MAN page from Mandrake 10.X dev86-0.16.3-2mdk.i586.rpm
Section: User Commands (1)
Updated: Mar, 1999Index
as86 - Assembler for 8086..80386 processors
as86_encap prog.s prog.v[prefix_][as86 options]
is an assembler for the 8086..80386 processors, it's syntax is closerto the intel/microsoft form rather than the more normal generic form ofthe unix system assembler.
Thesrcfile can be '-' to assemble the standard input.
This assembler can be compiled to support the 6809 cpu and may even work.
as86_encapis a shell script to call as86 and convert the created binary into a C fileprog.vto be included in or linked with programs like boot block installers.Theprefix_argument is a prefix to be added to all variables defined by the source,it defaults to the name of the source file. The variables defined includeprefix_startprefix_sizeandprefix_datato define and contain the code, plus integers containing the values of allexported labels.Either or both theprog.sandprog.varguments can be '-' for standard in/out.
- start with 16-bit code segment, warn for all instructions > 8086
- start with 16-bit code segment, warn for all instructions > 80186
- start with 16-bit code segment, warn for all instructions > 80286
- start with 32-bit code segment, don't warn for any instructions. (not even486 or 586)
- enable partial compatibility with Minix asld. This swaps the interpretationof round brackets and square brackets as well as making alterations to thecode generation and syntax for 16bit jumps and calls. ("jmp @(bx)" is thena valid instruction)
- only put global symbols in object or symbol file
- replace all short jumps with similar 16 or 32 bit jumps, the 16 bitconditional branches are encoded as a short conditional and a longunconditional branch.
- this causes the assembler to add extra passes to try to use forwardreferences to reduce the bytes needed for some instructions. If the labels move on the last pass the assembler will keep adding passesuntil the labels all stabilise (to a maximum of 30 passes)It's probably not a good idea to use this with hand written assembler use the explicitbr bmi bccstyle opcodes for 8086 code or thejmp nearstyle for conditional i386 instructions and make sure all variables aredefined before they are used.
- produce list file, filename may follow
- print macro expansions in listing
- name of module follows (goes in object instead of source name)
- produce object file, filename follows
- produce a raw binary file, filename may follow.This is a 'raw' binary file with no header, if there's no-soption the file starts at location 0.
- produce an ASCII symbol file, filename follows.The format of this table is designed to be easy to parse for encapsulationand related activities in relation to binary files created with the-boption. If a binary file doesn't start at location zero the first twoitems in the table are the start and end addresses of the binary file.
- assume undefined symbols are imported-with-unspecified segment.
- allow the assembler to print warning messages.
- -t n
- move all text segment data in segment n+3.
- Address of the start of the current line.
- ; !
- Either of these marks the start of a comment. In addition any 'unexpected'character at the start of a line is assumed to be a comment (but it's alsodisplayed to the terminal).
- Prefix for hexadecimal numbers, the 'C' syntax, eg 0x1234, is also accepted.
- Prefix for binary numbers.
- Prefix for immediate operands.
- [ ]
- Specifies an indirect operand.
Unlike MASM the assembler has no type information on labels just asegment and offset. This means that the way this operator and theimmediate prefix work are like traditional assemblers.
Direct register addressing, the jump copies BX into PC.
mov ax,[bx] jmp [bx]Simple indirect register addressing, the jump moves the contents of the location specified by BX into the PC.
Immediate value, ax becomes 1234.
mov ax,1234 mov ax,_hello mov ax,[_hello]Absolute addressing, ax is set to contents of location 1234. Note thethird option is not strictly consistant but is in place mainly for asldcompatibility.
