inline assemblers implement the full Thumb
307. ed and memory configuration of a proposed system pinpoint where an application can be streamlined leading to a reduction in system memory requirements identify performance critical sections of code that you can then optimize either by using a more efficient algorithm or by rewriting in assembly language Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Benchmarking Performance Analysis and Profiling 11 2 Measuring code and data size To measure code size do not look at the linked image size or object module size as these include symbolic information that is not part of the binary data Instead use one of the following armlink options info sizes this option gives a breakdown of the code and data sizes of each object file or library member making up an image info totals this option gives a summary of the total code and data sizes of all object files and all library members making up an image 11 2 1 Interpreting size information ARM DUI 0040D The information provided by the info sizes and info totals options can be broken down into code or read only segment data or read write segment debug data Code or read only segment code size Size of code excluding any data that has been placed in the code segment see Table 11 1 on page 11 5 inline data Size of read only data included in the code segment by the compiler Typically this data contains the addresses of variabl
308. ed as follows The M C and W bits are set in the control register CP15 register 1 to enable the Protection Unit the Cache and the Write Buffer The cacheable register is initialized to 1 marking region O as cacheable CP15 register 2 The bufferable register is initialized to 1 marking region 0 as bufferable CP15 register 3 The protection register is initialized to 3 marking region 0 as read write access CP15 register 5 Finally the Memory area definition register for region 0 is initialized to Ox3F marking the size of region 0 as 4GB and as enabled For the 940T the Protection Unit would be initialized as follows The P D and I bits are set in the control register CP15 register 1 to enable the Protection Unit the data cache and the instruction cache The cacheable registers are initialized to 1 marking region 0 as cacheable for the I and D caches CP15 register 2 This is displayed as 0x010 where the low byte bits 0 7 represent the dcache cacheable register the high byte bits 8 15 represent the icache cacheable register The bufferable register is initialized to 1 marking region 0 as bufferable CP15 register 3 The Protection registers are initialized to 3 marking region 0 as read write access for I and D caches CP15 register 5 This is displayed as 0x00030003 where the low halfword bits 0 15 represent the dcache protection register the high halfword
309. ed for hello c Note Your code may differ slightly from Example 4 1 on page 4 5 depending on the version of compiler you are using Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D x codeseg DATA include lt stdio h gt een a0 4 Tiaa 000000 0 SN 000004 000008 Paro dre 00000c 000010 000014 000018 00001c 000020 egy megs alk 4 1 5 Command Line Development Example 4 1 int main void e52de004 printf e28fF0F02 ebfffffc return e3a00000 e49df004 6c6c6548 6f77206f 0a646c72 00000000 main STR Ir sp 4 Hello world n ADD al pc L000014 8 BL _printf Q MOV al 0 LDR pc sp 4 L000014 DCB 0x48 0x65 0x6c Ox6c Hell DCB Ox6F Qx20 0x77 Ox6F O wWOo DCB 0x72 0x6c 0x64 0x0a rid n DCB 0x00 0x00 0x00 0x00 RAVAN AVANI END For more information ARM DUI 0040D For a description of the ARM C compiler options and the ARM linker options see the ARM Software Development Toolkit Reference Guide Copyright 1997 1998 ARM Limited All rights reserved 4 5 Command Line Development 4 2 4 2 1 4 2 2 4 2 3 armsd The ARM command line debugger armsd enables you to debug your ARM targeted image using any of the debugging systems described in Debugging systems on page 3 5 This section describes how to carry out basic tasks such as loading a C language based image into armsd and setting simple breakpoints
310. ed in a consecutive byte Refer to Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide for more information The LDR and STR instructions use post indexed addressing to update their address registers For example the instruction LDRB r2 r1 1 loads r2 with the contents of the address pointed to by rl and then increments rl by 1 Example 5 9 String copy Mark first instruction to execute Pointer to first string Pointer to second string Call subroutine to do copy gt angel_SwIreason_ReportException ADP_Stopped_ApplicationExit Angel semihosting ARM SWI Load byte and update address Store byte and update address Check for zero terminator Keep going if not gt Return Strings DATA READWRITE Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming srcstr DCB First string source Q dststr DCB Second string destination Q END Converting to Thumb There is no post indexed addressing mode for Thumb LDR and STR instructions Because of this you must use an ADD instruction to increment the address register after the LDR and STR instructions For example LDRB r2 r1 load register 2 ADD rl 1 Increment the address in register 1 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 33 Basic Assembly Language Programming 5 7 5 34 Load and store multiple register in
311. ed license Figure A 1 Finding a license Copyright 1997 1998 ARM Limited All rights reserved A 11 FlexLM License Manager A 8 A 8 1 Using FlexLM with more than one product FlexLM is a widely used product for license management so it is possible that you have more than one product using FlexLM The latest version of the FlexLM software will always work with vendor daemons built using previous versions Consequently you must always use the latest version of Imgrd and the FlexLM utilities Note The FlexLM software currently shipped by ARM is FlexLM version 6 0 If you have multiple products using FlexLM you may encounter two situations all the products use the same license server all the products use different license servers All products use the same server If the license files for every product contain exactly the same Server lines ignoring different TCP port numbers then there are two possible solutions L Start a separate Imgrd daemon for each license file There are no real disadvantages with this approach as the separate daemons consume very little system resources or CPU time Combine the the license files together Take the the SERVER line from one of the license files then add all of the other lines that is the DAEMON VENDOR and FEATURE lines to create a new license file You will need to store the new combined license file in use local flexim licenses license lic or give its location via
312. edInstr 0x20001 ADP_Stopped_Softwarelnterrupt 0x20002 ADP_Stopped_PrefetchAbort 0x20003 ADP_Stopped_DataAbort 0x20004 ADP_Stopped_AddressException 0x20005 ADP_Stopped_IRQ 0x20006 ADP_Stopped_FIQ 0x20007 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 97 Angel Name defined in adp h Table 13 6 Software reason codes Hexadecimal value ADP_Stopped_BreakPoint 0x20020 ADP_Stopped_WatchPoint Ox20021 ADP_Stopped_StepComplete 0x20022 ADP_Stopped_RunTimeErrorUnknown 0x20023 ADP_Stopped_InternalError 0x20024 ADP_Stopped_UserInterruption 0x20025 ADP_Stopped_ApplicationExit 0x20026 ADP_Stopped_StackOverflow 0x20027 ADP_Stopped_DivisionByZero 0x20028 ADP_Stopped_OSSpecific 0x20029 Return No return is expected from these calls However it is possible for the debugger to request that the application continue by performing an RDI_Execute request or equivalent In this case execution continues with the registers as they were on entry to the SWI or as subsequently modified by the debugger 13 8 3 angel_SWlreason_LateStartup 0x20 13 98 This SWI is obsolete Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 9 The Fusion IP stack for Angel This section describes the Fusion IP stack supplied with the Ethernet Upgrade Kit No KPI 0015A 13 9 1 How Angel Fusion and the PID hardware fit together The Ethernet interface for the PID car
313. edule_IRQ An IRQ is raised after n cycles where n is the bottom 8 bits of the address Schedule_FIQ An FIQ is raised after n cycles where n is the bottom 8 bits of the address Out channel The character represented by the bottom 8 bits of the data is sent to the screen for a write and is ignored on read In channel A byte is read from the terminal for a read or ignored for a write 12 30 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 14 2 Implementation ARM DUI 0040D There are eight banks of 128KB of RAM one of which is currently mapped in to the top page The memory model has two pieces of state an array representing the model of memory the number of the page currently mapped into the top page In this model the ARM does not need to run in different endian modes You can assume that the ARM is configured to be the same endianness as the host architecture Note If you want to allow the ARM to run in different endian modes you must have a ConfigChange callback as in armflat c However you do occasionally need to ensure that a write is allowed only if the nTRANS signal is HIGH indicating that the processor is in a privileged mode To enable you to know this you must install a callback for changes to nTRANS because it is not supplied to the memory access function The core calls the callback whenever nTRANS changes on mode changes and when executing an LDRT STRT i
314. el support 13 27 13 50 Fusion IP stack for Angel 13 99 Evaluating expressions 3 70 Examining memory 3 12 3 39 search paths 3 36 source files 3 37 variables 3 37 example c ARMulator model 12 4 Exception handlers and Angel 13 20 chaining 9 37 data abort 9 35 9 41 extending 9 37 FIQ 9 41 installing 9 9 installing from C 9 11 installing on reset 9 9 interrupt 9 22 IRQ 9 41 Index 6 nested 9 22 prefetch abort 9 34 9 41 reentrant 9 22 reset 9 32 returning from 9 5 subroutines in 9 44 SWI 9 14 9 15 9 17 9 41 Thumb 9 39 undefined instruction 9 33 9 41 Exceptions 9 2 and Angel 13 20 13 97 data abort 9 2 9 8 entering 9 5 FIQ 9 2 9 7 initialization code for ROM images 10 5 installing handlers 9 9 IRQ 9 2 9 7 leaving 9 5 prefetch abort 9 2 9 7 priorities 9 3 reporting in Angel 13 97 reset 9 2 response by processors 9 5 returning from 9 7 9 41 SWI 9 2 9 7 SWI handlers 9 14 9 15 9 17 undefined instruction 9 2 9 7 use of modes 9 3 use of registers 9 3 vector table 9 3 9 9 Executable image APM template 2 52 Execution profile 11 19 speed 5 19 5 56 7 2 7 17 9 22 stopping 3 26 3 34 window 3 15 Exiting debugger 3 10 Expanding project view 2 17 Expressions evaluating in ADW ADU 3 70 formatting watches 3 69 regular 3 42 setting watches in ADW ADU 3 66 window 3 21 Extending exception handlers 9 37 extern C 8 15 8 17 8 19 ES 13 68 Copyright 1997 1998 ARM Limited All rights reserved F F
315. el to use whenever an armsd map file exists in the directory where armsd is started Under the ARM GUI debuggers ARMmap is automatically selected whenever a memory map file is specified You specify map files using the Memory Maps tab of the debugger configuration dialog gt If there s a memory mapfile use that 1f MemConfigToLoad amp amp MEMORY_MapFi le Default MapFi le endif 12 10 3 How ARMmap calculates wait states ARM DUI 0040D The memory map file specifies access times in nanoseconds for non sequential sequential reads writes to various regions of memory By inserting wait states the ARMmap memory model ensures that every access from the ARM processor takes at least that long Copyright 1997 1998 ARM Limited All rights reserved 12 21 ARMulator The number of wait states inserted is the least number required to take the total access time over the number of nanoseconds specified in the memory map file For example with a clock speed of 33MHz a period of 30ns an access specified to take 70ns in a memory map file results in two wait states being inserted to lengthen the access to 90ns This can lead to inefficiencies in your design For example if the access time were 60ns only 14 faster ARMmap would insert only one wait state 33 quicker A mismatch between processor clock speed and memory map file can sometimes lead to faster processor speeds having worse performance For example a 100MHZ processo
316. eld angel_EthernetPol1 is invoked and non blocking recv calls are made to the Fusion stack to see if data is waiting on any of the sockets Outgoing packets are passed to the Fusion stack in a single step by calling sendto Interrupt handling The bottom of the Fusion stack is driven by interrupts from the Olicom card Interrupts are handled in the following sequence 1 suppasm S angel_DeviceInterruptHandler calls the GETSOURCE macro in pid target s to identify the PCMCIA controller as the source 2 pcmcia c angel_PCMCIAIntHandler establishes that it is an I O interrupt and calls the routine registered during initialization 3 olicom c olicom_isr checks the interrupt switches off interrupts from the Olicom card and serializes 0l1icom_process to do the processing with all other interrupts enabled 4 olicom c olicom_ process identifies the reason for the interrupt and passes it as an event to olicom_state Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel 5 olicom c olicom_state calls an appropriate routine in 82595 c to handle packet reception and transmission 6 82595 c routines control the 182595 chip and transfer packets in both directions between Fusion buffers and the chip Calls are made to Fusion functions as appropriate 7 olicom c olicom_process checks to see whether all interrupt events have been serviced If so Olicom interrupts are re ena
317. em into a single array element you must amend the code The first remedy is to comment the structure to prevent changes affecting this area Misc_I 4 gt Do not split reorder Misc_J 4 these 3 elements STM Misc_K 4 and LDM instructions used If the code is strongly commented no deliberate changes are likely to be made that would affect the workings of the program Unfortunately mistakes can still occur A second method of catching these problems would be to add ASSERT directives just before the STM LDM instructions to check that the labels are consecutive and in the correct order ArrayBase RN R9 Check that the structure elements are correctly ordered for LDM ASSERT Misc_J Misc_I 4 LAND Misc_K Misc_J 4 ADR ArrayBase Misc_I LDMIA ArrayBase RQ R2 This ASSERT directive stops assembly at this point if the structure is not in the correct order to be loaded with an LDM Remember that the element with the lowest address is always loaded from or stored to the lowest numbered register 5 60 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 6 Using the Procedure Call Standards This chapter describes how to use the ARM and Thumb Procedure Call Standards to ensure that separately compiled and assembled modules follow a standard set of rules for interworking It contains the following sections About the procedure call standards on page 6 2 Using the ARM Procedur
318. em to work with the ARM Software Development Toolkit and the EmbeddedICE interface Angel and so on Most of this chapter applies to both the Windows and the UNIX version of the ARM Debugger The term ARM Debugger refers to whichever version you are using depending on your operating system If a section applies to one version only that is indicated in the text or in the section heading When you have started ADW or ADU you can display online help giving details relevant to your current situation or navigate your way to any other page of ADW ADU online help F1 key Press the F1 key on your keyboard to display help if available on the currently active window Help button Many APM windows contain a Help button Click this button to display help on the currently active window Help menu Select Contents from the Help menu to display a Help Topics screen with Contents Index and Find tabs The tab you used last is selected Click either of the other tabs to select it instead Select Search from the Help menu to display the Help Topics screen with the Index tab selected Under Contents click on a closed book to open it and see a list of the topics it contains Click on an open book to close it Select a topic and click the Display button to display online help Under Index either scroll through the list of entries or start typing an entry to bring into view the index entry you want Select an index entry and click the Display button
319. emented with the following instructions and assembler directives EQU is an assembler directive It is used to give a value to a symbol In this example it assigns the value 2 to num When num is used elsewhere in the code the value 2 is substituted Using EQU in this way is similar to using define to define a constant in C DCD declares one or more words of store In this example each DCD stores the address of a routine that handles a particular clause of the jump table LDR The LDR pc r3 r0 LSL 2 instruction loads the address of the required clause of the jump table into the pc It AREA Jump CODE READONLY num EQU 2 ENTRY start MOV rQ 0 MOV rl 3 MOV r2 2 BL arithfunc multiplies the clause number in r0 by 4 to give a word offset adds the result to the address of the jump table loads the contents of the combined address into the program counter Example 5 7 Name this block of code Number of entries in jump table Mark first instruction to execute First instruction to call Set up the three parameters Call the function ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 29 Basic Assembly Language Programming stop MOV LDR SWI arithfunc CMP BHS ADR LDR JumpTable DCD DCD DoAdd ADD MOV DoSub SUB MOV END ro 0x18 gt angel_SwIreason_ReportException rl 0x20026 ADP_Stopped_ApplicationExit Qx123456 Angel semihosting ARM SWI Label the function rO num
320. emicolon on a line marks the beginning of a comment except where the semicolon appears inside a string constant The end of the line is the end of the comment A comment alone is a valid line All comments are ignored by the assembler Copyright 1997 1998 ARM Limited All rights reserved 5 11 Basic Assembly Language Programming Constants Numbers Strings Boolean Characters Numeric constants are accepted in three forms Decimal For example 123 Hexadecimal For example 0x7b n_xxx where nis a base between 2 and 9 xxx is a number in that base Strings consist of opening and closing double quotes enclosing characters and spaces If double quotes or dollar signs are used within a string as literal text characters they must be represented by a pair of the appropriate character For example you must use if you require a single in the string The standard C escape sequences can be used within string constants The Boolean constants TRUE and FALSE must be written as TRUE and FALSE Character constants consist of opening and closing single quotes enclosing either a single character or an escaped character using the standard C escape characters Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 3 2 An example ARM assembly language module AREA ENTRY start MOV MOV ADD stop MOV LDR SWI END ARM DUI 0040D Example
321. ename to link the object file 3 Type armsd filename to load the image file into the debugger 4 Type go at the armsd prompt to execute it 5 Type quit at the armsd prompt to return to the command line To see how the assembler converts the source code enter decaof c filename o or run the module in ADW or ADU with interleaving on See armsd on page 4 6 for details on armsd Chapter 3 ARM Debuggers for Windows and UNIX for details on ADW and ADU Chapter 6 Linker in the ARM Software Development Toolkit Reference Guide for details on armlink ARM object file decoder on page 8 10 of the ARM Software Development Toolkit Reference Guide for additional details on decaof Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 2 Overview of the ARM architecture This section gives a brief overview of the ARM Architecture Refer to the ARM Architectural Reference Manual for a detailed description of the points described here The ARM is typical of RISC processors in that it implements a load store architecture Only load and store instructions can access memory Data processing instructions operate on register contents only 5 2 1 Architecture versions The ARM architecture exists in four major versions The information and examples in this book assume that you are using a processor that implements Architecture 3 or later Refer to the ARM Architectural Reference Manual
322. ent 1 scratch register result rl a2 argument 2 scratch register result r2 a3 argument 3 scratch register result r3 a4 argument 4 scratch register result r4 vl register variable r5 v2 register variable r6 v3 register variable r7 v4 register variable r8 v5 register variable r9 sb v6 static base register variable r10 sl v7 stack limit stack chunk handle register variable rll fp v8 frame pointer register variable r12 Ip scratch register new sb in inter link unit calls r13 sp lower end of the current stack frame r14 lr link register scratch register r15 pe program counter 6 4 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Name fO Using the Procedure Call Standards Table 6 2 APCS floating point registers Number APCS Role FP argument 1 FP result FP scratch register fl FP argument 2 FP scratch register f2 FP argument 3 FP scratch register f3 FP argument 4 FP scratch register f4 floating point register variable f5 floating point register variable f6 floating point register variable f7 To summarize al a4 f0 f3 vl v8 f4 f7 floating point register variable These are used to pass arguments to functions al is also used to return integer results and fO to return FP results These registers can be corrupted by a called function These are used as register variables They must be preserved by called functions sb sl fp ip s
323. er based symbols Register based symbols can be very useful but you must be careful when using them As a general rule use them only in the following ways As the location for a load or store instruction to load from or store to If Location is a register based symbol based on the register Rb and with numeric offset the assembler automatically translates for example LDR Rn Location into LDR Rn Rb offset In an ADR or ADRL instruction ADR Rn Location is converted by the assembler into ADD Rn Rb offset Adding an ordinary numeric expression to a register based symbol to get another register based symbol Subtracting an ordinary numeric expression from a register based symbol to get another register based symbol Subtracting a register based symbol from another register based symbol to get an ordinary numeric expression Do not do this unless the two register based symbols are based on the same register Otherwise you have a combination of two registers and a numeric value This results in an assembler error As the operand of a BASE or INDEX operator These operators are mainly of use in macros Other uses usually result in assembler error messages For example if you write LDR Rn Location where Location is register based you are asking the assembler to load Rn from a memory location that always has the current value of the register Rb plus offset in it It cannot do this because there is no such memor
324. er one a descending stack or upwards starting from a low address and progressing to a higher address an ascending stack full or empty The stack pointer can either point to the last item in the stack a full stack or the next free space on the stack an empty stack In practice stacks are almost always full descending The C compilers produce full descending stacks 5 36 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming To make it easier for the programmer stack oriented suffixes can be used instead of the Increment Decrement and Before After suffixes See Table 5 6 for a list of stack oriented suffixes Table 5 6 Suffixes for load and store multiple instructions Stack type Push Pop Full Descending STMFD DB LDMFD IA Full Ascending STMFA IB LDMFA DA Empty Descending STMED DA LDMED IB Empty Ascending STMEA IA LDMEA DB For example STMFD LDMFD STMFA LDMFA STMED LDMED STMEA LDMEA Stacking registers for nested subroutines r13 r13 r13 r13 r13 r13 r13 r13 r0 r5 r0 r5 r0 r5 r0 r5 r0 r5 r0 r5 r0 r5 r0 r5 Push onto a Full Descending Stack Pop from a Full Descending Stack Push onto a Full Ascending Stack Pop from a Full Ascending Stack Push onto Empty Descending Stack Pop from Empty Descending Stack Push onto Empty Ascending Stack Pop from Empty Ascending
325. erates a reference to the symbol __main to force the linker to include the basic C run time system from the semihosting ANSI C library If you are not linking with the C library when building the ROM this causes an error If you use the main function only when building an application version for debugging comment it out with an ifdef when building a ROM image 10 8 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 4 Example 1 Building a ROM to be loaded at address 0 ARM DUI 0040D This example shows how to construct a piece of code suitable for running from ROM In a real example much more would have to go into the initialization section but because the initialization process is very hardware specific it has been omitted here The code for init s and ex c is in the Examples ROM init subdirectory of your SDT install directory normally c ARM250 Examples ROM init and is included in Sample code on page 10 12 for reference L Compile the C file ex c with the following command armcc c ex c ARM tcc c ex c Thumb where C tells the compiler to compile only not to link Assemble the initialization code init s armasm PD ROM_AT_ADDRESS_ZERO SETL TRUE init s or for Thumb armasm PD THUMB SETL TRUE PD ROM_AT_ADDRESS_ZERO SETL TRUE 1nit s This tells the assembler to predefine PD the symbol ROM_AT_ADDRESS_ZERO and to give it the logical or Boolea
326. erates an error message or puts the variable into another register to avoid conflicts int bad_f int x x in rO asm ADD r0 r0 1 wrongly asserts that x is still in rQ return x x in r This code returns x unaltered The compiler assumes that x and r0 are two different variables despite the fact that x is allocated to r0 on both function entry and function exit As the assembly language code does not do anything useful it is optimized away The instruction should be written as ADD x x 1 Do not save and restore physical registers that are used by an inline assembler The compiler will do this for you If physical registers other than cpsr and spsr are read without being written to an error message is issued For example int f int x __asm STMFD sp r0 save r illegal read before write ADD r x 1 EOR x r0 x LDMFD sp r0 restore r not needed ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 8 9 Mixed Language Programming 8 1 6 8 10 Examples return x The following examples demonstrate some of the ways in which you can use inline assembly language effectively Enabling and disabling interrupts Interrupts are enabled or disabled by reading the cpsr flags and updating bit 7 Example 8 2 shows how this can be done by using small functions that can be inlined These functions work only in a privileged mode bec
327. errupt Request IRQ Interrupt Request Supervisor Abort Undefined System ARM version 4 architectures only Most application programs execute in User mode The other modes are entered to service exceptions or to access privileged resources Refer to Chapter 9 Handling Processor Exceptions for more information The ARM processor has 37 registers The registers are arranged in partially overlapping banks There is a different register bank for each processor mode The banked registers give rapid context switching for dealing with processor exceptions and privileged operations Refer to Chapter 9 Handling Processor Exceptions for a detailed description of how registers are banked The following registers are available in version 3 and later of the ARM architecture 30 general purpose 32 bit registers Fifteen of these are visible at any one time depending on the current processor mode as r0 rl r13 r14 By convention in ARM assembly language r13 is used as a stack pointer sp The C compilers always do this In User mode r14 is used as a link register Ir to store the return address when a subroutine call is made It can also be used as a general purpose register if the return address is stored on the stack In the exception handling modes r14 holds the return address for the exception or a subroutine return address if subroutine calls are executed within an exception r14 can be used as a general p
328. ers enter break without any arguments To remove a breakpoint enter unbreak if only one breakpoint is set unbreak n to delete breakpoint number n unbreak function_name to delete a breakpoint on the first statement of function function_name You can use any of these methods to remove a breakpoint regardless of the way in which the breakpoint was set break can be abbreviated to b and unbreak can be abbreviated to unb 4 2 4 Setting and removing simple watchpoints A watchpoint halts the image when a specified variable changes To set a simple watchpoint on a variable enter watch variable To list all the current watchpoints and their corresponding numbers enter watch without any arguments To remove a watchpoint enter unwatch if only one watchpoint is set unwatch n to delete watchpoint numbered n unwatch variable to delete a watchpoint on a specified variable You can use any of these methods to remove a watchpoint regardless of the way in which it was set watch can be abbreviated to w and unwatch can be abbreviated to unw ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 4 7 Command Line Development 4 2 5 Executing the program The following commands enable you to control program execution To execute the program enter go Execution continues until abreakpoint halts the program awatchpoint halts the program the program exits To stop the executi
329. erved Writing Code for ROM Example 10 5 ex c 10 15 Writing Code for ROM void C_Entry void if rom_data_base ram_data_base WriteQ Warning Image has been linked as an application r n Writed To link as a ROM image link with the options r n WriteQ RO lt rom base gt RW lt ram base gt r n Write factory_id is at address pr_hex unsigned amp factory_1d WriteQ contents pr_hex unsigned factory_id WriteQ r n WriteQ display is at address pr_hex unsigned display WriteQ r n Exit 10 16 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 5 Example 2 Building a ROM to be entered at its base address This example shows how to construct a ROM image where the ROM is normally located at a non zero address but is mapped to address 0x0 on reset The code for init s and ex c is in the Examples ROM init subdirectory of your SDT install directory normally c ARM250 Examples ROM init and are included in Sample code on page 10 12 for reference 10 5 1 Building the ROM image ARM DUI 0040D Follow this procedure to build the ROM image L Compile the C file ex c with the following command armcc c ex c ARM tcc c ex c Thumb where C tells the compiler not to link Assemble the initialization code init s armasm init s or for Thumb armasm PD THUMB SETL TRUE init s Build the
330. es Display ANSI Headers Mdcc un a pid AL Mpstack drag list tems to reorder them Delete Update directory list Ee E Use amp R path search rules dd Replace Equivalent Command Line D__ TARGET_CPU_ARM TM DLATE_STARTUP 0 DDEBUG 0 DRETRANS DTHUMB_SUPPORT 1 DMINIMAL ANGEL 0 DLOGTERM_DEBLUIGGING 0 DETHERNET_SUPPORTED 0 DASSERT_ENABLED 0 4 support l dec LAL LA Apid 4 Nipstack Cancel Help Figure 13 10 Compiler Configuration Click on the Include Files tab and edit the list of include file directories to reflect the new directory structure Click OK to apply the changes Repeat steps 10 and 11 using the lt asm gt tasm submenu to configure the assembler Remove and re add all target specific source files to the project These are the files that are located in the renamed pid directory such as devices c and makelo c see Figure 13 11 on page 13 56 In general you will have to replace these files with your own code when porting Angel Select a file and press the delete key to remove it Select Add files from the Project menu to re add the file to the Sources partition In addition you must replace makelo c in the Host Sources partition Copyright 1997 1998 ARM Limited All rights reserved 13 55 Angel ST ARM Project Manager C 4Port Source Example _ bApmi ngelPid api File Edit View Project Tools Window Help x Bol EleT amp E
331. es The address given by a label is calculated during assembly The assembler calculates the address of a label relative to the origin of the area where the label is defined A reference to a label within the same area can use the program counter plus or minus an offset This is called program relative addressing Labels can be defined in a map See Describing data structures with MAP and directives on page 5 46 The origin of the map is usually placed in a specified register at run time and references to the label use the specified register plus an offset This is called register relative addressing Addresses of labels in other areas are calculated at link time when the linker has allocated specific locations in memory for each area Local labels Local labels are a subclass of label A local label begins with a number in the range 0 99 Unlike other labels a local label can be defined many times Local labels are useful when you are generating labels with a macro When the assembler finds a reference to a local label it links it to a nearby instance of the local label The scope of local labels is limited by the AREA directive You can use the ROUT directive to limit the scope more tightly Refer to Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide for details of the syntax of local label declarations how the assembler associates references to local labels with their labels Comments The first s
332. es below and press the Add or Replace button to edit the above list Ad SubProjects kpath gt lt sl gt lt prj gt apj Replace Output Partition Pattern ewe lt path gt lt sl gt lt pri gt alf Delete Type in the boxes below and press the Add or Replace button to edit the above list Add Command Lines build lt path gt lt sl gt lt prj gt apj Fa OK Cancel Help Apply Figure 2 24 Edit Build Step Pattern dialog 3 Edit the build step pattern as required possibly deleting editing or adding input output patterns as follows Deleting an input output pattern a Select the pattern line from the list in the Input or Output Partition box The selected pattern is loaded on the edit line b Click Delete to remove the pattern Editing an input output pattern a Select the pattern line from the list in the Input or Output Partition box The selected pattern is loaded on the edit line b Edit the pattern as required see Specifying input and output patterns in a build step pattern on page 2 47 c Click Replace to change the pattern Adding a new input output pattern a Enter an Input or Output Partition b Enter the pattern for the partition c Click Add 4 Change the Command Line as required 2 50 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 5 Click OK to save the changes and exit the dialog 6 Click Close to close the Proje
333. es that are accessed by the code plus any floating point immediate values or immediate values that are too big to load directly into a register It does not include inline strings which are listed separately see Table 11 1 on page 11 5 inline strings Size of read only strings placed in the code segment The compiler puts such strings here whenever possible to reduce runtime RAM requirements const Size of any variables explicitly declared as const These variables are guaranteed to be read only and so are placed in the code segment by the compiler Copyright 1997 1998 ARM Limited All rights reserved 11 3 Benchmarking Performance Analysis and Profiling Data or read write segment RW data Size of read write data This is data that is read write and also has an initializing value Read write data occupies the displayed amount of RAM at runtime but also requires the same amount of ROM to hold the initializing values that are copied into RAM on image startup Q init data Size of read write data that is zero initialized at image startup Typically this contains arrays that are not initialized in the C source code Zero initialized data requires the displayed amount of RAM at runtime but does not require any space in ROM Debug data debug data Reports the size of any debugging data if the files are compiled with the g option Note There are totals for the debug data even though the code has not been compiled for
334. et these flags except when one or more high registers are specified as operands to the MOV or ADD instructions In these cases the flags cannot be set You cannot have any data processing instructions between an instruction that sets a condition and a conditional branch that depends on it You must use conditional branches over any instructions that you wish to be conditional Register access In Thumb state most instructions can access only r0 r7 These are referred to as the low registers Registers r8 to r15 are limited access registers In Thumb state these are referred to as high registers They can be used for example as fast temporary storage Refer to the ARM Architectural Reference Manual for a complete list of the Thumb data processing instructions that can access the high registers Access to the barrel shifter In Thumb state you can use the barrel shifter only in a separate operation using an LSL LSR ASR or ROR instruction ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 9 Basic Assembly Language Programming 5 3 5 3 1 5 10 Structure of assembly language modules Assembly language is the language that the ARM assembler armasm parses and assembles to produce object code This can be ARM assembly language Thumb assembly language a mixture of both The armasm assembler assembles both ARM and Thumb assembly languages The obsolete Thumb assembler tasm is provided i
335. eue Item TQI A TQI contains task information such as the register context for the task the current priority of the task the type of the task for example TP_Application the task state for example TS_Blocked the initial stack value for the task a pointer to the next lower priority task The elements in the angel_TQ_Pool array are managed by routines within the serializer and must not be modified externally Angel calls Angel_NewTask to create new tasks This function initializes a free TQI with the values required to run the task When the task is selected for execution Angel_SelectNextTask loads the register context into the CPU The context is restored to the same TQI when Angel_SerialiseTask is called as the result of exception processing or a call to Angel_Yield Angel_Wait determines that the task must be blocked When the debugger requests information about the state of the application registers the Angel debug agent retrieves the register values from the TQI for the application The application TQI is updated from the appropriate global register block when exceptions cause Angel code to be run Overview of Angel stacks for each mode The serialization mechanism described in Angel task management on page 13 33 ensures that only one task ever executes in Supervisor mode Therefore all Angel Supervisor mode tasks share a single stack on the basis that itis always empty when a ta
336. example Write a string x __swi SemiSWI void _Write unsigned op char string define WriteQ string _WriteQ 0x4 string fx Exit x __swi SemiSwWI void _Exit unsigned op unsigned except define Exit _Exit 0x18 0x20026 void C_Entry void int 1 char buf 20 for 1 0 1 lt 10 i sprintf buf Hello World d n 1 WriteQ buf Exit ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 10 21 Writing Code for ROM 10 7 Example 4 Simple scatter loading example 10 7 1 10 22 Scatter loading provides a more flexible mechanism for mapping code and data onto your memory map than the armlink ro base and rw base options These options are described in detail in Chapter 6 Linker of the ARM Software Development Toolkit Reference Guide The following example shows a scatter loading application that runs under the ARMiulator and also uses sprintf from the Embedded C library The example displays the linker generated scatter symbols on the screen It is not normally necessary to access these linker symbols in application code they are only really needed in initialization code The linker symbols are accessed here for illustration only The code for this example is in Examples rom ARMul_Scatter in your SDT installation directory normally c ARM250 Examples rom ARMul_Scatter Memory map This example shows FLASH is 0 on RESET and is remapped to 0x04000000 after RE
337. executing Angel code Note Angel is not always capable of downloading a new copy of itself and then restarting Your board must contain sufficient spare RAM to copy the new Angel into RAM before relocating it and running it If you do not have sufficient RAM you can use EmbeddedICE or Multi ICE to download Angel providing it has been compiled to run from the download location Angel is built to relocate a downloaded new Angel to the address that the new Angel is built to execute from and then to execute it If you download a copy of Angel that is built to run from ROM it will fail See Configuring where Angel runs on page 13 70 for more information on specifying the Angel execution address Using the debuggers to download Angel From armsd use the loadagent command to download a new version of Angel The loadagent command cannot write to Flash If you use loadagent Angel must be compiled to run from RAM In the ARM debuggers ADW and ADU select Flash Download from the File menu to download a new version of Angel to Flash Copyright 1997 1998 ARM Limited All rights reserved 13 67 Angel 13 4 8 Debugging your Angel port 13 68 You can use a number of methods to debug your Angel port The method you choose will depend on the stage of development you have reached and the hardware available to you Note You should take debug requirements into consideration when designing your development board Your boar
338. f decaxf refer to the ARM Software Development Toolkit Reference Guide 2 38 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 8 Working with project templates This section gives further details of project templates and how they are used within APM It also discusses how you can modify various components of a template 2 8 1 General information This section explains what a project template is how to use a template to create a project how to modify a project template What is a project template The following elements make up a project template build step patterns tools partitions variants variables Build step patterns Tools Partitions Variants A build step pattern controls how a specific tool works within the project environment and it specifies how a particular file type is handled within that environment It controls how a tool transforms its input into output as an intermediate step in building the output of your project A build step pattern has a global effect within a project However you can use variables to change the effect at the source partition or variant level of the project hierarchy Build step patterns are discussed in Build step patterns on page 2 12 Tools are the programs used by a build step pattern to transform a source file into a derived file Tool configuration is discussed in Configuring tools on page 2 20
339. filing is also supported by Angel except when used with StrongARM To collect profiling information 1 Load your image file 2 Select Options Profiling Toggle Profiling 3 Execute your program 4 When the image terminates select Options Profiling Write to File 5 A Save dialog appears Enter a file name and a directory as necessary 6 Click Save Copyright 1997 1998 ARM Limited All rights reserved 3 43 ARM Debuggers for Windows and UNIX Note You cannot display profiling information from within the ARM Debugger You must capture the data using the Profiling functions on the Options menu then use the armprof command line tool After you have started program execution you cannot turn profile collection on However if you want to collect information on only a certain part of the execution you can initiate collection before executing the program clear the information collected up to a certain point such as a breakpoint by selecting Options Profiling Clear Collected then execute the remainder of your program See Chapter 11 Benchmarking Performance Analysis and Profiling for more information on profiling 3 5 8 Saving or changing an area of memory You can either copy an area of memory to a disk file copy the contents of a disk file to an area of memory Follow these steps to save an area of memory to a file on disk 1 Select Put File from the File menu to display the Pu
340. fpe dhry Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D EE Benchmarking Performance Analysis and Profiling Set a breakpoint on the first instruction of Proc_5 break Proc_5 Type go at the armsd prompt to begin execution When prompted request at least two runs through Dhrystone When the breakpoint at the start of Proc_5 is reached display the system variable statistics which gives the total number of instructions and cycles taken so far and restart execution print statistics go When the breakpoint is reached again you can obtain the number of instructions and cycles consumed by one iteration print statistics_inc If you are using the Windows toolkit l 10 11 If you have not already done so build the Dhrystone project as described in Code and data sizes example Dhrystone on page 11 4 If you use ADW and are running APM then click on the Debug button to start ADW and load the Dhrystone project If you use ADU then start ADU and select Load Image from the File menu to load the Dhrystone project Disable floating point emulation Select Options Configure Debugger Target ARMulate and switch the FPE check box off Locate function Proc_5 by selecting Low Level Symbols from the View menu Double click on Proc_5 to open the Disassembly Window Toggle the breakpoint on Proc_5 in the Disassembly Window by selecting the instruction then clicking
341. ftware Development Toolkit Reference Guide for details of hardware support for halfwords Other changes Modify performance critical C source to compile efficiently on the ARM See Improving performance and code size on page 11 16 Port small performance critical routines into ARM assembly language Compile with the S option to produce assembly output without generating object code and take this as a starting point for your own hand optimized assembly language When you specify the S option you can also specify fs to write a file containing interleaved C or C and assembly language see Specifying output format on page 2 18 of the ARM Software Development Toolkit Reference Guide You can make significant performance improvements by using Load and Store Multiple instructions in memory intensive algorithms When optimizing the routines use load store multiple instructions for memory intensive algorithms use 64 bit result multiply instructions where available for fixed point arithmetic replace small performance critical functions by macros or use the __inline preprocessor directive avoid the use of setjmp in performance critical routines particularly in pcc mode Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 11 5 Profiling Benchmarking Performance Analysis and Profiling Profiling allows the time spent in specific parts of an application to be examined It does not require
342. g ENTRY ARMProg MOV r0 1 BL ThumbProg MOV r2 3 MOV ro 0x18 ARM DUI 0040D Mark Ist instruction to call Set rO to show in ARM code Call Thumb subroutine Set r2 to show returned to ARM Terminate execution ange 1_SWIreason_ReportException Copyright 1997 1998 ARM Limited All rights reserved 7 19 Interworking ARM and Thumb LDR r1 0x20026 SWI xAB END ale als ale ale ale ale als WAN 48 48 WAN thumb s j L A I ala ale ala ADP_Stopped_ApplicationExit Angel semihosting Thumb SWI AREA Thumb CODE READONLY INTERWORK CODE16 EXPORT ThumbProg ThumbProg MOV rl 2 BX Ir END Name this block of code Subsequent instructions are Thumb Set r1 to show reached Thumb code Return to ARM subroutine Mark end of this file Follow these steps to build and link the modules and examine the interworking veneers L 2 7 20 Type armasm arm s to assemble the ARM code Type armasm 16 thumb s to assemble the Thumb code Type armlink arm o thumb o o count to link the two object files Type armsd count to load the code into the debugger Type list 0x8000 at the armsd command prompt to list the code Figure 7 5 on page 7 21 shows an example armsd list Qx8000 Arm 0000 Ox00008000 Oxe3a00001 gt mov ro 1 0004 Ox00008004 OxebQ0Q005 bl 0x8020 ThumbProg 0x4 0008 0x00008008 Oxe3a02003 mov r2 3 000c Ox0000800c Oxe3a00018 mov
343. g Processor Exceptions 9 1 9 2 9 3 9 4 9 5 9 6 9 7 9 8 9 9 9 10 9 11 9 12 OVOCIVICW M Re A A 9 2 Entering and leaving an exception cccccecseeeeeceeeeeeseeeeeeeeeeeesaeeesaeeeesaaees 9 5 Installing an exception handler ccccceseeeeeceeseeeeeneneeeeeenaereeeenanerensaaeees 9 9 SV AICS IS 2e Sn a en ER ne Meet names aise eee 9 14 iMerup Handlers EE es in ad Sin ne nur ae 9 22 R SOLNANOIGIS RS EN nn NN Qu nl 9 32 Undefined instruction handlers ccccceeeeecceeeeeeeeceeseeeeeceeeeeeeeaceeeeesaaeeees 9 33 Pr efeteh abornt handler tnt nn A meet 9 34 DATA ADOM handier Es ane Dee tata nie a onu 9 35 Chaining exception handlers ss 9 37 Handling exceptions on Thumb capable processors ccceseeeeesseeeeeees 9 39 SYSLEMMOMR HELENE ar T ENE 9 44 Writing Code for ROM 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 10 9 10 10 10 11 About writing Code for ROM Us 10 2 Memory map considerations VU 10 3 Mitalizing TAS System sise nine a E tenes sine 10 5 Example 1 Building a ROM to be loaded at address 0 ceeeeeeeeeees 10 9 Example 2 Building a ROM to be entered at its base address 10 17 Example 3 Using the embedded C library ccccseecceeeseeeeeeeseeeeeeeneees 10 19 Example 4 Simple scatter loading example ccccccceeeeeeeeeeeeeeeeanees 10 22 Example 5 Complex scatter load example cccccceeceeceeeeeeeeeeeeaeeees 10 26 Scatter
