UNREL(TM) - REL to ASM translator Table of Contents General
Contents
1. 11 set location counter 13 define program size 14 end program 15 end file The undocumented special link items 4 and 8 as well as chain address SLI 12 are not supported The later is used in Microsoft s one pass compilers SLI 4 and SLI 8 are used in a more recent version of M80 for handling 8 bit externs with greater support of arithmetic expressions resolvable at link time however Microsoft wasn t too potent in letting the world know of the specific details associated with that link item In any event we re not supporting it in UNKEL UNREL TM REL to ASM translator Here is a small sample program used to demonstrate the behavior of UNREL It is the assembly listing using MRAS mras testmod 1 MRAS 1 0a Copyright c 1985 MTSOSYS Inc All rights reserved Including TESTMOD 1 00001 CSEG 0000 210000 00002 START LD HL MESSAGE 0003 3EOA 00003 LD A 10 0005 EF 00004 RST 28H 0006 Cc30000 00005 JP NEXT 00006 DSEG 0000 48 00007 MESSAGE DB Hello World 13 65 6C 6C 6F 20 77 6F 72 6C 64 21 OD 0000 00008 END START 0000 is the transfer address 00000 Total errors 36974 Free space Note that this module contains an external symbol NEXT It also contains both a code and a data segment There are also two symbols local to the module one in each segment We can process the resulting REL module with UNREL using a command such as UNREL TESTMOD UNREL will generate the file TESTMOD ASM which contains2. 1 0 0 6 BUFFER entry symbol for library search 1 0 10 0 00 09 define data area size 1 0 13 1 00 1F define program size 1 0 11 1 00 00 set loading location counter code 0 21 absolute lst byte in code segment 1 2 00 00 data relative ref to BUFFER 0 CD absolute 0 70 absolute 0 44 absolute 0 3E absolute 0 OD absolute 0 32 absolute 1 2 00 08 data relative ref to BUFFER 8 0 21 absolute 1 2 00 00 data relative ref to BUFFER 0 11 absolute ref to MESSAGE follows 0 00 absolute this plus next byte are 0 00 absolute end of external chain 0 01 absolute UNREL TM REL to ASM translator 0 09 absolute 0 00 absolute 0 ED absolute 0 BO absolute 0 21 absolute ref to MESSAGE follows 0 1 00 OF program relative link in chain 0 CD absolute 0 67 absolute 0 44 absolute 0 c3 absolute 0 2D absolute 0 40 absolute 1 0 11 2 0000 set loading location counter data 1 0 11 2 00 09 set loading location counter data 1 0 7 2 0000 6 BUFFER define entry point data 1 0 6 1 00 17 7 MESSAGE chain external head of list 1 0 7 1 0000 5 START define entry point code 1 0 14 1 00 00 end program force to next byte 1 0 15 end file marker What follows is a complete definition of the relocation format supported by this package The REL file is an encoded bit stream containing relocatable object code information It follows the format documented by Microsoft for the M80 assembler and L80 linker however only 16
3. BUFFER 8 A 000B 21 0000 LD HL BUFFER OOOE 11 0000 LD DE MESSAGE 0011 01 0009 LD BC BUFFLEN 0014 ED BO LDIR 0016 21 0000 LD HL MESSAGE 0019 CD 4467 CALL DSPLY 001C C3 402D JP EXIT DSEG data starts here ENTRY BUFFER UNREL TM REL to ASM translator 0000 BUFFER DS 9 0009 BUFFLEN EQU BUFFER END START DATE 4470 DSPLY 4467 EXIMO02D BUFFER 0000 BUFFLEN 0009 CR 000D MESSAGE 0017 START 0000 Notice how the external label MESSAGE is defined in the symbol table the value 0017H represents the relative location of the LAST reference to MESSAGE in the assembled code and the trailing asterisk denotes an external symbol both in this table and in the assembled code listing The following is a tabular picture of the decoded REL file Each column represents 1 Absolute 0 orrelocatable 1 item 1 bit If absolute column 2 shows the value in hex 8 bits 2 Relocation type 0 special link item 1 2 or 3 segment relative 2 bits See column 8 3 Special link item control field in decimal 4 bits See column 8 4 A field address type same as column 2 2 bits 5 A field value displayed as high low but reversed in file 16 bits 6 B field length 3 bits 7 B field symbol in ASCII 8 bits each character Description of the object file record as decoded 1 2 3 4 5 6 7 8 1 0 2 4 TEST program name 1 0 0 5 START entry symbol for library search