mov ax,_table[bx] mov ax,_table[bx+si] mov eax,_table[ebx*4] mov ax,[bx+_table] mov ax,[bx+si+_table] mov eax,[ebx*4+_table]Indexed addressing, both formats are ok, I think the first is more correctbut I tend to used the second. :-)
- IF, ELSE, ELSEIF, ENDIF
- Numeric condition
- IFC, ELSEIFC
- String compare (str1,str2)
- FAIL .FAIL
- Generate user error.Segment related
- .TEXT .ROM .DATA .BSS
- Set current segment. These can be preceded by the keyword.SECT
- Set numeric segment 0=TEXT, 3=DATA,ROM,BSS, 14=MAX. The segment order set by the linker is now 0,4,5,6,7,8,9,A,B,C,D,E,1,2,3.Segment 0 and all segments above 3 are assumed to be text segment.Note the 64k size restrictions are not imposed for segments 3-14.Label type definition
- EXPORT PUBLIC .DEFINE
- Export label defined in this object
- Force linker to include the specified label in a.out
- .GLOBL .GLOBAL
- Define label as external and force import even if it isn't used.
- EXTRN EXTERN IMPORT .EXTERN
- Import list of externally defined labels
NB: It doesn't make sense to use imports for raw binary files.
- Mark entry for old binary file (obs)Data definition
- DB .DATA1 .BYTE FCB
- List of 1 byte objects.
- DW .DATA2 .SHORT FDB .WORD
- List of 2 byte objects.
- DD .DATA4 .LONG
- List of 4 byte objects.
- .ASCII FCC
- Ascii string copied to output.
- Ascii string copied to output with trailingnulbyte.Space definition
- .BLKB RMB .SPACE
- Space is counted in bytes.
- .BLKW .ZEROW
- Space is counted in words. (2 bytes each)
- COMM .COMM LCOMM .LCOMM
- Common area data definitionOther useful pseudo operations.
- .ALIGN .EVEN
- Define label
- Define re-definable label
- ORG .ORG
- Set assemble location
- Set assemble location and stack old one
- Return to stacked assemble location
- GET INCLUDE
- Insert new file (no quotes on name)
- USE16 [cpu]
- Define default operand size as 16 bit, argument is cpu type the code isexpected to run on (86, 186, 286, 386, 486, 586) instructions for cpuslater than specified give a warning.
- USE32 [cpu]
- Define default operand size as 32 bit, argument is cpu type the code isexpected to run on (86, 186, 286, 386, 486, 586) instructions for cpuslater than specified give a warning. If the cpu is not mentioned theassembler ensures it is >= 80386.
- End of compilation for this file.
- Switch warnings
- Listings on/off (1,-1)
- Macro listings on/off (1,-1)Macros, now working, the general form is like this.
- Define object identity string.
- Set DP value on 6809
- Set binary symbol table map number.
BP BX DI SI
EAX EBP EBX ECX EDI EDX ESI ESP
AX CX DX SP
AH AL BH BL CH CL DH DL
CS DS ES FS GS SS
CR0 CR2 CR3 DR0 DR1 DR2 DR3 DR6 DR7
TR3 TR4 TR5 TR6 TR7 ST
- Operand type specifiers
- BYTE DWORD FWORD FAR PTR PWORD QWORD TBYTE WORD NEAR
The 'near and 'far' do not allow multi-segment programming, all 'far'operations are specified explicitly through the use of the instructions:jmpi, jmpf, callf, retf, etc. The 'Near' operator can be used to forcethe use of 80386 16bit conditional branches. The 'Dword' and 'word' operators can control the size of operands on far jumps and calls.
- General instructions.
- These are in general the same as the instructions found in any 8086 assembler,the main exceptions being a few 'Bcc' (BCC, BNE, BGE, etc) instructionswhich are shorthands for a short branch plus a long jump and 'BR' whichis the longest unconditional jump (16 or 32 bit).