344. g is displayed Figure 13 8 on page 13 53 13 52 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel Edit Build Step Pattern x Build Step Pattern Name Input Partition Pattern Sources lt path gt lt slashl gt lt file gt s Delete IncludedFiles lt path gt lt slashl gt lt hdillolevel gt s Type in the boxes below and press the Add or Replace button to edit the above list EE Output Partition Pattern i lt file gt o Delete Type in the boxes below and press the Add or Replace button to edit the above list _ 49d Replace Command Lines lt asm gt o lt file gt o 32 PD ROADDRbPSETAB lt ROADDR gt lt ENDIANNESS gt i pathk lt pathl gt oid OK Cancel Help Figure 13 8 Edit Build Step Pattern 4 The Command Lines section of the dialog contains the command line for the assembler The last part of the command line is path lt path I gt lt path gt lt path gt lt slash gt lt file gt s Change this to path2 lt path I gt lt path gt lt path gt lt slash gt lt file gt s by adding the number 2 to the first path 5 Click the Apply button and then click OK 6 Repeat steps 3 and 4 for the build step patterns Assemble for ROM and Compile 7 Select MakeLo from the list of build step patterns and click on the Edit button The Edit Build Step Pattern dialog is displayed Figure 13 9 on page 13 54 ARM DUI 0040D Copy
345. g veneers The assembly language ARM Thumb interworking method described in Basic assembly language interworking on page 7 4 carried out all the necessary intermediate processing There was no need for the linker to insert interworking veneers and no need to set the INTERWORK attribute that the linker uses to decide whether to add an interworking veneer This section describes how you can make use of interworking veneers to interwork between assembly language modules interwork between assembly language and C or C modules 7 4 1 Assembly only interworking using veneers a la als ala ale ala j 29 29 29 29 2 arm s You can write assembly language ARM Thumb interworking code to make use of interworking veneers generated by the linker To do this you write the caller routine just as any non interworking routine using a BL instruction to make the call the callee routine using a BX instruction to return and set the INTERWORK attribute for the area in which it is located Example of assembly language interworking using veneers Example 7 5 sets registers r0 to r2 to the values 1 2 and 3 respectively Registers rO and r2 are set by the ARM code Register r1 is set by the Thumb code Note that the INTERWORK attribute is set in the area definition of thumb s a BX lr instruction is used to return instead of the usual MOV pc Ir Example 7 5 AREA Arm CODE READONLY Name this block of code IMPORT ThumbPro
346. ge the EmbeddedICE configuration options L Select Configure EmbeddedICE from the Options menu The configuration dialog is displayed Figure 3 20 EmbeddedICE Configuration x E mbeddedICE Versions fary Load Agent Load Contig Cancel Apply Help Figure 3 20 Configuration of EmbeddediCE target Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 2 Change the following configuration settings as required Name Name given to the EmbeddedICE configuration Valid options are ARM7DI for use with an ARM7 core with debug extensions and EmbeddedICE macrocell includes ARM7DMI ARM7TDI for use with an ARMY core with Thumb and debug extensions and EmbeddedICE macrocell includes ARM7TDMI Version Version given to the EmbeddedICE configuration Specify the specific version to use or enter any if you do not require a specific implementation Load Agent Specify a new EmbeddedICE ROM image file download it to your board and run it Use this for major updates to the ROM Load Config Specify an EmbeddedICE configuration file to be loaded Click OK to run Use this for minor updates ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 61 ARM Debuggers for Windows and UNIX 3 8 ARM Debugger with C This section describes the additions that ARM C makes to ADW and ADU It does not describe those parts of ADW and ADU
347. gement system aliases the ROM from its physical address to 0 in order to allow ROM resident code to be available at reset This macro is called from startrom s for target specific startup In the PID example the startup macros reset both the ramsize counter and the interrupt controller This macro initializes the MMU for processors that include an MMU The location of the pagetable is important to the operation of this code and you must be specify it correctly If the system is operating in big endian mode and the MMU is responsible for the endianness of the core it must be set up early to enable to code to operate correctly This macro is not used by Angel It is provided as a place holder to allow you to initialize any timers required by your application It is called after interrupts are disabled and the processor is set to Supervisor mode There is no code included in the example because it does not make use of system timers Profiling support code contains its own timer initialization code Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel GETSOURCE This macro is called by the Angel support routines in interrupt s It determines whether the current interrupt is for an Angel device and if so which one The routine returns a small integer representing the current interrupt source as defined in devconf h see devconf h on page 13 60 These values are used by the interrupt handler for
348. generated by the assembler Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example AREA Loadcon CODE READONLY ENTRY start BL funcl BL func2 stop MOV rO 0x18 LDR rl 0x20026 SWI 0x123456 i func1 LDR r0 42 LDR rl 0x55555555 LDR r2 0xFFFFFFFF MOV pc lr LTORG func2 LDR r3 0x55555555 LDR r4 0x66666666 MOV pc Ir LargeTable 4200 END 5 26 Copyright 1997 1998 ARM Limited All rights reserved Example 5 5 Mark first instruction to execute Branch to first subroutine Branch to second subroutine ange _SWIreason_ReportException ADP_Stopped_ApplicationExit Angel semihosting ARM SWI gt MOV RO 42 gt LDR R1 PC offset to Literal Pool 1 gt MVN R2 0 Literal Pool 1 contains literal 0x55555555 gt LDR R3 PC offset to Literal Pool 1 If this is uncommented it fails because Literal Pool 2 is out of reach Starting at the current location clears a 4200 byte area of memory to zero Literal Pool 2 1s empty ARM DUI 0040D Basic Assembly Language Programming 5 6 Loading addresses into registers It is often necessary to load an address into a register You may need to load the address of a string constant or the start location of a jump table Addresses are normally expressed as offsets from the current pc or other register This section describes two methods for loading an address into a register
349. ger desktop ARM DUI 0040D The main features of the ARM Debugger desktop are A menu bar toolbar mini toolbar and status bar For details see Menu bar toolbar mini toolbar and status bar on page 3 8 A number of windows that display a variety of information as you work through the process of debugging your executable image For details see ARM Debugger desktop windows on page 3 14 A window specific menu that is available for each window as described in Window specific menus on page 3 25 Figure 3 2 on page 3 8 shows the ARM Debugger with the Execution Console Globals and Locals windows in the process of debugging the sample image DHRY Copyright 1997 1998 ARM Limited All rights reserved 3 7 ARM Debuggers for Windows and UNIX a ARM Debugger C arm dhry Debug dhry axt File Edit Search Mew C Execute Options Window Help shoes BE e APY eee ji ARM Executing dhry_1 c Oz00000000 char Enumeration Str_ 30 otr_1_Log Str_30 mtr_2 Lac REG int Run_Index REG int Number Of Ru Tnitializations ext_Ptr_Glob Rec Pointer mall Ptr_Glob Rec Pointer malloc s Ptr_Glob Ptr Comp Ptr_Glob Diser Ux 00000000 Ptr_blob variant var_1l Enum Comp Ox00000000 Ptr lob gt iant 1 Int_ a r_Glob gt variant var_1 Int_Comp strepy Ptr_Glob gt variant var_1l st Ox00000000 i 0 00000000 DHEYSTONE PROGRAM SOME oe Hz mt rers Qt 1 Toe UND YOTARTE DD Ox00000000 Console Windo
350. ges and ARM libraries ARM Executable Image Build and debug an ARM executable image made from C and ARM assembly language source files and ARM object libraries You can build your object libraries using sub projects Thumb Executable Image Build and debug a Thumb executable image made from C and Thumb ARM assembly language source files and Thumb object libraries You can build your object libraries using sub projects You can compile some C sources for ARM state by setting the cc Project variable to armcc for just those source files see Editing a variable on page 2 42 ARM Object Library Build a library of ARM object files from C and ARM assembly language source files You can use the library as a component in Projects to build ARM executable images Thumb Object Library Build a library of Thumb object files from C and Thumb ARM assembly language source files You can use the library as a component in Projects to build Thumb executable images You can compile some C sources for ARM state by setting the cc Project variable to armcc for just those source files Thumb ARM Interworking Image Build and debug a Thumb ARM interworking image made from Thumb C source files ARM C source files Thumb ARM assembly language source files Thumb object libraries ARM object libraries You can build your object libraries using sub projects ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 41
351. gger for Windows ADW and ARM Debugger for UNIX ADU These are two versions of the same debugger adapted to run under Windows and UNIX respectively ADW is part of the ARM Software Development Toolkit ADU is an extra cost addition that requires SDT 2 1 1a or greater ADW and ADU screens differ slightly in appearance Your screens might look different from the figures in this chapter If you have purchased the ARM C compiler the C installation process adds extra features to the ARM Debuggers to support debugging C Refer to ARM Debugger with C on page 3 62 for details This chapter contains the following sections About the ARM Debuggers on page 3 2 Getting started on page 3 7 ARM Debugger desktop windows on page 3 14 Breakpoints watchpoints and stepping on page 3 26 Debugger further details on page 3 36 Channel viewers Windows only on page 3 49 Configurations on page 3 51 ARM Debugger with C on page 3 62 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 1 ARM Debuggers for Windows and UNIX 3 1 3 1 1 3 2 About the ARM Debuggers Online help The ARM Debuggers enable you to debug your ARM targeted image using any of the debugging systems described in Debugging systems on page 3 5 You can also use the ARM Debugger to benchmark your application Refer to the documentation supplied with your target board for specific information on setting up your syst
352. gging To debug your application you must choose a debugging system which can be hardware based on an ARM core software that emulates an ARM core a debugger such as ADW ADU and armsd Figure 3 1 shows a typical debugging arrangement of hardware and software Ho st ADV serial or EmbeddediCE SeralParalel ARM head board PID board Figure 3 1 A typical debugging set up 3 4 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 1 3 Debugging systems ARM DUI 0040D The following debugging systems are available for applications developed to run on an ARM core the ARMulator the EmbeddedICE interface or Multi ICE the Angel Debug Monitor These systems are described in the following sections The ARMulator The ARMulator is a collection of programs that emulate the instruction sets and architecture of various ARM processors The AR Mulator provides an environment for the development of ARM targeted software on the supported host systems enables benchmarking of ARM targeted software The ARMulator is instruction accurate meaning that it models the instruction set without regard to the precise timing characteristics of the processor It can report the number of cycles the hardware would have taken As a result the ARMulator is well suited to software development and benchmarking EmbeddediCE and Multi ICE EmbeddedICE
353. ghest section of memory should equate to Oxffffffff when the base and size are defined as a sum and it may wrap around to 0 For example if there is memory mapped I O at Oxffd00000 the definition should be define IOBase xFFDO0000 define IOSize 0x002fffff define IOTop IOBase I0S1ze not define I0Base xFFDO0000 define I0Size 0x00300000 define IOTop IOBase 10Size Copyright 1997 1998 ARM Limited All rights reserved 13 69 Angel 13 5 2 Configuring timers and profiling The PID board has two timers available and by default profiling and Ethernet are configured to use the same timer The PID board uses pc sampling for profiling This requires a fast interrupt The interrupt service routine records where the program was when it was interrupted If you do not use profiling or Ethernet you can use the timer for your application You can turn off profiling by setting a runtime debugger variable but this does not free the timer In the Angel PID port profiling is specified in the PROFILE entry of devconf h You must recompile Angel to remove profiling support Refer to devconf h on page 13 60 for more information System timers can be initialized by implementing the INITTIMER macro in target s This macro is not implemented by the PID port It is provided as a place holder to enable you to initialize your own system timers Refer to farget s on page 13 58 for more information 13 5 3 Configuring exception h
354. ghts reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX Watchpoints window The Watchpoints window displays a list of all watchpoints Use the Watchpoints window to delete a watchpoint edit a watchpoint Window specific menus Each of the ARM Debugger desktop windows displays a window specific menu when you click the secondary mouse button over the window The secondary button is typically the right mouse button Item specific options require that you position the cursor over an item in the window before they are activated Each of the window specific menus is described in the online help for that window Copyright 1997 1998 ARM Limited All rights reserved 3 25 ARM Debuggers for Windows and UNIX 3 4 3 4 1 3 26 Breakpoints watchpoints and stepping You use breakpoints and watchpoints stop program execution when a selected line of code is about to be executed or when a specified condition occurs You can also execute your program step by step This section contains the following subsections Simple breakpoints Simple watchpoints on page 3 29 Complex breakpoints on page 3 30 Complex watchpoints on page 3 32 Backtrace on page 3 33 Stepping through an image on page 3 34 Simple breakpoints A breakpoint is a point in the code where your program is halted by the ARM Debugger When you set a breakpoint it is marked in red in the left pane of the breakpoints windo
355. ghts reserved ARM DUI 0040D ARM DUI 0040D Angel Angel_Wait Angel_Wait works in conjunction with Angel_Signal to enable a task to wait for a predetermined event or events to occur before continuing execution When AngelWait is called the task is blocked unless the predetermined event has already been signalled with AngelSignal AngelWait is called with an event mask The event mask denotes events that will result in the task continuing execution If more than one bit is set any one of the events corresponding to those bits will unblock the task The task remains blocked until some other task calls Angel_Signal with one or more of the event mask bits set The meaning of the event mask must be agreed beforehand by the routines If AngelWait is called with a zero event mask execution continues normally Angel_Signal Angel_Signal works in conjunction with Angel_Wait This function sends an event to a task that is now waiting for it or will in the future wait for it If the task is blocked Angel_Signal assumes that the task is waiting and subtracts the new signals from the signals the task was waiting for The task is unblocked if the event corresponds to any of the event bits defined when the task called Angel_Wait If the task is running Angel_Signal assumes that the task will call Angel_Wait at some time in the future The signals are marked in the task signalWaiting member Angel_Signal takes
356. gister r15 pe program counter Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Using the Procedure Call Standards 6 4 Passing and returning structures This section describes the default method for passing structures to and from functions cases in which passing structures 1s automatically optimized telling the compiler to return a struct value in several registers 6 4 1 The default method ARM DUI 0040D Unless special conditions apply as detailed in following sections C structures are passed in registers that if necessary overflow onto the stack and are returned through a pointer to the memory location of the result For struct valued functions a pointer to the location where the struct result is to be placed is passed in a1 the first argument register The first argument is then passed in a2 the second in a3 and so on It is as if struct s f int x were compiled as void f struct s result int x Example 6 5 typedef struct two_ch_struct char chl char ch2 two_ch two_ch max two_ch a two_ch b return a chl gt b chl a b Example 6 5 is available in the file examples candasm two_ch c and can be compiled to produce assembly language source using armcc S two_ch c 11 Example 6 6 on page 6 14 shows the code armcc produces the version of armcc supplied with your release may produce output slightly different from that listed here Copyright
357. gister names and usage ARM DUI 0040D The Thumb register subset has eight visible general purpose registers r0 r7 called the low registers a stack pointer sp a full descending stack is assumed a link register lr a program counter pc In addition the Thumb subset can access the other ARM registers r8 r12 called the high registers singly using a set of special instructions Refer to the ARM Architectural Reference Manual for details Copyright 1997 1998 ARM Limited All rights reserved 6 11 Using the Procedure Call Standards In the context of the TPCS each Thumb register has a special name and function as shown in Table 6 3 Register TPCS name Table 6 3 TPCS registers TPCS role rO al argument 1 scratch register result rl a2 argument 2 scratch register result r2 a3 argument 3 scratch register result r3 a4 argument 4 scratch register result r4 vl register variable r5 v2 register variable r6 v3 register variable r7 v4 wr register variable work register in function entry exit T8 v5 ARM v5 register no defined role in Thumb r9 v6 ARM v6 register no defined role in Thumb r10 sl v7 stack limit rll fp v8 frame pointer not usually used in Thumb state r12 ip ARM ip register no defined role in Thumb May be used as a temporary register on Thumb function entry exit r13 Sp stack pointer full descending stack r14 Ir link re
358. guments to the callback The callback executes when all tasks of a higher priority have completed Table 13 1 on page 13 34 shows relative task priorities Angel_BlockApplication This function is called to allow or disallow execution of the application task The application task remains queued but is not executed If Angel is processing an application SWI when Angel_BlockApplication is called the block might be delayed until just before the SWI returns Angel_NextTask This is not a function in that it is not called directly Angel_NextTask is executed when a task returns from its main function This is done by setting the link register to point to Angel_NextTask on function entry The Angel_NextTask routine enters Supervisor mode disables interrupts calls Angel_SelectNextTask to select the first task in the task queue that has not been blocked and run it Angel_ Yield This is a yield function for polled devices It can be called either by the application by Angel while waiting for communications on a polled device within processor bound loops such as the idle loop Angel_Yield uses the same serialization mechanism as IRQ interrupts Like an IRQ it can be called from either User or Supervisor mode and returns cleanly to either mode If it is called from User mode it calls the Angel_EnterSVC SWI to enter Supervisor mode and then disables interrupts Copyright 1997 1998 ARM Limited All ri
359. guration file The armul cnf file contains the configuration for the ARMulator It sets the options for the various ARMulator components for example defining configurations for different processors and caches See Application Note 52 The ARMulator Configuration File ARM DAI 0052A for more information 12 13 3 The armsd map File 12 28 It is the responsibility of the memory model to translate map files New models do not understand the map file unless support is written in Only one supplied model armmap c supports this Adding armsd map file support to memory models To support the map data a memory model has to intercept upcall UnkRDIInfoUpcal1 watching for RDIMemory_Map The debugger makes this call to pass the data parsed from the armsd map file argl points to an array of RDI_MemDescr structures arg2 gives the number of elements in the array RDIMemory_Map can be called many times during initialization RDIInfo_Memory_Stats The model should return RDIError_NoError to indicate that memory maps are supported RDIMemory_Access The debugger makes this call to obtain access statistics see memory_statistics or the equivalent in the ARM GUI Debuggers arg1 points to an RDI_MemAccessStats structure for the memory model to fill in One call is made for each mapped area passed to RDIMemory_Map arg2 identifies the area by the handle passed in the RDIMemDescr passed to RDIMemory_Map These structures a
360. gure Debugger from the Options menu On the Target tab select Remote_A Click the Configure button The Angel Remote Configuration dialog is displayed Select the Channel Viewer Enabled option The Add and Remove buttons are activated Click the Add button and a list of DLLs will be displayed Select the appropriate DLL and click the Open button Click the OK button on either the Angel Remote Configuration dialog or the Debugger Configuration dialog to restart ADW with an active channel viewer See Angel remote configuration on page 3 59 for more information on the Remote_A Configuration dialog box ThumbCV DLL provides the viewer illustrated in Figure 3 14 Thumb Comms Channel Viewer Control Options Send Left to send OO00 Figure 3 14 Thumb Comms Channel Viewer Copyright 1997 1998 ARM Limited All rights reserved 3 49 ARM Debuggers for Windows and UNIX 3 50 The window has a dockable dialog bar at the bottom that is used to send information down the channel Typing information in the edit box and clicking the Send button will store the information in a buffer The information is sent when requested by the target The Left to send counter displays the number of bytes that are left in the buffer Sending information To send information to the target type a string into the edit box on the dialog bar and click the Send button The information is sent when requested by the target in ASCII character codes
361. guring run address 13 70 configuring serial ports 13 61 configuring S WI numbers 13 72 context switching 13 38 ControlRx 13 65 ControlTx 13 65 DEBUG 13 50 debug agent interaction SWIs 13 95 debug method 13 61 Debug Monitor ADM 3 6 Debug Protocol ADP 3 6 debug support 13 3 debugger functions 13 31 debugging 13 47 13 68 device configuration 13 46 device driver layer 13 77 downloading 13 27 13 46 13 63 downloading new versions of 13 67 enabling assertions 13 21 Enter SVC mode 13 95 Ethernet support 13 50 13 99 exception handlers 13 70 exception handling 13 5 exception vectors 13 9 full Angel 13 11 hardware timers 13 66 heartbeat mechanism 13 77 initialization 13 29 initialization code 13 64 interrupt handlers 13 64 13 65 13 100 interrupt table 13 20 logging 13 68 makefile 13 45 13 47 memory requirements 13 9 minimal Angel 13 13 13 24 minimal Angel initialization 13 30 planning development 13 17 polled devices 13 66 porting 13 43 prebuilt images 13 11 processor exception vectors 13 71 profiling 13 70 programming restrictions 13 18 raw serial drivers 13 25 Report Exception SWI 13 97 Index 2 reporting memory and processor status 13 31 ring buffers 13 64 ROADDR 13 49 RWADDR 13 50 semihosting support 13 3 13 16 13 18 semihosting SWIs_ 13 79 setting breakpoints 13 31 setting debug method 13 61 stacks 13 10 13 39 stacks setting up 13 62 supervisor mode 13 20 super
362. h ARM code can be run without the overhead of fetching each instruction from 8 bit or 16 bit memory Functionality Thumb instructions are less flexible than their ARM equivalents Some operations such as accessing the program status registers directly are not possible in Thumb state This means that a state change is required in order to carry out these operations Exception handling The processor automatically enters ARM state when a processor exception occurs This means that the first part of an exception handler must be coded with ARM instructions even if it re enters Thumb state to carry out the main processing of the exception At the end of such processing the processor must be returned to ARM state to return from the handler to the main application Refer to Handling exceptions on Thumb capable processors on page 9 39 for more information 7 2 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb Standalone Thumb programs A Thumb capable ARM processor always starts in ARM state To run simple Thumb assembly language programs under the debugger add an ARM header that carries out a state change to Thumb state and then calls the main Thumb routine See Example ARM header on page 7 5 for an example ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 7 3 Interworking ARM and Thumb 7 2 7 2 1 Basic assembly language interworking The simplest met
363. h C This section describes how to use APM with ARM C It also describes the APM templates distributed with ARM C 2 10 1 APM templates for C ARM C provides additional project templates to enable you to build C projects in APM The C project templates are based on the corresponding C project templates for the Software Development Toolkit The templates provide options for producing C executable images and object libraries from within APM By default the templates are installed in the template directory of your SDT installation directory If you installed SDT in the default location this will be c ARM250 template The C APM templates are ARM C Executable Image This template builds an ARM C executable image from C C and ARM assembly language source files and ARM object libraries Thumb C Executable Image This template builds a Thumb C executable image from C C and Thumb ARM assembly language source files and Thumb object libraries ARM C Object Library This template builds an ARM object library file from C C and ARM assembly language source files You can use the library as a component in other projects to build ARM executable images Thumb C Object Library This template builds a Thumb object library file from C C and Thumb ARM assembly language source files You can use the library as a component in other projects to build Thumb executable images Thumb ARM C Interworking Im
364. h a case the methods described above are not appropriate There are several ways of dealing with this For example Construct the SWI instruction from the SWI number store it somewhere then execute it Use a generic SWI that takes as an extra argument a code for the actual operation to be performed on its arguments The generic SWI decodes the operation and performs it The second mechanism can be implemented in assembly language by passing the required operation number in a register typically rO or r12 The SWI handler can then be rewritten to act on the value in the appropriate register Because some value has to be passed to the SWI in the comment field it would be possible for a combination of these two methods to be used For example an operating system might make use of only a single SWI instruction and employ a register to pass the number of the required operation This leaves the rest of the SWI space available for application specific SWIs This method can also be used if the overhead of extracting the SWI number from the instruction is too great in a particular application A mechanism is included in the compiler to support the use of r12 to pass the value of the required operation Under the ARM Procedure Call Standard r12 is the ip register and has a dedicated role only during function call At other times it may be used as a scratch register The arguments to the generic SWI are passed in registers r0 r3 and values
365. hange and modify another variable 6 When you have completed your changes exit the dialog click OK to save the changes and exit the dialog 2 42 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager click Cancel to abandon any changes not yet applied and exit the dialog The following restrictions apply 2 8 4 Editing a path Variables prefixed by are read only and cannot be modified or deleted Variables prefixed by are reserved for use by APM but can be modified Variables containing a for example path Debug have a standard purpose defined by APM Use caution when editing config xxx variables especially if these contain symbols These are the internal representation of tool configurations created by the tools Follow these steps to use a tool in your project that is not on the Windows search path l ARM DUI 0040D Select Edit Paths from the Project menu The Edit Paths dialog is displayed Figure 2 21 Edit Variables for hello apj x build_target Delete Value Sprojectname gt ad Figure 2 21 Edit Paths dialog Select a tool from the scroll box Change the path as required in the Edit Path field If you have additional tool paths to modify click Apply to save the change and go on to modify another path When you have completed your changes exit the dialog click OK to save the changes and exit click Cancel to abandon any
366. hat editor Follow these steps to select a source editor 1 Select Editor from the Tools menu to display the Editor Preferences dialog Figure 2 15 2 Select the options you require Internal Editor Tab Stops Editor Preferences Internal Editor Tab Stops a fa Font Help Codewright l Use Premia Codewright 4 Codewright5 Location CACW32 CW32 EXE Browse Figure 2 15 Editor Preferences dialog Changes the tab stops used in the Edit Window Font Displays a standard font dialog Use Premia CodeWright 4 CodeWright 5 Use Premia CodeWright 4 5 if it is available on your machine instead of the APM built in editor Location The location of CodeWright if different from the standard installation Copyright 1997 1998 ARM Limited All rights reserved 2 33 ARM Project Manager 2 6 Working with source files You can use APM to edit your C and assembly language source files and C header files You can use Premia Codewright version 4 or version 5 or the APM built in editor You select your editor using the Editor Preferences dialog see Editor preferences on page 2 33 If you have selected the file from the Project View you can build the output from your source file from within the editor Any messages from the build tool are written to the build log You can edit files that are not associated with a project but until they are added to a project APM has no informa
367. he ADW or ADU View menu statistics can be used to output any statistics that the ARMulator has been keeping statistics_inc shows the number of cycles of each type since the previous time statistics or statistics_inc was displayed This is only applicable for armsd or the command line window in ADW or ADU statistics_inc_w outputs the difference between the current statistics and the point at which you asked for the statistics_inc_w window This is only applicable for ADW or ADU not for armsd Make sure you have not compiled with source level debugging enabled armcc g because this causes sub optimal code to be generated larger and slower The 01 02 and gt compiler options can reduce this Refer to Chapter 2 The ARM Compilers in the ARM Software Development Toolkit Reference Guide for more information on the effect of debug and optimization options If your code makes use of floating point mathematics a considerable amount of time may be spent in the floating point code libraries or FPE 11 3 2 Cycle counting example Dhrystone In this example the number of instructions executed by the main loop of the Dhrystone application and the number of cycles consumed are determined A suitable place to break within the loop is the invocation of function Proc_5 If you are using the command line tools 1 Load the executable produced in Code and data sizes example Dhrystone on page 11 4 into the debugger armsd no
368. he ARM C compiler provides a number of options for building debug images You can use the Compiler Configuration window in APM to set these options Figure 3 30 shows an example of the Compiler Configuration window Compiler Configuration Target Warnings C Specific Warnings Error Handling Language and Debug Include F 4 gt Debug Table Format Debug Control Optimisation Criterion wert 1 PF Enable debug table generation Default balance wart 2 M Include preprocessor symbols For space asd obsolete Fortime Optimisation Level source language None best debug view Draf conforming C Most good debug view good code Extra command line arguments Equivalent Command Line J cn Hee Figure 3 30 Compiler configuration window By default the C compiler produces DWARF2 format debug tables The available formats are dwarf 2 This is the default format produced by APM for C projects You should use this format unless you have specific reasons for using DWARF1 dwarf 1 You should use this format only if you have specific reasons for doing so For example you may want to use a debugger that does not support DWARE2 3 74 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX asd Do not use this format for C The ASD format cannot represent some C constructs such as pointers to member functions Using ASD will produce unpredictab
369. he Angel port from that manufacturer The following examples and recommendations refer to the Angel PID port however the same general principles apply no matter which Angel port you select as a template ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 43 Angel 13 4 1 Angel source code directory structure The Angel sources are distributed in a directory structure that separates the target dependent code such as device drivers and board specific setup code from the main generic code directory There is a separate build directory for the specific build information for each target This directory contains the makefile or APM project file and is usually used as the output directory for object files and the final ROM image Figure 13 5 shows the directory structure for the Angel PID port Angel Source pid b pid generic Angel source files make directories target specific for supported source files platforms Figure 13 5 Angel source directory structure 13 4 2 Overview of porting steps and recommendations These are the steps required in the porting process Choose a target template Set up the makefile or APM project file Perform a trial build using the template files Modify target specific files Define the target macros Write the device drivers Build for the new target Download your Angel port to the target ee a A eA S Debug your Angel port These steps are explained in mo
370. he second port is being transferred ril and r12 Point to the last address to transfer to r11 for the first port r12 for the second The entire sequence to handle a normal transfer takes nine instructions Code situated after the conditional return is used to signal that the transfer is complete r13 r8 10Stat r13 IO0PortlActive r13 r8 10Port1 r13 r8 10Port2 r13 r9 4 r13 r10 4 r9 ril r10 r12 pc Ir 4 Load status register to find which port caused the interrupt Load port 1 data Load port 2 data Store to buffer 1 Store to buffer 2 Reached the end On either channel Return Insert transfer complete code here 9 28 Copyright 1997 1998 ARM Limited All rights reserved Example 9 15 ARM DUI 0040D Handling Processor Exceptions Byte transfers can be made by replacing the load instructions with load byte instructions Transfers from memory to an I O device are made by swapping the addressing modes between the conditional load instructions and the conditional store instructions Interrupt prioritization Example 9 16 dispatches up to 32 interrupt sources to their appropriate handler routines Because it is designed for use with the normal interrupt vector IRQ it should be branched to from location 0x18 External hardware is used to prioritize the interrupt and present the high priority active interrupt in an I O register In the example code IntBase Hold
371. he value stored by the processor in Ir_mode is therefore pc Prefetch abort handlers The handler s return instruction SUBS pc 1r 4 changes the program counter to the address of the aborted instruction Because the program counter is not updated before the exception is taken the aborted instruction is at pc 4 The value stored by the processor in Ir_mode is therefore pc Data abort handlers The handler s return instruction SUBS pc 1r 8 changes the program counter to the address of the aborted instruction Because the program counter is updated before the exception is taken the aborted instruction is at pc 6 The value stored by the processor in Ir_mode is therefore pc 2 Copyright 1997 1998 ARM Limited All rights reserved 9 41 Handling Processor Exceptions 9 11 3 Determining the processor state An exception handler may need to determine whether the processor was in ARM or Thumb state when the exception occurred SWI handlers especially may need to read the processor state This is done by examining the SPSR T bit This bit is set for Thumb state and clear for ARM state Both ARM and Thumb instruction sets have the SWI instruction We have already examined how to handle SWIs called from ARM state in SWI handlers on page 9 14 Here we address the handling of SWIs that are called from Thumb state When doing so there are three considerations to bear in mind the address of the instruction is at lr
372. hedules tasks accordingly controls the Angel environment processor mode Angel task management requires control of the processor mode This can impose restrictions on using Angel with an RTOS Refer to Using Angel with an RTOS on page 13 19 for more information Task priorities Angel assigns task priorities to tasks under its control Angel ensures that its tasks have priority over any application task Angel takes control of the execution environment by installing exception handlers at system initialization The exception handlers enable Angel to check for commands from the debugger and process application semihosting requests Angel will not function correctly if your application or RTOS interferes with the execution of the interrupt SWI or Data Abort exception handlers Refer to Chaining exception handlers on page 13 20 for more information ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 33 Angel 13 34 When an exception occurs Angel either processes it completely as part of the exception handler processing or calls Angel_SerialiseTask to schedule a task For example When an Angel SWI occurs Angel determines whether the SWI is a simple SWI that can be processed immediately such as the EnterSVC SWI or a complex SWI that requires access to the host communication system and therefore to the serializer Refer to Angel C library support SWIs on page 13 79 for more information When an IRQ occurs
373. hen you change to User mode to start executing the application 10 3 5 Initializing any critical I O devices Critical I O devices are any devices that you must initialize before you enable interrupts Typically you must initialize these devices at this point If you do not they may cause spurious interrupts when interrupts are enabled 10 3 6 Initializing RAM variables required by the interrupt system If your interrupt system has buffer pointers to read data into memory buffers the pointers must be initialized before interrupts are enabled 10 6 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 10 3 7 IMPORT IMPORT IMPORT IMPORT LDR LDR LDR CMP BEQ O CMP LDRCC STRCC BCC 1 LDR MOV 2 MP STRCC BCC Writing Code for ROM Initializing memory required by C code The initial values for any initialized variables RW must be copied from ROM to RAM All other ZI variables must be initialized to zero Note If the application uses scatter loading see Initialization code on page 10 24 for details of how to initialize these areas Example 10 1 shows an example of code to initialize variables in RAM if the application does not use scatter loading Image RO Limit Image RW Base Image Z1I Base Image ZI Limit rO Image RO Limit rl Image RW Base r3 Image ZI Base r rl F1 rl r3 r2 r0 4 r2 r1 4 XBQ rl Image Z1 Limit
374. here s a memory mapfile use that 1f MemConfigloLoad amp amp MEMORY_MapFi le Default MapFi le endif Default default is the flat memory map Default Flat Default Fast Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 12 10 armmap ARMulator ARMmap armmap c provides a memory model of a user configurable memory system You can specify the size access width access type and access speeds of individual memory blocks in the memory system in a memory map file The debugger internal variables memstats and statistics give details of accesses of each cycle type regions of memory accessed and time spent accessing each region ARMmap may generate aborts if you specify a memory region with access type as 12 10 1 Clock frequency You must specify an emulated clock frequency when using this memory model or the number of wait states for each memory region cannot be calculated To configure the clock frequency Under armsd use the command line option clock clockspeed This is described in Command line options on page 7 3 Under the ARM GUI debuggers select the Configure debugger option from the Options menu In the debugger configuration dialog click on Configure to display the ARMulator configuration dialog This contains a Clock Speed box that you can edit to the required frequency 12 10 2 Selecting the ARMmap memory model Under armsd ARMmap is automatically selected as the memory mod
375. hod of interworking between ARM and Thumb state is to use hand coded assembly language In this case it is up to you to make sure that register usage is compatible between any interworking routines To interwork between ARM and Thumb state you must change the processor state with the Branch Exchange BX instruction instruct the assembler to generate the correct code for the processor state with the CODE32 and CODE16 directives The following section describes these steps in more detail Refer to Assembly language interworking using veneers on page 7 19 for information on using linker generated interworking veneers from assembly language The Branch Exchange instruction The BX instruction branches to the address contained in a specified register The value of bit O of the branch address determines whether execution continues in ARM state or Thumb state Bit O of an address can be used in this way because All ARM instructions are word aligned This means that bits O and 1 of the address of any ARM instruction are ignored because these bits refer to the halfword and byte part of the address All Thumb instructions are halfword aligned This means that bit 0 of the address of any Thumb instruction is ignored because it refers to the byte part of the address The BX instruction is implemented on Thumb capable ARM processors only Syntax The syntax of BX is one of Thumb BX Rn ARM BX cond Rn where Rn is a regis
376. ht 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 3 Initializing the system One of the main considerations with application code in ROM is the way in which the application initializes itself and starts executing If there is an operating system present this does not cause a problem because the application is entered automatically through the main function No automatic initialization takes place on RESET so the application entry point must perform some initialization before it can call any C code Typically the initialization code should carry out some or all of the following tasks defining the entry point setting up exception vectors initializing the memory system initializing the stack pointer registers initializing any critical I O devices initializing any RAM variables required by the interrupt system enabling interrupts changing processor mode if necessary changing processor state if necessary initializing memory required by C entering C code These items are described in more detail below 10 3 1 Defining the entry point The initialization code must define the entry point The assembler directive ENTRY marks the entry point 10 3 2 Setting up exception vectors ARM DUI 0040D The initialization code sets up required exception vectors as follows If the ROM is located at address 0 the vectors consist of a sequence of hard coded instructions to branch to the handler for e
377. hts reserved ARM DUI 0040D Basic Assembly Language Programming 5 4 Conditional execution In ARM state each data processing instruction has an option to set ALU status flags in the Current Program Status Register CPSR according to the result of the operation In Thumb state there is no option All data processing instructions set the ALU status flags in the CPSR except when one or more high registers are used in MOV and ADD instructions MOV and ADD cannot update the status flags in these cases Every ARM instruction can be executed conditionally on the state of the ALU status flags in the CPSR See Table 5 1 on page 5 18 for a list of the suffixes to add to instructions to make them conditional In ARM state you can set the ALU status flags in the CPSR on the result of a data operation execute several other data operations without updating the flags execute following instructions or not according to the state of the flags set in the first operation In Thumb state you cannot execute data operations without updating the flags and conditional execution can only be achieved using conditional branches The only Thumb instruction that can be conditional is the conditional branch instruction B The suffixes for this instruction are the same as in ARM state The branch with link BL or branch and exchange instruction set BX instructions cannot be conditional 5 4 1 The ALU status flags ARM DUI 0040D The CPSR contai
378. ide Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 7 1 ARM LDM and STM Instructions ARM DUI 0040D The load or store multiple instruction loads stores any subset of the 16 general purpose registers from to memory using a single instruction Syntax The syntax of the LDM instructions is LDM cond address mode Rn reg list A where cond is an optional condition code Refer to Conditional execution on page 5 17 for more information address mode specifies the addressing mode of the instruction See LDM and STM addressing modes on page 5 36 for details Rn is the base register for the load operation The address stored in this register is the starting address for the load operation Do not specify r15 pc as the base register specifies base register write back If this is specified the address in the base register is updated after the transfer It is decremented or incremented by one word for each register in the register list register list is acomma delimited list of symbolic register names and register ranges enclosed in braces There must be at least one register in the list Register ranges are specified with a dash For example r0 r1 r4 r6 pc Do not specify writeback if the base register Rn is in register list A Do not use this option in User or System mode For details of its use in privileged modes see Chapter 9 Handling Processo
379. ied or moved when you add them to a partition They remain where you normally keep them Partitions help to control the effect of adding a file to a project The partitions created for a project are determined by the project template The partitions used by standard APM templates include Sources Contains source files used to build the project output Other source partitions may be added depending on the template such as Thumb C ARM C ASM Sources IncludedFiles Contains any files included by the sources used by the project Objects Contains the object files built from the sources SubProjects Contains other projects that are to be used in the construction of the project output If the project output from a sub project is a library the library file is built in the Libraries partition Libraries Contains any libraries that are to be used by the project Image Contains the project output of your build as specified in the project template Miscellanea Anything else you want to add to a project Note You can use other names for partitions this list is only an example Project templates A project template defines how to build a particular type of project output In a project template build step patterns describe the necessary processes their input files and their output files Project templates give you great flexibility when you build your project output You can select a template from those supplied with APM or you can
380. if a map file is specified the armmap memory model is used Start ADW or armsd The debugger responds ARMulator 2 0 ARM7 User manual example 1MB memory Dummy MMU Soft Angel 1 4 Angel SWIs FPE initialization failed Profiler Tracer Pagetables Big endian You may see the following errors The Floating Point Emulator FPE initialization failed because this model does not have a standard memory map and the FPE could not be loaded Alternatively you might see the error Initialization failed Memory model Example incompatible with bus interface This is the memory model reporting that it cannot talk to the selected processor for example ARM7TDMI or ARMOTDMI Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 13 Angel This chapter describes the Angel debug monitor It contains the following sections About Angel on page 13 2 Developing applications with Angel on page 13 11 Angel in operation on page 13 29 Porting Angel to new hardware on page 13 43 Configuring Angel on page 13 69 Angel communications architecture on page 13 73 Angel C library support SWIs on page 13 79 Angel debug agent interaction SWIs on page 13 95 The Fusion IP stack for Angel on page 13 99 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 1 Angel 13 1 13 2 About Angel Angel is a program that enables you to develop and debug