4. faithful representation of the actual machine language ones and zeros that the Z80 will execute when you want your program to run This object code can only load and execute at a FIXED address in the 2Z80 s memory space On the other hand a RELOCATABLE assembler such as M80 or MRAS will generate object code which can be relocated to any address in the 2Z80 s 64K memory space before the program is to be executed Let s look at an example of absolute assembly The following program has been assembled at an ORIGIN of 0100H Notice especially the values assigned to the memory addresses QDATE EXIT DSPLY START and BUFFER 0100 00100 ORG 0100H 4470 00110 DATE EQU 4470H 402D 00120 QEXIT EQU 402DH 4467 00130 DSPLY EQU 4467H 000D 00140 CR EQU ODH 0100 211401 00150 START LD HL BUFFER 0103 CD7044 00160 CALL DATE 0106 3E0D 00170 LD A CR 0108 321C01 00180 LD BUFFER 8 A 010B 211401 00190 LD HL BUFFER 010E CD6744 00200 CALL DSPLY 0111 C32D40 00210 JP EXIT 0114 00220 BUFFER DS 9 0100 00230 END START DATE 4470 DSPLY 4467 EXIT 402D BUFFER 0114 CR 000D START 0100 The program has been reassembled below at a new origin 0200H Some of the addresses for the above labels have changed while some remain the same 0200 00100 ORG 0200H 4470 00110 DATE EQU 4470H 402D 00120 EXIT EQU 402DH 4467 00130 DSPLY EQU 4467H 000D 00140 CR EQU ODH 0200 211402 00150 START LD HL BUFFER 0203 CD7044 00160 CALL DATE 0206 3E0D 001
5. bit externals are described 1 IF the next bit is a zero THEN the following eight bits are loaded according to the value of the location counter currently in effect THEN recycle to 1 ELSE IF the next bit is a one THEN the next two bits represent a code which is interpreted as follows 01 Indicates a code relative value follows The next 16 bits are loaded after being offset by the code segment origin THEN recycle to 1 10 Indicates a data relative value follows The next 16 bits are loaded after being offset by the data segment origin THEN recycle to 1 11 Indicates a common relative value follows The next 16 bits are loaded after being offset by the selected common segment origin THEN recycle to 1 00 Indicates a Special Link item The SL item consists of the following four bits which are interpreted as one of 16 different items described below an optional VALUE field which consists of a 2 bit address type 00 absolute 01 code relative 10 data relative 11 common relative and a 16 bit address and an optional NAME field that consists of a 3 bit name length followed by the name in 8 bit bytes SLs 0000 0100 use only a NAME field SLs 0101 1000 use both a VALUE field and a NAME field SLs 1001 1110 use only a VALUE field SL 1111 has neither a NAME nor a VALUE field Unless otherwise specified at the UNREL TM REL to ASM translator conclusion of processing a special link item processing recycles
6. gt END end of module 1 Module 2 EXTRN LABEL1 this is an EXTERNAL declaration could also be EXT CALL LABEL1 and this is a reference to the external END end of module 2 The relocatable format also allows you to do other things In many applications program code and data areas must be separated This most often occurs when code must be placed in ROM such as the BASIC interpreter ina TRS 80 However the data areas cannot be in ROM they must be imwriteable memory RAM and thus must be separated from the code areas This can be accomplished by use of the CSEG and DSEG commands to the assembler A CSEG pseudo operation signals the start of a code area while a DSEG indicates the start of a data area Code and data SEGMENTS may be intermixed in a program source file and the assembler will automatically keep them separate by the use of two distinct program or location counters one for each segment When you link a program with the linker you may tell the linker at what address to place the code and also where to place the data Thus the two segments are separated The above example is shown below using this technique 4470 DATE EQU 4470H 402D EXIT EQU 402DH 4467 DSPLY EQU 4467H 000D CR EQU ODH 0000 CSEG code starts here 0000 21 0000 START LD HL BUFFER 0003 CD 4470 CALL DATE 0006 3E OD LD BUFFER 8 A 0008 32 0008 LD HL BUFFER OOOB 21 0000 CALL DSPLY 000E CD 4467 JP QEXIT 0011 C3 402D DSEG data sta