- Long branches
- BCC BCS BEQ BGE BGT BHI BHIS BLE BLO BLOS BLT BMI BNE BPC BPL BPS BVC BVSBR
- CALLI CALLF JMPI JMPF
- Segment modifier instructions
- ESEG FSEG GSEG SSEG
- Byte operation instructions
- ADCB ADDB ANDB CMPB DECB DIVB IDIVB IMULB INB INCB MOVB MULB NEGB NOTB ORBOUTB RCLB RCRB ROLB RORB SALB SARB SHLB SHRB SBBB SUBB TESTB XCHGB XORB
- Standard instructions
- AAA AAD AAM AAS ADC ADD AND ARPL BOUND BSF BSR BSWAP BT BTC BTR BTS CALLCBW CDQ CLC CLD CLI CLTS CMC CMP CMPS CMPSB CMPSD CMPSW CMPW CMPXCHGCSEG CWD CWDE DAA DAS DEC DIV DSEG ENTER HLT IDIV IMUL IN INC INS INSBINSD INSW INT INTO INVD INVLPG INW IRET IRETD J JA JAE JB JBE JC JCXEJCXZ JE JECXE JECXZ JG JGE JL JLE JMP JNA JNAE JNB JNBE JNC JNE JNG JNGEJNL JNLE JNO JNP JNS JNZ JO JP JPE JPO JS JZ LAHF LAR LDS LEA LEAVE LESLFS LGDT LGS LIDT LLDT LMSW LOCK LODB LODS LODSB LODSD LODSW LODW LOOPLOOPE LOOPNE LOOPNZ LOOPZ LSL LSS LTR MOV MOVS MOVSB MOVSD MOVSW MOVSXMOVW MOVZX MUL NEG NOP NOT OR OUT OUTS OUTSB OUTSD OUTSW OUTW POP POPAPOPAD POPF POPFD PUSH PUSHA PUSHAD PUSHF PUSHFD RCL RCR REP REPE REPNEREPNZ REPZ RET RETF RETI ROL ROR SAHF SAL SAR SBB SCAB SCAS SCASB SCASDSCASW SCAW SEG SETA SETAE SETB SETBE SETC SETE SETG SETGE SETL SETLESETNA SETNAE SETNB SETNBE SETNC SETNE SETNG SETNGE SETNL SETNLE SETNOSETNP SETNS SETNZ SETO SETP SETPE SETPO SETS SETZ SGDT SHL SHLD SHR SHRDSIDT SLDT SMSW STC STD STI STOB STOS STOSB STOSD STOSW STOW STR SUB TESTVERR VERW WAIT WBINVD XADD XCHG XLAT XLATB XOR
- Floating point
- F2XM1 FABS FADD FADDP FBLD FBSTP FCHS FCLEX FCOM FCOMP FCOMPP FCOSFDECSTP FDISI FDIV FDIVP FDIVR FDIVRP FENI FFREE FIADD FICOM FICOMPFIDIV FIDIVR FILD FIMUL FINCSTP FINIT FIST FISTP FISUB FISUBR FLD FLD1FLDL2E FLDL2T FLDCW FLDENV FLDLG2 FLDLN2 FLDPI FLDZ FMUL FMULP FNCLEXFNDISI FNENI FNINIT FNOP FNSAVE FNSTCW FNSTENV FNSTSW FPATAN FPREMFPREM1 FPTAN FRNDINT FRSTOR FSAVE FSCALE FSETPM FSIN FSINCOS FSQRT FSTFSTCW FSTENV FSTP FSTSW FSUB FSUBP FSUBR FSUBRP FTST FUCOM FUCOMPFUCOMPP FWAIT FXAM FXCH FXTRACT FYL2X FYL2XP1
The Gnu assembler preprocessor provides some reasonable implementationsof user biased pseudo opcodes.
It can be invoked in a form similar to:
as86[...]-[-o obj] [-b bin]Be aware though that Gasp generates an error for .orgcommands, if you're not using alternate syntax you can use orginstead, otherwise use blockandendb.The directiveexportis translated into.global,which forces an import, if you are making a file using-busepublicor .defineinstead.
The GASP list options have no support in as86.
The 6809 version does not support -0, -3, -a or -j.
If this assembler is compiled with BCC this is classed as a 'small'compiler, so there is a maximum input line length of 256 charactersand the instruction to cpu checking is not included.
The checking for instructions that work on specific cpus is probablynot complete, the distinction between 80186 and 80286 is especiallyproblematic.
The.textand.datapseudo operators are not useful for raw binary files.
When using theorgdirective the assembler can generate object files that may break ld86(1).
- AS86 SOURCE
- Using GASP
- SEE ALSO
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