381. ild step by clicking on the New button in the Project template Editor dialog The Create a new build step pattern dialog is displayed 6 Type CreateROM in the Name field and click OK An empty Edit Build Step Pattern dialog for CreateROM appears 7 Inthe Command Lines field type on one line lt fromelf gt lt FROMELFOPTIONS gt lt projectname gt axf bin lt projectname gt bin The bin option produces a Plain Binary image suitable for blowing into ROM Other output formats are also available for example Motorola 32 bit Hex m32 Intel 32 bit Hex 132 Intellec Hex ihf 8 In the Input Partition type Image 9 Inthe Input Pattern type lt projectname gt axf This should match the Link build step output pattern 10 32 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 10 11 12 13 14 15 16 17 Writing Code for ROM Click Add In the Output Partition type Eprom In the Output Pattern type lt projectname gt bin This should match the Link build step output pattern Click Add then OK Select Edit variables for project apj from the Project menu a In the Name field of the Edit variables dialog type FROMELFOPT IONS b Inthe Value field type your chosen options for example nozeropad Click OK If you want to re use this template for another project save the template with the Save As Template option from the File menu
382. iled or assembled with software stack checking enabled and parts without Alternatively you have linked with a library that has software stack checking enabled whereas your code has it disabled or vice versa Solution Recompile your C code with stack checking disabled Stack checking is disabled by default Link with a library built with the same options undefined main The linker reports __main as being undefined Cause When the compiler compiles the function main it generates a reference to the symbol __main to force the linker to include the basic C runtime system from the ANSI semihosted C library If you are not linking with an ANSI semihosted C library and have a function main you may get this error Solution This problem may be fixed in one of the following ways If the main function is used only when building an application version of your ROM image for debugging purposes comment it out with an ifdef when building a ROM image When building a ROM image and linking with the Embedded C Library call the C entry point something other than main such as C_Entry or ROM_Entry If you do need a function called main define a symbol __main in your ROM initialization code Usually this is defined to be the entry point of the ROM image so you should define it just before the ENTRY directive as follows EXPORT __main ENTRY __main B main Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0
383. ilename or typed in a filename the debugger does not check for the existence of the file or the validity of its format If the format of the file is found to be invalid at re initialization the debugger displays an error message In that case or if the file does not exist the debugger defaults to the No Map File option and uses the ARMulator default settings Use the Remove button to remove the currently selected file from the list Note Map files are used only at re initialization not when a program is loaded When you select the Local Map File option the map file in the working directory of the current image is used If you load a new image the same map file is used To use a map file that is associated with the new image you must re initialize the debugger by selecting Configure Debugger from the Options menu and clicking OK Save or discard your changes click OK to save any changes and exit click Apply to save any changes click Cancel to ignore all changes not applied and exit Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 7 2 ARMulator configuration Use the Armulator Configuration dialog to change configuration settings for the ARMulator Follow these steps to change configuration settings for the ARMulator 1 Select Configure Debugger from the Options menu 2 Click on the Target tab 3 Select ARMulate in the Target Environment fie
384. in the license file Imdiag displays the port numbers of all ports that are listening and indicates which ones are Imgrd processes If Imdiag finds the armlmd daemon for the for feature being tested it displays the correct port number to use in the license file Imdown Imdown c license_file_list vendor name q The program allows you to shut down gracefully all license daemons on all nodes both Imgrd and all vendor daemons c license_file_list Path to file s to be shut down If more than one file use a colon separator vendor name If you specify a vendor name only that vendor daemon is shut down and Imgrd is not shut down q Do not issue the Are you sure prompt You should restrict the execution of Imdown to license administrators by starting Imgrd with the p 2 switch as shutting down the server causes loss of licenses To disable Imdown the license administrator can use Imgrd x Imdown To stop and restart a single vendor daemon use Imdown vendor name then Imreread vendor name Copyright 1997 1998 ARM Limited All rights reserved A 15 FlexLM License Manager Imhostid Imhostid This program returns the correct host ID on any computer supported by FlexLM Imremove Imremove c license_file_list feature user host display This utility allows you to remove a single user license for a specific feature For example when a user is running the software and the host crashes the user license is so
385. ing package that controls the usage of licensed software applications Licensing is controlled by means of a license file that describes the software you may use and how many copies of it you may run concurrently You must obtain a valid license file from ARM Limited before you can run licensed ARM software Obtaining your license file on page A 4 describes how to apply for your license file You must specify one or more computers to act as a license server on which license management software runs Any computer running FlexLM licensed software must either be a license server or have access to a license server ARM Debugger for UNIX ADU is one example of software that requires a license server before you can run it The license server can be any one of your local machine a remote machine several remote machines If you choose to use more than one you must use three license server machines These communicate with one another and co ordinate the licensing The advantage of this is that if one of the license server machines fails to operate correctly the other two will continue to allow licensed software to be used This arrangement is known as a 3 server redundant set Remote license servers do not need to be running on the same hardware platform as the software they are controlling A 1 1 Installing FlexLM software License management software for various platforms is supplied on the CD ROM of any ARM licensed softwar
386. inline assemblers 8 5 Context switch 9 30 and Angel 13 38 Controlling use of licensed software A 2 ControIRx 13 63 13 65 ControlTx 13 63 13 65 Converting project format 2 30 Coprocessors ARMulator models 12 3 12 4 12 24 undefined instruction handlers CPSR 5 5 5 17 9 5 interworking ARM and Thumb 7 2 Crash Barrier 13 68 Current program status register 5 5 5 17 Customizing license file A 9 Cycle counts Dhrystone example 11 6 displaying 11 6 C asm 8 2 calling conventions 8 18 creating APM projects 2 53 9 33 ARM DUI 0040D menu 3 62 string literal 8 2 C data types in mixed languages 8 18 D Data abort exception 9 2 handler 9 35 9 41 LDM 9 35 LDR 9 35 returning from 9 8 STM 9 35 STR 9 35 SWP 9 35 DATA directive 7 11 Data maps assembly 5 46 Data processing instructions 5 6 Data processing instructions Thumb 5 8 Data size measuring 11 3 Data structure assembly 5 46 Data types 8 18 DC_INIT 13 64 DC_RECEIVE MODE 13 65 DC_RESET 13 64 DC_RX_PACKET_FLOW 13 65 DC_SET_PARAMS 13 65 Debug agent 3 6 Debug interaction SWIs 13 95 Debugger breakpoints 4 6 closing down 3 10 command line instructions 3 46 debugger variables 4 9 executing a program 4 8 extra tools with C 3 63 ini file 4 6 internals window 3 18 introduction to 3 2 program variables 4 9 see also ADW ADU single stepping 4 8 starting 3 9 table formats in ADW ADU 3 74 using 4 2 4 6 watchpoints 4 7 Copyright 1997 1998 ARM Limited Al
387. instead of a call to a long long multiply function if x and y are of type int Angel enhancements Angel has been enhanced to enable full debug of interrupt driven applications ARMulator enhancements The following enhancements have been made to the ARMulator Total cycle counts are always displayed Wait states and true idle cycles are counted separately if a map file is used F bus cycle counts are displayed if appropriate Verbose statistics are enabled by the line Counters True in the armul cnf file For cached cores this adds counters for TLB misses write buffer stalls and cache misses The instruction tracer now supports both Thumb and ARM instructions A new fast memory model is supplied that enables fast emulation without cycle counting This is enabled using Default Fast in the armul cnf file Trace output can be sent to a file or appended to the RDI log window New fromELF tool The fromELF translation utility is a new tool in SDT 2 50 It can translate an ELF executable file into the following formats AIF family Plain binary Extended Intellec Hex IHF format Motorola 32 bit S record format Intel Hex 32 format Textual Information This tool does not have a GUI integrated with APM It can be called directly from the command line or by editing your APM project to call fromELF after it calls the linker Copyright 1997 1998 ARM Limited All rights reserved 1 11
388. instruction set The instruction set is optimized for production by a C compiler All Thumb instructions are 16 bits long and are stored halfword aligned in memory Because instructions are stored halfword aligned the bottom bit of the address of an instruction is always set to zero in Thumb state This bit is ignored by all Thumb instructions that have an address operand except for the Branch Exchange BX instruction All Thumb data processing instructions operate on full 32 bit values use full 32 bit addresses for data access and for instruction fetches In general the Thumb instruction set differs from the ARM instruction set in the following ways Refer to the ARM Architectural Reference Manual for detailed information on the syntax of the Thumb instruction set and how Thumb instructions differ from their ARM counterparts Branch instructions These instructions are used to branch backwards to form loops to branch forward in conditional structures to branch to subroutines and to change the processor from Thumb state to ARM state Program relative branches particularly conditional branches are more limited in range than in ARM code and branches to subroutines can only be unconditional Data processing instructions These operate on the general purpose registers The result of the operation is put in one of the operand registers not in a third register There are fewer data processing operations available than in ARM sta
389. instruction stream as data Thumb instructions have the same limitation for similar reasons A data load can place any 32 bit value in a register but there are more direct and efficient ways to load many commonly used constants The following sections describe how to use the MOV and MVN instructions to load a range of immediate values how to use the LDR pseudo instruction to load any 32 bit constant Direct loading with MOV and MVN In ARM state you can use the MOV and MWN instructions to load a range of 8 bit constant values directly into a register The MOV instruction loads any 8 bit constant value giving a range of 0x0 to Oxff 0 255 The MVN instruction loads the bitwise complement of these values giving a range of Oxffffff00 to Ox ftir In addition you can use either MOV or MVN in conjunction with the barrel shifter to generate a wider range of constants The barrel shifter can right rotate 8 bit values through any even number of positions from 2 to 30 You can use MOV to load values that follow the pattern shown in Table 5 4 in a single instruction Use MVN to load the bitwise complement of these values Right rotates by 2 4 or 6 bits produce bit patterns with a few bits at each end of a 32 bit word Table 5 4 ARM state immediate constants Equivalent Step Decimal values q 3 between Rotate Hexadecimal values 0 255 O Oxff 1 No rotate 256 260 264 1020 0x100 0x3fc 4 Right by 30 bits
390. into the RAM In this case you must use load pc instructions and copy the storage locations to make the code relocatable Example 9 2 copies down the vectors given in Example 9 1 on page 9 9 to the vector table in RAM Example 9 2 MOV r8 0 ADR r9 Vector_Init_Block LDMIA r9 r0 r7 Copy the vectors 8 words STMIA r8 r r7 LDMIA r9 r0 r7 Copy the DCD ed addresses STMIA r8 r r7 8 words again Alternatively you can use the scatter loading mechanism to install the vector table Refer to Chapter 10 Writing Code for ROM for more information 9 10 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 3 2 Installing the handlers from C ARM DUI 0040D Sometimes during development work it is necessary to install exception handlers into the vectors directly from the main application As a result the required instruction encoding must be written to the appropriate vector address This can be done for both the branch and the load pc method of reaching the handler Branch method The required instruction can be constructed as follows 1 Take the address of the exception handler 2 Subtract the address of the corresponding vector 3 Subtract Ox8 to allow for prefetching 4 Shift the result to the right by two to give a word offset rather than a byte offset 5 Test that the top eight bits of this are clear to ensure that the result is only 24 bits long beca
391. ion of size_t Error stdio h line 151 prototype and old style Te m Suite DebugRel Figure 2 4 Built project with error in source You can see from the messages in the build log that the build was not successful The red X next to hello c in the Project view indicates that there is an error in the hello c source file The section headed Correcting problems on page 2 12 explains how APM can help you to resolve problems in building your project Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Project Manager Building from a single source file You can perform a build step from a single source file if the file is associated with a project and has been opened as a part of a project If the file can be processed compiled or assembled for example the appropriate menu item in the Project menu is enabled and labeled with the name of the build step pattern that is used to perform the build step If the project template does not define a build step for the selected file type the Build menu item and the Build button are disabled APM performs the actions associated with the build step and displays the results in the build log pane Force building a project Select Force Build to build all of the output files in your project for the selected variant regardless of whether they have been changed since the last build If you first select APM from the Tools menu and ch
392. iorities continued Priority Task Description Application The user application AngelInit Boot task Emits boot message on reset and then exits Lowest IdleLoop Angel task management is implemented through the following top level functions Angel_SerialiseTask Angel_NewTask Angel_QueueCallback Angel_BlockApplication Angel_NextTask Angel_Yield Angel_Wait Angel_Signal Angel_TaskID Some of these functions call other Angel functions not documented here The functions are described in brief below For full implementation details refer to the source code in serlock h serlock c and serlasm s Angel_SerialiseTask In most cases this function is the entrance function to Angel task management The only tasks that are not a result of a call to Angel_SerialiseTask are the boot task the idle task and the application These are all created at startup When an exception occurs Angel_SerialiseTask cleans up the exception handler context and calls Angel_NewTask to create a new high priority task It must be entered in a privileged mode Angel_NewTask Angel_NewTask is the core task creation function It is called by Angel_SerialiseTask to create task contexts Copyright 1997 1998 ARM Limited All rights reserved 13 35 Angel 13 36 Angel_QueueCallback This function queues a callback specifies the priority of the callback specifies up to four ar
393. is of type char short or int No sign extension is performed on char and short types You must perform sign extension explicitly for these types The compiler may add code to evaluate these expressions and allocate them to registers When an operand is used as a destination the expression must be assignable an lvalue When writing code that uses both physical registers and expressions you must take care not to use complex expressions that require too many registers to evaluate The compiler issues an error message if it detects conflicts during register allocation Physical registers The inline assemblers allow restricted access to the physical registers It is illegal to write to pc Only Branches using B or BL are allowed In addition it is inadvisable to intermix inline assembler instructions that use physical registers and complex C or C expressions The compiler uses r12 ip for intermediate results and r0 r3 r12 ip r14 lr for function calls while evaluating C expressions so these cannot be used as physical registers at the same time Physical registers like variables must be set before they can be read When physical registers are used the compiler saves and restores C C variables that may be allocated to the same physical register However the compiler cannot restore sp sl fp or sb in calling standards where these registers have a defined role Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0
394. isplay the source disassembled code pointed to by the selected symbol set edit or remove a breakpoint on the line of code pointed to by the selected symbol You can display the low level symbols in either name or address order Right click in the window to display the Low Level Symbols window menu and select Sort Symbols by to toggle between the two settings Memory window The Memory window displays the contents of memory at a specified address Addresses are listed in the left hand pane and the memory content is displayed in the right hand pane Use the Memory window to display other areas of memory by scrolling or specifying an address set edit or remove a watchpoint change the contents of memory double click on an address You can have multiple Memory windows open at any time Registers window The Registers window displays the registers corresponding to the mode named at the top of the window with the contents displayed in the right hand pane You can double click on an item to modify the value in the register Use the Registers window to display the contents of the register memory display the memory pointed to by the selected register edit the contents of a register set edit or remove a watchpoint on a register Copyright 1997 1998 ARM Limited All rights reserved 3 23 ARM Debuggers for Windows and UNIX 3 24 Note Multiple register mode windows can be open at any one tim
395. isplaying signed byte values ubyte_format Contains the default format for displaying unsigned byte values string_format Contains the default format for displaying string values complex_format Contains the default format for displaying complex values fpresult Contains the floating point value returned by last called function junk if none or if a floating point value was not returned fpresult returns a result only if the image has been build for hardware floating point If the image is built for software floating point it returns zero This variable is read only inputbase Contains the base for input of integer constants initially set to 10 list_lines Contains the default number of lines for the list command initially set to 16 pr_linelength Contains the default number of characters displayed on a single line initially set to 72 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 19 ARM Debuggers for Windows and UNIX rdi_log result sourcedir statistics Sets RDI logging see Table 3 1 Table 3 1 RDI logging Bit1 BitO Meaning 0 0 Off 0 1 RDI on 1 0 Device Driver Logging on l 1 RDI and Device Logging on You can set these bits of the rdi_log internal variable from the Debugger Internals window For more information see RDI Log window on page 3 24 and Remote debug information on page 3 41 Contains the integer result returned by last called f
396. ister variable v6 that must be preserved across function calls sb must always be preserved Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Using the Procedure Call Standards 6 3 Using the Thumb Procedure Call Standard The Thumb Procedure Call Standard TPCS is a set of rules that govern inter calling between functions written in Thumb code The TPCS is essentially a cut down APCS There are fewer options with TPCS than with the APCS This reflects the different ways in which ARM and Thumb code are used and also reflects the reduced nature of the Thumb instruction set Specifically the TPCS does not support disjoint stack extension stack chunks Under the TPCS the stack must be contiguous However this does not prohibit the use of multiple stacks to implement co routines for example reentrancy Reentrant code is code that calls the same entry point with different sets of static data You can implement reentrancy by placing in a struct all variables that must be multiply instantiated and passing each function a pointer to the struct hardware floating point Thumb code cannot access floating point instructions without switching to ARM state Floating point is supported indirectly by defining how FP values are passed to and returned from Thumb functions in the Thumb registers Refer to the ARM Software Development Toolkit Reference Guide for the full specification of the TPCS 6 3 1 TPCS re
397. istics However your application program may sometimes need to access a clock for example if it contains calls to the standard C function clock or the Angel SYS_CLOCK SWI so ARMulator must always be able to give clock information It does so in the following way if a clock speed has been specified to the ARM Debugger or armsd then ARMulator uses that frequency value for its timing if Real time is selected for the ARM Debugger or unspecified for armsd the real time clock of the host computer is used by ARMulator instead of an emulated clock In either case the clock information is used by ARMulator to calculate the elapsed time since execution of the application program began This elapsed time can be read by the application program using the C function clock or the Angel SWI_clock and is also visible to the user from the debugger as clock It is also used internally by the ARM Debugger and armsd in the calculation of memstats The clock speed whether specified or unspecified has no effect on actual real time speed of execution under ARMulator It affects the simulated elapsed time only memstats 1s handled slightly differently because it does need a defined clock frequency so that ARMulator can calculate how many wait states are needed for the memory speed defined in an armsd map file If a clock speed is specified and an armsd map file is present then memstats can give useful information about memory accesses a
398. it is invoked with the 16 option Because all Thumb capable ARM processors start in ARM state you must use the BX instruction to branch and exchange to Thumb state and then use the CODE16 directive to instruct the assembler to assemble Thumb instructions Refer to the ARM Software Development Toolkit Reference Guide for more information on these directives Example ARM header Example 7 1 on page 7 6 implements a short header section of ARM code that changes the processor to Thumb state Copyright 1997 1998 ARM Limited All rights reserved 7 5 Interworking ARM and Thumb The header code uses An ADR instruction to load the branch address and set the least significant bit The ADR instruction generates the address by loading r2 with the value pc offset See Direct loading with ADR and ADRL on page 5 27 for more information on the ADR instruction A BX Branch exchange instruction to branch to the Thumb code and change processor state The main body of the module is prefixed by a CODE16 directive that instructs the assembler to treat the following code as Thumb code The Thumb code adds the contents of two registers together The code section labeled stop uses the Thumb Angel SWI to exit The SWI reports an exception reason specified in rl to the debugger In this case it is used to report normal application exit Refer to Chapter 13 Angel for more information on Angel Note The Thumb Angel semihosting SWI is b
399. iting memory Exceptions support This handles all ARM exceptions C library support C library support consists of the ARM ANSI C libraries supplied with the SDT and the semihosting support that is built into Angel to send requests to the host when necessary Booting and initialization The Angel booting and initialization support code performs startup checks sets up memory stacks and devices send a boot message to the debugger User application This is an application on the target system 13 1 3 Angel system resource requirements 13 8 Where possible Angel resource usage can be statically configured at compile and link time For example the memory map exception handlers and interrupt priorities are all fixed at compile and link time Refer to Configuring Angel on page 13 69 for more information The following sections describe the system and memory resources required by Angel System resources Angel requires the following configurable and non configurable resources Configurable resources Angel requires the following for semihosting purposes one ARM SWI Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel one Thumb SWI Non configurable resources For breakpoints Angel requires two ARM Undefined instructions one Thumb Undefined instruction ROM and RAM requirements Angel requires ROM or Flash memory to store the debug monitor code
400. k Go to start the program The program runs and stops at the breakpoint on main Click Go again The program resumes execution When execution completes select Options Profiling Write to file to write the profile data to the file sort2 prf Exit ADW or ADU and invoke a DOS session Generate the profile by entering the following at the DOS prompt armprof Parent sort2 prf gt prof2 The Parent option instructs armprof to include information about the callers of each function armprof generates the profile report and sends its output to the text file prof2 that you can examine Copyright 1997 1998 ARM Limited All rights reserved 11 25 Benchmarking Performance Analysis and Profiling 11 5 7 Profiling and instruction tracing with ARMulator 11 26 In addition to profiling the time spent in specific parts of an application the ARMulator provides facilities for profiling other performance statistics and for generating full instruction traces The ARMulator provides Enhanced profiling with the Profiler module The ARMulator has an Events mechanism that enables events such as cache misses and branch mispredictions to be profiled For example profiling cache misses enables you to find areas of code that are causing high levels of cache activity You can then optimize and tune the code accordingly The profiling is controlled through a configuration file rather than from the debugger However the data is
401. k pointer r13_SVC and the I and F bits in the current CPSR are set disabling normal and fast interrupts Note If you are debugging with an EmbeddedICE interface the User mode stack pointer is not copied to the Supervisor stack pointer the I and F bits of the CPSR are not set Entry On entry rO contains 0x17 Register rl is not used The CPSR can specify User or Supervisor mode Return On exit rO contains the address of a function to be called to return to User mode The function has the following prototype void ReturnToUSR void Note If debugging with ARMulatororMulti ICE rO is set to zero to indicate that no function is available for returning to User mode Copyright 1997 1998 ARM Limited All rights reserved 13 95 Angel If debugging with an EmbeddedICE interface rO is set to an undefined value and no function is available for returning to User mode If EnterSVC is called in User mode this routine returns the caller to User mode and restores the interrupt flags If EnterSVC is not called in User mode the action of this routine is undefined If entered in User mode the Supervisor stack is lost as a result of copying the user stack pointer The return to User routine restores r13_SVC to the Angel Supervisor mode stack value but this stack should not be used by applications After executing the SWI the current link register will be r14_SVC not r14_USR If the value of r14_USR is neede
402. k register immediately before the BX instruction is executed In addition the Thumb instruction set version of BL sets bit O when it loads the link register with the return address When a Thumb to ARM interworking subroutine call returns using a BX Ir instruction it causes the required state change to occur automatically If you always use the same register to store the address of the ARM subroutine that is being called from Thumb this segment can be used to send an interworking call to any ARM subroutine The __call_via_r4 procedure in Example 7 2 on page 7 9 demonstrates this technique Note You must use a BX 1r instruction at the end of the ARM subroutine to return to the caller You cannot use the MOV pc 1r instruction to return in this situation because it does not cause the required change of state If you do not use a BL instruction to call the BX instruction then you must ensure that the link register is updated and that bit O is set either by the calling Thumb routine or by the called ARM routine Calling a Thumb subroutine from ARM When carrying out an ARM to Thumb interworking subroutine call you do not need to set bit O of the link register because the routine is returning to ARM state In this case you can store the return address by copying the program counter into the link register with a MOV 1r pc instruction immediately before the BX instruction Remember that the address operand to the BX instruction that calls
403. l home license my license txt You have 3 license servers Assuming your license file is called license lic and is stored in the local directory opt arm licenses type either one of the following two commands setenv ARMLMD_LICENSE_FILE opt arm licenses setenv ARMLMD_LICENSE_FILE opt arm licenses license lic Copyright 1997 1998 ARM Limited All rights reserved A 7 FlexLM License Manager A 5 2 Running your application When you have set the environment variable ARMLMD_LICENSE_FILE to a suitable value as described above you can run your licensed software A 8 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager A 6 Customizing your license file Your license file contains information similar to that shown in one of the following examples Example A 1 Typical 1 server license file SERVER jupiter 80826d02 VENDOR armimd opt arm flex Im solaris FEATURE adu armimd 1 000 1 jan 1999 4 5B7E20C1A2338616F456 ck 42 Example A 2 Typical 3 server license file SERVER jupiter 80826d02 7117 SERVER saturn 80af8111 7117 SERVER uranus 81873622 7117 VENDOR armimd opt arm flex Im solaris FEATURE adu armimd 1 000 1 jan 1999 4 5B7E20C1A2338616F456 ck 42 Although you must not change Feature lines you may need to change the SERVER and VENDOR lines in your license file A 6 1 Server and Vendor lines You may need to change SERVER and VENDOR lines for the following reasons Ho
404. l rights reserved Index Debugger variables viewing and changing 3 12 Debuggers downloading Angel 13 67 Debugging Angel 13 68 Angel assertions 13 21 decaof 2 38 decaxf 2 38 Deleting breakpoints 3 26 Demon 1 6 Destktop APM 2 15 develnt c 13 100 devclnt h 13 63 13 64 devconf h 13 31 13 46 13 59 13 61 13 69 13 71 13 93 devdriv h 13 60 13 63 Device Data Control 13 62 Device driver layer Angel 13 77 Device drivers Angel 13 63 Deviceldent structure 13 63 devices c 13 57 13 63 devices h 13 64 Dhrystone code size 11 4 example 11 4 map files 11 13 Directives assembler ENTRY 10 5 Directives assembly language ALIGN 5 51 AREA 5 11 5 13 AREA literal pools 5 25 ASSERT 5 50 5 60 CODE16 5 16 7 4 CODE32 5 16 7 4 DATA 7 11 END 5 14 END literal pools 5 25 ENTRY 5 14 IMPORT 8 14 MACRO 5 43 MAP 5 46 ROUT 5 11 5 46 Disassembly mode 3 40 window 3 21 Index 5 Index Display formats 3 38 Download agent area 13 63 dummymmu c ARMulator model 12 4 12 24 DWARF 3 74 DWARF limitations 3 75 E Editing breakpoints 3 26 project source files 2 18 ELF converting to binary ROM formats 10 32 file format 1 6 Embedded C library ROM applications 10 19 EmbeddedICE 3 5 3 6 configuring 3 60 END directive 5 14 END directive literal pools 5 25 ENTRY directive 5 14 Entry point assembly 5 14 Environment variable ARMLMD_LICENSE_FILE A 7 errno C library variable 13 91 Ethernet Ang
405. l rights reserved ARM DUI 0040D ARM Project Manager 2 5 Setting preferences This section describes and explains how to set APM preferences Editor preferences 2 5 1 APM preferences Follow these steps to set APM preferences 1 Select APM from the Tools menu The APM Preferences dialog is displayed Figure 2 14 APM Preferences x M Force overwriting of existing project files Ok Save changed files quietly Cancel M Continue building even if errors are found Help ais F Retain partition selection after adding files Build also builds sub projects Echo command lines verbosely Create New Projects from Templates found in C ARM Template Browse Figure 2 14 APM Preferences dialog 2 Select the preferences you require An item is check marked when selected The options are Force overwriting of existing project files If you create a new project with an existing filename the original project file is overwritten without a request for confirmation Save changed files quietly Save changed files without prompting when the project is closed Continue building even if errors are found If an error is detected do not stop but continue building and ignore any files that depend on erroneous components ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 31 ARM Project Manager Retain partition selection after adding files After adding a file to a partition retain
406. l that automates the routine operations of managing source files and building your software development projects APM helps you to construct the environment and specify the procedures needed to build your software Utilities The following utility tools are provided to support the main development tools fromELF The ARM image conversion utility This accepts ELF format input files and converts them to a variety of output formats including AIF plain binary Extended Intellec Hex IHF format Motorola 32 bit S record format and Intel Hex 32 format armprof The ARM profiler displays an execution profile of a program from a profile data file generated by an ARM debugger armlib The ARM librarian enables sets of AOF files to be collected together and maintained in libraries You can pass such a library to the linker in place of several AOF files decaof The ARM Object Format decoder decodes AOF files such as those produced by armasm and armcc decaxf The ARM Executable Format decoder decodes executable files such as those produced by armlink topcc The ANSI to PCC C Translator helps to translate C programs and headers from ANSI C into PCC C primarily by rewriting top level function prototypes topcc is available for UNIX platforms only not for Windows ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 1 3 Introduction Supporting software The following support software is provided to enable you to debug
407. l_yield_count gt call_yield_every_n_irqs call_yield_count 0 Ange _SerialiseTask Q angel_SerialisedFn Angel_YieldCore NULL empty_stack amp Angel_GlobalRegBlock RB_Interrupted The value call_yield_every_n_irqs must be calculated such that Angel_Yield is called approximately every 0 2 seconds Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 4 7 Downloading a new version of Angel ARM DUI 0040D Angel can download a new version of itself There are a number of methods you can use to do this depending on whether you are using armsd or ADW ADU Downloading a new debug agent is often preferable to replacing ROM because it is usually quicker and does not require you to remove the ROM from its socket and reprogram it with an EPROM programmer However downloading a new Angel to RAM is not permanent If the board is powered down or reset the downloaded Angel is lost The best method is to download Angel to Flash if your board supports it This allows you to replace your Angel as often as required without losing the image at reset or power down The ARM PID board supports Flash Refer to your board documentation for more information on downloading to Flash If your board does not have Flash and does have sufficient RAM you can load Angel to RAM and either run it in place or relocate and run If you are using Angel to replace Angel with this method you cannot overwrite the currently
408. lar expression and work only if such regular expression 1s given Zero or more of the preceding regular expressions For example A B would match B AB and AAB Zero or one of the preceding regular expression For example AC B matches AB and ACB but not ACCB One or more of the preceding regular expression For example AC B matches ACB and ACCB but not AB The following special characters are regular expressions in themselves Precedes any special character that you want to include literally in an expression to form a single regular expression For example matches a single asterisk and matches a single backslash The regular expression x 1s equivalent to x as the character x is not a special character Allows grouping of characters For example 202 matches 202202202 as well as nothing at all and AC B looks for sequences of AB or ACB such as ABACBAB Exactly one character This is different from in that the period is a regular expression in itself so matches all while is invalid Note that does not match the end of line character A set of characters any one of which can appear in the search match For example the expression r 23 would match strings r2 and r3 The expression a z would match all characters between a and z Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 5 6 High level and low level symbols
409. ld 4 Click on the Configure button The ARMulator Configuration dialog is displayed Figure 3 18 ARMulator Configuration x Processor Variant ARM TDMI v Clock C Emulated Speed Real time Options MV Floating Point Emulation Figure 3 18 Configuration of ARMulator 5 Change the following configuration settings as required Variant Processor type required for emulation Clock Clock speed to be used for emulation If the Emulated radio button is selected then the clock speed used is the value that you enter into the Speed field Values stored in debugger internal variable clock depend on this setting and are unavailable if you select Real time see Debugger Internals window on page 3 18 If the Real time radio button is selected then the real time clock of the host computer is used and the Speed field is unavailable ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 57 ARM Debuggers for Windows and UNIX The ARM Debugger clock speed defaults to 0 00 for compatibility with the defaults of armsd Selecting Real time in the ARM Debugger is equivalent to omitting the clock armsd option on the command line In other words the clock frequency is unspecified For the ARMulator an unspecified clock frequency is of no consequence because ARMulator does not need a clock frequency to be able to execute instructions and count cycles for stat
410. ld and a carriage return on the screen The code is created using a text editor compiled and linked using armcc and run using armsd This section also provides a brief introduction to armsd More information is given in armsd on page 4 6 armcce oreh e C source mode 2 oma Figure 4 1 Compiling and linking C Create compile link and run Follow these steps to create compile link and run a simple C program L Enter the following code using any text editor include lt stdio h gt int main void printf Hello World n return Q Save the file as hello c Enter armcc hello c o hello to compile and link the code The argument to the o option gives the name of the file that will hold the final output of the link step The linker 1s called by the compiler after compilation To prevent the compiler from calling the linker enter the c compiler option on the command line Compiler options are case sensitive Enter armsd hello to execute the code under software emulation armsd starts loads the file and displays the armsd prompt Enter go and press Return The debugger responds with Hello World followed by a message indicating that the program terminated normally Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 6 Command Line Development To reload and run the program again enter reload and then go at the armsd prompt To quit the debugger enter q
411. ld step pattern uses simple pattern expressions to describe the inputs to which it can be applied the outputs it generates the command line options that are used to generate those outputs When you add a file to a project APM searches for an input pattern expression to match the filename If a match is found the pattern variables used in the input pattern become defined and are used to generate output filenames When the project is built the same pattern variables are used to generate command lines for the tools invoked by the build Step pattern Input pattern expressions An input pattern can contain three kinds of pattern element Variable written as lt name gt that matches any sequence of characters not containing the next literal Literal written as is that matches only itself Conditional literal written as lt name literal gt that either matches and lt name gt takes on the value of the literal fails to match and lt name gt takes on the value null Patterns match from right to left and in a pattern matches or in the filename For example the input pattern element lt path gt lt slash gt lt file gt c supplied with the string myfile c sets the variables to the following values Copyright 1997 1998 ARM Limited All rights reserved 2 47 ARM Project Manager 2 48 path wT slash file myfile and the same input pattern element supplied with the string c
412. le results DWARF 1 limitations The DWARF debug table format has limitations that introduce severe restrictions to debugging C code These include DWARF provides no support for include files Stepping into member functions defined in include files and setting breakpoints on such functions results in incorrect behavior DWARF1 is less descriptive than DWARF 2 and therefore has limited potential for building optimized debug images and objects DWARFI1 produces a much larger debug table than DWARF 2 As a result DWARFI1 images can be significantly slower to load than DWARF2 images For these reasons it is recommended that you use the DWAREF2 debug table format ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 75 ARM Debuggers for Windows and UNIX 3 76 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 4 Command Line Development This chapter gives a brief overview of using the command line tools It contains the following sections The hello world example on page 4 2 armsd on page 4 6 Refer to the ARM Software Development Toolkit Reference Guide for more information on the command line tools ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 4 1 Command Line Development 4 1 4 1 1 4 2 The hello world example This example shows you how to write compile link and execute a simple C program that prints Hello Wor
413. ler 12 12 profiling 11 26 quitting from the tracer 12 6 real time simulation 11 8 ARM DUI 0040D rebuilding with a new model 12 32 regular calls to the debugger 12 13 responsiveness 12 13 sample models see also ARMulator models basic 12 3 coprocessor 12 4 memory 12 3 operating system 12 4 SA 110 page table flags 12 15 SWIs 12 26 tracer 12 6 user configurable memory system 12 21 windows hourglass 12 13 with ADW 12 13 yieding control to ADW 12 13 ARMiulator functions Tracer_Close 12 6 Tracer_Dispatch 12 6 Tracer_Flush 12 6 Tracer_Open 12 6 ARMulator models angel c 12 4 armfast c 12 3 armflat c 12 3 armmap c 12 4 armpie c 12 4 bytelane c 12 4 dummymmu c 12 4 endianism 12 31 example c 12 4 12 29 12 32 12 34 noos c 12 4 pagetab c 12 3 profiler c 12 3 stubs 12 5 tracer c 12 3 12 4 12 6 trickbox c 12 4 validate c 12 4 winglass c 12 3 armul cnf file 12 6 12 28 12 34 ARM740T protection unit page table model 12 17 ARM940T protection unit page table model 12 17 arm h 13 59 13 72 13 79 asd in ADW ADU 3 75 ASIC 3 5 Copyright 1997 1998 ARM Limited All rights reserved Index Assembler inline armasm differences 8 6 inline see Inline assemblers mode changing 7 5 Assembly language Absolute maps 5 46 alignment 5 51 and C 8 22 areas 5 13 base register 5 47 block copy 5 39 boolean constants 5 12 calling from C 8 19 case rules 5 10 code size 5 56 comments 5 11 condition code suffixes
414. les on page 2 34 Viewing object and executable files on page 2 37 Working with project templates on page 2 39 Build step patterns on page 2 47 Using APM with C on page 2 52 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 1 ARM Project Manager 2 1 2 1 1 2 2 About the ARM Project Manager Online help The ARM Project Manager APM is a graphical user interface tool that automates the routine operations of managing source files and building your software development projects APM helps you to construct the environment and specify the procedures necessary to build your software APM builds derived files as directed by your choice of project template but you have full control over the options passed to the build tools APM schedules the calling of development tools such as compilers linkers and your own custom tools This is particularly helpful when you need to perform a sequence of operations frequently and consistently APM uses the concept of a project to maintain information about the system you are building You specify what to build and how to build it When you have described your system as a project you can build all of it or just part of it If the project output is an image you can execute it or debug it by calling the ARM Debugger for Windows ADW or a third party debugger such as XRAY directly from APM When you create a project with APM all the tools you need for your
415. lf_words max half_words a half_words b half_words x x a fieldl gt b field1 a b return x Arguments a and b are passed in registers al and a2 and because half_word_struct is integer like you would expect al to return the result structure directly rather than a pointer to it This code is available in the file examples candasm half_str c and can be compiled to produce assembly language source using armcc S half_str c 1i Example 6 8 shows the code armcc produces The version of armcc supplied with your release may produce output slightly different from that listed here Example 6 8 max MOV a3 al LSL 16 CMP a3 a2 LSL 16 MOVLS a1 a2 MOV pc ir From this you can see that the contents of the half_words structure is returned directly in al as expected 6 4 3 Returning non integer like structures in registers ARM DUI 0040D There are occasions when a function must return more than one value The usual way to achieve this is to define a structure that holds all the values to be returned and to pass a pointer to the structure back in al The pointer is then dereferenced allowing the values to be stored Copyright 1997 1998 ARM Limited All rights reserved 6 15 Using the Procedure Call Standards For applications in which such a function is time critical the overhead involved in wrapping and then unwrapping the structure can be significant In this case you can tell the compiler that a structure shoul
416. listing annotated with the original C or C source that produced the assembly language Use the command line options S fs to get interleaved source and assembly language This facility is not available if ASD debug tables are requested g asd This facility is only easily accessible from the command line and is not integrated with APM New assembler directives and behavior The SDT 2 11a assemblers armasm and tasm have been merged into a single assembler called armasm that supports both ARM code and Thumb code In addition it provides functionality previously supported only by tasm such as the CODE16 and CODE32 directives and the 16 and 32 command line options The assembler starts in ARM state by default A tasm binary is shipped with SDT 2 50 for compatibility reasons however this binary only invokes armasm 16 The assembler now supports the following FPA pseudo instructions LDFS fp register fp constant LDFD fp register fp constant LDFE fp register fp constant and the new directives DCWU and DCDU Long long operations now compile inline In the C and C compilers the implementation of the long long data type has been optimized to inline most operators This results in smaller and faster code In particular Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Introduction long long res long long x long long y translates to a single SMULL instruction