7. the assembler source code for testmod as determined from itsrelocatable object module During the translation process UNREL will display some messages which indicate its progress These messages will look like the following UNREL Disassemble REL Module Version 1 0b Copyright 1987 Riclin Computer Products All rights reserved Pass 1 building segments and symbol tables Pass 2 resolving relocations and local labels Pass 3 disassembling to output After this operation UNREL has generated the source file which can then be assembled by either M80 or MRAS or other M80 compatible assembler The assembler source file would look like this TESTMOD ASM 1 NAME C TESTMO EXTRN NEXT CSEC CSEGS0000 LD HL DSEGS0000 LD A OAH RST 28H JP NEXT DSEG UNREL TM REL to ASM translator DSEGS0000 DB 48H DB 65H DB 6CH DB 6CH DB 6FH DB 20H DB 77H DB 6FH DB 72H DB 6CH DB 64H DB 21H DB ODH END CSEG 0000 As can be observed the external symbol has been noted by means of an EXTRN statement The source code prologue section will include all such externals and PUBLIC symbols as well Symbols local to the module will be identified by a unique symbol The data segment region will be generated as discrete byte values In cases where the original assembler source module was fraught with non code fragments in the code segment or code fragments in the data or common segments UNREL will not be able to generat
8. used Ifoutfile is entered without an extension RMP will be assumed The source drive will be used unlessoutfile includes a drive specification If we want to process the TESTMOD REL module previously illustrated and generate an analysis map we would use a command such as DECODREL TESTMOD The following analysis is generated to the file named TESTMOD RMP 0000 7 Program name 02 TESTMO 0007 5 Data area size OA Absolute O 000D 000A 4 Program size OD Program relative 1 0009 000D 3 Set counter OB Program relative 1 0000 001A 0 Set counter OB Data relative 2 0000 002C 2 Chain external 06 Program relative 1 0007 NEXT 0034 6 End program OE Program relative 1 0000 0038 7 End file OF Since we did not specify the F flag the BRIEF analysis is generated Such an analysis does not include any absolute data relative code relative or common relative bytes The presentation includes the bit stream flow of special link items The first field noted is the relative byte and bit offset of the referenced item within the relocatable object module file remember bits are used hi order to lo order or 7 to 0 This may prove useful for specialized purposes The information presented on each line describes the special link item by name the contents of and description where appropriate each SLI field is also noted in hexadecimal The technical specification section des
9. 70 LD A CR 0208 321C02 00180 LD BUFFER 8 A 020B 211402 00190 LD HL BUFFER 020E CD6744 00200 CALL DSPLY 0211 C32D40 00210 JP EXIT 0214 00220 BUFFER DS 9 UNREL TM REL to ASM translator 0200 00230 END START DATE 4470 DSPLY 4467 EXIT 402D BUFFER 0214 CR 000D START 0200 To be specific START and BUFFER have changed while the others aran changed Both START and BUFFER have been relocated START instead of being at 0100H is now at 0200H and BUFFER has moved from 0114H to 0214H This offset of 0100H is due to the changed origin 0100H versus 0200H START and BUFFER are therefore internally relocatable values while DATE for example will always be 4470B and is thus known as an absolute value The same program as assembled using relocation looks like this 4470 DATE EQU 4470H 402D QEXIT EQU 402DH 4467 DSPLY EQU 4467H 000D CR EQU ODH 0000 21 0014 START LD HL BUFFER 0003 CD 4470 CALL DATE 0006 3E OD LD A CR 0008 32 001C LD BUFFER 8 A 000B 21 0014 LD HL BUFFER OOOE CD 4467 CALL DSPLY 0011 C3 402D JP EXIT 0014 BUFFER DS 9 END START DATE 4470 DSPLY 4467 EXIT 402D BUFFER 0014 CR 000D START 0000 All of the internal program addresses have been assembled as if the program had an origin of 0000H and are noted with a following single quote This is relocation at work The binary output of this assembly a REL file cannot be executed by the Z80 until you choose an origin for the progra
10. CII assembler source file using Z80 mnemonics Invoke UNREL with the syntax UNREL infile REL outfile ASM infile Is the filename of the REL module If the extension is omitted REL will be assumed Z80 assembler file If omitted then ainfile ASM will be used Ifoutfile is entered without an extension ASM will be assumed The source drive will be used unlessoutfile includes a drive specification outfile Is the name to be used for the output The action of UNREL is to take a binary REL file which looks like this when displayed in hexadecimal 8091D15391D494204505345548194149154D155205504F494E5481131253 916054C494E454281931253915091A0553455458598194D455161654A064 44F424F5846819113D1D49412206424F584C494E819113D3125391605584 4454C548156511153152064745545058598151D15516166054E4547484C8 152131191116034444548115925155E06475250434C3180D0D314E500001 into a form more usable by your MRAS or M80 assembler an ASCII file such as the following GENGRP ASM 1 NAME GENGRP EXTRN BAKCLR CLIPP DCOMPR DOWNC FCERR FETCHC FORCLR GRPACX EXTRN GKPACY GXPOS GYPOS ICOMP LEFTC LINSTL MAPXYC MAXDEL EXTRN MAXUPD MINDEL MINUPD NSETCX PGRPCX PGRPC READC RIGHTC EXTRN SCALXY SCNCRD SEEGRP SETATR SETC STOREC UPC VIEWMP EXTRN VXLEFT VXRGHT VYLEFT VYRGHT XCHGAC XCHGX XCHGY PUBLIC BOXLLN CLS DDT DOBOXF DOGRPH DOLINE GETPXY
11. PUBLIC GRPCL1 HLFDE LINE LINEB LINEBF NEGHL POINT PUBLIC PSET SETXY SETXYR VIEW XDELT YDELT CSEG SETXYR PUSH DE PUSH HL LD HL GRPACX LD PGRPCX HL UNREL TM REL to ASM translator EX SP HL LD E HL INC HL LD D HL POP HL ADD HL DE LD GRPACX HL LD GXPOS HL LD HL GRPACY LD PCRPCY HL EX SP HL LD E HL INC HL LD D HL POP HL ADD HL DE LD GRPACY HL LD GYPOS HL RET SETXY The example above incidentally is from the graphics library GRPLIB REL which is distributed with Tandy s hi res graphics board This miraculous transformation is made possible by the UNREL utility Of course there are limitations First UNREL makes the assumptions that anything in a code segment is code and anything in a data segment is data Those of you already having experience with object code disassemblers know that decoders can sometimes get fooled by data being interpreted as code With object module REL files this problem still exists However if good programming practices such as segregation of code and data have been followed by the original programmer of the REL module your decoding job is simpler Second UNREL supports only the following special link items SLI O entry symbol 1 select common block 2 program name 3 request library search 5 define common size 6 chain external 7 define entry point 9 externtoffset 10 define data size
12. TRY point is identified by its name 1 to 7 ASCII characters although some releases of M80 L80 support only 1 6 and its relative location within one of the module s code data or common segments Each EXTERNAL reference is identified by its name and also by a chain or linked list of pointers each of which locates the relative address within the module where the external was used The last pointer in the chain is zero The REL file also contains internal relocation data necessary for resolution of label references within the module All external and internal relocatable references are changed to absolute values at link time when the program s segment origins have been established The remainder of the information in the REL file consists of absolue code and data bytes which do not need relocation and numerous other fields which describe common blocks the module name the module segment lengths and the REL file end or EOF byte A library file would contain many such modules each separated by program end indicators and terminated by an EOF byte Let s take one Last look at our example modified slightly to see what the relocatable object file assembled from this source code would look like NAME TEST 4470 QDATE EQU 4470H 402D QEXIT EQU 402DH 4467 QDSPLY EQU 4467H 000D CR EQU ODH CSEG code starts here ENTRY START EXT MESSAGE 0000 21 0000 START LD HL BUFFER 0003 CD 4470 CALL DATE 0006 3E OD LD A CR 0008 32 0008 LD
13. UNREL TM REL to ASM translator Table of Contents General Information 22 eee eee 1 UNREL Convert REL to ASM 2 DECODREL Generate a REL bit stream map 6 SPLITLIB Split library into files 8 Technical Specifications 9 Warranty and Customer Support 16 UNREL TM User Manual Copyright C 1987 MISOSYS Inc All rights reserved Published by MISOSYS Inc PO BOX 239 Sterling VA 22170 0239 The distribution and sale of this program s is intended for the personal use of the original purchaser only and for use only on the computer system noted herein Furthermore copying duplicating selling or otherwise distributing copies of this product is expressly forbidden In accepting this product the purchaser recognizes and accepts this agreement The purchaser is entitled to make as many working copies of this disk as is needed for his or her personal use UNREL DEDCODREL SPLITLIB Copyright O 1986 7Riclin Computer Products All rights reserved CP M is a trademark of Digital Research Incorporated LDOS is a trademark of MISOSYS Inc LS DOS a trademark of Logical Systems Incorporated Microsoft is a trademark of Microsoft Corporation General This product can be used to aid in the conversion ofrelocatable object modules to a Z80 source code file It consists of three utilities UNREL DECODREL and SPLLTLIB UNREL will decode a relocatable object