417. log 3 Use the default command line option c to display disassembled code areas other options are listed in the online help 4 Click OK The information is displayed in the specified format in a View window Figure 2 19 C examples DebugRel hello o Header file C examples DebugRel hello o AOF file type Little endian Relocatable object code AOF Version 311 No of areas 12 No of symbols 11 Area 0 CSScode Alignment 4 Size 32 0x0020 1 relocations Attributes Code 32bit NoSWStackCheck Read only EXPORT main main OxO00000 e92d4000 STMDB ri3 ri4 Ox000004 ez28f0f02 ADD rO pe 65 0x14 Ox000008 ebfffffc BL _printf Ox00000c e3a00000 MOV r0 0 Ox000010 e6bd6000 LDMIA rlil 4he 5512 xSlitpoolS0 Ox000014 6c6c6546 STCVSL p5 c6 r12 0x120 Ox000018 6f57206f SWIVS Ox57206 xSlitpool_eS0 0x3 nvANNnn te NnA4Ae RSARFN r r r RAR ri Figure 2 19 View window ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 37 ARM Project Manager 2 1 decaof The ARM Object Format AOF file decoder decaof decodes AOF files such as those produced by armasm and armcc For a full specification of AOF and a full description of decaof refer to the ARM Software Development Toolkit Reference Guide 2 7 2 decaxf The ARM Executable Format AXE file decoder decaxf decodes executable files such as those produced by armlink For a full description o
418. lude file This window is opened when you double click on a code or include file in the Project View open an existing code or include file select New from the File menu and create a source or include file Figure 2 7 shows an example of the Edit window The Edit window provides a fully functional editor in which you can copy paste search and replace using the appropriate toolbar buttons or the menu selections in the Edit menu B C examples abc c include any h ifndef REG define REG REG becomes defined as empty i e no register variables ha endif extern int Int_Glob extern char Ch_1 Glob Prac _6 Enum_ Val _ Par Enum_ Ref Far EEEEEHEEEHEHEEHEERREHEHERREHREBHRHREHREHHEE YS executed once 7 Enum Val Par Ident 3 Enum_Ref_ Par becomes Ident_z Enumeration Enum Val Par Enumeration Enum Ref Par Fnum Ref Par Enum Val Par if i Fune_s Enum_Val_Par then not executed Fnum Ref Par Ident 4 switch Enum Val _ Pari Figure 2 7 Edit window using that source file from the Edit window by clicking the Perform Build Step button You are prompted to save the file 1f you have not already done so The Project window is displayed and the results of the build appear in the build log es If you are editing a source file as a component of a project you can perform a build 2 18 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D A
419. lways look for the vendor specific environment variable ahead of the LM_LICENSE_FILE environment variable Copyright 1997 1998 ARM Limited All rights reserved A 13 FlexLM License Manager A9 FlexLM license management utilities The flexim directory on your product CD ROM contains subdirectories holding the license manager utilities and the ARM vendor daemon armlmd for various platforms Installing FlexLM software on page A 2 describes how to install the software on your one or three license server machines The installation process creates a series of hard links to make your usage of the license management tools easier Specifically it allows you to execute the utilities by using their short names for example you can type Imver instead of Imutil Imver All the license tools are actually contained within the single executable Imuti1 the behavior of which is determined by the value of its argv A 9 1 License administration tools The Imdown Imremove and Imreread commands are privileged If you started Imgrd with the p 2 switch then you must be a license administrator to run any of these three utilities A license administrator is a member of the UNIX Imadmin group or if that group does not exist a member of group In addition Imgrd x can disable Imdown and or Imremove All utilities take the following arguments V print version and exit c license_file operate on a specific license file Imchecksu
420. m Imchecksum k c 7cense_f1 e_name The Imchecksum utility performs a checksum of a license file Use it to check for data entry errors in your license file Imcksum prints a line by line checksum for the file as well as an overall file checksum If the license file contains cksum nn attributes the bad lines are indicated automatically This utility is particularly useful if you received your license by Fax and typed the file because of the possibility of data entry errors Use the k switch to force the checksum to be case sensitive Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D FlexLM License Manager By default Imchecksum checks the contents of license dat in the current directory Use the c switch to check a different file Imdiag Imdiag c license_file_list n feature This utility allows you to check for problems when you cannot check out a license c license_file_list Path to file s to check If more than one file use a colon separator n Run in non interactive mode feature Diagnose this feature only If you do not specify a feature all lines of the license file are checked The Imdiag program first tries to check the feature If this fails the reason for failure is printed If the check failed because Imdiag could not connect to the license server then you can run extended connection diagnostics These diagnostics try to check the validity of the port number
421. mbols 3 43 Copyright 1997 1998 ARM Limited All rights reserved list order 3 23 Window 3 23 M MACRO directive 5 43 Macros RegionInit 10 24 10 28 makelo c 13 57 13 59 13 60 13 63 Managing projects see APM Mangling symbol names 8 17 8 19 MAP directive 5 46 Map files 11 9 armsd map 11 9 Dhrystone example 11 13 format 11 10 Maps assembly language absolute 5 46 program relative 5 49 register based 5 48 relative 5 47 Matching strings 3 42 Member functions in ADW ADU expressions 3 72 Memory displaying contents 4 3 examining 3 12 3 39 flash 3 48 map files 3 55 simulating in map file 11 9 window 3 23 Memory management unit 10 6 Memory map Angel 13 62 configuring for Angel 13 69 layout 10 3 organization of 10 3 RAM at address O 10 3 ROM at address O 10 3 Menu bar 3 8 Menus C 3 62 window specific 3 25 MINIMAL_ANGEL macro 13 24 13 49 Mixed language programming interworking ARM and Thumb 7 19 7 21 ARM DUI 0040D models h file 12 5 Mode disassembly 3 40 Modifying debugger variables 3 12 MOV instruction 5 22 5 48 MRS instruction 5 7 MSR instruction 5 7 Multi ICE debugging Angel 13 68 Multiple register transfers 5 34 Multiple register transfers see also STM LDM multiplication returning a 64 bit result 6 16 MVN instruction 5 22 N Naming projects 2 28 Nested interrupts 9 23 Nested SWIs 9 18 Nesting subroutines assembly language 5 37 Next line stepping to 3 34 neXus 13 68
422. message if the address cannot be constructed in two instructions The range of an ADRL pseudo instruction is 64KB for a non word aligned address and 256KB for a word aligned address ADRL assembles to two instructions if successful The assembler generates two instructions even if the address could be loaded in a single instruction Refer to Loading addresses with LDR Rd label on page 5 30 for information on loading addresses that are outside the range of the ADRL pseudo instruction Copyright 1997 1998 ARM Limited All rights reserved 5 27 Basic Assembly Language Programming Note guarantee that different area The label used with ADR or ADRL must be within the same code area There is no the label will be within range after linking if it is defined in a The assembler can only fault references to labels that are out of range in the same area Example 5 6 shows In Thumb state ADR can generate word aligned addresses only ADRL is not available in Thumb code Use it only in ARM code the type of code generated by the assembler when assembling ADR and ADRL pseudo instructions It is supplied as adrlabel s in the examples asm subdirectory of the toolkit Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example The instructions listed in the comments are the ARM instructions generated by the assembler AREA adrlabel CODE READONL ENTRY Start BL func stop MOV r
423. metimes left checked out and unavailable to other users Imremove frees the license and makes it available to other users c license file name The full pathname of the license file to be used If this is omitted the LM_LICENSE_FILE environment variable is used instead feature The name of the feature the user has checked out user The name of the user host The name of the host the user was logged into display The name of the display where the user was working You can obtain the user host and display information from the output of Imstat a If the application is active when its license is removed by Imremove it checks out the license again at the next application heartbeat Imreread Imreread vendor name c license_file_list This utility causes the license daemon to reread the license file and start any new vendor daemons that have been added All the existing daemons are signalled to reread the license file to check for any changes in their licensing information vendor name If you specify a vendor name only that vendor daemon rereads the license file If the vendor daemon is not running Imgrd starts it To disable Imreread the license administrator can use Imgrd x Imreread Imreread does not cause server host names or port numbers to be reread from the license file To make any changes to those items effective you must restart Imgrd To stop and restart a single vendor daemon use Imdown vendor name then Imre
424. mory mogel sarreria a a aa 12 29 Rebuilding the ARMulator a sssneneeenneennnnsnnnsennssnrenrrrnersrssrrrssrrenrnrrernrene 12 32 Configuring ARMulator to use the example ccccsseseeeceeseeeeeeeeeeeeeees 12 34 ADOULANGE I ES RS Me dieu nt Maat an ease 13 2 Developing applications with Angel ccccccccccseeeeeeeeeeeeeeesseeeeeseneeeeeaes 13 11 Angel AOD SLALOM SR et ances 13 29 Porting Angel to new hardware ss 13 43 CORAN ANJE RSS AR nd siennes aste 13 69 Angel communications architecture VV 13 73 Angel C library support SWIS eee ceeccsseeeeeeeeeeeeeeeeeeeeeeeeeaeeeeessanseeesanaees 13 79 Angel debug agent interaction SWIS cccccseseeeecseseeeeeeeeeeeeeseaeeeeeeaaees 13 95 The FUSIOnIP Stack TOR ANGEN Ass ie ste tee ge 13 99 FlexLM License Manager A 1 A 2 A 3 A 4 A 5 A 6 A 7 A 8 A 9 A 10 About license management ss A 2 Obtaining your license THe sorida a aA aE A 4 What to do with your license file cccsseeeeecceeeseeeceeeeeeeeeeesseeesseseeeeeeees A 5 Starting the server software ccccccseseeecessseeeeceeeeeeeceuseeeceseeeeessaaseessseaess A 6 Running your licensed software ccccccseseeeeceeeseeeeceaeeeeeeesaeeeeeeseeneeeesaas A 7 Customizing your license file ccccseseeecceessececceeseeececeueeeecssseeesssaseeess A 9 FIV a CENS E SE Re annee den te a bi A 11 Using FlexLM with more than one product eceeeeeeeeeeeeeeeeeeeeeeeeeeaes A 12
425. mpiler Configuration ES Target Warnings C Specific Warnings Error Handling Language and Debug Include F_4 gt Byte Sex Floating Point Processor Little Endian C Big Endian none software library Choose APCS3 Options Processor M Software stack check C Architecture M Frame pointer ARM7TDMI M FP arguments passed in FP registers M Arm Thumb interworking Equivalent Command Line O2 Figure 2 9 Compiler Configuration dialog When you change the settings the modifications are reflected in the Equivalent Command Line box near the bottom of the dialog Note If a tool DLL is not in the directories searched by Windows or if a found tool is not a DLL with APM compliant entry points an error will be reported because the tool cannot be configured graphically You can take any of the following actions install the product containing the missing APM compliant tool DLL for example C projects will need armcpp d11 which is part of C 1 10 for SDT 2 50 specify command line options in the command line box in the Failed to Locate the Tool dialog select Edit Project Template Project menu and enter the command line options in the Command Lines field of the appropriate Build step pattern see Working with project templates on page 2 39 use the Edit Paths dialog to specify the correct location of the tool DLL see Editing a path on page 2 43 Copyright 1997
426. mpromise of code size versus execution speed However there are a number of compiler options that can affect the size and performance of generated code These may be used individually or may be combined to give the required effect For a full description of optimization and other command line options see Chapter 2 The ARM Compilers in the ARM Software Development Toolkit Reference Guide That chapter includes a description of the pcc option but a little more information about that option follows pcc The code generated by the compiler can be slightly larger when compiling with the pcc switch This is because of extra restrictions on the C language in the ANSI standard that the compiler can take advantage of when compiling in ANSI mode If your code compiles in ANSI mode do not use the pcc option The Dhrystone application provides a good example It is written in old style Kernighan and Ritchie C but compiles more efficiently in ANSI mode even though it causes the compiler to generate a number of warning messages Improving image size with the linker You can reduce image size by using the embedded C libraries instead of the standard ANSI C library which adds a minimum of around 15KB to an image Refer to Chapter 4 The C and C Libraries in the ARM Software Development Toolkit Reference Guide for more information See also Chapter 10 Writing Code for ROM in this book for an example of their use Copyright 1997 1998 ARM Limited
427. n value TRUE Note On UNIX systems use single quotes instead of double quotes or put a backslash before any double quotes For example ROM_AT_ADDRESS_ZERO SETL TRUE The assembler file init s tests this symbol and generates different code depending on whether or not the symbol is set If the symbol is set it generates a sequence of branches to be loaded directly over the vector area at address 0 Link the image using the following command armlink o rom0 axf ro base 0x0 rw base 0x10000000 first init o Init map info Sizes init o ex o or for Thumb armlink o trom axf ro base 0x0 rw base 0x10000000 First init o Init map info Sizes init o ex o where 0 specifies the output file Copyright 1997 1998 ARM Limited All rights reserved 10 9 Writing Code for ROM 10 4 1 10 10 ro base QxQ tells the linker that the read only or code segment will be placed at Qx00000000 in the address map rw base 0x10000000 tells the linker that the read write or data segment will be placed at Qx10000000 in the address map This is the base of the RAM in this example first init o Init tells the linker to place this area first in the image On UNIX systems you might need to put a backslash before each parenthesis map tells the linker to print an area map or listing showing where each code or data section will be placed in the address space The output is shown in Area listing for the co
428. n Embedded ARM application is the layout of the memory map in particular the memory that is situated at address 0x0 Following reset the core starts to fetch instructions from 0x0 so there must be some executable code accessible from that address In an embedded system this requires ROM to be present at least initially The simplest layout is to locate the application in ROM at address 0 in the memory map The application can then branch to the real entry point when it executes its first instruction at the reset vector at address 0x0 0xX10000000 gt 0x0F000000 gt 0x04000000 gt 0x00000000 gt Figure 10 1 Example of a system with ROM at 0x0 However there are disadvantages with this layout ROM is typically narrow and slow requires wait states to access it This slows down the handling of processor exceptions especially interrupts through the vector table Also if the vector table is in ROM it cannot be modified by the code For more information on exception handling see Chapter 9 Handling Processor Exceptions RAM is normally faster and wider than ROM For this reason it is better for the vector table and FIQ handlers if the memory at 0x0 is RAM However if RAM is located at address 0x0 there is not a valid instruction in the reset vector entry on power up Therefore you need to allow ROM to be located at 0x0 at power up so there is a valid reset vector but to also allow RAM to be
429. n sequential access You can disable this by setting SpotISCycles False in armul cnf However this is likely to result in exaggerated performance figures particularly when modeling cached ARM processors ARMmap can optimize merged I S cycles using one of three strategies Speculative This models a system where the memory manager hardware speculatively decodes all addresses on idle cycles This gives both the I and S cycles time to perform the access resulting in one less wait state Early This starts the decode when the ARM declares that the next cycle is going to be an S cycle that is half way through the I cycle This can result in one fewer wait state Whether or not there are fewer wait states depends on the cycle time and the non sequential access time for that region of memory This is the default setting You can change this by setting ISTiming Spec or ISTiming Late in armul cnf Late This does not start the decode until the S cycle Copyright 1997 1998 ARM Limited All rights reserved 12 23 ARMulator 12 11 Dummy MMU DummyMMU dummymmu c provides a dummy implementation of an ARM Architecture v 3 v 4 system coprocessor This does not provide any of the cache and MMU functions but does prevent accesses to this coprocessor being Undefined Instruction exceptions Reads from r0 return a dummy ARM ID register value that can be configured Writes to rl of the dummy coprocessor the system configuration register
430. n the Angel development procedure are 1 2 3 4 Evaluate the application Build with high dependence on Angel Build with low dependence on Angel Move to final production hardware Figure 13 2 shows an example of this development procedure The stages of the development procedure are described in more detail below 13 14 Application under ARMulator or on an evaluation board Application using Full Angel on Development Board very dependent Application using Full Angel on Development Board minimal dependency Application under minimal Angel on final product Application on final product No Angel Figure 13 2 The Angel development process Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel Stage 1 Evaluating applications If you want to evaluate the ARM to ensure that it is appropriate for your application you must have a program or suite of programs to run on the ARM You can rebuild your programs using the ARM Software Development Toolkit and link them with an ARM C or C library You can run your ported applications in two ways ARMulator You can run your programs under the ARMulator and evaluate cycle counts to see if the performance is sufficient This method does not involve Angel however you can use an Angel targeted ARM C or C library because the ARMulator supports the Angel semihosting SWIs so C library calls are handled by the host C library support
431. n the Software Development Toolkit for backwards compatibility only Layout of assembly language source files The general form of source lines in assembly language is label instruction directive pseudo instruction comment Note Instructions pseudo instructions and directives must be preceded by white space such as a space or a tab even if there is no label All three sections of the source line are optional You can use blank lines to make your code more readable Case rules Instruction mnemonics can be written in uppercase or lowercase but not mixed Directives must be written in uppercase Symbolic register names can be written in uppercase or lowercase but not mixed Line length To make source files easier to read a long line of source can be split onto several lines by placing a backslash character at the end of the line The backslash must not be followed by any other characters including spaces and tabs The backslash end of line sequence is treated by the assembler as white space Note Do not use the backslash end of line sequence within quoted strings Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Basic Assembly Language Programming The exact limit on the length of lines including any extensions using backslashes depends on the contents of the line but is generally between 128 and 255 characters Labels Labels are symbols that represent address
432. n time You should avoid setting this to 8000 if possible because this is the default application area Refer to Configuring where Angel runs on page 13 70 for more information on RWADDR DEBUG If set to 1 this option enables debugging code within Angel 13 4 4 Modifying an APM project 13 50 If you are using the ARM project manager on a Windows system you must change the project file when you copy an Angel template directory If you are using UNIX refer to Editing makefile build options on page 13 48 The build directory is separate from the target source code directory In the supplied examples it has the same name as the target code directory with a b extension The APM projects are located in a subdirectory of the build directory For example the PID project is located in c ARM250 Angel Source pid b Apm The simplest way to use the PID Angel port as a template is to copy the entire Angel directory structure to a working directory If you want to change the names of the directories to reflect the name of your board you must modify the APM project file so that it uses your directories compiles and assembles your source and links your object files This is described in Editing the APM project directory structure on page 13 52 In addition to setting up the project file for your new directory structure you must set a number of build options The options include Thumb support Angel data area and execution addresses If
433. n using the scatter loading facilities of the ARM linker Chapter 11 Benchmarking Performance Analysis and Profiling Read this chapter for a description of how to analyze the performance of your ARM targeted programs Chapter 12 ARMulator Read this chapter for an introduction to the ARM processor emulator Chapter 13 Angel Read this chapter for a description of how to use the Angel debug monitor This chapter also provides information on porting Angel to your own hardware Appendix A FlexLM License Manager Read this appendix for instructions on using the FlexLM License Manager FlexLM is used to manage licenses for the ARM Debugger for UNIX Copyright 1997 1998 ARM Limited All rights reserved Ix Preface Further reading ARM publications Other publications This section lists publications from both ARM Limited and third parties that provide additional information on developing for the ARM processor and general information on related topics such as C and C development This book contains reference information that is specific to the ARM Software Development Toolkit For additional information refer to the following ARM publications ARM Software Development Toolkit Reference Guide ARM DUI 0041 ARM Architectural Reference Manual ARM DUI 0100 ARM Reference Peripheral Specification ARM DDI 0062 ARM Target Development System User Guide ARM DUI 0061 the ARM datasheet for your hardware devic
434. n you have set up the makefile or APM project for your development directory structure you should perform a trial build to ensure that the modifications are complete and that all necessary project build files have been copied correctly Modifying target specific files The PID Angel port includes a number of target specific source files that you must modify to support your hardware and environment You should examine each of the target specific files described in Modifying target specific files on page 13 57 Copyright 1997 1998 ARM Limited All rights reserved 13 45 Angel You must pay particular attention to the following Defining the device configuration in devconf h You should take a great deal of care to modify this file correctly Time spent checking at this stage will save a lot of debug time later You must ensure that you define support only for features that are supported by your hardware For example if you select DCC Support for a non DI core such as the ARM710a Angel calls a subroutine to poll a coprocessor This halts Angel on an undefined instruction trap In addition you must define a complete memory map for your implementation allocate stack space for each processor mode used by Angel ensure that interrupts are used in the same way as for production hardware It is recommended that Angel interrupts are handled by the IRQ Refer to devconf h on page 13 60 for more information on modifying this
435. nager 2 4 8 2 30 Converting old projects If you open a project that was created with an earlier version of the ARM Project Manager you are asked to confirm that you want to convert the project to the current format After you convert a project file to a later format you can no longer read it with the earlier version of APM Follow these steps to convert an old project to the current format 1 Open the project The Project Conversion Wizard starts Figure 2 13 2 Confirm that the conversion should proceed and that the old file can be overwritten 3 Click the Next button to proceed Project file conversion output The old project was intended to produce alittle endian ARK AIF executable caled CHAY in D Sarme 114E samples Or The converted project will build dhru axt Converted Project Name dhr api Converted Project Directory D arm2114E xamples D hy Browse ros Figure 2 13 Project Conversion wizard 4 Examine and change if necessary the project name and directory then click the Next button 5 Verify the source files that are to be added to the project and click the Next button By default all files belonging to the original project are carried over to the new project file 6 Confirm that you want to proceed with the conversion by clicking the Finish button If you elected to overwrite the existing file the conversion cannot be reversed Copyright 1997 1998 ARM Limited Al
436. nd times Otherwise for the purposes of calculating the wait states an arbitrary default of 1MHz is used to calculate a core memory clock ratio so that memstats can still give useful memory timings Floating point emulation Toggles floating point emulation on and off If you are using the software floating point C libraries ensure that this option is off blank The option should be on checked only if you are using the floating point emulator FPE 3 58 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 7 3 Angel remote configuration ARM DUI 0040D If you are using Angel or EmbeddedICE use the Angel Remote Configuration dialog to configure the settings for the remote connection you are using to debug your application Follow these steps to change configuration settings for Angel 1 Select Configure Debugger from the Options menu 2 Click on the Target tab 3 Select Remote_A in the Target Environment field to select ADP Angel Debug Protocol 4 Click on the Configure button The Angel Remote Configuration dialog is displayed Figure 3 19 Angel Remote Configuration Remote Connection oo M Heartbeat ea i Disabling heartbeat will disable host Serial Parallel timeout and packet resend Ethernet Parts Serial come Parallel LPT 2 Channel Viewers FM Enabled Thumb dll Serial Line Speed Baud Rate 15200
437. nd sequential access times are the same Note Do not simply enter the times quoted on top of a memory chip You must add a 20 30ns signal propagation time to them write times describes the nonsequential and sequential write times The format is identical to that of read times The following examples assume a clock speed of 20MHz Example 1 O 80000000 RAM 4 rw 135 85 135 85 This describes a system with a single contiguous section of RAM from 0 to Ox7fffffff with a 32 bit data bus read write access and N and S access times of 135ns and 85ns respectively The N cycle access time is one clock cycle longer than the S cycle access time For a faster system a smaller N cycle access time should be used For example for a 33MHz system the access times would be defined as 115 85 115 85 Example 2 Q 80000000 RAM 1 rw 150 100 150 100 This describes a system with the same single contiguous section of memory but with an 8 bit external data bus and slightly different access times Example 3 The following description file details a typical embedded system with 32KB of on chip memory 16 bit ROM and 32KB external DRAM 00000000 8000 SRAM 4 rw 1 1 1 1 00008000 8000 ROM 2 r 100 100 100 100 00010000 8000 DRAM 2 rw 150 100 150 100 7FFF8000 8000 Stack 2 rw 150 100 150 100 Copyright 1997 1998 ARM Limited All rights reserved 11 11 Benchmarking Performance Analysis and Profiling There are four regions of memory A f
438. ndled ADP_Stopped exception 13 97 UNMAPROM macro 13 58 13 71 User mode 9 3 Using ADW ADU with C 3 62 APM 2 4 APM templates 2 53 APM with C 2 52 the class view window 3 63 Utilities for license management A 14 V validate c ARMulator model 12 4 Variables Copyright 1997 1998 ARM Limited All rights reserved changing contents of in ADW ADU 3 70 formatting watches 3 69 halt if changed 3 29 project 2 26 properties of 3 39 setting watches in ADW ADU 3 66 viewing 3 37 memstate 12 21 statistics 12 21 Variants of projects 2 27 building 2 11 Vector table 9 3 9 9 9 22 9 39 Vector table and caches 9 13 Vectors exception 10 5 RESET 10 4 VENDOR line in license file A 9 Veneers see Interworking View menu 3 14 of project expanding collapsing 2 17 window 2 19 Viewing code in ADW ADU 3 64 debugger variables 3 12 files in APM 2 37 memory 3 12 3 39 project 2 8 search paths 3 36 source files 3 37 variables 3 37 watchpoints 3 29 W Watch window in ADW ADU 3 66 Watchpoints 4 7 simple 3 29 simple and complex 3 26 3 29 viewing 3 29 window 3 25 Window backtrace 3 18 3 33 breakpoints 3 18 3 26 command 3 16 ARM DUI 0040D console 3 15 debugger internals 3 18 disassembly 3 21 execution 3 15 expression 3 21 function names 3 22 3 43 globals 3 22 locals 3 22 low level symbols 3 23 memory 3 23 project 2 15 RDI log 3 24 3 41 registers 3 23 search paths 3 24 source file 3 24 source files list 3
439. ne arguments for your program 3 Click OK Refer to Starting and closing the debugger on page 3 9 for a list of valid command line options Note You can also specify command line arguments when you load your program in the Open File dialog or by changing the Debugger internal variable cmdline 3 5 10 Using command line debugger instructions 3 46 If you are familiar with the ARM symbolic debugger armsd you may prefer to use almost the same set of commands from the Command window The armsd commands Pause and Quit are unavailable in the Command window Follow these steps to use all other armsd commands from within ADW or ADU 1 Select Command from the View menu to open the Command window The Command window displays a Debug command line 2 Enter ARM command line debug commands at this prompt The syntax used is the same as that used for armsd Type help for information on the available commands Refer to Chapter 4 Command Line Development and Chapter 7 ARM Symbolic Debugger in the ARM Software Development Toolkit Reference Guide for more information on armsd Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 5 11 Changing the data width for reads and writes You can use the Command window to enter a command that reads data from or writes data to memory You must however be aware of the default width of data read or written and how to change it if necess
440. ne is start size name width access read times write times where Start size name width access is the start address of the memory region in hexadecimal forexample 80000 is the size of the memory region in hexadecimal for example 4000 is a single word that you can use to identify the memory region when memory access statistics are displayed You can use any name To ease readability of the memory access statistics give a descriptive name such as SRAM DRAM or EPROM is the width of the data bus in bytes that is 1 for an 8 bit bus 2 for a 16 bit bus or 4 for a 32 bit bus describes the type of access that may be performed on this region of memory r for read only w for write only rw for read write for no access An asterisk may be appended to the access to describe a Thumb based system that uses a 32 bit data bus but which has a 16 bit latch to latch the upper 16 bits of data so that a subsequent 16 bit sequential access can be fetched directly out of the latch 11 10 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Benchmarking Performance Analysis and Profiling read times describes the nonsequential and sequential read times in nanoseconds These should be entered as the nonsequential read access time followed by slash followed by the sequential read access time Omitting the and using only one figure indicates that the nonsequential a
441. ng the RDI_Info call RDISet_Cmd1 ine AddrCmdLine 0xf00 12 12 2 ARMulator SWIs 12 26 In addition to the standard Angel SWIs the ARMulator uses a set of SWIs for default exception vector handlers These are known as the soft vector SWIs The soft vector code is installed by the Angel model There are two sets of SWIs SWIs 0x90 0x98 are used to implement vector_catch that is they return control to the debugger if the user has set vector_catch for the relevant exception vector SWI 0x90 is used for the reset vector 0x91 for the undefined instruction vector and so on SWIs 0x80 0x88 are used to stop the ARMulator if the exception cannot be handled The 0x80 SWIs are used as a final stop if the exception is not caught by such an exception handler Note These SWIs are for internal use by the ARMulator only Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 13 Controlling the ARMulator using the debugger 12 13 1 About RDI ARM DUI 0040D This section gives configuration information for the ARMulator and describes how to configure the debugger using RDI The debugger communicates with ARMulator using RDI whether it is the command line armsd ADW or ADU The RDI allows the debugger to configure the processor type the clock speed Only one clock speed is allowed usually taken to be the processor clock speed For systems with multiple clocks for example a cache
442. ningless Turning sampling on and off does not affect the gathering of call counts 11 5 3 Collecting profile data 11 20 The debugger collects profiling data while an application is executing You can turn data collection on and off during execution so that only the relevant sections of code are profiled If you are using armsd use the profon and profoff commands If you are using ADW or ADU select Options Profiling Toggle Profiling see Profiling on page 3 43 The format of the execution profile obtained depends on the type of information stored in the data file pe sampling provides a flat profile of the percentage time spent in each function excluding the time spent in its children Function call count provides a call graph profile showing the percentage time spent in each function plus the percentage time accounted for by calls to the children of each function and the percentage time allocated to calls from different parents Note No count is taken if the function calls children through an ARM Thumb interworking veneer The debugger needs to know which profiling method you require when it loads the image The default is pc sampling To obtain a call graph profile If you are using armsd load the image with load callgraph image file If you are using ADW or ADU select Options Profiling Call Graph Profiling Then execute the code to collect the profile data Copyright
443. nitor is removed from the system then directly install the application handler Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 11 Handling exceptions on Thumb capable processors Note This section applies only to Thumb capable ARM processors This section describes the additional considerations you must take into account when writing exception handlers suitable for use on Thumb capable processors Thumb capable processors use the same basic exception handling mechanism as processors that are not Thumb capable An exception causes the next instruction to be fetched from the appropriate vector table entry The same vector table is used for both Thumb state and ARM state exceptions An initial step that switches to ARM state is added to the exception handling procedure described in The processor response to an exception on page 9 5 9 11 1 Thumb processor response to an exception ARM DUI 0040D When an exception is generated the processor takes the following actions 1 Copies cpsr into spsr_mode Switches to ARM state pA Sets the CPSR mode bits 3 Stores the return address in Ir_mode See The return address on page 9 41 for further details 4 Sets the program counter to the vector address for the exception The switch from Thumb state to ARM state in step 1 ensures that the ARM instruction installed at this vector address either a branch or a pc relative load is co
444. not used to set watchpoints Select Set or Edit Watchpoint from the Execute menu to set watchpoints Refer to Simple watchpoints on page 3 29 and Complex watchpoints on page 3 32 for more information Evaluation of function pointers and member functions is not available in this version of ADW or ADU You can specify the contents and format of the Watch window using the Watch window menu The following sections describe how to view the Watch window display the Watch window menu delete and add watch items format watch items change the contents of watched items recalculate watches Viewing the Watch window Follow these steps to view the Watch window 1 Select Show Watch Window from the C menu or click on the Show Watches button in the toolbar The Watch window displays a list of watched variables and expressions Figure 3 24 on page 3 67 shows an example 3 66 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Watch Window Ea Figure 3 24 The Watch window Expressions that return a scalar value are displayed as an expression value pair Non scalar values such as structures and classes are displayed as a tree of member variables If a class is derived the base classes are represented by lt base class gt member variables of the class Note You can also open the Watch window from the Evaluate Expression window Refer to Evaluating expressi
445. ns the following ALU status flags N Set when the result of the operation was Negative Z Set when the result of the operation was Zero C Set when the operation resulted in a Carry V Set when the operation caused oVerflow A carry occurs if the result of an add subtract or compare is greater than or equal to 232 or as the result of an inline barrel shifter operation in a move or logical instruction Overflow occurs if the result of an add subtract or compare is greater than or equal to 231 or less than 23 Add an S suffix to an ARM instruction to make it set the ALU status flags in the CPSR Do not use the S suffix with CMP CMN TST or TEQ These comparison instructions always update the flags This is their only effect Copyright 1997 1998 ARM Limited All rights reserved 5 17 Basic Assembly Language Programming 5 4 2 Execution conditions The relation of condition code suffixes to the N Z C and V flags is shown in Table 5 1 Table 5 1 Condition code suffixes Suffix Flags Meaning EQ Z set Equal NE Z clear Not equal CS HS C set higher or same Unsigned gt CC LO C clear lower Unsigned lt MI N set Negative PL N clear Positive or zero VS V set Overflow VC V clear No overflow HI C set and Z clear higher unsigned gt LS C clear and Z set lower or same unsigned lt GE N and V the same signed gt LT N and V differ signed lt GT Z clear N and V the
446. ns the system heap parameters The values returned are typically those used by the Angel C library during initialization These values are defined in the devconf h header file Refer to Modifying target specific files on page 13 57 for a description of devconf h The C library can override these values but will do so only if __heap_base is defined at link time In this case the values of the following symbols are used __heap_base __heap_limit s __stack_base __stack_limit This call returns sensible answers if EmbeddedICE is being used but the values are determined by the host debugger using the top_of_memory debugger variable Entry On entry rl points to a single word data block word 1 is the address at which the heap descriptor is located Return On exit rl points to a single word data block word 1 is the address at which the heap descriptor is located The heap descriptor is a block of four words of data that contains the stack and heap base and limit word 1 Heap Base word 2 Heap Limit word 3 Stack Base word 4 Stack Limit ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 93 Angel 13 7 22 SYS ELAPSED 0x30 Returns the number of elapsed target ticks since the support code started execution Ticks are defined by SYS_TICKFREQ If the target cannot define the length of a tick it can supply SYS_ELAPSED Entry Register rl contains a pointer to a double word in which to put th
447. nstruction For an example of implementation code look at the rebuild kit file on UNIX in armsd source example c or on PC in C ARM250 Source Win32 ARMulate example c Copyright 1997 1998 ARM Limited All rights reserved 12 31 ARMulator 12 15 Rebuilding the ARMulator The file example c defines an extra memory model see A sample memory model on page 12 29 For ARMulator to know about this model you must declare the model in models h by adding the line MEMORY Examp leMemory The reference ExampleMemory comes from ARMul_MemStub ExampleMemory in the file example c You must also add the object file to the supplied Makefile along with a rule for building the model 12 15 1 Rebuilding on UNIX Follow these steps to rebuild the ARMulator under UNIX L 2 12 32 Place the source code in the directory sources Load the Makefile in build into an editor Add the object to the list of objects to be built Change the lines OBJALL main o angel o armfast o armflat o armmap o armpie o bytelane o dummymmu o ebsa110 0 errors o models o pagetab o profiler o tracer o trickbox o validate o watchpnt o winglass o to read OBJALL main o angel o armfast o armflat o armmap o armpie o bytelane o dummymmu o ebsa110 0 errors o models o pagetab o profiler o tracer o trickbox o validate o watchpnt o winglass o example o Add a rule for building the example example o SRCDIR1 example c example o S
448. ntended you can ignore the warning Note When both versions of an identically named routine are present in an image and a call is made through a function pointer it is not possible to determine which version of the routine will be called Therefore if you are using function pointers to call such routines you must compile both routines and the routine making the call for interworking 7 3 6 The C and C interworking libraries ARM DUI 0040D Two variants of the Thumb C libraries are provided with the Toolkit compiled for interworking armlib_1 161 and armlib_1 16b not compiled for interworking armlib 161 and armlib 16b Use the non interworking set only if your application consists solely of Thumb code Only a non interworking variant of the ARM C library is provided armlib 321 and armlib 32b Interworking versions of the ARM library are not supplied They are typically of little use because only ARM routines are likely to call ARM library routines For example it is unlikely that you will want a Thumb routine running from 16 bit memory to use an ARM library routine that takes up more memory and takes longer to execute than the Thumb library equivalent If you want to build interworking versions of the ARM library refer to ARM Software Development Toolkit Reference Guide for details of how to rebuild the libraries Copyright 1997 1998 ARM Limited All rights reserved 7 17 Interworking ARM and Thumb 7 18
449. nts of the IRQ vector are discarded Load pc method The required instruction can be constructed as follows 1 Take the address of the exception handler 2 Subtract the address of the corresponding vector 3 Subtract Ox8 to allow for the pipeline 4 Logically OR this with Oxe59ff000 the opcode for LDR pc pc offset to produce the value to be placed in the vector 5 Put the address of the handler into the storage location Example 9 4 shows a C routine that implements this method Example 9 4 unsigned Install_Handler unsigned location unsigned vector Updates contents of vector to contain LDR pc pc offset Instruction to cause long branch to address in location Function return value is original contents of vector unsigned vec oldvec vec unsigned location unsigned vector x8 xe59FF000 oldvec vector vector vec return oldvec The following code calls this to install an IRQ handler 9 12 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Handling Processor Exceptions unsigned xirqvec unsigned 0x18 unsigned irqaddr unsigned 0x38 For example irqaddr unsigned IRQHandler Install_Handler irgaddr irqvec Again in this example the returned original contents of the IRQ vector are discarded but they could be used to create a chain of handlers Refer to Chaining exception handlers on page 9 37
450. ny SWI number if you are developing an operating system or application that uses these SWI numbers Refer to the Configuring Angel on page 13 69 for more information The semihosting operation type is passed in r0 rather than being encoded in the SWI number All other parameters are passed in a block that is pointed to by r1 The result is returned in rO either as an explicit return value or as a pointer to a data block If no result is returned rO is corrupted Registers rl r3 are preserved by Angel when an Angel system call is made See the description of each operation below In the following descriptions the number in parentheses after the operation name for example 0x01 is the value rO must be set to for this operation If you are calling Angel SWIs from assembly language code it is best to use the operation names that are defined in arm h You can define the operation names with an EQU directive For example SYS_OPEN EQU 0x01 SYS_CLOSE EQU 0x02 13 7 1 Angel task management and SWIs ARM DUI 0040D Angel SWIs are divided into two main categories Simple SWIs These are SWIs such as EnterS VC and undefined SWIs These SWIs do not use the Angel serializer and do not store anything in the global registers blocks They can be treated like an APCS function call Registers rO to r3 and r12 are corrupted Complex SWIs These are SWIs such as the C library support SWIs These SWIs use the serializer and the global register block
451. o models h Copyright 1997 1998 ARM Limited All rights reserved 12 5 ARMulator 12 3 Tracer A sample implementation of a tracer is provided This can trace instructions memory accesses and events to an RDI log window or a file in text or binary format See the source file tracer c and Configuring the Tracer below for details of the formats used in these files The configuration file armul cnf controls what is traced Alternatively you can link your own tracing code onto the Tracer module allowing real time tracing No examples are supplied but the required functions are documented here The formats of Trace_State and Trace_Packet are documented in tracer h unsigned Tracer_Open Trace_State ts This is called when the tracer is initialized The implementation in tracer c opens the output file from this function and writes a header void Tracer_Dispatch Trace_State ts Trace_Packet packet This is called on each traced event for every instruction event or memory access In tracer c this function writes the packet to the trace file void Tracer_Close Trace_State ts This is called at the end of tracing The file tracer c uses this to close the trace file extern void Tracer_Flush Trace_State ts This is called when tracing is disabled The file tracer c uses this to flush output to the trace file The default implementations of these functions can be changed by compiling tracer c with EXTERNAL_DISPATCH defined
452. o spsr Restore registers and return Mark end of this file Nested SWis in C By default the ARM compilers do not take into account the fact that an inline SWI will overwrite the contents of the link register if it is called from Supervisor mode If the nested SWI handlers are written in C or C you must use the fz compiler option to instruct the compiler to generate code that stores Ir_SVC For example if the C function is in module c_swi_handle c the following command produces the object code file armcc c fz c_swi_handle c Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 4 4 Calling SWls from an application ARM DUI 0040D The easiest way to call SWIs from your application code is to set up any required register values and call the relevant SWI in assembly language For example MOV rQ 65 load r with the value 65 SWI 0x0 Call SWI 0x0 with parameter value in rQ The SWI instruction can be conditionally executed as can all ARM instructions Calling a SWI from C is more complicated because it is necessary to map a function call onto each SWI with the __swi compiler directive This allows a SWI to be compiled inline without additional calling overhead provided that any arguments are passed in r0 r3 only any results are returned in r0 r3 only Note You must use the fz compiler option when compiling code that contains inline SWIs Th
453. o start the Flash programming The Command Window displays the progress as the Flash is programmed and a message when the operation is complete Flash written and verified successful ly 6 Exit ADW and switch off the power to the PID board 7 Put REMAP link LK18 IN to execute from Flash 8 Switch on the power to the PID board and launch ADW 9 In ADV select Load from the File menu and enter the name of the debug image scatter axf 10 Select Debugger Internals from the View menu and make vector_catch 0 to free a watchpoint unit 11 You can now debug your ROM code for example set breakpoints single step view backtrace 12 To break on each interrupt put a breakpoint on line 112 of C_main c if IntCT1 Copyright 1997 1998 ARM Limited All rights reserved 10 29 Writing Code for ROM 10 9 Scatter loading and long distance branching Long distance branching is defined for ARM and Thumb architectures as follows The branch instructions in the ARM instruction set allow a branch forwards or backwards by up to 32MB A subroutine call is a variant of the standard branch As well as allowing a branch forwards or backwards up to 32MB the BL Branch with Link instruction preserves the return address in register 14 link register Ir The Thumb instruction set has much shorter branch ranges Conditional instructions have a range of 256 bytes Unconditional branches have a range of 2048 bytes The BL l