14. ave been processed Define Data Size The VALUE field is used by the linker to establish the size of the data segment of the current module Set Location Counter The location counter is set to the value identified by the VALUE field Chain Address The VALUE field contains thethe head pointer of a linked list each entry in the list is to be replaced by the current value of the location counter Chain address is generated by one pass assemblers or compilers to have the linkerfixup forward references Define Code Size The VALUE field is used by the linker to establish the size of the code segment of the current module UNREL TM REL to ASM translator 1110 End of Module The VALUE field defines the transfer address for the module if other than absolute zero This item denotes the end of the module The bit stream is also advanced to a byte boundary Recycle to 1 if loading a module from other than a library search 1111 End of File This is used to indicate the end of the file It is used when searching libraries or when loading modules to detect the end of the file Warranty This software program s is warranted to perform as documented when used on the specified hardware operating under the specified disk operating system as shown on the accompanying documentation If within 90 days of the date of purchase the program is found to be defective due to a bug in the code the publisher will upon request provide a patc
15. cribes the structure of an M80 compatiblerelocatable object module That section should UNREL TM REL to ASM translator be reviewed if you are either unfamiliar with that format or have at most read only sketchy details of the format If you would prefer the DECODREL analysis to include information on the entire REL module bit stream the preceding command invocation would be changed to DECODREL F TESTMOD ALLDATA This example also illustrates the specification of dutfile The following analysis is generated to the file named ALLDATA RMP 0000 7 Program name 02 TESTMO 0007 5 Data area size 0A Absolute O 000D 000A 4 Program size 0D Program relative 1 0009 000D 3 Set counter 0B Program relative 1 0000 0010 2 0000 Absolute item 21 0011 1 0001 Data relative 2 0000 0014 6 0003 Absolute item 3E 0015 5 0004 Absolute item OA 0016 4 0005 Absolute item EF 0017 3 0006 Absolute item C3 0018 2 0007 Absolute item 00 0019 1 0008 Absolute item 00 001A 0 Set counter 0B Data relative 92 0000 001E 7 0000 Absolute item 48 OO1F 6 0001 Absolute item 65 0020 5 0002 Absolute item 6C 0021 4 0003 Absolute item 6C 0022 3 0004 Absolute item 6F 0023 2 0005 Absolute item 20 0024 1 0006 Absolute item 77 0025 0 0007 Absolute item 6F 0027 7 0008 Absolute item 72 0028 6 0009 Absolute item 6C 0029 5 000A Abs
16. e an accurate representation of the original code This is to be expected Also UNREL will group all code segments into one single code segment Similarly all data segments will be grouped into one This does not effect the logic of the original source code UNREL can work properly only ona single module don t expect it to produce meaningful output if you try to tnrel a library composed of more than one module If you have the MISOSYS librarian for M 80 type REL files MLIB ora CP M librarian such as LIB80 or LIB you can easily pull apartrelocatable libraries into their individual module members and then translate the associated modules into ASM source Without the resources of a librarian you may be able to split a library into single modules with the SPLITLIB utility provided as part of this package UNREL TM REL to ASM translator DECODREL REL bit stream analysis The DECODREL utility generates an analysis of the bit stream of a REL file This can be used to more fully understand the actual bit stream DECODREL is invoked with the syntax DECODREL f infile REL outfile RMP f Flag used to designate a FULL output versus a brief output DECODREL will default to brief Specify f for a FULL report infile Is the filename of the REL module If the extension is omitted REL will be assumed outfile Is the name to be used for the output analysis file If omitted Then nfile RMP will be