454. o the ELF description in c ARM25 PDF specs for details of the ARM implementation of standard ELF format Demon based C libraries are no longer included in the toolkit release and RDP is no longer supported as a remote debug protocol The following sections describe the changes in more detail Functionality enhancements and new functionality on page 1 7 Changes in default behavior on page 1 12 Obsolete and deprecated features on page 1 15 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Introduction 1 3 1 Functionality enhancements and new functionality ARM DUI 0040D This release of the ARM Software Development Toolkit introduces numerous enhancements and new features The major changes are described in Improved support for debug of optimized code Instruction scheduling compilers on page 1 8 Reduced debug data size on page 1 8 New supported processors on page 1 9 ADW enhancements on page 1 9 Interleaved source and assembly language output on page 1 10 New assembler directives and behavior on page 1 10 Long long operations now compile inline on page 1 10 Angel enhancements on page 1 11 ARMulator enhancements on page 1 11 New fromELF tool on page 1 11 New APM configuration dialogs on page 1 12 Improved support for debug of optimized code Compiling for debug g and the optimization level 0 have been made orthogonal in the compilers There are
455. of emulators is exhausted no further processing of the instruction can take place so the undefined instruction handler should report an error and quit Refer to Chaining exception handlers on page 9 37 for more information Note The Thumb instruction set does not have coprocessor instructions so there should be no need for the undefined instruction handler to emulate such instructions ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 33 Handling Processor Exceptions 9 8 Prefetch abort handler If the system contains no MMU the Prefetch Abort handler can simply report the error and quit Otherwise the address that caused the abort must be restored into physical memory Ir_ABT points to the instruction at the address following the one that caused the abort so the address to be restored is at Ir_ABT 4 The virtual memory fault for that address can be dealt with and the instruction fetch retried The handler should therefore return to the same instruction rather than the following one 9 34 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 9 9 Data abort handler Handling Processor Exceptions If there is no MMU the data abort handler should simply report the error and quit If there is an MMU the handler should deal with the virtual memory fault The instruction that caused the abort is at Ir_ABT 8 because Ir_ABT points two instructions beyond the instruction that caused the
456. oid using functions that require a large amount of stack space You can pass values in and out of such a handler written in C provided that the top level handler passes the stack pointer value into the C function as the second parameter in rl MOV r1 sp Second parameter to C routine 1S pointer to register values BL C_SWI_Handler Call C routine to handle the SWI and the C function is updated to access it void C_SWI_handler unsigned number unsigned reg The C function can now access the values contained in the registers at the time the SWI instruction was encountered in the main application code see Figure 9 2 on page 9 17 It can read from them Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions value_in_reg_O value_in_reg_1 value_in_reg_2 reg value_in_reg_3 reg I Il 3 3 D WM WH ra m 1 ea U Ne Lu LU e and also write back to them reg 0 updated_value_ 0 reg 1 updated_value_1 reg 2 updated_value_2 reg 3 updated_value_3 causing the updated value to be written into the appropriate stack position and then restored into the register by the top level handler Previous sp_SVC sp_SVC Figure 9 2 Accessing the supervisor stack 9 4 3 Using SWls in supervisor mode When a SWI instruction is executed the processor enters supervisor mode the CPSR is stored into spsr_SVC and the return address is stored in Ir_
457. ole input stream for an open read or the console output stream for an open write Opening these streams is performed as part of the standard startup code for those applications ARM DUI 0040D that reference the C stdio streams Entry On entry rl contains a pointer to a three word argument block word 1 is a pointer to a null terminated string containing a file or device name word 2 is an integer that specifies the file opening mode Table 13 4 on page 13 82 gives the valid values for the integer and their corresponding ANSI C fopen mode Copyright 1997 1998 ARM Limited All rights reserved 13 81 Angel word 3 is an integer that gives the length of the string pointed to by word 1 The length does not include the terminating null character that must be present Table 13 4 mode 0 1 2 3 4 5 6 7 8 9 10 1l ANSI C fopen mode r b rt rtb w wb wt wtb a ab a a b Return On exit rO contains a non zero handle 1f the call is successful if the call is not successful 13 82 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 3 SYS CLOSE 0x02 Closes a file on the host system The handle must reference a file that was opened with SYS_OPEN Entry On entry rl contains a pointer to a one word argument block word 1 is a file handle referring to an open file Return On exit rO contains 0 if the call is successful if the call is not successful 13 7 4 S
458. ollowing ways select Toggle Breakpoint from the Execute menu click the Toggle breakpoint button press the F9 key A new breakpoint is displayed as a red marker in the left pane of the Execution window the Disassembly window or the Source File window In a line with several statements you can set a breakpoint on an individual statement as demonstrated in the following example int main hello world return Q If you position the cursor on the word world and click the Toggle breakpoint button hello is executed and execution halts before world is executed To see all the breakpoints set in your executable image select Breakpoints from the View menu To set a simple breakpoint on a function 1 Display a list of function names in the Function Names window by selecting Function Names from the View menu 2 Select Toggle Breakpoint from the Function Names window menu or click the Toggle breakpoint button Copyright 1997 1998 ARM Limited All rights reserved 3 27 ARM Debuggers for Windows and UNIX 3 28 The breakpoint is set at the first statement of the function This method also works for the Low Level Symbols window but the breakpoint is set to the first machine instruction of the function that is at the beginning of its entry sequence Removing a simple breakpoint There are several methods of removing a simple breakpoint Method 1 1 Double click on a line containing a breakpoint
459. ome flags only apply to certain processors For example BranchPredict only applies to the ARM810 and ICache to the SA 110 and ARM940T processors 12 7 2 Controlling registers 2 and 3 ARM DUI 0040D The second set of options controls on an MMU based processor the Translation Table Base Register System Control Register 2 the Domain Access Control Register Register 3 The Translation Table Base Register should be aligned to a 16KB boundary PageTab eBase 0xa000000 DAC 0x00000003 Copyright 1997 1998 ARM Limited All rights reserved 12 15 ARMulator 12 7 3 Pagetable contents 12 16 Finally the configuration file can contain an outline of the pagetable contents The module writes out a top level pagetable to the address specified for the Translation Table Base Register whenever ARMulator resets on MMU based processors By default armul cnf contains a description of a single region covering the whole of the address space You can add more regions A region entry consists of Region 0 VirtualBase 0 PhysicalBase 0 S1ze 4GB Cacheable Yes Bufferable Yes Updateable Yes Domain 0 AccessPermissions 3 Translate Yes Region n names the regions starting with Region nis an integer VirtualBase is the virtual address of the base of this region This address should be aligned to a 1MB boundary on an MMU processor PhysicalBase is the address that the base of the region maps to PhysicalBase defaults to
460. on OK Build and debug an ARM executable image made from C and ARM Assembly Lanquage Cancel source files and ARM Object Libraries The DebugRel variant compiles smaller faster code that can be debugged tested and released unchanged You can build your object libraries using sub projects Type APM Executable Image Project Name hello Project Directory examples Browse Figure 2 2 New Project dialog 4 Select the template Type that you want to use for the project The template description is displayed For this example select ARM Executable Image 5 Enter a Project name such as hello This is used for the project file and the project output 6 Modify the Project Directory to c ARM250 Examples hello When you build the project the directories containing derived files variant directories are created within this directory 7 Click OK Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager If you have specified a directory that does not currently exist you are prompted to confirm that you want a new project directory created The new project file is created in the project directory and the Project window is displayed Creating a new source file For the hello project you created in the previous section follow these steps to create a new source file from within APM L 2 Click the New button or select New from the File menu The New dialog appears
461. on of a program press Ctrl C To restart a program that is already loaded either enter reload targetname to reload the target and then execute the program again with go enter pc start_address typically Ox8000 and CPSR IFt_SVC32 and then type go To configure your target to run with command line arguments enter let cmdline arguments For example let cmdline high p M These arguments replace any arguments set when armsd was started go can be abbreviated to g and reload can be abbreviated to rel 4 2 6 Stepping through the program The following commands enable you to step through your target To execute a single source code line enter step To step into a function call enter step in To step out of a function to the line that immediately follows the call to that function enter step out This command is useful if step in has been used too often To display your current position in the target enter where step can be abbreviated to s and where can be abbreviated to wh 4 8 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Command Line Development 4 2 7 Exiting the debugger To exit the debugger type quit You are returned to the command line quit can be abbreviated to q 4 2 8 Viewing and setting program variables The following commands enable you to view and set program variables To list all the variables defined within the current contex
462. on path includes the statement selected with the cursor ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 35 ARM Debuggers for Windows and UNIX 3 5 3 5 1 3 36 Debugger further details Various debugger windows are described in ARM Debugger desktop windows on page 3 14 This section gives more details of some of those windows and describes other information that is also available to you during a debugging session The topics covered in this section are Working with source files Working with variables on page 3 37 Displaying disassembled and interleaved code on page 3 40 Remote debug information on page 3 41 Using regular expressions on page 3 42 High level and low level symbols on page 3 43 Profiling on page 3 43 Saving or changing an area of memory on page 3 44 Specifying command line arguments for your program on page 3 46 Using command line debugger instructions on page 3 46 Changing the data width for reads and writes on page 3 47 Flash download on page 3 48 Working with source files The debuggers provide a number of options that enable you to view the paths that lead to the source files for your program list the names of your source files examine the contents of specific source files The following sections describe these options in detail Search paths To view the source for your program image during the debugging session you must
463. on return address In earlier versions of the ARM architecture this problem has been solved by either carefully avoiding subroutine calls in exception code or changing from the privileged mode to user mode The first solution is often too restrictive and the second means the task may not have the privileged access it needs to run correctly ARM Architecture 4 and later provide a processor mode called system mode to overcome this problem System mode is a privileged processor mode that shares the User mode registers Privileged mode tasks can run in this mode and exceptions no longer overwrite the link register Note System mode cannot be entered by an exception The exception handler modify the CPSR to enter System mode Refer to Reentrant interrupt handlers on page 9 24 for an example 9 44 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 10 Writing Code for ROM ARM DUI 0040D This chapter describes how to build ROM images typically for embedded applications There are also hints on how to avoid the most common errors in writing code for ROM This chapter contains the following information About writing code for ROM on page 10 2 Memory map considerations on page 10 3 Initializing the system on page 10 5 Example 1 Building a ROM to be loaded at address 0 on page 10 9 Example 2 Building a ROM to be entered at its base address on page 10 17 Example 3 Using the embedded C library on page
464. onExit BL __call_via_r4 Stop MOV r0 0x18 LDR r1 0x20026 SWI xAB Angel semihosting Thumb SWI __call_via_r4 This Thumb code segment will BX to the address contained in r4 BX r4 Branch exchange CODE32 Subsequent instructions are ARM ARMSubroutine ADD r0 rQ rl Add the numbers together BX LR and return to Thumb caller bit of LR set by Thumb BL END Mark end of this file Example 7 3 on page 7 10 1s a modified form of Example 7 2 The main routine is now in ARM code and the subroutine is in Thumb code Notice that the call sequence is now a MOV instruction followed by a BX instruction ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 7 9 Interworking ARM and Thumb AREA ThumbAdd CODE READONLY ENTRY main MOV rQ 2 MOV r1 3 ADR r4 ThumbSub 1 MOV Ir pc BX r4 Stop MOV rQ 0x18 LDR r1 0x20026 SWI x123456 CODE16 ThumbSub ADD r0 r0 rl BX LR END Example 7 3 Name this block of code Mark 1st instruction to call Assembler starts in ARM mode Load r with value 2 Load r1 with value 3 Generate branch target address and set bit 0 hence arrive at target in Thumb state Store the return address Branch exchange to subroutine ThumbSub Terminate execution angel_SWIreason_ReportException ADP_Stopped_ApplicationExit Angel semihosting ARM SWI Subsequent instructions are Thumb Add the numbers together and return to ARM caller Mark en
465. onf h on page 13 60 for more information Stacks Angel requires control over its own Supervisor stack If you want to make Angel calls from your application you must set up your own stacks Refer to Developing an application under full Angel on page 13 17 for more information Angel also requires that the current stack pointer points to a few words of usable full descending stack whenever an exception is possible because the Angel exception return code uses the application stack to return 13 10 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 2 Developing applications with Angel This section describes how you can develop applications under Angel It gives an overview of the development process and describes how you can use Angel in two distinct ways full Angel debug agent minimal Angel library It also describes the programming restrictions that you must be aware of when developing an application under Angel and provides some workarounds for Angel intrusions 13 2 1 Full Angel debug agent Full Angel is a stand alone system that resides on the target board and is always active Full Angel is used during the development of the application code It supports all debugger functions and you can use it to download your application image from a host debug your application code develop the application before converting to stand alone code Full Angel is supplied in the following fo
466. ong branch with link instruction has a range of 4MB 10 9 1 Range restrictions The linker ensures that no branch or subroutine call violates these range restrictions If you place your execution regions in such a way as to require inter region branches beyond the range the linker generates an error message stating Relocated value too big for instruction sequence There are two ways to work around this restriction Using function pointers in code removing the dependence on branch ranges Calling the out of range routines through assembly language veneers Function pointers For example if the application currently has a function int func int a int b that is invoked as func a b you can change this using function pointers into typedef int FuncType int int FuncType fn func and invoke the function as fn a b 10 30 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM Assembly language veneers If you use assembly language veneers you can write the function as asm_func a b where asm_func is an assembly language routine Because ARM and Thumb assembly languages differ the code for the veneers is slightly different The following is the assembly language veneer for ARM AREA arm_longbranch_veneers CODE READONLY EXPORT asm_func IMPORT func asm_func LDR pc addr_func addr_func DCD func END The following is the assembly language veneer fo
467. ons and adding watches on page 3 71 for more information Displaying the Watch window menu The Watch window menu enables you to add and delete watches to change the display format of watches and to change the contents of watched variables Follow these steps to display the Watch window menu 1 Display the Watch window 2 Click the right mouse button in the Watch window The Watch window menu is displayed This menu is context sensitive The menu items that it contains will depend on whether or not you have clicked on an existing watch item the type of watch item you have clicked on For example Figure 3 25 on page 3 68 shows the Watch window menu that is displayed when the right mouse button is clicked on the character array buf ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 67 ARM Debuggers for Windows and UNIX 3 68 Watch Window Ea ch but e wel Contract Add ltem INS Hide Window ESC Format Window Figure 3 25 The Watch window menu Deleting a watch item Follow these steps to delete a watch item from the Watch window L 7 Display the Watch window Either click the right mouse button on the item you want to delete and select Delete Item from the Watch window menu click on the item you want to delete and press the Delete key The watch item is deleted from the Watch window Adding a watch item Follow these steps to add a watch item to th
468. or However this is not possible in ROM at zero systems In this case a branch through zero causes a system reboot if the processor is executing in a privileged mode a system crash if the processor is not executing in a privileged mode 13 5 5 Configuring SWI numbers 13 72 Angel requires one SWI in order to operate The SWI is used to change processor mode to gain system privileges make semihosting requests report an exception to the debugger The SWI passes a reason code in r0 to determine the type of request Depending on the SWI additional arguments are passed in rl Refer to Angel C library support SWIs on page 13 79 more information The SWI number is different for ARM state and Thumb state By default the SWI numbers used are ARM state 0x123456 Thumb state Oxab If you want to use either of these SWI numbers for your system you can reconfigure the SWI to use any of the available SWI numbers If you change these values you must Recompile the C library specifying the new SWI value in the Angel definition files Refer to Retargeting the ANSI C library on page 4 6 of the ARM Software Development Toolkit Reference Guide for more information Recompile the debug agent using the new value Refer to Chapter 9 Handling Processor Exceptions for more general information on handling SWIs In C the Angel SWI numbers are defined in Angel Source arm h as define angel_SWI_ARM 0x123456 define angel
469. or each of other SWI routines SWInum SWI number code B EndofSUI SWInum1 SWI number 1 code B EndofSUI Rest of SWI handling code EndofSwI Return execution to top level SWI handler so as to restore registers and return to program 9 4 2 SWI handlers in C and assembly language Although the top level header must always be written in ARM assembly language the routines that handle each SWI can be written in either assembly language or in C Refer to Using SWIs in supervisor mode on page 9 17 for a description of restrictions ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 15 Handling Processor Exceptions The top level header uses a BL Branch with Link instruction to jump to the appropriate C function Because the SWI number is loaded into r0 by the assembly routine this is passed to the C function as the first parameter in accordance with the ARM Procedure Call Standard The function can use this value in for example a switch statement The following line can be added to the SWI_Handler routine in Example 9 5 on page 9 14 BL C_SWI_Handler Call C routine to handle the SWI Example 9 7 shows how the C function can be implemented Example 9 7 void C_SWI_handler unsigned number switch number case Q x SWI number code break case 1 x SWI number 1 code break default Unknown SWI report error The supervisor stack space may be limited so av
470. or example if an RTOS installs an ISR to perform interrupt driven context switches and the ISR is enabled when Angel is active for example handling a debug request an interrupt occurs when Angel is running code then the ISR switches the Angel context not the RTOS context That is the ISR puts values in processor registers that relate to the application not to Angel and it is very likely that Angel will crash There are two ways to avoid this situation Detect ISR calls that occur when Angel is active and do not task switch The ISR can run provided the registers for the other mode are not touched For example timers can be updated Disable either IRQ or FIQ interrupts whichever Angel is not using while Angel is active This is not easy to do In summary the normal process for handling an IRQ under an RTOS is 1 IRQ exception generated 2 Do any urgent processing 3 Enter the IRQ handler 4 Process the IRQ and issue an event to the RTOS if required 5 Exit by way of the RTOS to switch tasks if a higher priority task is ready to run Under Angel this procedure must be modified to 1 IRQ exception generated Copyright 1997 1998 ARM Limited All rights reserved 13 19 Angel 13 20 2 Do any urgent processing 3 Check whether Angel is active a If Angel is active then the CPU context must be restored on return so scheduling cannot be performed although for example a counter could be
471. ory even if the board is switched off You can also download application only images using this method but you cannot then use Angel Refer to your development board documentation for more information on downloading to Flash Using a ROM emulator to download a new ROM image This provides medium to fast downloading depending on the ROM Emulator You must have access to a ROM Emulator that is compatible with the hardware You cannot replace application only images using this method You must replace the complete ROM image ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 27 Angel 13 28 Blowing a new ROM or EPROM each time This provides slow replacement in that it takes a relatively fixed amount of time to physically remove your ROM or EPROM blow a new ROM image and replace it If you need to erase your EPROM this will add to the time required However this method might be preferable for extremely large ROM images where only a slow download mechanism is available Replacing the ROM or EPROM also has the advantage that the application is permanently available and does not have to be reloaded when the board is switched off You cannot replace only a part of the program using this method You must replace the complete ROM image If you use one of the ROM replacement methods then you must change from building application images to building ROM images as soon as the development phase starts If yo
472. osting operations By default the SWI is 0x123456 in ARM state and Oxab in Thumb state You can change this number if required Refer to Configuring Angel on page 13 69 for more information If semihosting support is not required you can disable it by setting the semihosting_enabled variable in the ARM debuggers In armsd set semihosting_enabled 0 In ADW or ADU select Debugger Internals from the View menu to view and edit the variable Refer to Chapter 3 ARM Debuggers for Windows and UNIX for more information Refer to Angel C library support SWIs on page 13 79 for details of the Angel semihosting SWIs Communications support Angel communicates using ADP and uses channels to allow multiple independent sets of messages to share a single communications link Angel provides an error correcting communications protocol over Serial and serial parallel connection from host to the target board with Angel resident on the board Ethernet connection from the host to PID board with Angel resident on the board This requires the Ethernet Upgrade Kit No KPI 0015A available separately from ARM Limited The host and target system channel managers ensure that logical channels are multiplexed reliably The device drivers detect and reject corrupted data packets The channel managers monitor the overall flow of data and store transmitted data in buffers in case retransmission is required Refer to Angel communications archi
473. oth can be displayed depending on your image To display interleaved C or C and assembly language code 1 Select Toggle Interleaving from the Options menu to display interleaved source and assembly language in the Execution window Disassembled code is displayed in grey The C or C code is displayed in black Follow these steps to display an area of memory as disassembled code 1 Select Disassembly from the View menu or click the Display Disassembly button The Disassembly Address dialog is displayed 2 Enter an address 3 Click OK The Disassembly window displays the assembler instructions derived from the code held in the specified area of memory Use the scroll bars to display the content of another memory area or a Select Goto from the Search menu b Enter an address C Click OK Specifying a disassembly mode The ARM debugger tries to display disassembled code as ARM code or Thumb code as appropriate Sometimes however the type of code required cannot be determined This can happen for example if you have copied the contents of a disk file into memory When you display disassembled code in the Execution window you can choose to display ARM code Thumb code or both To specify the type of code displayed select Disassembly mode from the Options menu Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 5 4 Remote debug information ARM DUI 0040
474. oth static and non static always have mangled names You can determine the mangled symbol by using decaof sm on the object file that defines the function Refer to Chapter 8 Toolkit Utilities in the ARM Software Development Toolkit Reference Guide for information on decaof C inline functions cannot be called from C unless you ensure that the C compiler generates an out of line copy of the function For example taking the address of the function results in an out of line copy Non static member functions receive the implicit this parameter as a first argument in r0 or as a second argument in rl if the function returns a non int like structure Static member functions do not receive an implicit this parameter 8 4 2 C specific information The following applies specifically to C C calling conventions ARM C uses the same calling conventions as ARM C with the following exceptions When an object of type struct or class is passed to a function and the type has an explicit copy constructor the object is passed by reference and the called function makes a copy Non static member functions are called with the implicit this parameter as the first argument or as the second argument 1f the called function returns a non int like struct C data types ARM C uses the same data types as ARM C with the following exceptions and additions C objects of type struct or class have the same layout as would be expecte
475. p lr pc These have a dedicated role in some APCS variants though certain registers may be used for other purposes even when strictly conforming to the APCS In some variants of the APCS some of these registers are available as additional variable registers Refer to A more detailed look at APCS register usage on page 6 10 for more information Hand coded assembly language routines that interface with C or C must conform to the APCS They are not required to conform strictly This means that any register that is not used in its APCS role by an assembly language routine for example fp can be used as a working register provided that its value on entry is restored before returning ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 6 5 Using the Procedure Call Standards 6 2 2 6 6 An example of APCS register usage 64 bit integer addition This example illustrates how to use ARM assembly language to code a small function so that it can be used by C modules The function performs a 64 bit integer addition It uses a two word data structure to store each 64 bit operand We will consider the following stages writing the function in C examining the compiler output modifying the compiler output looking at the effects of the APCS revisiting the first implementation Writing the function in C In ARM assembly language you can code the addition of double length integers by using the Carry fl
476. partially determines the build order to ensure for example that compilation takes place before linking Copyright 1997 1998 ARM Limited All rights reserved 2 9 ARM Project Manager Ee When you have added the necessary files to a project you can build that project As your project is being built the progress indicator at the bottom of the project window is updated and any diagnostic information generated is displayed in the build log The simplest way to turn source files into project output is to build the entire project You can also process a single source file force build an entire project or select multiple variants to be built Building a project After you have added the example source files to your project you can build it Click the Build button or select Build project name from the Project menu When you start the build the button in the status area changes to Stop Build and a build status indicator appears next to the button Messages from the build tools are displayed in the build log The build log is opened by APM if it is not already open Figure 2 4 shows the APM desktop when the build is complete H C examples hello apj ow HD ARM Executable Image i P DebugPel Sources ne Xe LA Fallon oom IncludedFiles Objects bd hello o common SybProjects Libraries Image Miscellanea o Error stdio h line 150 expected or inserted l Serious Error stdio h line 151 duplicate definit
477. plate location 2 52 templates 2 41 using 2 4 using templates 2 53 viewing files 2 37 Application heap and Angel 13 62 AREA directive 5 11 5 13 AREA directive literal pools 5 25 Arguments command line 3 46 ARM code interworking template 2 52 ARM core 3 5 ARM Debuggers for Windows and UNIX see ADW ADU ARM licensed software A 1 ARM processors 3 5 ARM Project Manager see APM ARM Software Development Toolkit SDT 3 1 armasm 5 10 armcpp 2 53 ARM DUI 0040D armfast c ARMulator model 12 3 12 20 armflat c ARMulator model 12 3 12 19 ARMLMD_LICENSE_FILE environment variable A 7 armmap c ARMulator model 12 4 12 21 armpie c ARMulator model 12 4 armprof see profiler armsd and Angel downloading 13 67 map files 11 9 armsd map file 11 9 12 28 ARMulator 3 5 3 6 overview 12 2 and Angel 13 68 angel model 12 25 armsd map file 12 28 armul cnf file 12 28 12 34 ARM810 page table flags 12 15 ARM940T page table flags 12 15 clock frequency 12 21 configuration file armul cnf 12 6 configuring 3 57 tracer 12 6 under RDI 12 27 controlling using the debugger 12 27 dummy system coprocessor model 12 24 emulation speed 12 13 12 20 example 12 29 12 34 flushing output to the tracer 12 6 functions see ARMulator functions initializing MMU 12 15 tracer 12 6 instruction tracing 11 26 internal SWIS 12 26 linking tracing code 12 6 memory watchpoints 12 14 model stub exports 12 5 models see ARMulator models page tables 12 15 profi
478. plicationExit Qx123456 Angel semihosting ARM SWI rQ start gt LDR RO PC offset to Litpool 1 rl Darea 12 gt LDR R1 PC offset to Litpool 1 r2 Darea 6000 gt LDR R2 PC offset to Litpool 1 pc Ir gt Return Literal Pool 1 r3 Darea 6000 gt LDR r3 PC offset to Litpool 1 sharing with previous literal If uncommented produces an error as Litpool 2 is out of range pc Ir Return r4 Darea 6004 Copyright 1997 1998 ARM Limited All rights reserved 5 31 Basic Assembly Language Programming Darea END AREA ENTRY Start LDR LDR BL stop MOV LDR SWI strcopy LDRB STRB CMP BNE MOV AREA 5 32 8000 Starting at the current location clears a 8000 byte area of memory to zero Literal Pool 2 is out of range of the LDR instructions above An LDR Rd label example string copying Example 5 9 shows an ARM code routine that overwrites one string with another string It uses the LDR pseudo instruction to load the addresses of the two strings from a data area Note the following instructions and directives DCB LDR STR StrCopy CODE READONLY rl srcstr rQ dststr strcopy rQ 0x18 rl 0x20026 Qx123456 r2 r1 1 r2 rQ 1 r2 0 strcopy pc Ir The DCB Define Constant Byte directive defines one or more bytes of store In addition to integer values DCB accepts quoted strings Each character of the string is plac
479. preferred way to generate an image in an deprecated format is to create an ELF format image from the linker and then to use the new fromELF tool to translate the ELF image into the desired format Future release In a future release of the linker these formats will be obsolete and their use will be faulted Copyright 1997 1998 ARM Limited All rights reserved 1 15 Introduction Shared library support This feature is obsolete The Shared Library support provided by previous versions of the SDT has been removed for SDT 2 50 The linker faults the use of the sh command line option Impact Any makefile or APM project file that uses the Shared Library mechanism will now generate an error from the linker The SDT 2 1 1a linker can be used if this facility is required Future release A new Shared Library mechanism will be introduced in a future release of the linker Overlay support Use of the overlay option to the linker and use of the OVERLAY keyword in a scatter load description file are now warned against by the linker Impact Any makefile APM project file or scatter load description file that uses the overlay mechanism will now generate a warning from the linker Future release A future release of the linker will subsume the overlay functionality into the scatter loading mechanism Frame pointer calling standard Use of a frame pointer call standard when compiling C or C code is warned against in the SDT
480. projdir myproj myfile c sets the variables to the following values path c projdir myproj slash file myfile Note An input pattern element lt path gt lt file gt c does not recognize the string myfile c because the string does not contain the specified literal Output and command line pattern expressions An output or command line pattern can use a mixture of pattern variables conditional literals and literals The variables are those matched in the input pattern expressions or defined within the project For example the output pattern element lt path I gt lt path gt consists of the pattern variable and conditional literal I defined only if the pattern variable lt path gt is non empty followed by the pattern variable lt path gt value When given with the filename myfile c this expression resolves to a null string When given with the fully qualified filename I c projdir myproj myfile c the expression resolves to Ic projdir myproj because in the first case the input pattern variable lt path gt is set to so the output pattern element lt path I gt lt path gt becomes Zee 215 which produces resulting in a final value of In the case of the fully qualified filename the input pattern variable lt path gt is set to c projdir myproj so the output pattern element lt path I gt lt path gt becomes lt c projdir myproj I gt c projdir myproj Copyright 1997 1998
481. projectname path variant config tool Note Affects how the location of a file is resolved in the directory structure of the project When you create a project this variable is set to and the name of the project is contained in projectname When you change the value of this variable projectname is set to the new value You cannot change the value of this variable directly It contains the name of the project as assigned when you created the project or whenever it is saved This value is also changed if the variable ProjectName is set to a non empty value The path specifying the directory of a variant created as a sub directory below the directory that holds the project file You can change the value of this variable if necessary This variable stores an encoding of the configuration of a tool or the command line arguments for a tool that is not configurable User defined variables cannot begin with Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 2 4 6 Variants ARM DUI 0040D ARM Project Manager You can use variants to create different versions of your project output from the same source files Typically you use variants to create a debug release version or separate debug and release versions of your project output You can change variant level variables to control how the project output for the variant is built The derived files for each variant such as object files and project o
482. ption ADP_Stopped_ApplicationExit Angel semihosting ARM SWI Out 5 N T 0 0 0 0 0 0 0 ARM DUI 0040D Basic Assembly Language Programming 5 7 5 Thumb LDM and STM instructions ARM DUI 0040D The Thumb instruction set contains two pairs of multiple register transfer instructions LDM and STM for block memory transfers PUSH and POP for stack operations LDM and STM These instructions can be used to load or store any subset of the low registers from or to memory The base register is always updated at the end of the multiple register transfer instruction You must specify the character The only valid suffix for these instructions is IA Examples of these instructions are LDMIA r1 r0 r2 r7 STMIA r4 r0 r3 PUSH and POP These instructions can be used to push any subset of the low registers and optionally the link register onto the stack and to pop any subset of the low registers and optionally the pc off the stack The base address of the stack is held in r13 Examples of these instructions are PUSH r0 r3 POP r0 r3 PUSH r4 r7 lr POP r4 r7 pc The optional addition of the lr pc to the register list provides support for subroutine entry and exit The stack is always Full Descending Thumb state block copy example The block copy example Example 5 10 on page 5 39 can be converted into Thumb instructions An example conversion can be found as tblock s in the examples asm subdirectory of the
483. r ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 85 Angel 13 7 8 SYS READC 0x07 Reads a byte from the debug channel The read is notionally from the keyboard attached to the debugger Entry There are no parameters Register rl must contain zero Return On exit rO contains the byte read from the debug channel 13 7 9 SYS_ISERROR 0x08 13 86 Determines whether the return code from another semihosting call is an error status or not This call is passed a parameter block containing the error code to examine Entry On entry rl contains a pointer to a one word data block word 1 is the required status word to check Return On exit rO contains 0 if the status word is not an error indication a non zero value if the status word is an error indication Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 7 10 SYS_ISTTY 0x09 Checks whether a file is connected to an interactive device Entry On entry rl contains a pointer to a one word argument block word 1 is a handle for a previously opened file object Return On exit rO contains if the handle identifies an interactive device 0 if the handle identifies a file a value other than 1 or 0 if an error occurs 13 7 11 SYS_SEEK 0x0a ARM DUI 0040D Seeks to a specified position in a file using an offset specified from the start of the file The file is assumed to
484. r 10ns period will take 5 wait states to access 60ns memory total access time 60ns At 110MHz ARMmap must insert 6 wait states total access time 63ns So the 1OOMHz processor system is faster than the 1 I0OMHZ processor if connected to 60ns memory This does not apply to cached processors where the 1 1OMHz processor would be faster 12 10 4 Configuring the ARMmap memory model 12 22 You can configure ARMmap to model several memory managers by editing its entry in the armul cnf file MapFile gt Options for the mapfile memory model CountWaitStates True AMBABusCounts False SpotISCycles True ISTiming Ear ly Counting wait states By default ARMmap is configured to count wait states in statistics This can be disabled by setting CountWaitStates False in armul cnf Counting AMBA decode cycles You can configure ARMmap to insert an extra decode cycle for every non sequential access from the processor This models the decode cycle seen on AMBA bus systems You enable this by setting AMBABusCounts True in armul cnf Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARMulator Merged I S cycles All ARM processors particularly cached processors can perform a non sequential access as a pair of idle and sequential cycles known as merged I S cycles By default ARMmap treats these cycles as a non sequential access inserting wait states on the S cycle to lengthen it for the no
485. r Exceptions and the ARM Architectural Reference Manual The syntax of the STM instruction corresponds exactly except for some details in the effect of the option Usage See Implementing stacks with LDM and STM on page 5 36 and Block copy with LDM and STM on page 5 39 Copyright 1997 1998 ARM Limited All rights reserved 5 35 Basic Assembly Language Programming 5 7 2 _LDM and STM addressing modes There are four different addressing modes The base register can be incremented or decremented by one word for each register in the operation and the increment or decrement can occur before or after the operation The suffixes for these options are IA meaning increment after IB meaning increment before DA meaning decrement after DB meaning decrement before There are alternative addressing mode suffixes that are easier to use for stack operations See Implementing stacks with LDM and STM below 5 7 3 Implementing stacks with LDM and STM The load and store multiple instructions can update the base register For stack operations the base register is usually the stack pointer r13 This means that you can use load and store multiple instructions to implement push and pop operations for any number of registers in a single instruction The Load and Store Multiple Instructions can be used with several types of stack descending or ascending The stack grows downwards starting with a high address and progressing to a low
486. r FEATURE If you received the license file by fax you will need to create a text file and key in the information using the editor of your choice When data entry is complete you can use the Imchecksum utility to check that you typed everything in correctly Instructions for using Imchecksum are given under FlexLM license management utilities on page A 14 later in this appendix You may save the license file in any directory on each license server It should however be on a locally mounted file system You usually need to edit the VENDOR line of the license file on each license server The default license file sent you you contains VENDOR armimd opt arm flex Im solaris Change the text opt arm flexIm solaris so that it specifies the directory that holds your license server software Specifically the directory that holds file armlmd Remember to do this on each license server Full instructions for editing the license file can be found under Customizing your license file on page A 9 later in this appendix Copyright 1997 1998 ARM Limited All rights reserved A 5 FlexLM License Manager A 4 Starting the server software To start the license server software on each machine go to the directory containing the license server software and type nohup Imgrd c J1cense_file name 1 logile_name amp where license file name specifies the fully qualified pathname of the license file logfile_name specifies the fully
487. r Thumb AREA thumb_longbranch_veneers CODE READONLY EXPORT asm_func IMPORT func asm_func SUB sp 4 PUSH rQ LDR r addr_func STR rQ sp 4 POP r0 pc ALIGN addr_func DCD func END Note You must ensure that the file containing these veneers is within range of the module calling asm_func a b ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 10 31 Writing Code for ROM 10 10 Converting ARM linker ELF output to binary ROM formats By default the ARM SDT 2 50 linker produces industry standard ELF images For embedded applications the image usually needs to be converted into a binary format suitable for an EPROM programmer For more information on the ARM ELF implementation refer to the ELF documentation in c ARM250 PDF specs For the command line options for fromELF see Chapter 8 Toolkit Utilities in the ARM Software Development Toolkit Reference Guide Follow these steps to add a FromELF build step to a project template 1 Select the root of the project tree view Choose Edit variables for project apj from the Project menu The Edit variables dialog is displayed 2 Find the variable named build_target and change its value from lt projectname gt axf to lt projectname gt bin and click OK 3 Choose Edit Project template from the Project menu The Project Template Editor dialog is displayed 4 Select Edit Details and add ROM to the title 5 Create a CreateROM bu
488. r debug communications serial port B for application use with raw not packet data options for parallel download and application use You can change any of these options to suit the communications requirements of your application by redefining the relevant label The memory map You must define the memory map to allow the debugger to control illegal read writes using the PERMITTED checks These check that writes are not made to Angel data or code space and provide primitive memory protection These should reflect the permitted access of the system memory architecture Refer to Configuring the memory map on page 13 69 for detailed information on setting up an Angel memory map Setting up the stacks You must define a stack for each processor mode used by Angel These always include User Supervisor Undefined and the selected Interrupt modes The location of the stacks can be fixed or can be set to the top of memory when this has been defined Refer to Configuring the memory map on page 13 69 for detailed information on setting up an Angel memory map All other Angel defined memory spaces fusion stack and heaps profile work area application stacks can be defined to sit relative to the stacks or can be given fixed locations The default for the Application Heap space 1s above the run time Angel code and the available space is to the lowest limit of the stacks 13 62 Copyright 1997 1998 ARM Limited All rights reserved
489. r effective C development Meyers S More Effective C 1996 Addison Wesley Publishing Company Reading Massachusetts ISBN 0 201 63371 X The sequel to Effective C C programming guides The following books provide general C programming information Kernighan B W and Ritchie D M The C Programming Language 2nd edition 1988 Prentice Hall Englewood Cliffs NJ USA ISBN 0 13 110362 8 This is the original C bible updated to cover the essentials of ANSI C Harbison S P and Steele G L A C Reference Manual second edition 1987 Prentice Hall Englewood Cliffs NJ USA ISBN 0 13 109802 0 This is a very thorough reference guide to C including useful information on ANSI C Koenig A C Traps and Pitfalls Addison Wesley 1989 Reading Mass ISBN 0 201 17928 8 This explains how to avoid the most common traps and pitfalls in C programming It provides informative reading at all levels of competence in C ANSI C reference ISO IEC 9899 1990 C Standard This is available from ANSI as X3J11 90 013 The standard is available from the national standards body for example AFNOR in France ANSI in the USA ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved xi Preface Typographical conventions xii The following typographical conventions are used in this book typewriter typewriter Denotes text that may be entered at the keyboard such as commands file and program n