17. h to correct the bug or will update the program diskette with a corrected copy within a reasonable time period after return of the program diskette to the publisher If within 90 days of the date of purchase the documentation proves defective due to missing pages the publisher will provide substitutes for the missing pages upon request The publisher shall have no liability or responsibility to the purchaser or any other person company or entity with respect to any liability loss or damage caused or alleged to have been caused by this product including but not Limited to any interruption of service loss of business and anticipatory profits or consequential damages resulting from the operation or use of this program Customer Support Customer service information on this product may be acquired by contacting MYSOSYS Inc at the following address MYSOSYS Inc P O Box 239 Sterling Virginia 22170 0239 703 450 4181
18. m this is done by a utility known as a LINKER and can be ANY address in the Z80 memory space The linker will determine from the origin you have selected where START and BUFFER really will be when the program is run If you choose 0100H as the origin then START will be located at 0100H and BUFFER at 0114H Other origins will produce similar results START and BUFFER will be at different addresses but the offset between them 0014H will always be the same This characteristic of relocatable object files that they can be LINKED at any origin is extended by a further capability relocatable object files may be linked TOGETHER to form a complete program from many smaller pieces This allows you to write a very large program in lesser chunks which are easier to edit and to understand In addition you can develop libraries of standard and useful subroutines each thoroughly tested and debugged which any main program may call upon when necessary The Microsoft FORTRAN library FORLIB REL for example thus contains many subroutines which can be used by any FORTRAN or Z80 assembler program The mechanism of program and subroutine linkage that is often used is implemented by the ENTRY and EXTERNAL attributes A label which is declared ENTRY or GLOBAL or PUBLIC in one module can be accessed by another module in the following way UNREL TM REL to ASM translator Module 1 ENTRY LABEL1 this is an entry point LABEL1 lt code follows
19. module which has been assembled by either Microsoft s M80 or MISOSYS MRAS assemblers The output is an assembler source file compatible with MRAS and one which should also be equally usable with M80 DECODREL can be used to obtain a bit stream analysis of a REL module or library Finally SPLITLIB can be used to break a large REL library into smaller pieces suitable for loading into memory constrained REL Librarians so that your librarian can extract single modules to be UNRELed This documentation provides information on both the UNREL T80 product usable on a TRS 80 with either LDOS TM 5 x or LS DOS TM 6 x and the UNREL CP M product usable with CP M 2 x or 3 x Although file specifications are shown in this document in the form filename gxt d under CP M this will be assumed to represent the form d filename ext The CP M version requires a Z80 based computer UNREL TM REL to ASM translator The files on the accompanying DATA diskette may be easily copied to your working SYSTEM disk by means of the DOS COPY or PIP utility There may be a file named README TXT on the disk If so that file will contain important information which may not appear in this printed documentation You should read this file by issuing the command LIST README or TYPE README TXT UNREL REL to ASM translator UNREL will decode a relocatable object module which has been assembled by either Microsoft s M80 or MISOSYS MRAS assemblers The output is an AS
20. olute item 64 002A 4 000B Absolute item 21 002B 3 000C Absolute item OD 002C 2 Chain external 06 Program relative 1 0007 NEXT 0034 6 End program OE Program relative 1 0000 0038 7 End file OF This analysis includes the segment relative address of each item being presented followed by the standard segment indicator character UNREL TM REL to ASM translator SPLITLIB REL library splitter Librarians which work by loading a REL library into a memory buffer may limit the size of the library it can deal with This is the case with MLIB To overcome this limitation SPLITLIB can be used to split a large library file into two or more smaller files SPLITLIB is invoked with the syntax SPLITLIB infile REL maxlength drivespec infile Is the filename of the REL library If the extension is omitted REL will be assumed maxlength Is the maximum length of an output file in bytes The module currently being output will be continued to it s module end which will be followed by an end file byte X 9E Maxlength must be in the range lt 100 32767 drivespec This designates the drive to which the file partitions will be written If omitted the drive specified with Anfile will be used Each output partition will be named i nfile Rxx kx being 01 02 for the first second etc pa