490. r example eQ4ec00f gives the disassembly uppercase if the instruction is taken for example SUB r12 r14 pc This is optional and is controlled by armul cnf Set Disassemble True to enable this The format of the event E lines is as follows E addr1 addr2 event_number For example E 00000048 00000000 10005 where addr addr2 event_number gives the first of a pair of words such as the pc value gives the second of a pair of words such as the aborting address gives an event number for example 0x10005 This is MMU Event_ITLBWalk Events are fully described in Events on page 12 87 in the ARM Software Development Toolkit Reference Guide Copyright 1997 1998 ARM Limited All rights reserved 12 11 ARMulator 12 4 Profiler The profiler is controlled by the debugger For more details on the profiler see ARM profiler on page 8 6 in the ARM Software Development Toolkit Reference Guide The file profiler c contains code to implement the profiling options in the debugger It does so by providing an UnkRDIInfoHandler that handles the profiling requests from the debugger In addition to profiling program execution time it allows you to use the profiling mechanism to profile events such as cache misses 12 4 1 Configuring the profiler 12 12 The Profiler section in the configuration file is as follows Profiler For example to profile the PC value when cache misses happen set Type Event E
491. r must be able to handle messages that are longer than 256 bytes in order to handle memory write messages The actual length of memory write messages is determined by your Angel port Refer to Download on page 13 31 for more information Note Raw device drivers that are purely interrupt driven must fit in with the interrupt scheme described Example of Angel processing a simple IRQ on page 13 40 angel_DeviceControlFn This function is defined in devcint h It is implemented in a manner similar to the UNIX ioct1 call It controls the device by passing in a set of standard control values that are defined in devices h Examples of the controls available to this function are DC_INIT Device initialization This provides device specific initialization at the start of a session DC_RESET Device Reset This provides device re initialization to set the device into a known operational state ready to accept input from the host at the default setup Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel DC_RECEIVE_MODE Receive mode select This sets the device into and out of receive mode DC_SET_PARAMS Set Device operational parameters This sets the device parameters at initialization It is also used if the host needs to re negotiate the parameters for example if the baud rate changes DC_RX_PACKET_FLOW This control disables packet delivery when required while still allowing the devic
492. r0 using LDR rO Ir 4 The handler can then examine the comment field bits to determine the required operation The SWI number is extracted by clearing the top eight bits of the opcode BIC rO rO 0xff000000 Example 9 5 shows how these instructions can be put together to form a top level SWI handler See Determining the processor state on page 9 42 for an example of a handler that deals with both ARM state and Thumb state SWI instructions Example 9 5 AREA TopLevelSwi CODE READONLY Name this block of code EXPORT SWI_Handler SWI_Handler STMFD sp r r12 Ir Store registers LDR r 1r 4 Calculate address of SWI instruction and load it into rQ Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions BIC rQ r0 0xff000000 Mask off top 8 bits of gt Instruction to give SWI number Use value in rQ to determine which SWI routine to execute LDMFD sp r r12 pc A Restore registers and return END Mark end of this file 9 4 1 SWI handlers in assembly language The easiest way to call the handler for the requested SWI number is to use a jump table If rO contains the SWI number the code in Example 9 6 can be inserted into the top level handler given in Example 9 5 on page 9 14 following on from the BIC instruction Example 9 6 SWI Jump Table ADR r2 SWIJumpTable LDR pc r2 r0 LSL 2 SwIJumpTable DCD SWInumQ DCD SWInum1 DCD f
493. rce file the start of an area is marked by the AREA directive This directive names the area and sets its attributes The attributes are placed after the name separated by commas Refer to Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide for a detailed description of the syntax of the AREA directive Copyright 1997 1998 ARM Limited All rights reserved 5 13 Basic Assembly Language Programming You can choose any name for your areas However names starting with any nonalphabetic character must be enclosed in bars or a missing AREA name error is generated For example 1_DataArea Certain names are conventional For example C code is used for code areas produced by the C compiler or for code areas otherwise associated with the C library Example 5 1 on page 5 13 defines a single area called ARMex that contains code and is marked as being READONLY The ENTRY directive The ENTRY directive marks the first instruction to be executed within an application Because an application cannot have more than one entry point the ENTRY directive can appear in only one of the source modules In applications containing C code the entry point is often contained within the C library initialization code Application execution The application code in Example 5 1 on page 5 13 begins executing at the label start where it loads the decimal values 10 and 3 into registers rO and rl These registers are added together an
494. rd tab and ensure that the APCS3 radio button is selected in the APCS3 Qualifiers group Click OK to save the configuration 7 5 3 Modifying a project to support interworking This section describes how to modify an existing project to support interworking Converting an ARM executable image to an ARM Thumb interworking project Follow these steps for each file in the Sources partition that you want to be compiled with tcc rather than armcc 1 ARM DUI 0040D Select the C file to be compiled into Thumb code from the Sources partition for example foo c Select Edit variable for foo c from the Project menu The Edit Variables dialog box is displayed Type cc in the Name field and tcc in the Value field and click OK Configure the Thumb compiler for interworking for this file a Select the C file from step 1 b Select Tool Configuration for foo c cc Set from the Project menu The Compiler Configuration dialog is displayed C Click the Target tab and ensure that the check box for Arm Thumb Interworking in the APCS3 Qualifiers group is selected d Modify the other APCS3 options if necessary e Click OK to save the configuration Copyright 1997 1998 ARM Limited All rights reserved 7 25 Interworking ARM and Thumb Note To revert to armcc set the Value from step 3 to an empty string and perform step 4 clicking Unset This may remove any other per file options you had set Converting a Thumb exec
495. re are no items in a queue You should use assertions whenever possible when writing device drivers The ASSERT macro is available if the code is a simple condition check variable value Setting breakpoints Angel can set breakpoints in RAM only You cannot set breakpoints in ROM or Flash In addition you must be careful when using single step or breakpoints on the UNDEF IRQ FIQ or SWI vectors Do not single step or set breakpoints on interrupt service routines on the code path used to enter or exit Angel 13 22 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel Changing from little endian to big endian Angel You can use the Flash download program to change from a little endian version of Angel on the ARM PID board to a big endian version However because of an incompatibility between the way big endian and little endian code is stored in 16 bit wide devices this works only if the target device is an 8 bit Flash device 1 Make sure you are using the 8 bit Flash device U12 2 Start little endian Angel by switching on the board and connecting to the debugger 3 Run the Flash download program and program the Flash with the big endian Angel image This works because Angel operates out of SRAM 4 Quit the debugger and switch off the board 5 Change the EPROM controller U10 to be the big endian controller Refer to your board documentation for details 6 Insert the BI
496. re defined in rdi_stat h Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 14 A sample memory model The sample memory model includes an address decoder a memory mapped I O area some RAM that is paged by writing to another area of memory 12 14 1 The memory map This example deals with example c a device in which memory is split into two 128KB pages the bottom page is read only the top page has one of eight 128KB memory pages mapped into it page 0 being the low page Addresses wrap around above 256KB for the first 1GB of memory as if bits 29 18 of the address bus were ignored Bits 31 30 are statically decoded Table 12 1 Address bus bit31 bit30 Description 0 0 Memory access 0 1 Bits 18 16 of the address select the physical page mapped in to the top page 1 0 I O port see 7 0 area split on page 12 30 1 1 Generates an abort This produces the memory map shown in Figure 12 1 on page 12 30 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 12 29 ARMulator PFFFFFFF Paged RAM Read only RAM Figure 12 1 Memory map CO000000 80000000 40000000 00040000 00020000 00000000 The I O area that is accessible only in privileged modes is split as follows Figure 12 2 I O area split CO000000 B0000000 A0000000 90000000 80000000 These function as follows Sch
497. re detail below together with some recommendations that might be useful when porting Angel to any new hardware 13 44 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel Choosing a target template The first step in the porting process is to select a target template If you are basing your port on an ARM supplied Angel port it is recommended that you use the PID port as a starting point The PID board is a complex system with a varied memory map comprising SSRAM SRAM and DRAM ROM and Flash memory two serial and one parallel communications channels two PC card slots There are also memory mapped peripherals such as dual timers The peripherals conform to the ARM Reference Peripheral Specification The system has a memory remap facility Setting up makefiles and APM project templates After you have copied your template directory pair you must set up the makefile or APM project template to reflect your new directory structure In addition you must set a number of build options to suit your requirements You can build Angel on the following platforms Solaris 2 5 or 2 6 HPUX 10 Windows 95 or 98 Windows NT 4 0 Refer to Modifying the UNIX makefile on page 13 47 for information on modifying a UNIX makefile or Modifying an APM project on page 13 50 for information on setting up the ARM Project Manager project for your build Performing a trial build Whe
498. read vendor name Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D FlexLM License Manager Imstat Imstat a A c Jicense file list f feature 1 feature s server S daemon t value This utility helps you to monitor the status of all network licensing activities including which daemons are running users of individual features users of features served by specific daemons The optional arguments are a Displays all information Lists all active licenses c license_file_list Uses all the license files listed f feature List users of a specific feature 1 feature Print information about the named feature or all features if feature is ommitted s server Display status of server node s S daemon List all users and features of a specific daemon t value Set the Imstat timeout to value Imver Imver filename This utility reports the FlexLM version of a specific library or binary file ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved A 17 FlexLM License Manager A 10 Frequently asked questions about licensing Q A Why can I not find the LMHOSTID program You have to run the makelinks sh script that is in the directory containing the FlexLM software This script creates a series of links to the Imutil program one of which is for Imhostid How does an application find its license file An application and
499. rently being fetched Because each instruction is one word long the instruction being decoded is at address pc 4 and the instruction being executed is at pc 8 9 6 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Handling Processor Exceptions Note See The return address on page 9 41 for details of the return address on Thumb capable processors when an exception occurs in Thumb state Returning from SWI and Undefined instruction The SWI and Undefined instruction exceptions are generated by the instruction itself so the program counter is not updated when the exception is taken Therefore storing pc 4 in lr_mode makes Ir_mode point to the next instruction to be executed Restoring the program counter from the Ir with MOVS pc Ir returns control from the handler The handler entry and exit code to stack the return address and pop it on return is STMFD sp reglist Ir LDMFD sp reglist pc A Returning from FIQ and IRQ After executing each instruction the processor checks to see whether the interrupt pins are LOW and whether the interrupt disable bits in the CPSR are clear As a result IRQ or FIQ exceptions are generated only after the program counter has been updated Storing pc 4 in Ir_mode causes lr_mode to point two instructions beyond where the exception occurred When the handler has finished execution must continue from the instruction prior to the on
500. res The compiler generates the following code Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D MOV a3 al SMULL al a2 a3 a2 MOV pc Ir Copyright 1997 1998 ARM Limited All rights reserved Mixed Language Programming 8 13 Mixed Language Programming 8 2 Accessing C global variables from assembly code Global variables can only be accessed indirectly through their address To access a global variable use the IMPORT directive to import the global and then load the address into a register You can access the variable with load and store instructions depending on its type For unsigned variables use LDRB STRB for char LDRH STRH for short LDRB STRB for Architecture 3 LDR STR for int For signed variables use the equivalent signed instruction such as LDRSB and LDRSH Small structures of less than eight words can be accessed as a whole using LDM STM instructions Individual members of structures can be accessed by a load store instruction of the appropriate type You must know the offset of a member from the start of the structure in order to access it Example 8 6 loads the address of the integer global globvar into r1 loads the value contained in that address into rO adds 2 to it then stores the new value back into globvar Example 8 6 AREA globals CODE READONLY EXPORT asmsubroutine IMPORT globvar asmsubroutine LDR r1 globvar read address of globv
501. results back to the callers Note Calls between separately assembled or compiled modules must comply with the restrictions and conventions defined by the ARM and Thumb Procedure Call Standards Refer to Chapter 6 Using the Procedure Call Standards for more information Example 5 2 shows a subroutine that adds the values of its two parameters and returns a result in rO It is supplied as subrout s in the examples asm subdirectory of the toolkit Refer to Code examples on page 5 2 for instructions on how to assemble link and execute the example Example 5 2 AREA subrout CODE READONLY Name this block of code ENTRY Mark first instruction to execute start MOV rQ 10 Set up parameters MOV rl 3 BL doadd Call subroutine stop MOV rO 0x18 gt angel_SwIreason_ReportException LDR rl 0x20026 ADP_Stopped_ApplicationExit SwI Qx123456 Angel semihosting ARM SWI doadd ADD r rQ rl Subroutine code MOV pc Ir Return from subroutine END Mark end of file ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 15 Basic Assembly Language Programming 5 3 4 header Start stop doadd An example Thumb assembly language module Example 5 3 illustrates some of the core constituents of a Thumb assembly language module It is based on subrout s It is supplied as thumbsub s in the examples asm subdirectory of the toolkit Refer to Code examples on page 5 2 for instructions on how to assembl
502. revious processor status when handling such exceptions so that execution of the program that was running when the exception occurred can resume when the appropriate exception routine has completed Table 9 1 shows the seven different types of exception recognized by ARM processors Table 9 1 Exception types Exception Description Reset Occurs when the processor reset pin is asserted This exception is only expected to occur for signalling power up or for resetting as 1f the processor has just powered up A soft reset can be done by branching to the reset vector 0x0000 Undefined Instruction Occurs 1f neither the processor or any attached coprocessor recognizes the currently executing instruction Software Interrupt This is a user defined synchronous interrupt instruction that allows a SWD program running in user mode for example to request privileged operations that run in supervisor mode such as an RTOS function Prefetch Abort Occurs when the processor attempts to execute an instruction that has prefetched from an illegal address that is an address that the memory management subsystem has determined is inaccessible to the processor in its current mode Data Abort Occurs when a data transfer instruction attempts to load or store data at an illegal address IRQ Occurs when the processor external interrupt request pin is asserted LOW and the I bit in the CPSR is clear FIQ Occurs when the processor external fast interrupt request pin is asse
503. right 1997 1998 ARM Limited All rights reserved 13 53 Angel 13 54 10 Edit Build Step Pattern Build Step Pattern Name Input Partition Pattern Host Source pathi eslashi lt file gt c Pelete Type in the boses below and press the Add or Replace button to edit the above list Ex Fence Output Partition Pattern A Api lolevel Pelete Type in the boses below and press the Add or Replace button to edit the above list Add Command Lines dcc lt path gt lt slash gt lt file c 1 4 1 4 pid DTARGET DRETRANS OMINIMAL ANGEL samed exec armul makelo af pid lolevel s Figure 13 9 Edit makelo c build step Change the Included Files and Command Lines sections of the dialog to reflect the new directory structure For example if you have copied the complete Angel directory structure and renamed the pid and pid b directories change pid to your new directory name When you have finished editing the build steps click Close to exit the Build Step dialog box Select Project Tool Configuration lt cc gt armcc Set The Compiler Configuration dialog is displayed Figure 13 10 on page 13 55 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D 11 12 13 Angel Compiler Configuration x Language and Debug Include Files Preprocessor Code Generation 4 x List of include directori
504. rious Angel channels onto a single device and for providing reliable communications over those channels The channels layer is also responsible for managing the pool of buffers used for all transmission and reception over channels Raw device I O does not use the buffers Although there are several channels that could be in use independently for example CLIB and HADP the channel layer accepts only one transmission attempt at a time Channel restrictions To simplify the design of the channels layer and to help ensure that the protocols operating over each channel are free of deadlocks the following restriction is placed on the use of each channel For a particular channel all messages must originate from either the Host or the Target and responses can be sent only in the opposite direction on that channel Therefore two channels are required to support ADP one for host originated requests Read Memory Execute Interrupt Request one for target originated requests Thread has stopped 13 74 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel Each message transmitted on a channel must be acknowledged by a reply on the same channel Buffer management Managing retransmission means that the channels layer must keep messages that have been sent until they are acknowledged The channel layer supplies buffers to channel users who want to transmit and then keeps transmitted buffers un
505. rms In target board ROM The ARM development and evaluation boards are supplied with full Angel built into ROM or Flash or both To use Angel in this form you simply connect your target board to a host machine running a debugger such as ADW ADU or armsd Prebuilt images Full Angel is supplied as prebuilt images for the ARM PID board with SDT 2 50 These are located in Angel Images pid little for a little endian configuration of the ARM PID board Angel Images pid big for a big endian configuration of the ARM PID board The supplied binaries are angel rom This is aROM image of full Angel You can use this image in place of the Angel in your target board ROM if your board contains an older version In ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 11 Angel addition if you are porting Angel to your own hardware this image provides you with a working default to test against angel hex This is an Intellec Hex format version of full Angel angel m32 This is a Motorola M32 version of full Angel Refer to Downloading a new version of Angel on page 13 67 for information on how to download a new version of Angel to the target Full source code You can port the Angel source code to your own development board if you are developing an application on your own hardware Refer to Porting Angel to new hardware on page 13 43 for more information 13 12 Copyright 1997 1998 ARM Limited
506. rmsd map 00000000 80000000 RAM 4 RW 135 85 135 85 This describes a system that has a single contiguous section of memory starting at address 0x0 0x80000000 bytes in length labeled as RAM a 32 bit 4 byte data bus read and write access read access times of 135ns nonsequential and 80ns sequential write access times of 135ns nonsequential and 80ns sequential Copyright 1997 1998 ARM Limited All rights reserved 11 13 Benchmarking Performance Analysis and Profiling 11 14 If you are using the command line tools L Load the executable produced in Code and data sizes example Dhrystone on page 11 4 into the debugger telling the debugger that its clock speed is 20MHz armsd clock 20MHz nofpe dhry As the debugger loads you can see the information about the memory system that the debugger has obtained from the armsd map file Type go at the armsd prompt to begin execution When requested for the number of Dhrystones enter 30000 When the application completes record the number of Dhrystones per second reported This is your performance figure If you are using the Windows toolkit ADW and ADU by default use a file called armsd map as their map file To change to the map file you have created L Select Configure Debugger from the Options menu This displays the Debugger configuration dialog Select the Memory Maps tab to change the default memory map Click the Local Map Fil
507. rmsd obj gccsolrs dbglib a armsd obj gccsolrs armdbg a armsd obj gccsolrs armsd a armsd obj gccsolrs c150t100 a armsd obj gccsolrs clx a echo Made armsd Made armsd 12 15 2 Rebuilding on Windows To rebuild the ARMulator load armulate mak into Microsoft Visual C Developer Studio version 4 0 or greater Alternatively type nmake armulate mak ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 12 33 ARMulator 12 16 Configuring ARMulator to use the example The ARMulator determines which memory model to use by reading the configuration file armul cnf Before the example memory model can be used by ARMulator a reference to it must be added to the configuration file By default the ARMulator uses the built in Flat or MapFile memory models Follow these steps to edit the configuration file so that the ARMulator selects the sample memory model L 12 34 Load the armul cnf file into a text editor and find the following lines approximately halfway through the file gt List of memory models Memories the default default is the flat memory map Default Flat Change the last two lines to Use the new memory model instead Default Example where Example is the name of the model in the MemStub given in Implementation on page 12 31 The changed lines specify that the default memory model is now Example rather than Flat Note If a map file exists or for ADW
508. rogramming 8 26 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 9 Handling Processor Exceptions This chapter describes how to handle the various types of exception supported by ARM processors It contains the following sections Overview on page 9 2 Entering and leaving an exception on page 9 5 Installing an exception handler on page 9 9 SWI handlers on page 9 14 Interrupt handlers on page 9 22 Reset handlers on page 9 32 Undefined instruction handlers on page 9 33 Prefetch abort handler on page 9 34 Data abort handler on page 9 35 Chaining exception handlers on page 9 37 Handling exceptions on Thumb capable processors on page 9 39 System mode on page 9 44 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 1 Handling Processor Exceptions 9 1 9 2 Overview During the normal flow of execution through a program the program counter increases sequentially through the address space with branches to nearby labels or branch and links to subroutines Processor exceptions occur when this normal flow of execution is diverted to allow the processor to handle events generated by internal or external sources Examples of such events are externally generated interrupts an attempt by the processor to execute an undefined instruction accessing privileged operating system functions It is necessary to preserve the p
509. rotocol Debugger toolbox This provides an interface between the debugger and the Remote Debug Interface RDI ADP support This translates between RDI calls from the debug controller and Angel ADP messages Boot support This establishes communication between the target and host systems For example it sets baud rates and re initializes Angel in the target C library support This handles semihosting requests from the target C library Host channel manager This handles the communication channels providing the functionality of the devices at a higher level Device drivers These implement specific communications devices on the host Each driver provides the entry points required by the channel manager Target system components summary The target system components are Device drivers These implement specific communications devices on the development boards Each driver provides the entry points required by the channel manager Channel manager This handles the communication channels It provides a streamed packet interface that hides details of the device driver in use Copyright 1997 1998 ARM Limited All rights reserved 13 7 Angel Generic debug support This handles the Angel Debug Protocol by communicating with the host over a configured channel and sending and receiving commands from the host Target dependent debug support This provides system dependent features such as setting up breakpoints and reading wr
510. rrays are displayed as ellipses If the format is changed it reverts to the standard array representation Variable properties If you have a list of variables displayed in a Locals Globals window you can display additional information on a variable by selecting Properties from the window specific menu see Figure 3 9 To display the window specific menu right click on an item The information is displayed in a dialog General Variable name Ch_1_Glob Type Unsigned byte character Value Ox00000000 Figure 3 9 Variable Properties dialog Indirection Select Indirect through item from the Variables menu to display other areas of memory ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 39 ARM Debuggers for Windows and UNIX 3 5 3 3 40 If you select a variable of integer type the value is converted to a pointer Sign extension is used if applicable and the memory at that location is displayed If you select a pointer variable the memory at the location pointed to is displayed You cannot select a void pointer for indirection Displaying disassembled and interleaved code You can display disassembled code in the Execution window or in the Disassembly window Select Disassembly from the View menu to display the Disassembly window You can also choose the type of disassembled code to display by selecting the Disassembly mode submenu from the Options menu ARM code Thumb code or b
511. rrectly fetched decoded and executed This forces a branch to a top level veneer that you must write in ARM code Handling the exception Your top level veneer routine should save the processor status and any required registers on the stack You then have two options for writing the exception handler Write the whole exception handler in ARM code Perform a BX branch and exchange to a Thumb code routine that handles the exception The routine must return to an ARM code veneer in order to return from the exception because the Thumb instruction set does not have the instructions required to restore cpsr from spsr Copyright 1997 1998 ARM Limited All rights reserved 9 39 Handling Processor Exceptions 9 40 This second strategy 1s shown in Figure 9 4 See Chapter 7 Interworking ARM and Thumb for details of how to combine ARM and Thumb code in this way Thumb coded ARM coded Thumb coded application Vector table veneers handler Save CPU and register state Switch to Thumb state Switch to ARM state Entry Veneer Handle the exception Restore CPU and register state Switch to ARM state Switch to Thumb state and return Exit veneer Figure 9 4 Handling an exception in Thumb state Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 11 2 The return address ARM DUI 0040D If an exception occurs in ARM st
512. rs to the SWI Usually if more parameters need to be passed to a subroutine in addition to r0 r3 this can be done using the stack However stacked parameters are not easily accessible to a SWI handler because they typically exist on the user mode stack rather than the supervisor stack employed by the SWI handler Alternatively one of the registers typically rl can be used to point to a block of memory storing the other parameters ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 21 Handling Processor Exceptions 9 5 9 5 1 9 22 Interrupt handlers The ARM processor has two levels of external interrupt FIQ and IRQ both of which are level sensitive active LOW signals into the core For an interrupt to be taken the appropriate disable bit in the CPSR must be clear FIQs have higher priority than IRQs in two ways FIQs are serviced first when multiple interrupts occur Servicing a FIQ causes IRQs to be disabled preventing them from being serviced until after the FIQ handler has re enabled them This is usually done by restoring the CPSR from the SPSR at the end of the handler The FIQ vector is the last entry in the vector table at address x1c so that the FIQ handler can be placed directly at the vector location and run sequentially from that address This removes the need for a branch and its associated delays and also means that if the system has a cache the vector table and FIQ handler may
513. rted LOW and the F bit in the CPSR is clear Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Handling Processor Exceptions 9 1 1 The vector table Processor exception handling is controlled by a vector table The vector table is a reserved area of 32 bytes usually at the bottom of the memory map It has one word of space allocated to each exception type and one word that is currently reserved This is not enough space to contain the full code for a handler so the vector entry for each exception type typically contains a branch instruction or load pc instruction to continue execution with the appropriate handler 9 1 2 Use of modes and registers by exceptions Typically an application runs in user mode but servicing exceptions requires privileged that is non user mode operation An exception changes the processor mode and this in turn means that each exception handler has access to a certain subset of the banked registers its own r13 or Stack Pointer sp_mode its own r14 or Link Register lr_mode its own Saved Program Status Register spsr_mode and in the case of a FIQ five more general purpose registers r8_FIQ to r12_FIQ Each exception handler must ensure that other registers are restored to their original contents upon exit You can do this by saving the contents of any registers the handler needs to use onto its stack and restoring them before returning If you are using Angel or
514. ry_cycle indicates the type of memory cycle 5 sequential N non sequential ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 12 9 ARMulator 12 10 I idle C coprocessor read_write indicates either a read or a write operation R read W write mem_acc_size indicates the size of the memory access 4 word 32 bits 2 halfword 16 bits 1 byte 8 bits opcode_fetch indicates an opcode fetch 0 opcode fetch no opcode fetch locked_access indicates a locked access L locked access LOCK signal HIGH no locked access spec_fetch indicates a speculative instruction fetch S speculative fetch ARM810 only no speculative fetch addr gives the address For example 00008008 data can show one of the following value gives the read written value For example EBQQ000C wait indicates nWAIT was LOW to insert a wait state abort indicates ABORT was HIGH to abort the access Trace instructions I lines The format of the trace instruction D lines is as follows IT IS instr_addr opcode disassembly For example IT 00008044 eQ4ecQ00f SUB r12 r14 pc where IT instruction taken Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D IS instr_addr opcode disassembly Events E lines ARMulator instruction skipped all ARM instructions are conditional shows the address of the instruction For example 00008044 gives the opcode fo
515. s Table 13 2 shows the global register blocks Table 13 2 Global register blocks Register block Description RB_Interrupted This is used by the FIQ and IRQ exception handlers RB_Desired This is used by Angel_SerialiseTask RB_SWI This is saved on entry to a complex SWI and restored on return to the application RB_Undef This is saved on entry to the undefined instruction handler RB_Abort This is saved on entry to the abort handler RB_Yield This is used by the Angel_Yield and Angel_Wait functions RB_Fatal This is used only in a debug build of Angel It saves the context in which a fatal error occurred In the case of RB_SWI and RB_Interrupted the register blocks contain the previous task register context so that the interrupt can be handled If the handler function calls Angel_SerialiseTask the global register context is saved into the current task TQI In the case of RB_ Yield the register block is used to store temporarily the context of the calling task prior to entering the serializer The serializer saves the contents of RB_Yield to the TQI entry for the current task if required Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel The Angel task queue angel_TQ_Pool The serializer maintains a task queue by linking together the elements of the angel_TQ_Pool array The task queue must contain an idle task entry Each element of the array is a Task Qu
516. s Angel_SerialiseTask to schedule processing If the driver does not use polled input the handler calls Angel_SerialiseTask to schedule processing if the end of packet character is reached the end of request is reached for a raw device determined by length the ring buffer is empty tx or full rx If Angel_SerialiseTask is not required the ISR reads out any characters from the interrupting device and returns immediately Angel_SerialiseTask saves the stored context from step 2 and creates a new task It then executes the current highest priority task The new task is executed after all tasks of higher priority have been executed The new task executes in Supervisor mode It reads the packet from the device driver to create a proper ADP packet from the byte stream When the packet is complete the task schedules a callback task to process the newly arrived packet The callback routine processes the packet and terminates Angel_NextTask finds that the application is the highest priority task and Angel_SelectNextTask restarts the application by loading the context stored at step 2 into the processor registers Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 4 Porting Angel to new hardware This section describes the steps you must take to port Angel to your own hardware It assumes that you have a general understanding of how Angel works Refer to Angel in operation on page 1
517. s as OS gt Angel configuration Fes The configuration options are Ange SWIARM 0x123456 Ange ISWIThumb 0xab Ange1SWIARM and Ange lSWIThumb declare the SWI numbers that Angel uses For descriptions see Chapter 13 Angel in the ARM Software Development Toolkit User Guide Heapbase 0x40000000 HeapLimi t 0x70000000 Stackbase 0x80000000 StackLimi t 0x70000000 where HeapBase HeapLimit defines the application heap StackBase StackLimit defines the application stack The Angel model automatically detects at runtime whether a model uses Angel or Demon SWIs The following options define the initial locations of the exception mode stack pointers Copyright 1997 1998 ARM Limited All rights reserved 12 25 ARMulator AddrSuperStack 0xa00 AddrAbortStack 0x800 AddrUndefStack 0x700 AddrIRQStack 0x500 AddrFIQStack 0x400 The next option is the default location of the user mode stack and the default value returned by SWI_SYSHEAPINFO that returns the top of the memory application A different value may be returned if a memory model calls ARMul_SetMemSize for example AddrUserStack 0x80000 These options define the location in memory where the ARMulator places the code to handle the hardware exception vectors AddrSoftVectors 0xa40 AddrsOfHand1 ers 0xadQ0 SoftVectorCode 0xb80 The final option points to a buffer where the Angel model places a copy of the command line This can be retrieved be by catchi
518. s c on page 13 60 for details devconf h This is the main configuration file It includes device declarations memory layout details stack sizes and interrupt source information IRQ or FIQ You must check every item in this file to ensure that it is set up correctly for your board Refer to devconf h on page 13 60 for details ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 57 Angel 13 58 Device Drivers target s All other files in the target specific source directory are device driver sources You might need to modify these even if your board uses the same communications chips as those supported by the port you are using as a template If you are using different communications hardware you must rewrite these files for your own hardware Refer to Writing the device drivers on page 13 63 for more information on writing device drivers This file defines the code in the macros called from the initialization and interrupt routines in the main code in startrom s and suppasm s The following macros are defined UNMAPROM STARTUPCODE INI TMMU INITTIMER This macro is called by the startrom s ROM initialization code The macro is called in systems that use ROM remapping to ensure that the ROM image is at 0 at reset When the system initialization is complete a remap is called to map the ROM to its physical address and map RAM to Q This method is used in the PID board system where the memory mana
519. s in the Examples rom embed_lib subdirectory of your SDT installation directory normally c ARM250 Examples rom embed_lib and is included below for reference For more information on the Embedded C library refer to Chapter 4 The C and C Libraries in the ARM Software Development Toolkit Reference Guide 10 6 1 Initialization code 10 6 2 Ccode Before any C code can be called some startup code to initialize the system is needed For the ARMulator all that is required is to initialize the stack pointer The initialization code is called startup s and is shown in Code listings for example 3 on page 10 20 The Embedded C Library does not contain printf so here Angel SWIs are used together with sprintf to display text onto the console This mechanism is portable across ARMulator Angel EmbeddedICE and Multi ICE The C code to print ten strings using sprintf is shown in full in Code listings for example 3 on page 10 20 10 6 3 Compiling linking and running the program ARM DUI 0040D Follow these steps to compile and link the program 1 Compile print c by typing armcc print c ARM tcc print c Thumb 2 Assemble startup s by typing armasm startup s ARM armasm 16 startup s Thumb 3 Type armlink o print axf info totals startup o print o c ARM250 1lib embedded armlib_cn 321 or for Thumb Copyright 1997 1998 ARM Limited All rights reserved 10 19 Writing Code for ROM armlink o print axf
520. s in two different registers as in Example 5 26 Example 5 26 Q Non register based relative map used twice for 4 old and new data at oldloc and newloc 4 oldloc and newloc are labels for 4 memory allocated in other areas r8 oldloc r9 newloc r3 r8 Pointx load from oldloc r8 r3 r3 rQ r3 r9 Pointx store to newloc r9 r3 r8 Pointy Foul ovre r3 r9 Pointy r3 r8 Pointz r3 r3 r2 r3 r9 Pointz Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming 5 9 9 Avoiding problems with MAP and directives ARM DUI 0040D Using MAP and directives can help you to produce maintainable data structures However this is only true if the order the elements are placed in memory is not important to either the programmer or the program You can have problems if you load or store multiple elements of a structure in a single instruction These problems arise in operations such as loading several single byte elements into one register using a Store Multiple or Load Multiple instruction STM and LDM to store or load multiple words from or to multiple registers These operations require the data elements in the structure to be contiguous in memory and to be in a specific order If the order of the elements is changed or a new element is added the program is broken in a way that cannot be detected by the assembler There are a number methods for avoiding problem
521. s such as this Example 5 27 shows a sample structure Example 5 27 MiscBase RN r10 MAP Q MiscBase MiscStart Q Misc_a Misc_b Misc_c Misc_d MiscEndOfChars MiscPadding Misc_I Misc_J Misc_K Misc_data MiscEnd MiscLen INDEX MiscEndOfChars AND 3 20 CT HE HE HE HHH HH HHH HH 1 1 1 1 Q 4 4 4 4 Q M 1scEnd MiscStart QU There is no problem in using LDM STM instructions for accessing single data elements that are larger than a word for example arrays An example of this is the 20 word element Misc_data It could be accessed as follows ArrayBase RN R9 ADR ArrayBase MiscBase LDMIA ArrayBase RQ R5 Copyright 1997 1998 ARM Limited All rights reserved 5 59 Basic Assembly Language Programming This example loads the first six items in the array Misc_data The array is a single element and therefore covers contiguous memory locations It is unlikely that in the future anyone will split it into separate arrays However for the case of loading Misc_I Misc_J and Misc_K into registers rO rl and r2 the following would work but could cause problems in the future ArrayBase RN R9 ADR ArrayBase Misc_I LDMIA ArrayBase RQ R2 Problems arise if the order of Misc_I Misc_J and Misc_K is changed or if a new element Misc_New is added in the middle Either of these small changes breaks the code If these elements need to be accessed separately elsewhere so you do not want to amalgamate th
522. s the base address of the interrupt controller IntLevel Holds the offset of the register containing the highest priority active interrupt r13 Is assumed to point to a small full descending stack Interrupts are enabled after ten instructions including the branch to this code The specific handler for each interrupt is entered after a further two instructions with all registers preserved on the stack In addition the last three instructions of each handler are executed with interrupts turned off again so that the SPSR can be safely recovered from the stack Note Application Note 30 Software Prioritization of Interrupts ARM DAI 0030 describes multiple source prioritization of interrupts using software as opposed to using hardware as described here Example 9 16 first save the critical state SUB Ir Ir 4 gt Adjust the return address before we save it STMFD sp Ir Stack return address MRS r14 SPSR gt get the SPSR STMFD sp r12 r14 gt and stack that plus a working register too ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 9 29 Handling Processor Exceptions Now get the priority level of the highest priority active interrupt MOV r12 IntBase Get the interrupt controller s base address LDR r12 r12 IntLevel Get the interrupt level to 31 Now read modify write the CPSR to enable interrupts MRS r14 CPSR Read the status register BI
523. s the block copy module rewritten to use LDM and STM for copying Copyright 1997 1998 ARM Limited All rights reserved 5 39 Basic Assembly Language Programming AREA Block CODE READONLY num EQU 20 ENTRY start LDR r src LDR rl dst MOV r2 num MOV Sp 0x400 blockcopy MOVS r3 r2 LSR 3 BEQ copywords STMFD spl r4 r11 octcopy LDMIA rQ r4 r11 STMIA r1l r4 r11 SUBS r3 r3 1 i BNE octcopy i LDMFD sp r4 r11 i copywords ANDS r2 r2 7 BEQ stop wordcopy LDR r3 r0 4 s STR r3 r1 4 3 SUBS r2 r2 1 BNE wordcopy stop MOV r0 0x18 LDR rl 0x20026 SWI 0x123456 AREA BlockData DATA READWRITE src DCD 1 2 3 4 5 6 7 8 1 2 3 4 5 dst DCD 0 0 0 0 0 0 0 0 0 0 0 0 0 END 5 40 Copyright 1997 1998 ARM Limited All rights reserved Example 5 11 name this block of code set number of words to be copied mark the first instruction to call r pointer to source block rl pointer to destination block r2 number of words to copy Set up stack pointer r13 Number of eight word multiples Less than eight words to move Save some working registers Load 8 words from the source and put them at the destination Decrement the counter copy more Don t need these now restore originals Number of odd words to copy No words left to copy load a word from the source and store it to the destination Decrement the counter copy more ange 1_SWIreason_ReportExce
524. s the entity that performs the actions requested by the debugger such as setting breakpoints reading from memory or writing to memory It is not the program being debugged or the ARM Debugger itself Examples of debug agents include the EmbeddedICE interface Multi ICE the ARMulator and the Angel Debug Monitor Remote debug interface The Remote Debug Interface RDI is a procedural interface between a debugger and the image being debugged through a debug monitor or controlling debug agent RDI gives the debugger core a uniform way to communicate with a controlling debug agent or debug monitor linked with the debugger a debug agent executing in a separate operating system process a debug monitor running on ARM based hardware accessed through a communication link a debug agent controlling an ARM processor through hardware debug support 3 6 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 2 Getting started This section explains the main features of the debugger desktop and gives you enough information to start working with the debugger Additional features are described in Debugger further details on page 3 36 This section describes The ARM Debugger desktop Starting and closing the debugger on page 3 9 Loading reloading and executing a program image on page 3 10 Examining and setting variables registers and memory on page 3 12 3 2 1 The ARM Debug
525. s used to organize the project defines the command line options to be used by the tools when the build step is executed during the building of the project Stopping a build You can stop a build at the end of its current step by clicking the Stop build toolbar button or by clicking the Stop Build variant button in the status area at the bottom of the Project Window Correcting problems When you build your project you may find errors and problems As the build progresses messages are written to the build log see Project window on page 2 15 that appears in the lower pane of the Project window These may be informational messages or diagnostic messages from the tools that are invoked by the project template When the build is complete you can double click on any error message that relates to an editable source file such as a compile error with a file line tag and APM takes you to the location where the error was detected In the case of a compile error this is the line of code listed in the log If a line relates to a sub project the project is loaded into the Project Window You can also locate errors by selecting Next Error and Previous Error from the View menu To find and correct the problem in the hello c source file in your sample project and rebuild the project i Double click on the serious error line indicated by a solid red exclamation mark in the build log The Edit window displays the appropriate source file with th
526. set the bigend lateabt and other signals 12 11 1 Configuring the Dummy MMU 12 24 You can set the code of the DummyMMU in the configuration file Use the following entry in the Coprocessors section of armul cnf Coprocessors Here is the list of co processors in the form Coprocessor lt n gt Name 1f COPROCESSOR_DummyMMU gt By default install a dummy MMU on co processor 15 CoProcessor 15 DummyMMU Here is the configuration for the co processors gt The Dummy MMU can be configured to return a given Chip ID s DummyMMU Chi pID end1f The line DummyMMU Chi pID can be uncommented and set to any value For example to configure DummyMMU to return the ARM710 ID code x44007100 change this line to Here is the configuration for the co processors gt The Dummy MMU can be configured to return a given Chip ID DummyMMU Chi pID 0x44007100 endif Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 12 12 Angel ARMulator The Angel model angel c is an operating system model that allows code that has been built to run with the Angel Debug Monitor to run under ARMulator The model intercepts Angel SWIs and emulates the functionality of Angel directly on the host transparently to the program running under ARMulator 12 12 1 Configuring Angel ARM DUI 0040D The configuration for the Angel model exists in a section called OS in the armul cnf file This appear
527. sing a simple IRQ on page 13 40 for more information on Angel task management Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 3 3 Angel debugger functions ARM DUI 0040D This section gives a summary of how Angel performs the basic debugger functions reporting memory and processor status downloading a program image setting breakpoints Reporting processor and memory status Angel reports the contents of memory and the processor registers as follows Memory The memory address being examined is passed to a function that copies the memory as a byte stream to the transmit buffer The data is transmitted to the host as an ADP packet Registers Processor registers are saved into a data block when Angel takes control of the target usually at an exception entry point When processor status is requested a subset of the data block is placed in an ADP packet and transmitted to the host When Angel receives a request to change the contents of a register it changes the value in the data block The data block is stored back to the processor registers when Angel releases control of the target and execution returns to the target application Download When downloading a program image to your board the debugger sends a sequence of ADP memory write messages to Angel Angel writes the image to the specified memory location Memory write messages are special because they can be longer than other ADP
528. sion of the compiler linker and library in use and the processor for which the ARMulator is configured 11 3 7 Reducing the time required for simulation ARM DUI 0040D You may be able to significantly reduce the actual time taken for a simulation by dividing the specified clock speed by a factor of ten or a hundred and multiplying the memory access times by the same factor Take the time reported by the clock function or by SYS_CLOCK and divide by the same factor This works because the simulated time is recorded internally in microseconds but SYS_CLOCK only returns centiseconds Dividing the clock speed shifts digits from the nanosecond count into the centisecond count allowing the same level of accuracy but taking much less time to simulate Copyright 1997 1998 ARM Limited All rights reserved 11 15 Benchmarking Performance Analysis and Profiling 11 4 11 4 1 11 4 2 11 16 Improving performance and code size There are two main goals when compiling a benchmark minimizing code size maximizing performance This section explains how using compiler options avoiding the standard C library and modifying your source code can all help to achieve these goals Compiler options The ARM C compiler has a number of command line options that control the way in which code is generated By default the ARM C compiler is highly optimizing By default the code produced from your source is balanced for a co
529. sk starts when the task returns all information that was on the stack is lost The application uses its own stack and executes in either User or Supervisor mode Callbacks due to application requests to read or write from devices under control of the Device Driver Architecture execute in User mode and use the application stack Copyright 1997 1998 ARM Limited All rights reserved 13 39 Angel The following Angel stacks are simple stacks exclusively used by one thread of control This is ensured by disabling interrupts in the corresponding processor modes IRQ stack FIQ stack UND stack ABT stack The User mode stack is also split into two cases because the Application stack and Angel stack are kept entirely separate The Angel User mode stack is split into array elements that are allocated to new tasks as required The application stack must be defined by the application 13 3 6 Example of Angel processing a simple IRQ 13 40 This section gives an example of processing a simple IRQ from start to finish and describes in more detail how Angel task management affects the receipt of data through interrupts Refer also to Angel communications architecture on page 13 73 for an overview of Angel communications Figure 13 4 on page 13 41 shows the application running when an interrupt request IRQ is made that completes the reception of a packet Copyright 1997 1998 ARM Limited All rights reserved ARM DU
530. solete features are identified explicitly Their use is faulted in SDT 2 50 Deprecated features will be made obsolete in future ARM toolkit releases Their use is warned about in SDT 2 50 These features are described in AIF Binary AIF IHF and Plain Binary Image formats Shared library support on page 1 16 Overlay support on page 1 16 Frame pointer calling standard on page 1 16 Reentrant code on page 1 17 ARM Symbolic Debug Table format ASD on page 1 17 Demon debug monitor and libraries on page 1 17 Angel as a linkable library and ADP over JTAG on page 1 17 ROOT ROOT DATA and OVERLAY keywords in scatter load description on page 1 18 Automatically inserted ARM Thumb interworking veneers on page 1 18 Deprecated PSR field specifications on page 1 18 ORG no longer supported in the assembler on page 1 18 AIF Binary AIF IHF and Plain Binary Image formats Because the preferred and default image format for the SDT is now ELF the linker emits a warning when instructed to generate an AIF image a binary AIF image an IHF image or a plain binary image Impact Any makefiles with a link step of aif aif bin ihf or bin now produce a warning from the linker For existing APM projects where an Absolute AIF image has been requested on the Linker configuration Output tab there will be no warning However an ELF image is created instead because this is the new default for the linker The
531. sponsiveness WindowsHourglass gt We can control how regularly we callback the frontend More often lower value means a slower emulator but gt faster response The default is 8192 Rate 8192 Copyright 1997 1998 ARM Limited All rights reserved 12 13 ARMulator 12 6 Watchpoints The Watchpoints module is a memory veneer that provides memory watchpoints It sits between the processor core and memory or cache as appropriate 12 6 1 Enabling watchpoints To enable watchpoints uncomment the Watchpoints line in armul cnf gt To enable watchpoints set WatchPoints Watchpoints 12 14 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 7 Page table manager The PageTable module is a model that sets up pagetables and initializes the MMU on reset The page tables model inclusion is controlled by setting the UsePageTables tag to be either True or False UsePageTables True The Pagetables section in the configuration file controls the contents of the pagetables and the configuration of the MMU Pagetables For full details of the flags control register and pagetables described in this section see the ARM Architectural Reference Manual 12 7 1 Controlling the MMU and cache The first set of flags controls the MMU and cache MMU Yes AlignFaults No Cache Yes WriteBuffer Yes Prog32 Yes Data32 Yes LateAbort Yes BigEnd No BranchPredict Yes ICache Yes S
532. state of these flags or not You can use the flags set by one instruction to control execution of other instructions even if there are many instructions in between Refer to Conditional execution on page 5 17 for a detailed description Register access In ARM state all instructions can access r0 r14 and most also allow access to r15 pc The MRS and MSR instructions can move the contents of the CPSR and SPSRs to a general purpose register where they can be manipulated by normal data processing operations Refer to the ARM Architectural Reference Manual for more information Access to the inline barrel shifter The ARM arithmetic logic unit has a 32 bit barrel shifter that is capable of very general shift and rotate operations The second operand to all ARM data processing and single register data transfer instructions can be shifted before the data processing or data transfer is executed as part of the instruction This supports but is not limited to scaled addressing multiplication by a constant 7 constructing constants Refer to the Loading constants into registers on page 5 22 for more information on using the barrel shifter to generate constants ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 7 Basic Assembly Language Programming 5 2 7 5 8 Thumb instruction set overview The functionality of the Thumb instruction set with one exception is a subset of the functionality of the ARM
533. stname on Server line On occasion you may need to change the hostname of a license server In such a case you must change the hostname in all copies of the license file that refer to that server If you supplied three hostnames on the license request form then there are three server lines in the license file TCP port on Server line It is possible to specify on a SERVER line the TCP port that the license manager uses to communicate with the licensed software If not specified the license manager will use the next available port in the range 27000 27009 When connecting to a server an application tries all the ports in the range 27000 27009 ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved A 9 FlexLM License Manager A port number must be specified on each SERVER line if a 3 server license is in use Daemon path on Vendor line On a VENDOR line you may need to change the second parameter the pathname of the vendor daemon executable This pathname must point to the directory containing file armlmd If the license server was running on a SunOS machine then the Vendor line could be similar to VENDOR armimd opt arm flex lm sunos A 6 2 Feature lines Feature lines describe the licenses that are available and must not be altered If they are altered the license is invalidated and the feature no longer operates Each Feature line specifies the feature name the vendor daemon name the feature version th
534. stores the value of Ir_IRQ from the stack so that it can be used by a SUBS instruction to return to the correct address after the interrupt has been handled Example 9 12 on page 9 24 shows how this works The top level interrupt handler reads the value of a memory mapped interrupt controller base address at Ox80000000 If the value of the address is 1 the top level handler branches to a handler written in C Copyright 1997 1998 ARM Limited All rights reserved 9 23 Handling Processor Exceptions Example 9 12 __1rq void IRQHandler void volatile unsigned int base unsigned int Ox80000000 if sbase 1 which interrupt was 1t C_int_handler process the interrupt x base 1 base clear the interrupt Compiled with armcc Example 9 12 produces the following code EXPORT IRQHandler IRQHand ler Qx000000 e92d591f P STMFD sp r0 r4 r12 1r Qx000004 e3a04102 A MOV r4 0x80000000 Qx000008 e5940000 LDR rQ r4 0 Qx00000c e3500001 P CMP rQ 1 Q0x000010 Obfffffa BLEQ C_int_handler Ox000014 e5940000 LDR r0 r4 0 0x000018 e5840004 STR rO r4 4 Qx00001c e8bd501f P LDMFD sp r r4 r12 1r Ox000020 e25ef004 A SUBS pc Ir 4 Compare this to the result of not using the __irq keyword EXPORT IRQHandler IRQHand ler QxQ00000 e92d4010 STMFD so r4 Ir Qx000004 e3a04102 A MOV r4 0x80000000 Qx000008 e5949000 LDR r0 r4
535. struction must be within 4KB of the data item it addresses because the offset is limited to 4KB The data structure must be in the same area as the instructions because otherwise there is no guarantee that the data items will be within range after linking Example 5 18 shows a program fragment with such a map It includes a directive which allocates space in memory for the data structure and an instruction which accesses it Example 5 18 datastruc 280 reserves 280 bytes of memory for datastruc MAP datastruc consta 4 constb 4 X 8 y 8 string 256 code LDR r2 constb gt LDR r2 pc offset In this case there is no need to load the base register before loading the data as the program counter already holds the correct address This is not actually the same as the address of the LDR instruction because of pipelining in the processor However the assembler takes care of this for you ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 5 49 Basic Assembly Language Programming 5 9 5 5 50 Finding the end of the allocated data You can use the directive with an operand of 0 to label a location within a structure The location is labeled but the location counter is not incremented The size of the data structure defined in Example 5 19 depends on the values of MaxStrLen and ArrayLen If these values are too large the structure overruns the end of available memory Example 5 19 uses an
536. structions The ARM and Thumb instruction sets include instructions that load and store multiple registers to and from memory Multiple register transfer instructions provide an efficient way of moving the contents of several registers to and from memory They are most often used for block copy and for stack operations for context changing at subroutine entry and exit The advantages of using a multiple register transfer instruction instead of a series of single data transfer instructions include Smaller code size There is only a single instruction fetch overhead rather than many instruction fetches Only one register writeback cycle is required for a multiple register load or store as opposed to one for each register On uncached ARM processors the first word of data transferred by a load or store multiple is always a nonsequential memory cycle but all subsequent words transferred can be sequential memory cycles Sequential memory cycles are faster in most systems Note The lowest numbered register is transferred to or from the lowest memory address accessed and the highest numbered register to or from the highest address accessed The order the of registers in the register list in the instructions makes no difference Use the checkreglist assembler option to check that registers in register lists are specified in increasing order See Command syntax on page 5 3 in the ARM Software Development Toolkit Reference Gu
537. suitable memory location within 4KB of the vector address 2 placing an instruction in the vector that loads the program counter with the contents of the chosen memory location 9 3 1 Installing the handlers at reset ARM DUI 0040D If your application does not rely on the debugger or debug monitor to start program execution you can load the vector table directly from your assembly language reset or startup code If your ROM is at location 0x0 in memory you can simply have a branch statement for each vector at the start of your code This could also include the FIQ handler if it is running directly from Oxlc See Interrupt handlers on page 9 22 Example 9 1 shows code that sets up the vectors if they are located in ROM at address zero Note that you can substitute branch statements for the loads Example 9 1 Vector_Init_Block LDR PC Reset_Addr LDR PC Undefined_Addr LDR PC SWI_Addr LDR PC Prefetch_Addr LDR PC Abort_Addr NOP Reserved vector Copyright 1997 1998 ARM Limited All rights reserved 9 9 Handling Processor Exceptions LDR PC IRQ_Addr LDR PC FIQ_Addr Reset_Addr DCD Start_Boot Undefined_Addr DCD Undefined_Handler SWI_Addr DCD SWI_Handler Prefetch_Addr DCD Prefetch_Handler Abort_Addr DCD Abort_Handler DCD 0 Reserved vector IRQ_Addr DCD IRQ_Handler FIQ_Addr DCD FIQ_Handler If there is RAM at location zero the vectors plus the FIQ handler if required must be copied down from an area in ROM
538. t End of ROM code start of ROM data IMPORT Image RW Base Base of RAM to initialize IMPORT Image ZI Base Base and limit of area IMPORT Image ZI Limit to zero initialize LDR rO Image RO Limit Get pointer to ROM data LDR r1 Image RW Base and RAM copy LDR r3 Image ZI Base Zero init base gt top of initialized data CMP r r1 Check that they are different BEQ F1 Q CMP oi RO be Copy init data LDRCC r2 r0 4 STRCC r2 r1 4 BCC BO 1 LDR r1 Image ZI Limit Top of zero init segment MOV r2 0 2 CMP r3 rl Zero init STRCC r2 r3 4 BCC B2 Enable interrupts Now safe to enable interrupts so do this and remain in SVC mode MOV RO Mode_SVC 0R F_Bit Only IRQ enabled MSR CPSR_c RQ Now change to User mode and set up User mode stack MOV RO Mode_USR 0R I_Bit OR F_Bit MSR CPSR_c RQ LDR sp USR_Stack Now enter the C code IMPORT C_Entry DEF THUMB ORR Ir pc 1 BX Ir CODE16 Next instruction will be Thumb BL C_Entry A real application wouldn t normally be expected to return however in case it does the debug monitor swi is used to halt the application MOV r0 0x18 gt angel_SwIreason_ReportException LDR rl 0x20026 ADP_Stopped_ApplicationExit DEF THUMB SWI xAB Angel semihosting Thumb SWI 10 14 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D SwI Qx123456 Angel semihosting ARM SWI
539. t enter symbols To view the contents of a variable enter print variable To view type and context information about a variable enter variable variable To set the value of a variable use the command let variable expression symbols can be abbreviated to sy print can be abbreviated to p and variable can be abbreviated to v 4 2 9 Displaying source code If your program has been compiled with the g compiler option you can display source code as follows To display C code around the current line enter type To display assembly code rather than C source enter list type can be abbreviated to t and list can be abbreviated to 1 4 2 10 Viewing and setting debugger variables Some features of armsd are specified by the value of the debugger variables These can be viewed and set in the same way as program variables For example the read write variable 1ist_lines is an integer value that specifies the number of lines displayed when the list command is issued Note Some armsd variables are read only ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 4 9 Command Line Development 4 10 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Chapter 5 Basic Assembly Language Programming This chapter provides an introduction to the general principles of writing ARM and Thumb assembly language It contains the following sections Introduction on page 5 2
540. t file dialog Figure 3 10 Put file Save in Sdeug OOO d Al aee Save as type Jal Files 4 Cancel Help rom address D Figure 3 10 Put File dialog 2 Enter the name of the file to write to 3 Enter a memory area in the From address and To fields 4 Click Save 3 44 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 5 Click OK The output is saved as a binary file Follow these steps to copy a file on disk to memory 1 Select Get File from the File menu to display the Get file dialog Figure 3 11 Get file RAEI Look in a Debug al c ize zee File name E Files of type Ja Files 4 gt Cancel Help Address 0x8000 Figure 3 11 Get File dialog 2 Select the file you want to load into memory 3 Enter a memory address where the file should be loaded 4 Click Open ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 45 ARM Debuggers for Windows and UNIX 3 5 9 Specifying command line arguments for your program Follow these steps to specify the command line arguments for your program 1 Select Set Command Line Args from the Options menu The Command Line Arguments dialog Figure 3 12 is displayed Command Line Arguments gt Please enter command line arguments for the debugqgee l cancel Figure 3 12 Command Line Arguments dialog 2 Enter the command li
541. t files 4 Type armsd strtest to load the files into the command line debugger and type go at the debugger command line to execute the example Example 8 10 shows how to call C from assembly language Example 8 10 Calling C from assembly language Define the function in C to be called from the assembly language routine int g int a int b int c int d int e return a b c d e In assembly language int f int 1 return g 1 2x1 3x1 4x1 5x1 EXPORT f AREA f CODE READONLY IMPORT g STR Ir sp 4 preserve Ir ADD r1 rQ rQ compute 2x1 2nd param ADD r2 rl rQ compute 3 1 3rd param ADD r3 rl r2 compute 51 STR r3 sp 4 5th param on stack ADD r3 r1 r1 compute 4x1 4th param BL g branch to C function ADD sp sp 4 remove 5th param RSB rO rO 0 negate result LDR pc sp 4 return END 8 20 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Mixed Language Programming Example 8 11 Calling a C function from C Declare and call the C function in C struct S has no base classes or virtual functions S int s i s int 1 ie extern C void cfunc S declare the C function to be called from C int f S s 2 initialize s cfunc amp s call cfunc so it can change s return s i 3 Define the function in C struct S int 1 void cfunc struct S xp the defini
542. t pseudo instruction can construct any 32 bit numeric constant in a single instruction Use this pseudo instruction to generate constants that are out of range of the MOV and MVN instructions The LDR pseudo instruction generates the most efficient code for a specific constant If the constant can be constructed with a MOV or MWN instruction the assembler generates the appropriate instruction If the constant cannot be constructed with a MOV or MWN instruction the assembler places the value in a literal pool a portion of memory embedded in the code to hold constant values generates an LDR instruction with a program relative address that reads the constant from the literal pool For example LDR rn pc offset to literal pool load register n with one word from the address pc offset You must ensure that there is a literal pool within range of the LDR instruction generated by the assembler See Placing literal pools for more information Refer to Chapter 5 Assembler in the ARM Software Development Toolkit Reference Guide for a description of the syntax of the LDR pseudo instruction Placing literal pools The assembler places a literal pool at the end of each area These are defined by the AREA directive at the start of the following area or by the END directive at the end of the assembly The END directives at the ends of included files do not signal the end of areas In large areas the default literal pool
543. tFn 13 65 L Labels assembly 5 11 Labels inline assemblers 8 5 LDM instruction 5 34 5 49 Thumb 5 41 LDR instruction 5 46 pseudo instruction 5 22 5 25 5 30 Leaf functions 7 12 Library adw_cpp dll 3 62 License file customizing A 9 finding A 11 obtaining A 4 typical A 9 License management questions A 18 Index 8 License management utilities A 14 Imchecksum A 14 Imdiag A 15 Imdown A 15 Imhostid A 16 Imremove A 16 Imreread A 16 Imstat A 17 Imver A 17 License server software A 6 Licensed software A 1 running A 7 Licenses multiple A 12 Line length assembly language 5 10 Link register 5 4 5 15 9 3 Linker attribute conflict 10 35 Linking and APM build steps patterns 2 12 and assembly language labels 5 11 and interworking 7 12 7 16 and the AREA directive 5 13 Angel C libraries 13 21 attribute conflicts 10 35 configuring in APM 2 20 improving image size 11 16 introduction 4 4 minimal Angel 13 24 the embedded C library 10 8 10 36 Literal pools assembly language 5 25 Imchecksum utility A 14 Imdiag utility A 15 Imdown utility A 15 Imhostid utility A 16 Imremove utility A 16 Imreread utility A 16 Imstat utility A 17 Imver utility A 17 loadagent command 13 63 Loading constants assembly language 5 22 Local labels assembly language 5 11 Local memory map file 3 55 Locals window 3 22 Location of APM templates 2 52 Log of project building 2 12 Logic analyzers debugging Angel 13 68 lolevel s 13 59 Low level sy
544. te They have limited access to registers r8 to r15 The ALU status flags in the CPSR are always set by these instructions except when MOV or ADD instructions access registers r8 to r15 Thumb data processing instructions that access registers r8 to r15 cannot set the flags Status register access instructions There are no Thumb instructions to access the CPSR or SPSR Single register load and store instructions These instructions load or store the value of a single low register from or to memory In Thumb state they cannot access registers r8 to r15 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming Multiple register load and store instructions These instructions load from memory or store to memory any subset of the registers in the range r0 to r7 In addition the PUSH and POP instructions implement a full descending stack using the stack pointer r13 as the base PUSH can stack the link register and POP can load the program counter Semaphore instructions There are no Thumb semaphore instructions Coprocessor instructions There are no Thumb coprocessor instructions Thumb instruction capabilities The following general points apply to Thumb instructions Conditional execution The conditional branch instruction is the only Thumb instruction that can be executed conditionally on the value of the ALU status flags in the CPSR All data processing instructions s
545. tecture on page 13 73 for more information Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel The full Angel Device Driver Architecture uses Angel task management functionality to control packet processing and to ensure that interrupts are not disabled for long periods of time You can write device drivers to use alternative devices for debug communication such as a ROMulator You can extend Angel to support different peripherals or your application can address devices directly Task management All Angel operations including communications and debug operations are controlled by Angel task management Angel task management ensures that only a single operation is carried out at any time assigns task priorities and schedules task accordingly controls the Angel environment processor mode Refer to Angel task management on page 13 33 for more information Exception handling Angel exception handling provides the basis for each of the system features described above Angel installs exception handlers for each ARM exception type except Reset SWI Angel installs a SWI exception handler to support C library semihosting requests and to allow applications and Angel to enter Supervisor mode Undefined Angel uses three undefined instructions to set breakpoints in code Refer to Setting breakpoints on page 13 22 for more information Data Prefetch Abort Angel installs basic Data
546. ted in angel source pid min Refer to Minimal Angel on page 13 13 for more information on building minimal Angel FIRST This option defines the object file that is linked at the beginning of the ROM image Valid values are FIRST startrom o ROMStartup The system can remap its memory map ROM is unmapped from 0 after reset The first line of the startup code is placed at the start of the ROM image The startup code copies the ARM exception vector table to RAM at 0 after remap This is the default FIRST except o __Vectors ROM is permanently mapped at 0 The ARM exception vector table is placed at the beginning of the ROM image ROADDR This defines the address of the Angel code at run time If ROADDR is set to a ROM address Angel executes from ROM If ROADDR is set to a RAM address Angel copies itself to RAM and executes from there ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 13 49 Angel You can use this option to move Angel to RAM when ROM is much slower than RAM For example the makefile for the PID Angel port specifies an ROADDR in SRAM ROADDR is the address on which the compiler bases its calculations for all the pc relative instructions such as branch instructions Refer to Configuring where Angel runs on page 13 70 for more information on ROADDR RWADDR This defines where Angel should store its read write data This is the address of the data used by Angel at ru
547. ter in the range r0 to r15 that contains the address to branch to The value of bit 0 in this register determines the processor state if bit O is set the instruction at the branch address is executed in Thumb state Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Interworking ARM and Thumb if bit O is clear the instruction at the branch address is executed in ARM state cond is an optional condition code Only the ARM version of BX can be executed conditionally Usage You can also use BX for branches that do not change state You can use this to execute branches that are out of range of the normal branch instructions Because BX takes a 32 bit register operand it can branch anywhere in 32 bit memory The B and BL instructions are limited to 32 MB in ARM state for both conditional and unconditional B and BL instructions 4MB in Thumb state for unconditional B and BL instructions 128 to 127 instructions in Thumb state for the conditional B instruction Note The BX instruction is only implemented on ARM processors that are Thumb capable If you use BX to execute long branches your code will fail on processors that are not Thumb capable The result of a BX instruction on a processor that is not Thumb capable is unpredictable Changing the assembler mode The ARM assembler can assemble both Thumb code and ARM code By default it assembles ARM code unless
548. ter way of adjusting the padding The example uses a directive with a 0 operand to label the end of the character data A second directive inserts the correct amount of padding based on the value of the label An AND operator is used to calculate the correct value The End0fChars AND 3 expression calculates the correct amount of padding Q if EndOfChars is mod 4 3 if EndOfChars is 1 mod 4 2 if EndOfChars is 2 mod 4 1 if EndOfChars is 3 mod 4 This automatically adjusts the amount of padding used whenever character variables are added or removed Copyright 1997 1998 ARM Limited All rights reserved 5 51 Basic Assembly Language Programming 5 52 StartOfData EndOfData Char Char2 Char3 EndOfChars Padding Integer Integer2 String Array BitMask EndOfUsedData Copyright 1997 1998 ARM Limited All rights reserved EQU 0x1000 EQU 0x2000 MAP StartOfData 1 1 1 Q EndOfChars AND 3 4 4 MaxStrLen ArrayLenx8 4 Q ASSERT EndOfUsedData lt EndOfData Example 5 21 ARM DUI 0040D Basic Assembly Language Programming 5 9 7 Using register based MAP and directives ARM DUI 0040D Register based MAP and directives define register based symbols There are two main uses for register based symbols defining structures similar to C structures gaining faster access to memory areas described by non register based MAP and directives Defining regist
549. terworking veneers when it detects interworking calls Specifying APCS options By default the APCS options for the ARM assembler and compilers are the same for ARM and Thumb The default options are nofp noswstackcheck If your code is compiled with other options for example with software stack checking enabled swstackcheck then you must ensure that all ARM modules and Thumb modules are compiled to the same standard if they are to be interworked If you do not do this the linker informs you where the incompatibilities occurred by generating warning messages of the form Attribute conflict between AREA object area and image code attribute difference NO_SwW_STACK_CHECK Refer to Chapter 6 Using the Procedure Call Standards for more information on APCS Refer to the ARM Software Development Toolkit Reference Guide for more information on command line options to the assembler and compilers Compiling code for Interworking The apcs interwork compiler option enables all ARM and Thumb C and C compilers to compile modules containing routines that can be called by routines compiled for the other processor state tcc apcs interwork armcc apcs interwork tcpp apcs interwork armcpp apcs interwork Modules that are compiled for interworking generate slightly typically 2 larger code for Thumb and marginally larger code for ARM For a leaf function that is a function whose body contains no function calls
550. that are included in the standard release This section covers the following topics About ADW for C Using the C debugging tools on page 3 63 Using the Class View window on page 3 63 Using the Watch window on page 3 66 Evaluating expressions on page 3 70 Debug Format Considerations on page 3 74 3 8 1 About ADW for C ARM C provides additions to ADW and ADU to support C debugging A dynamic link library adw_cpp d11 is installed in the same directory as adw exe The adw_cpp d11 adds A C menu between the View and Execute menus in the main menu bar Five new buttons in the ADW ADU toolbar tE Evaluate Expression to View Classes Feo Show Watches Fall Hide Watches Recalculate Watches Figure 3 21 on page 3 63 shows an example of the ARM Debugger C debug interface and the C menu 3 62 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX on ARM Debugger C arm dhry Debug dhry axt File Edit Search View ES Execute Options Window Help S les Bl ar ge se E E AF Evaluate Expression Ctrl Shift E ARM mlg View Classes Ctrl Shitt an ARM Executing dhry Show Watches Ctrl Shifti Hide atches Ctrl Shitt H Becalculate Watches Ctrl ShittR str _ 3 ptr l Loe Str_3d por 2 bor REG int Run_Index REG int Number Of Funs Tnitializations ext_Ptr_Glob Rec Pointer malloc sizeof Rec Type
551. the Set or Edit Watchpoint dialog Set or Edit Watchpoint ES tem stdin Target Value OK o Cancel Delete 1 out of fi Expression Count Figure 3 8 Set or Edit Watchpoint dialog This dialog contains the following fields Item The variable or register to be watched Target Value The value of the variable or register that is to halt the program If this value is not specified any change in the value of the item halts the program dependent on the other watchpoint conditions Expression Any expression that must be true for the program to halt in addition to any other watchpoint conditions As with breakpoints use C like operators such as 1 lt 10 1 ls j i l j k Count The program halts when all the watchpoint conditions apply for the nth time Setting and editing a complex watchpoint Follow these steps to set a complex watchpoint 1 Select the variable or register to watch 2 Select Set or Edit Watchpoint from the Execute menu The Set or Edit Watchpoint dialog is displayed 3 Specify the details of the watchpoint 4 Click OK 3 32 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Follow these steps to edit a complex watchpoint 1 Select Watchpoints from the View menu to display current watchpoints 2 Double click the watchpoint to edit it 3 Modify the details as required 4 Click OK 3 4 5 Backtrace When your program has halted
552. the Stop button Alternatively select Step from the Execute menu or click the Step button to step through the code a line at a time Refer to Stepping through an image on page 3 34 for more information on stepping through code While the program executes the Console window is active provided semihosting is in operation the program code is displayed in the Execution window To continue execution from the point where the program stopped use Go or Step Note If you want to execute your program again you must reload it first ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 3 11 ARM Debuggers for Windows and UNIX 3 2 4 3 12 Examining and setting variables registers and memory You can use the ARM Debugger to display and modify the contents of the variables and registers used by your executable image You can also examine the contents of memory Variables You can display and modify both local and global variables Follow these steps to display and modify a variable 1 Display either the Locals or Globals window a Select View Variables Local or click the Locals button on the toolbar to display a list of local variables b Select View Variables Global to display a list of global variables 2 Double click on the value you want to change in the right pane of the window The Memory window is displayed showing the area around your selected location 3 Double click on
553. the Thumb subroutine must have bit 0 set so that the processor executes in Thumb state on arrival As with Thumb to ARM interworking subroutine calls you must use a BX instruction to return Interworking subroutine call examples Example 7 2 on page 7 9 has an ARM code header and a Thumb code main routine The program sets up two parameters r0 and rl and makes an interworking call to an ARM subroutine that adds the two parameters together and returns Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb To build the example 1 Type asm g armadd s at the system command prompt to assemble the module 2 Type armlink armadd o o armadd to link the object file Example 7 2 AREA ArmAdd CODE READONLY name this block of code Mark 1st instruction to call Assembler starts in ARM mode ENTRY main ADR r2 ThumbProg 1 Generate branch target address and set bit 0 hence arrive at target in Thumb state BX r2 Branch exchange to ThumbProg CODE16 Subsequent instructions are Thumb ThumbProg MOV r0 2 Load r with value 2 MOV r1 3 Load r1 with value 3 ADR r4 ARMSubroutine Generate branch target address leaving bit 0 clear in order to arrive in ARM state Branch and link to Thumb code segment that will carry out the BX to the ARM subroutine The BL causes bit of Ir to be set Terminate execution ange _SWIreason_ReportException ADP_Stopped_Applicati
554. the build log in the lower pane of the Project window The build log is always displayed by APM when you build from a single source or build an entire project Hold the Tab key and click the mouse on a point in the project view where you want to set a tab to control the spacing of the project hierarchy All levels of the hierarchy are spaced evenly based on the position you have selected Select Variants from the View menu to toggle the display of the project variants When you do so partitions and their files are still displayed Select Toolbar or Status Bar from the View menu to toggle the display of the toolbar and status bar When you display the contents and structure of a project various arrow keys and numeric keypad keys act as shortcut keys Shortcut keys enable you to expand or collapse your view of the levels of the project See Table 2 1 for a list of shortcut keys Table 2 1 Shortcut keys Action required Shortcut key Move up the tree Up arrow Move down the tree Down arrow Expand the current level by one level Numeric keypad or Right arrow Expand fully the current and all lower levels Numeric keypad Collapse the current level Left arrow Collapse the current and all lower levels Numeric keypad ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 2 17 ARM Project Manager 2 3 3 Edit window Use the Edit window to create or modify a source file such as a code file or an inc
555. the focus for the next file addition This is useful when a file type can be stored in more than one partition Build also builds sub projects Check all files in all sub projects and perform all the builds necessary to bring the project up to date This setting is useful when the interfaces of library files are unstable and the build time of a main project will be impacted by changes to the implementation of the libraries built by sub projects Changes to shared interfaces force rebuilding anyway A sub project can be built separately before building the main project if required Force Build also force builds sub projects Force Build builds files in all sub projects Echo command lines verbosely Command lines that invoke tools are echoed in full in the build log This is useful for understanding or auditing project build behavior Echoing command lines verbosely shows the result of merging tool configurations at the tool project variant partition and file level Create New Projects from Templates found in Specifies the location of the project template definitions The default is the Template subdirectory below the main ARM installation directory 2 32 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D 2 5 2 Editor preferences ARM DUI 0040D ARM Project Manager The Editor Preferences dialog allows you to choose which editor to use when you edit source and include files and to modify the behavior of t
556. the license server software itself looks in the following places for license files ARMLMD_LICENSE_FILE LM_LICENSE_FILE opt arm licenses usr local flexIm license dat The ARMLMD_LICENSE_FILE and LM_LICENSE_FILE environment variables can each contain multiple license file names separated by colons In addition to full pathnames to files they can hold directory names If the license software finds a directory name it will search that directory looking for files that end with 1ic and treat all such files as license files opt arm licenses is the default location that ARM applications search for their license file Do I need to have the license file on my client machine Sometimes You need to have the license file on your client machines only when you are using the three license server option In this situation you need to point the ARMLMD_LICENSE_FILE environment variable at the local copy of the license file Ensure that the hostnames and TCP port numbers in the local license file are the same as in the license server copies On a single license server you can normally set ARMLMD_LICENSE_FILE to contain the hostname of the server Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Index A Absolute maps 5 46 Access protection in ADW ADU 3 73 Accessing host peripherals 3 5 online help 2 2 3 2 ADD instruction 5 53 Adding 64 bit integers 6 6 Addresses loading into registers 5 27 real time
557. the local variable 3 4 3 Complex breakpoints When you set a complex breakpoint you specify additional conditions in the form of expressions entered in the Set or Edit Breakpoint dialog Figure 3 7 set or Edit Breakpoint Ed File Breakpoint Size Execution Minc ony 16Bit Location D 32Bit Ox008010 Automatic M Setas Default Expression Count out of f Cancel Delete Figure 3 7 Set or Edit Breakpoint dialog This dialog contains the following fields File The source file that contains the breakpoint This field is read only Location The position of the breakpoint within the source file This position is a hexadecimal address for assembler code For C or C code it is shown as a function name followed by a line number and if the line contains multiple statements a column position This field is read only Expression An expression that must be true for the program to halt in addition to any other breakpoint conditions Use C like operators such as 1 lt 10 1 t 9 1 j k 3 30 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX Count The program halts when all the breakpoint conditions apply for the nth time Breakpoint Size You can set breakpoints to be 32 bit ARM or 16 bit Thumb size or allow the debugger to make the appropriate setting A checkbox allows to make your selection the default setting Setting or editing
558. the only change in the code generated by the compiler is to replace MOV pc 1r with BX Ir For non leaf functions the Thumb compiler must replace for example the single instruction Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Interworking ARM and Thumb POP r4 r5 pc with the sequence POP r4 r5 POP r3 BX r3 This has a correspondingly small effect on performance It is not necessary to compile all source modules for interworking only those that contain subroutines called through interworking calls In addition the apcs interwork option sets the interwork attribute for the code area into which the modules are compiled The linker detects this attribute and inserts the appropriate veneer The sizes of the veneers are Eight bytes for each called routine for calls from Thumb to ARM This consists of a Thumb BX instruction ahalfword of padding for alignment an ARM branch instruction Twelve bytes for each called routine for calls from ARM to Thumb This consists of an ARM LDR instruction to get the address of the function being called an ARM Bx instruction to execute the call a word to hold the address of the function Note ARM code compiled for interworking cannot be used on ARM processors that are not Thumb capable because these processors do not implement the BX instruction Use the armlink info total option to find the amount of space t
559. the profile report and sends its output to text file prof1 that you can examine Call graph information If you are using the command line tools L Restart the debugger armsd Load the sorts program into armsd with the callgraph option load callgraph sorts callgraph tells armsd to prepare an image for function call count profiling by adding code that counts the number of function calls Turn profiling on ProfOn Run the program as normal go When execution completes write the profile data to a file ProfWrite sort2 prf Exit armsd Quit Generate the profile by entering the following at the system prompt armprof Parent sort2 prf gt prof2 The Parent option instructs armprof to include information about the callers of each function armprof generates the profile report and sends its output to text file prof2 that you can examine Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ep Benchmarking Performance Analysis and Profiling If you are using the Windows tools 1 If you are using APM and ADW reload the debugger by clicking the Debug button on the APM toolbar If you are using ADU start ADU Select Options Profiling Call Graph Profiling to turn on call graph profiling Click Reload to reload the image This forces call graph profiling to take effect Select Options Profiling Toggle Profiling to turn on profiling in ADW or ADU Clic
560. the value to change it 4 Press Return when you have set the variable to the required value Registers To display a list of registers for the current processor mode click the Current Registers button on the toolbar Follow these steps to display and modify registers for a selected processor mode 1 Select the Registers submenu from the View menu 2 Select the required processor mode from the Registers submenu The registers are displayed in the appropriate Registers window 3 Double click on the register you want to modify The Memory window is displayed showing the area around your selected location 4 Double click on the value to change it 5 Press Return when you have set the variable to the required value Memory Follow these steps to display the contents of a particular area of memory 1 Select Memory from the View menu or click on the Memory button The Memory Address dialog is displayed Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX 2 Enter the address as a hexadecimal value prefixed by 0x or as a decimal value 3 Click OK The Memory window opens and displays the contents of memory around the address you specified When you have opened the Memory window you can display other parts of the current 4KB area of memory by using the scrollbar display more remote areas of memory by entering another address right click any
561. til acknowledged The number of available buffers might be limited by memory to less than the theoretical maximum requirement of one for each channel and one for each Angel aware device The buffers contain a header area sufficient to contain channel number and sequence IDs for use by the channels layer itself Any spare bits in the channel number byte are reserved as flags for future use Long buffers Most messages and responses are short typically less than 40 bytes although some can be up to 256 bytes long However there are some situations where larger buffers would be useful For example if the host is downloading programs or configuration data to the target a larger buffer size reduces the overhead created by channel and device headers by acknowledgment packets and by the line turnaround time required to send each acknowledgment for serial links For this reason a long target defined suggested size 4KB buffer is available for target memory writes which are used for program downloads Limited RAM When RAM is unlimited the easiest solution is to make all buffers large There is a mechanism that allows a single large buffer to be shared because RAM in an Angel system is not normally an unlimited resource When the device driver has read enough of a packet to determine the size of the packet being received it performs a callback asking for a suitably sized buffer If a small buffer is adequate a small buffer is provided
562. tion of the C function to be called from C p gt 1 5 Example 8 12 Calling assembly language from C Declare and call the assembly language function in C struct S has no base classes or virtual functions S int s i s int 1 fo extern C void asmfunc S declare the Asm function to be called int f S s 2 initialize s asmfunc amp s call asmfunc so it can change s return s i 3 Define the function in ARM assembly language Copyright 1997 1998 ARM Limited All rights reserved 8 21 Mixed Language Programming 8 22 AREA Asm CODE EXPORT asmfunc asmfunc the definition of the Asm LDR r1 rQ function to be called from C ADD r1 rl 5 STR r1 rQ MOV pc Ir END Define the function to be called in C struct S S int s i s int 1 i extern C void cppfunc S p p gt 1 5 Declare and call the function in C struct S int 1 ie extern void cppfunc struct S p int f void struct S s S 1 2 cppfunc amp s return s i 3 Example 8 13 Calling C from C has no base classes or virtual functions Definition of the C function to be called from C The function is written in C only the linkage is C a as ae can change s x Declaration of the C C function to be x from C initialize s call cppfunc so it
563. tion on how the file should be processed 2 6 1 Creating a new source file with APM Follow these steps to create a new source file 1 Select New from the File menu or click the New button The New dialog is displayed Figure 2 16 ore source Cancel C include tile Assembler source C source Figure 2 16 New dialog 2 Select the New file type for example C C source or C C include file from the scroll box 3 Click OK Note If you create a new source file and at the same time you have an open project the source file is not automatically added to the open project 2 34 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager 2 6 2 When a file type is associated with multiple partitions ARM DUI 0040D If the file type is associated with tools in multiple partitions the Files Matched Multiple Partitions dialog is displayed Figure 2 17 Files Matched Multiple Partitions First select a partition m the tree vieu Then select files in the list below and add agair ples hello hello Cancel Help Figure 2 17 Files Matched Multiple Partitions dialog Follow these steps to add the file to the correct partition 1 Select the correct partition in the Project window 2 Select the file or files to add to the selected partition from the Files Matched Multiple Partitions dialog 3 Click Add 4 Repeat for each file that is displayed in the dialog Note