21. rtitions Let s say we have a library named GRPLIB that we wish to split The following example illustrates splitting this library file into pieces approximately 6000 bytes in length slibd grplib 7 6000 1 SPLITLIB Split REL Library Version 1 0a Copyright 1986 Riclin Computer Products All rights reserved Reading input file GRPLIB REL 7 Writing output file GRPLIB RO1 1 Module ADVGRP Module GENGRP Writing output file GRPLIB RO2 1 Module TRSGRP This example illustrates how SPLITLIB informs you of the file it is reading the output files being generated and the modules being written to each output file partition If the last module of the source file being written to the last output partition results in a partition size exceedingnaxlength another file of NULL length will be generated This NULL file can be ignored UNREL TM REL to ASM translator Technical specifications This section describes the relocatable bit stream of a Microsoftrelocatable object module We do not intend this section to be an authority on the subject however its discussion accurately portrays our interpretation of the documentation appearing in the literature presented by Microsoft Microsoft compatible REL format All Z80 assemblers work in a similar fashion in that they convert a file containing SOURCE CODE written in Z80 assembly language mnemonics to OBJECT CODE in some binary format In ABSOLUTE assemblers this binary data is a
22. rts here BUFFER DS 9 0000 END START DATE 4470 DSPLY 4467 EXIT 402D BUFFER 0000 CR 000D START 0000 Notice how the label BUFFER is now located at 0000H but in the data segment as indicated by the double quote following the address An linker session illustrated with MLINK commands could then be as follows with user entries in BOLDFACE DOS Ready MLINK MLINK Ver 1 0a Copyright 1985 MISOSYS Inc All rights reserved p 100 d 1000 test 27937 Free space UNREL TM REL to ASM translator P lt 0100 0113 0014 gt D lt 1000 1008 0009 gt test n e DOW Ready The p command to the linker established the program or code segment origin while the d command did the same for the data segment After loading TEST REL with the next command the linker then tells us where the two segments are located and how long they are The final command writes out an executable command file CMD If we were to disassemble TEST CMD we would find that START is located at 0100H and BUFFER at 1000H Thus the program is separated into ROM and RAM sections Relocatable assemblers and linkers have other capabilities such as the use of COMMON blocks You can also generate absolute code if you use the ASEG pseudo op Finally we get to the actual format of a Microsoftrelocatable object file A REL file is composed of a bit not byte stream Each REL file may contain a table of ENTRY points and EXTERNAL references Each EN
23. to 1 The Special Link items are as follows 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 indicates an entry symbol This is used by the linker only when searching a library to see if the module is needed to satisfy an undefined extern Select Common Block Used to specify the NAMEd Common Block for subsequent common relative references Module name This is the name of the module The first one encountered is saved by MLINK for use in generating the optional HEADER record of the CMD file Request Library Search The library designated by the NAME field will be searched to resolve undefined externals prior to any object code generation An REL will be first assumed If one is not found an IRL will then be assumed This item is reserved by Microsoft Define Common Size This is used by MLZNK to establish the size of the common block designated by the NAME field Chain External The VALUE field contains a pointer to the head of a chain which ends with an absolute zero Each 16 bit element of the chain will be replaced with the value of the external symbol described in the NAME field Define Entry Point The VALUE field specifies the value of the symbol described by the NAME field This item is reserved by Microsoft External plus Offset This specifies that the VALUE field must be added to the following two bytes in the current segment after all chain externals h
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