564. tions Using MAP offset reg followed by label makes label into a register based symbol with register part reg and numeric part offset Example 5 25 shows this Example 5 25 StartOfI0Area EQU 0x1000000 SendFlag_Abs EQU 0x1000000 SendData_Abs EQU 0x1000004 RcvFlag_Abs EQU 0x1000008 RcvData_Abs EQU 0x100000C IOAreaBase RN r11 MAP SendFlag_Abs StartOfI0Area I0AreaBase SendFlag Q MAP SendData_Abs StartOfI0Area IOAreaBase SendData Q MAP RcvFlag_Abs StartOfI0Area IOAreaBase RcvF lag Q MAP RcvData_Abs StartOfI0Area I0AreaBase RcvData Q Load the base address with LDR I0AreaBase StartOfI0Area This allows the individual locations to be accessed with statements like LDR RQ RcvFlag and STR R4 SendData Copyright 1997 1998 ARM Limited All rights reserved 5 57 Basic Assembly Language Programming 5 9 8 Pointx Pointy Pointz 5 58 Using two register based structures MAP code ADR ADR LDR ADD STR LDR ADD STR LDR ADD STR Sometimes you need to operate on two structures of the same type at the same time For example if you want the equivalent of the pseudo code newloc x oldloc x value in rQ newloc y oldloc y value in rl newloc z oldloc z value in r2 The base register needs to point alternately to the oldloc structure and to the newloc one Repeatedly changing the base register would be inefficient Instead use a non register based map and set up two pointer
565. to display online help Under Find follow the instructions to search all the available online help text for any keywords you specify The first time you undertake a Find operation a database file is constructed and is then available for any later Find operations Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX Select Using Help from the Help menu to display a guide to the use of on screen help Hypertext links Most pages of online help include highlighted text that you can click on to display other relevant online help Clicking on highlighted text underscored with a broken line displays a popup box Clicking on highlighted text underscored with a solid line jumps to another page of help Browse buttons Most pages of online help include a pair of browse buttons that enable you to step through a sequence of related help pages Copyright 1997 1998 ARM Limited All rights reserved 3 3 ARM Debuggers for Windows and UNIX 3 1 2 Debugging an ARM application The ARM Debuggers work in conjunction with either a hardware or a software target system An ARM Development Board communicating through an EmbeddedICE interface Multi ICE or Angel is an example of a hardware target system The ARMiulator is an example of a software target system You debug your application using a number of windows that give you various views on the application you are debu
566. tore instructions These instructions load or store the value of a single register from or to memory In ARM architecture version 3 these instructions can load or store a 32 bit word or an 8 bit unsigned byte In ARM architecture version 4 they can also load or store a 16 bit unsigned halfword or load and sign extend a 16 bit halfword or an 8 bit byte Multiple register load and store instructions These instructions load or store any subset of the general purpose registers from or to memory Refer to Load and store multiple register instructions on page 5 34 for a detailed description of these instructions Semaphore instructions These instructions load and alter a memory semaphore Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Basic Assembly Language Programming Coprocessor instructions These instructions support a general way to extend the ARM Architecture Refer to the ARM Architectural Reference Manual for detailed information on the syntax of the ARM instruction set ARM instruction capabilities The following general points apply to ARM instructions Conditional execution All ARM instructions can be executed conditionally on the value of the ALU status flags in the CPSR You do not need to use branches to skip conditional instructions although it may be better to do so when a series of instructions depend on the same condition You can specify whether a data processing instruction sets the
567. ture 4 you must switch to Supervisor mode instead The steps needed to safely re enable interrupts in an IRQ handler are Construct return address and save on the IRQ stack Save the work registers and spsr_IRQ Clear the source of the interrupt Switch to System mode and re enable interrupts Save User mode link register and non callee saved registers Call the C interrupt handler function NN Le a When the C interrupt handler returns restore User mode registers and disable interrupts Switch to IRQ mode disabling interrupts 9 Restore work registers and spsr_IRQ 10 Return from the IRQ Example 9 13 shows how this works for System mode Registers r12 and r14 are used as temporary work registers after Ir_IRQ is pushed on the stack Example 9 13 AREA INTERRUPT CODE READONLY IMPORT C_irgq_handler IRQ SUB Ir Ir 4 construct the return address STMFD sp Ir and push the adjusted Ir_IRQ MRS r14 SPSR copy spsr_IRQ to r14 STMFD spl r12 r14 Save work regs and spsr_IRQ Add instructions to clear the interrupt here then re enable interrupts MSR CPSR_c 0x1F Switch to SYS mode FIQ and IRQ Copyright 1997 1998 ARM Limited All rights reserved 9 25 Handling Processor Exceptions 9 26 STMFD BL LDMFD MSR LDMFD MSR LDMFD END sp r r3 Ir C_irg_handler sp r r3 Ir CPSR_c 0x92 sp r12 r14 SPSR_cf r14 sp pc A enabled USR mode registers are now current
568. u have agreed a full source license with Pacific Softworks By default the makefile does not rebuild Fusion stack sources This option builds a debug version of Angel Editing makefile build options The following PID build options are not available as command line options You must edit the value of these options in the makefile The most important options are ROADDR and RWADDR You must edit these to reflect the operational memory of your system Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel The most important makefile options are THUMB_SUPPORT When set to this builds Angel with support for debugging Thumb code If this is not set the debugger does not support Thumb state debugging If Thumb code is encountered it generally causes an undefined instruction trap ASSERT_ENABLED This option controls debug assertions When set to 1 extra consistency checks are made throughout Angel If any checks fail the fatal error trap is taken This normally resets Angel Setting this to 0 is not recommended unless the Angel code is known to be fully functional and the small reduction in image size is important The default is 1 MINIMAL_ANGEL This option is used by the minimal Angel makefiles to build a minimal Angel library This option should always be set to 0 Use the separate makefile and build areas to build minimal Angel libraries For example the minimal Angel makefiles for the PID board are loca
569. u use a simple download method then the transition to the development phase is easier because you can move to building ROM images when everything else is working and you are preparing to move to production hardware Refer to The Flash downloader on page 8 15 of the ARM Software Development Toolkit Reference Guide for information on using the Flash download utility Refer to The fromELF utility on page 8 3 of the ARM Software Development Toolkit Reference Guide if you are using an EPROM programmer to program big endian code into 16 bit devices Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel 13 3 Angel in operation 13 3 1 Initialization ARM DUI 0040D This section gives a brief explanation of Angel operation that you should understand before you begin to port Angel to your own hardware It contains the following Initialization below Waiting for debug communications on page 13 30 Angel debugger functions on page 13 31 Angel task management on page 13 33 Context switching on page 13 38 Example of Angel processing a simple IRQ on page 13 40 The initialization of the code environment and system is almost identical whether the code is to initialize the debugger only full Angel or to launch an application minimal Angel The initialization sequence is as follows 1 The processor is switched from the current privileged mode to Supervisor mode with interrupts disabled Angel che
570. uctures for use by C and C routines Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Using the Procedure Call Standards 6 2 Using the ARM Procedure Call Standard ARM DUI 0040D APCS is a set of rules governing calls between functions in separately compiled or assembled code fragments The APCS defines constraints on the use of registers stack conventions argument passing and result return Code produced by compilers is expected to adhere to the APCS at all times Such code is said to be strictly conforming Handwritten code is expected to adhere to the APCS only when making calls to externally visible functions Such code is said to be conforming The APCS comprises a family of variants Each variant is exclusive Code that conforms to one variant cannot be used with code that conforms to another Note The reentrant APCS variants are obsolete Copyright 1997 1998 ARM Limited All rights reserved 6 3 Using the Procedure Call Standards 6 2 1 APCS register names and usage Table 6 1 and Table 6 2 on page 6 5 summarize the names and roles of integer and floating point registers under the APCS Note Not all ARM systems support floating point Refer to Chapter 11 Floating point Support in the ARM Software Development Toolkit Reference Guide for more information Table 6 1 APCS registers Register APCS name APCS role rO al argum
571. ug code and channels manager can access any valid device driver without requiring information about the peripheral being used devconf h This is the main configuration file for the target image It sets up the Angel resources for the specific target and defines the hardware configuration to Angel including a memory map of available memory interrupt operation the peripherals and devices available to Angel Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Angel All systems require a similar devconf h to that used for the PID The following explanation uses the PID devconf h file as an example It defines the following Number of Serial Ports The PID has two serial ports In the PID example one port is defined to Angel The other port is available for application use Board hardware setup This option is defined if not minimal Angel Parallel is for the use of a parallel port for faster download PCMCIA is to set up and use the PC card slots on the board PROFILE makes use of one timer to allow code profiling 1f requested by the host debugger This option is rarely used in final builds DCC and Cache Support DCC and CACHE support are processor dependent You must take care when defining these These options enable routines that will not work and will halt the Angel Debugger if your processor does not support them Debug Method The DEBUG_METHOD option is only applicable if DEBUG 1 is sp
572. uild the example do one of the following load the supplied scatter apj into APM use a batch file or makefile containing the following armasm g boot s list armasm g regioninit s list armasm g vectors s list armcc g c C_main c armcc g c C_int_handler c armlink boot o regioninit o vectors o C_main o C_func o info totals info sizes scatter scat txt list out txt map symbols xref c ARM250 lib embedded armlib_cb 321 o scatter axf fromelf nozeropad scatter axf bin scatter bin This creates an ELF debug image scatter axf for loading into a debugger ADW ADU or armsd a binary ROM image scatter bin suitable for downloading into the Flash memory of a PID board Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Writing Code for ROM 10 8 6 Running the example ARM DUI 0040D Follow these steps to execute debug the image with ADW EmbeddedICE and a PID board 1 Ensure REMAP link LK18 is OUT to Flash download 2 Switch on the power to the PID board and launch ADW 3 In ADW select Configure debugger from the Options menu and select remote_a 4 Select Flash download from the File menu and enter the name of the ROM image scatter bin The Command Window displays ARM Flash Programming Uti lity AT29C040A recognised Input File Is your_ROM_f7lename Please enter the number of the first sector to write Default is to start at sector 0 Start at sector 0x0 5 Click Enter t
573. uit 4 1 2 Debugging hello c Follow these steps to debug hello c at the source level l 2 Quit the debugger 1f it is still running Enter armcc g hello c o hello2 to recompile the program with high level debugging information The g option instructs the compiler to include debug information Enter armsd hello2 to load hello into the debugger Enter break main at the armsd prompt to set a breakpoint on the first statement in main Enter go to execute the program up to the breakpoint The debugger reports that it has stopped at breakpoint 1 and displays the source line You can enter debugging commands to examine register contents and source code To display the contents of the registers enter reg To list the C source enter type This displays the whole source file The type command can also display sections of code For example enter type 1 6 to display lines 1 to 6 of the source To list the assembly code enter list The assembly code around the current position in the program is shown You can also list memory at a given address for example list 0x8080 Refer to armsd on page 4 6 or the ARM Software Development Toolkit Reference Guide for more information on using the command line debugger ARM DUI 0040D Copyright 1997 1998 ARM Limited All rights reserved 4 3 Command Line Development 4 1 3 4 1 4 4 4 Separating the compile and link stages Follow these steps to separat
574. unction Junk if none or if an integer result was not returned This variable is read only Contains the directory name of the directory containing source code for the program being debugged Contains any statistics that the ARMulator has been keeping You can examine the contents of this variable by clicking on statistics in the Debugger Internals window This variable is read only statistics_inc Not available in the debugger internals window This variable can be used in the command window statistics_inc_w Similar to statistics but outputs the difference between the current statistics and the point at which you asked for the statistics_inc_w window To create a statistics_inc_w window select this item right click to display the pop up menu and select Indirect through item This variable is read only and is not available in the command window top_of_memory If you are using an EmbeddedICE interface set this variable to the total amount of memory normally on your development board If you add more memory to the board change this variable to reflect the new amount of memory 3 20 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX type_lines Contains the default number of lines for the type command initially set to 10 vector_catch Applies to ARMulator and EmbeddedICE only It sets the exceptions that result in control passing back to
575. unctionality as in SDT 2 1 1a but will not be supported by future releases Instruction scheduling compilers The compilers have been enhanced to perform instruction scheduling Instruction scheduling involves the re ordering of machine instruction to suit the particular processor for which the code is intended Instruction scheduling in this version of the C and C compilers is performed after the register allocation and code generation phases of the compiler Instruction scheduling is of benefit to code for the StrongARM 1 and ARM9 processor families if the processor option specifies any processor other than the StrongARMI1 instruction scheduling suitable for the ARM 9 is performed if processor StrongARM1 is specified instruction scheduling for the Strong ARM1 is performed By default instruction scheduling is turned on It can be turned off with the zpno_optimize_scheduling command line option Reduced debug data size In SDT 2 50 and C 1 10 the compilers generate one set of debug areas for each input file including header files The linker is able to detect multiple copies of the set of debug areas corresponding to an input file that is included more than once and emits only one such set of debug areas in the final image This can result in a considerable reduction in image size This improvement is not available when ASD debug data is generated In SDT 2 1 1a and C 1 01 images compiled and linked for debug could
576. undefined instruction handlers 9 33 Strings Software interrupt see SWIs specifying and matching 3 42 Sorts profiling example 11 22 structure passing and returning 6 13 Source files Sub projects 2 4 editing 2 18 Subroutines assembly language 5 15 examining 3 37 Supervisor mode 9 17 in APM 2 34 and Angel 13 20 list window 3 24 entering from Angel 13 95 window 3 24 Supervisor stack 9 17 Special characters 3 42 suppasm s 13 58 13 59 13 63 13 100 Specifying strings 3 42 SWI exception 9 2 Sprinti SWI instruction 8 6 9 14 as format string in ADW ADU 3 70 Thumb 9 42 SPSR 5 5 9 3 9 5 SWIs interworking ARM and Thumb 7 2 Angel C library support SWIs_ 13 79 T bit 9 42 ARMulator 12 26 Stacks 5 4 5 36 9 3 calling 9 19 Angel 13 39 configuring for Angel 13 72 initialization code for ROM images debug interaction SWIs_ 13 95 10 6 handlers 9 14 9 15 9 17 9 41 stack pointer 9 3 indirect 9 20 supervisor 9 17 returning from 9 7 Starting SYS_WriteO 10 34 ADW ADU 3 9 Thumb state 9 42 APM 2 4 0x80 0x88 12 26 license server software A 6 0x90 0x98 12 26 startrom s 13 58 Symbol names mangling 8 17 8 19 STARTUPCODE macro 13 58 Symbols high and low level 3 43 Statistics Symbols register based 5 53 ARMulator 11 6 System decoder 10 4 memory 11 12 System mode 9 44 Status bar 3 8 SYS_CLOCK 13 90 Status flags 5 17 SYS_CLOSE 13 83 Stepping through an image 3 34 SYS_ERRNO 13 91 Steps build 2 11 SYS_FLEN 13 88 STM instruction 5 34 5 49 SYS GET CMDLINE 1
577. under armsd type armsd rdi_log 16 To disable tracing type armsd rdi_log Interpreting trace file output This section describes how you interpret the output from the tracer Example of a trace file The following example shows part of a trace file Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator Date Fri Jul 10 13 29 16 1998 Source Armul Options Trace Instructions Disassemble Trace Memory Cycles MNR40__ 00008008 EBQQQ00C MSR40__ 0000800C EBO0001B MSR40__ 00008010 EFO00011 IT 00008008 ebQQ000c BL 0x8040 MNR40__ 00008040 E1A00000 MSR40__ 00008044 EQ4ECQQF MSR40__ 00008048 EQ8FCOQC IT 00008040 e1a00000 NOP MSR40__ 000804C E99CQQQF IT 00008044 eQ4ecQ0f SUB r12 r14 pc MSR40__ 00008050 E24CC010 IT 00008048 e 8fc00c ADD r12 pc r12 E 00000020 00000000 10005 MNR40__ 00000020 E1A00000 IT 00000018 eb00000a BL 0x48 E 00000048 00000000 10005 MNR40__ 00000048 E10F0000 E 0000004C 00000000 10005 MSR40__ 00000094C E1A00000 In a trace file there are three types of line trace memory lines M lines trace instruction lines I lines trace event lines E lines These are described in the following sections Trace memory M lines The format of the trace memory M lines is as follows access addr data For example MNR40__ 00008008 EBQQQ00C where access contains the following information memory_access indicates a memory access M in trace file memo
578. urpose register if the return address is stored on the stack The program counter Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Basic Assembly Language Programming This is accessed as r15 or pc It is incremented by one word four bytes for each instruction in ARM state or by two bytes in Thumb state Branch instructions load the destination address into the program counter You can also load the program counter directly using data operation instructions For example you can copy the link register into the program counter using MOV pc Ir This is the usual way to return from a simple subroutine The Current Program Status Register CPSR The CPSR holds copies of the Arithmetic Logic Unit ALU status flags the current processor mode interrupt disable flags On Thumb capable processors the CPSR also holds the current processor state ARM or Thumb The ALU status flags in the CPSR are used to determine whether or not conditional instructions are executed Refer to Conditional execution on page 5 17 for more information Five Saved Program Status Registers SPSRs These are used to store the CPSR when an exception is taken One SPSR is accessible in each of the exception handling modes User mode and System mode do not have an SPSR because they are not exception handling modes Refer to Chapter 9 Handling Processor Exceptions for more information Copyright
579. use the offset for the branch is limited to this 6 Logically OR this with 0xea000000 the opcode for the Branch instruction to produce the value to be placed in the vector Example 9 3 shows a C function that implements this algorithm It takes the following arguments the address of the handler the address of the vector in which the handler is to be to installed The function can install the handler and return the original contents of the vector This result can be used to create a chain of handlers for a particular exception Refer to Chaining exception handlers on page 9 37 for further details Example 9 3 unsigned Install_Handler unsigned routine unsigned vector Updates contents of vector to contain branch instruction to reach routine from vector Function return value is original contents of vector x NB Routine must be within range of 32MB from vector unsigned vec oldvec vec routine unsigned vector 0x8 gt gt 2 if vec amp Oxff000000 printf Installation of Handler failed Copyright 1997 1998 ARM Limited All rights reserved 9 11 Handling Processor Exceptions exit 1 vec Oxea000000 vec oldvec vector vector vec return oldvec The following code calls this to install an IRQ handler unsigned irqvec unsigned 0x18 Install_Handler unsigned IRQHandler irqvec In this case the returned original conte
580. utable image to a Thumb ARM interworking project Follow these steps for each file in the Sources partition that you want to be compiled with armcc rather than tcc 1 Select a C file in the partition Sources that is to be compiled into ARM code for example foo c 2 Select Edit Variable for foo c from the Project menu The Edit Variables dialog is displayed 3 Type cc in the Name field and armcc in the Value field 4 Configure the ARM compiler for interworking for this file Select the C file from step 1 b Select Tool Configuration for foo c cc Set from the Project menu The Compiler Configuration dialog is displayed C Click the Target tab and ensure that the check box for Arm Thumb Interworking in the APCS3 Qualifiers group is selected d Modify the other APCS3 options if necessary e Click OK to save the configuration Note To revert to tcc set the Value from step 3 to an empty string and perform step 4 clicking Unset This may remove any other per file options you had set 7 5 4 C library usage and the ARM Project Manager In certain circumstances you may not require the default ANSI C library for example if you are implementing an RTOS with its own stack and heap management Follow these steps to link with your own libraries 1 Select the project root 2 Select Tool Configuration for project apj armlink Set from the Project menu The Linker Configuration dialog is displayed
581. utput are created in a subdirectory of the project directory You specify the project directory when you create the project Note You cannot add a source file to only one variant of your project Adding a new variant to a project Follow these steps to add a new variant to your project template 1 Select Add Variant from the Project menu The Add Variant dialog is displayed Figure 2 10 Add Variant x Add Variant Like OK Pe ee ee ae ne eae Cancel DebugRel Release Help at New Variant Name _e o oaeeo Figure 2 10 Add Variant dialog 2 Select a variant from the Add Variant Like list The files and variable values from the original are assigned to the new template 3 Enter a new variant name The variant name cannot contain spaces 4 Click OK Copyright 1997 1998 ARM Limited All rights reserved 2 27 ARM Project Manager Building selected variants Follow these steps to build a variant or variants 1 Select Build Variants from the Project menu The Build Variants dialog is displayed Figure 2 11 Build Variants select Variants to build Cancel Force build regardless of timestamps Figure 2 11 Build Variants dialog 2 Select one or more variants from the Select Variants to build box 3 If you want to force build the selected variants check Force build regardless of timestamps Click OK to initiate the build 2 4 7 Changing a project name There ar
582. vector table is limited to 24 bit addresses Note If your application chains exception handlers Angel must be reset with a hardware reset if the application is killed This ensures that the vectors are set up correctly when the application is restarted The consequences of not passing an exception on to Angel from your exception handler depend on the type of exception as follows Undefined You will not be able to single step or set breakpoints from the debugger Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D Angel SWI If you do not implement the EnterSVC SWI Angel will not work If you do not implement any of the other SWIs you will not be able to use semihosting Prefetch abort The exception will not be trapped in the debugger Data abort The exception will not be trapped in the debugger If a Data abort occurs during a debugger originated memory read or write the operation might not proceed correctly depending on the action of the handler IRQ This depends on how Angel is configured Angel will not work if it is configured to use IRQ as its interrupt source FIQ This depends on how Angel is configured Angel will not work if it is configured to use FIQ as its interrupt source Linking Angel C library functions The C libraries provided with the ARM Software Development Toolkit use Angel SWIs to implement semihosting requests You have a number of options for using ARM C libr
583. ved ARM DUI 0040D ARM DUI 0040D Handling Processor Exceptions Note C interrupt handlers cannot be produced in this way using tcc The __irq keyword is faulted by tcc because tcc can only produce Thumb code and the processor is always switched to ARM state when an interrupt or any other exception occurs However the subroutine called by an __irq function can be compiled for Thumb with interworking enabled Refer to Chapter 7 Interworking ARM and Thumb for more information on interworking Example 9 11 shows a simple handler that does not call any subroutines The handler reads a byte from location Ox80000000 and clears the interrupt by writing it to location 0x80000004 The __irq keyword ensures that r0 r3 and r12 are preserved and that the function exits with SUBS pc ir 4 Example 9 11 __1rq void IRQHandler void volatile char base char 0x80000000 read a byte base 4 base clear the interrupt Compiled with armcc Example 9 11 gives the following code EXPORT IRQHandler IRQHand ler Qx000000 e92d190f STMFD sp r0 r3 r12 Qx000004 e3a00102 MOV rQ 0x80000000 Qx000008 e5d01000 LDRB r1 rQ 0 Qx00000c e5c01004 STRB r1 r0 4 Qx000010 e8bd100f LDMFD sp rQ r3 r12 Qx000014 e25ef004 A SUBS oc Ir 4 Calling subroutines from interrupt handlers If you call subroutines from your top level interrupt handler the __irq keyword also re
584. vent 0x00010001 EventWord pc By default this is empty If uncommented the example shown allows profiling of cache misses The Type entry controls how the profiling interval is interpreted The profiling interval nis set using the armsd command profon n or from ADW using the Debugger tab of the Debugger Configuration dialog as shown in Debugger on page 3 53 Type Microsecond the default is that samples are taken every microsecond Type Instruction samples are taken every n instructions where n is set using the armsd command profon n For example profon 2 Setting this value in the GUI is described in Debugger on page 3 53 Type Cycle samples are taken every n cycles Type Event the profiling interval is ignored Instead all relevant events are profiled See Events on page 12 87 of the ARM Software Development Toolkit Reference Guide for more information on events EventMask event_number is also allowed see the section Tracer on page 12 6 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARMulator 12 5 Windows Hourglass ARM DUI 0040D This module deals with calling the debugger regularly during execution This is required when you are using the GUI debuggers The WindowsHourglass section in the configuration file controls how regularly this occurs Increasing this rate decreases the regularity at which control is yielded to ADW or ADU This increases emulation speed but decreases re
585. visor stack 13 18 target specific files 13 57 task management 13 5 13 30 13 33 13 39 13 79 task management functions 13 35 task priorities 13 33 task queue 13 39 Task Queue Items 13 38 TDCC 13 26 templates for porting 13 45 Thumb debug communications channel 13 26 timers 13 70 undefined instruction 13 18 writing device drivers 13 63 13 64 angel c ARMulator model 12 4 angel hex 13 12 angel m32 13 12 angel rom 13 11 13 70 Angel_BlockApplication 13 35 13 36 Angel_DeviceControlFn 13 63 Angel_DeviceYield 13 66 Angel_NewTask 13 35 13 39 Angel_NextTask 13 35 13 36 13 42 Angel_QueueCallback 13 35 Angel_SelectNextTask 13 36 13 39 13 42 Angel_SerialiseTask 13 34 13 35 13 38 13 39 13 41 13 42 Angel_Signal 13 35 13 37 angel_SWIreason_EnterSVC 13 95 Angel_SWIreason_ReportException 13 97 Copyright 1997 1998 ARM Limited All rights reserved angel_SWIreason_ReportException 13 97 Angel_TaskID 13 35 13 37 angel_TQ Pool 13 39 Angel_Wait 13 35 13 37 13 38 Angel_Yield 13 35 13 36 13 38 13 66 13 100 ANSIC 8 19 header files 8 19 APCS defined 6 3 interworking ARM and Thumb 7 2 7 12 register usage 6 10 APM Angel project 13 45 13 50 building C projects 2 52 closing down 2 4 creating C projects 2 53 desktop 2 15 generating source dependencies 2 9 interworking ARM and Thumb 7 23 overview 2 2 partitions 2 24 preferences 2 31 source files 2 34 starting and stopping 2 4 tem
586. w There are two types of breakpoint a simple breakpoint that stops at a particular point in your code a complex breakpoint that stops when the program has passed the specified point a number of times stops at the specified point only when an expression is true You can set a breakpoint at a point in the source or in the disassembled code 1f it is currently being displayed To display the disassembled code either select Toggle Interleaving from the Options menu to display interleaved source and assembly language in the Execution window select Disassembly from the View menu to display the Disassembly window You can also set breakpoints on individual statements on a line if that line contains more than one statement You can set edit or delete breakpoints in the following windows Execution Disassembly Source File Backtrace Breakpoints Function Names Low Level Symbols Class View if C is installed Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM DUI 0040D ARM Debuggers for Windows and UNIX Setting a simple breakpoint There are two methods you can use to set a simple breakpoint Method 1 1 Double click on the line where you want to set the breakpoint 2 Click the OK button in the dialog box that appears Method 2 1 Position the cursor in the line where you want to set the breakpoint 2 Set the breakpoint in any of the f
587. w Program compiled without register attribute Please give the number of runs through the benchmark 4 SSS Executing larmulate Default Figure 3 2 A typical ARM Debugger desktop display Menu bar toolbar mini toolbar and status bar The menu bar is at the top of the ARM Debugger desktop Click on a menu name to display the pull down menu If you have installed the ARM C compiler a C menu appears between the View and Execute menus that provides options relevant only to C program debugging C also adds its own mini toolbar See ARM Debugger with C on page 3 62 for more information Underneath the menu bar is the toolbar Position the cursor over an icon and a brief description is displayed A processor specific mini toolbar is also displayed The menus the toolbar and the mini toolbar are described in greater detail in the online help At the bottom of the desktop is the status bar This provides current status information or describes the currently selected user interface component 3 8 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX 3 2 2 Starting and closing the debugger ARM DUI 0040D Start and close the ADW or ADU as follows Starting the ARM Debugger Start the ARM Debugger for Windows ADW in any of the following ways if you are running Windows 95 or Windows 98 click on the ARM Debugger for Windows icon in the ARM SD
588. w menu The Display Format dialog is displayed 2 Enter the display format Use the same syntax as a printf format string in C Table 3 2 lists the valid format descriptors 3 Click OK Table 3 2 Display formats Type Format Description int Only use this if the expression being printed yields an integer d Signed decimal integer default for integers u Unsigned integer X Hexadecimal lowercase letters char Only use this if the expression being printed yields a char C Character char S Pointer to character Only use this for expressions that yield a pointer to a null terminated string voids p Pointer same as 8x for example 00018abc This is safe with any kind of pointer 3 38 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Table 3 2 Display formats continued float Only use this for floating point results e Exponent notation for example 9 999999e 00 f Fixed point notation for example 9 999999 g General floating point notation for example 1 1 1 2e 06 Note If you change a single line that line is not affected by global changes Leave the Display Format dialog empty and click OK to restore the default display format Use this method to revert a line format change to the global format The initial display format of a variable declared as char is special The whole string is displayed whereas normally a
589. ween languages ARM DUI 0040D The following general rules apply to calling between C C and assembly language You should not rely on the following C implementation details These implementation details are subject to change in future releases of ARM C the way names are mangled the way the implicit this parameter is passed the way virtual functions are called the representation of references the layout of C class types that have base classes or virtual member functions the passing of class objects that are not plain old data POD structures The following general rules apply to mixed language programming Use C calling conventions In C non member functions may be declared as extern C to specify that they have C linkage In this release of the ARM Software Development Toolkit having C linkage means that the symbol defining the function is not mangled C linkage can be used to implement a function in one language and call it from another Note that functions that are declared extern C cannot be overloaded Assembly language modules must conform to the appropriate ARM or Thumb Procedure Calls Standard The following rules apply to calling C functions from C and assembly language To call a global non member C function declare it extern C to give it C linkage Copyright 1997 1998 ARM Limited All rights reserved 8 17 Mixed Language Programming Member functions b
590. where in the window to display the Memory window menu allowing you to display the contents as words half words or bytes with ASCH characters Follow these steps to enter another address 1 Select Goto from the Search menu or select Goto Address from the Memory Window menu The Goto Address dialog is displayed 2 Enter an address as a hexadecimal value prefixed by 0x or as a decimal value 3 Click OK See Saving or changing an area of memory on page 3 44 for more information on working with areas of memory Copyright 1997 1998 ARM Limited All rights reserved 3 13 ARM Debuggers for Windows and UNIX 3 3 ARM Debugger desktop windows The first time you run ADW or ADU you see the Execution window Console window Command window The following additional windows are available from the View menu Backtrace window Breakpoints window Debugger Internals window Disassembly window Expression window Function Names window Locals Globals window Low Level Symbols window Memory window Registers window RDI Log window Search Paths window Source Files List window Source File window Watchpoints window Some windows become available only after you have loaded an image You may change the format of displayed windows and the format of each window is automatically saved for future use Whatever arrangement of windows you have when you quit the Debugger is displ
591. work are accessible through the APM graphical interface the APM desktop When you have started APM you can display online help giving details relevant to your current situation or navigate your way to any other page of APM online help F1 key Press the F1 key on your keyboard to display help if available on the currently active window Help button Many APM windows contain a Help button Click this button to display help on the currently active window Help menu Select Contents from the Help menu to display a Help Topics screen with Contents Index and Find tabs The tab you used last is selected Click either of the other tabs to select it instead Select Search from the Help menu to display the Help Topics screen with the Index tab selected Under Contents click on a closed book to open it and see a list of the topics it contains Click on an open book to close it Select a topic and click the Display button to display online help Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Project Manager Under Index either scroll through the list of entries or start typing an entry to bring into view the index entry you want Select an index entry and click the Display button to display online help Under Find follow the instructions to search all the available online help text for any keywords you specify The first time you undertake a Find operation a suitable database file is constructed and is then
592. xample 6 2 shows the assembly language output in file add64_1 s It reveals that this is an inefficient implementation instructions may vary between compiler releases add_64 STMDB LDR MOV LDR MOV ADD STR MOV LDR LDR ADD TST CMPEQ MOVNE MOVEQ ADD STR LDMIA Modifying the compiler output sp vl Ir v1 a2 0 a4 v1 LSR 31 1p a3 0 Ir 1p LSR 31 1p v1 1p 1p lal 0 1p 1p LSR 31 a2 a2 4 a3 a3 4 a2 a2 a3 a4 Ir a4 1p a3 1 a3 0 a2 a2 a3 a2 al 4 sp v1 pc Example 6 2 Because you cannot specify the Carry flag in C you must get the compiler to produce almost the right code and then modify it by hand Start with incorrect code that does not perform the carry addition as in Example 6 3 on page 6 8 Copyright 1997 1998 ARM Limited All rights reserved 6 7 Using the Procedure Call Standards 6 8 Example 6 3 void add_64 int64 dest int64 srcl int64 src2 dest gt lo srcl gt lo src2 gt lo dest gt hi srcl gt hi src2 gt h1 return Copy file examples candasm add64_2 c which contains the code in Example 6 3 to your current working directory Compile it to ARM assembly language source as follows armcc li S add64_2 c You can find the assembly language produced by the compiler in the file add64_2 s Example 6 4 add_64 LDR a4 a2 0 LDR 1p a3 0 ADD a4 a4 1p STR a4 al 0 LDR a2 a2 4 LDR a3 a3 4 ADD a2 a2 a3 STR a2 al
593. xpression window provides similar functionality to the debugger Expression window with a C interpretation of the data being displayed 3 70 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D ARM Debuggers for Windows and UNIX Evaluating expressions and adding watches Follow these steps to enter an expression to be evaluated 1 Select Evaluate Expressions from the C menu or click on the Evaluate Expression button in the toolbar The Evaluate Expression window 1s displayed Figure 3 29 Evaluate Expression Ea Calculate Expression Le r Add watch 1 lt 5 Close Figure 3 29 The Evaluate Expression window 2 Enter the expression to be evaluated and press the Enter key or click on the Calculate button The value of the expression is displayed If the expression is a variable the value of the variable is displayed If the expression is a logical expression the window displays 1 if the expression evaluates to true or 0 if the expression evaluates to false If the expression is a function the value of the function is displayed Member functions of C classes cannot be evaluated Refer to Expression evaluation guidelines for more information on expression evaluation in C 3 Click on the Add Watch button to add the expression to the Watch window Expression evaluation guidelines Note The following guidelines apply to all areas of ADW or ADU where an expression can
594. y Int_1_Par_Val One_ Proc_Bfint An_1_Par_Retint Arr_2_F Figure 3 23 The Class View window menu Select View Source from the Class View window menu to display the source code for the function Note You can also double click the left mouse button on a member function to display the function source Select Set or Edit Breakpoint from the Execute menu if you want to add a breakpoint within the code you are viewing Refer to the next section for information on how to set a breakpoint at function entry Setting and clearing breakpoints from the Class View window Follow these steps to toggle a breakpoint that will halt the program when the source for a class or function is entered l 2 Display the Class View window Click the right mouse button on a member function A Class View window menu is displayed Figure 3 23 Copyright 1997 1998 ARM Limited All rights reserved 3 65 ARM Debuggers for Windows and UNIX 3 Select Toggle Breakpoint from the Class View window menu to set a breakpoint or unset an existing breakpoint Breakpoints are indicated by a red dot to the left of the function in the Class View window 3 8 4 Using the Watch window The Watch window allows you to set watches on variables and expressions The Watch window provides similar functionality to the debugger Local and Global windows In addition it provides a C interpretation of the data being displayed Note The Watch window is
595. y an Angel template directory If you are using APM refer to Editing the APM project directory structure on page 13 52 The build directory is separate from the target source code directory In the supplied examples it has the same name as the target code directory with a b extension For example the build directory for the PID Angel port is angel source pid b You must modify the makefile so that it uses your directories compiles and assembles your source and links your object files This is described in Setting up the makefile below In addition to setting up the makefile for your new directory structure you must set a number of build options either on the command line or in the makefile to provide support for your hardware The options include Thumb support Angel data area and execution addresses endianness This is described in Setting command line build options on page 13 48 and Editing makefile build options on page 13 48 Setting up the makefile The following instructions assume that you have copied the complete angel directory to your working directory copied the pid and pid b template directory pair to a directory pair that is named appropriately for your board At this stage the directory structure for your board specific files is similar to working_directory angel source your_board and working_directory angel source your_board b Copyright 1997 1998 ARM Limited All rights reserved 13 47
596. y default a different number from the ARM semihosting SWI OxAB rather than 0x123456 Example 7 1 AREA AddReg CODE READONLY Name this block of code ENTRY Mark first instruction to call main ADR r2 ThumbProg 1 Generate branch target address and set bit 0 hence arrive gt at target in Thumb state BX r2 Branch exchange to ThumbProg CODE16 Subsequent instructions gt are Thumb ThumbProg MOV r2 2 Load r2 with value 2 MOV r3 3 Load r3 with value 3 ADD r2 r2 r3 r2 r2 r3 stop MOV rO 0x18 LDR r1 0x20026 SWI xAB END ange 1_SWIreason_ReportException ADP_Stopped_ApplicationExit Angel semihosting Thumb SWI Mark end of this file 7 6 Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Interworking ARM and Thumb Building the example To build and execute the example 1 Enter the code using any text editor and save the file as addreg s 2 Type asm g addreg s at the command prompt to assemble the source file 3 Type armlink addreg o o addreg to link the file 4 Type armsd addreg to load the module into the command line debugger 5 Type break start at the armsd command prompt to set a breakpoint on the label start 6 Type go to execute the program 7 When the breakpoint is hit type step to single step through the rest of the program Type reg to display the registers after each step and watch the processor enter Thumb state This is denoted by the T in the
597. y location Similarly if you write ADD Rd Rn expression and expression is register based you are asking for a single ADD instruction that adds both the base register of the expression and its offset to Rn Again the assembler cannot do this You must use two ADD instructions to perform these two additions Copyright 1997 1998 ARM Limited All rights reserved 5 53 Basic Assembly Language Programming 5 54 Setting up a C type structure There are two stages to using structures in C declaring the fields that the structure contains generating the structure in memory and using it For example the following typedef statement defines a point structure that contains three float fields named x y and z but it does not allocate any memory The second statement allocates three structures of type Point in memory named origin oldloc and newloc typedef struct Point float x y Z Point Point origin oldloc newloc The following assembly language code is equivalent to the typedef statement above PointBase RN r11 MAP Q PointBase Point_x 4 Point_y 4 Point_z 4 The following assembly language code allocates space in memory This is equivalent to the last line of C code origin 12 oldloc 12 newloc 12 You must load the base address of the data structure into the base register before you can use the labels defined in the map For example LDR PointBase origin MOV rO 0 STR rQ Point_x MOV r
598. y only a flat profile giving the percentage time spent in each function excluding the time spent in any of its children If function call count information is present the profiler can display a call graph profile that shows not only the percentage time spent in each function but also the percentage time accounted for by calls to all children of each function and the percentage time allocated to calls from different parents The compiler automatically prepares the code for profiling so no special options are required at compile time At link time you must ensure that your program image contains symbols This is the default setting for the linker You can only profile programs that are loaded into store from the debugger Function call counting for code in ROM is not available You must inform the debugger that you wish to gather profile data when the program image is loaded The debugger then alters the image diverting calls to counting veneers Copyright 1997 1998 ARM Limited All rights reserved 11 19 Benchmarking Performance Analysis and Profiling The debuggers allow the collection of pc samples to be turned on and off at arbitrary times allowing data to be generated only for the part of a program on which attention is focussed omitting initialization code for example However care should be taken that the time between turning sampling on and off is long compared with the sample interval or the data generated may be mea
599. ying example Example 8 1 shows how to use labels and branches in a string copy routine The syntax of labels inside assembler blocks is the same as in C Function calls that use BL from inline assembly language must specify the input registers the output registers and the corrupted registers In this example the inputs to my_strcpy are rO and rl there are no outputs and the default APCS registers r0 r3 r12 lr PSR are corrupted Example 8 1 include lt stdio h gt void my_strcpy char src char dst int ch __asm loop ifndef __ thumb ARM version LDRB ch src 1 STRB ch dst 1 else Thumb version LDRB ch src ADD src 1 STRB ch dst ADD dst 1 endif CMP ch 0 BNE loop int main void char a Hello world char b 20 __asm Copyright 1997 1998 ARM Limited All rights reserved 8 3 Mixed Language Programming 8 1 2 8 4 MOV RQ a MOV R1 b BL my_strcpy RO R1 printf Original string s n a printf Copied string s n b return Q ARM and Thumb instruction sets The ARM and Thumb instruction sets are described in the ARM Architectural Reference Manual All instruction opcodes and register specifiers may be written in either lowercase or uppercase Operand expressions Any register or constant operand may be an arbitrary C or C expression so that variables can be read or written The expression must be integer assignable that
600. your programs either under emulation or on ARM based hardware ARMulator The ARM core emulator This provides instruction accurate emulation of ARM processors and enables ARM and Thumb executable programs to be run on non native hardware The ARMulator is integrated with the ARM debuggers Angel The ARM debug monitor Angel runs on target development hardware and enables you to develop and debug applications running on ARM based hardware Angel can debug applications running in either ARM state or Thumb state 1 1 2 Components of C version 1 10 ARM C is not part of the base Software Development Toolkit It is available separately Contact your distributor or ARM Limited if you want to purchase ARM C ARM C version 1 10 consists of the following major components armcpp This is the ARM C compiler It compiles draft conforming C source into 32 bit ARM code tcpp This is the Thumb C compiler It compiles draft conforming C source into 16 bit Thumb code support software The ARM C release provides a number of additional components to enable support for C in the ARM Debuggers and the ARM Project Manager Note The ARM C compilers libraries and enhancements to the ARM Project Manager and ARM Debuggers are described in the appropriate sections of the ARM Software Development Toolkit User Guide and Reference Guide Copyright 1997 1998 ARM Limited All rights reserved ARM DUI 0040D Introduction

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