as86

as86(1)                     General Commands Manual                    as86(1)



NAME
       as86 - Assembler for 8086..80386 processors

SYNOPSIS
       as86 [-0123agjuw] [-lm[list]] [-n name] [-o obj] [-b[bin]] [-s sym]
       [-t textseg] src

       as86_encap prog.s prog.v [prefix_] [as86_options]


DESCRIPTION
       as86 is an assembler for the 8086..80386 processors, it's syntax is
       closer to the intel/microsoft form rather than the more normal generic
       form of the unix system assembler.

       The src file can be '-' to assemble the standard input.

       This assembler can be compiled to support the 6809 cpu and may even
       work.

       as86_encap is a shell script to call as86 and convert the created
       binary into a C file prog.v to be included in or linked with programs
       like boot block installers.  The prefix_ 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 include prefix_start
       prefix_size and prefix_data to define and contain the code, plus
       integers containing the values of all exported labels.  Either or both
       the prog.s and prog.v arguments can be '-' for standard in/out.



OPTIONS
       -0     start with 16-bit code segment, warn for all instructions > 8086

       -1     start with 16-bit code segment, warn for all instructions >
              80186

       -2     start with 16-bit code segment, warn for all instructions >
              80286

       -3     start with 32-bit code segment, don't warn for any instructions.
              (not even 486 or 586)

       -a     enable partial compatibility with Minix asld. This swaps the
              interpretation of round brackets and square brackets as well as
              making alterations to the code generation and syntax for 16bit
              jumps and calls. ("jmp @(bx)" is then a valid instruction)

       -g     only put global symbols in object or symbol file

       -j     replace all short jumps with similar 16 or 32 bit jumps, the 16
              bit conditional branches are encoded as a short conditional and
              a long unconditional branch.

       -O     this causes the assembler to add extra passes to try to use
              forward references to reduce the bytes needed for some
              instructions.  If the labels move on the last pass the assembler
              will keep adding passes until 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 explicit br bmi bcc style
              opcodes for 8086 code or the jmp near style for conditional i386
              instructions and make sure all variables are defined before they
              are used.

       -l     produce list file, filename may follow

       -m     print macro expansions in listing

       -n     name of module follows (goes in object instead of source name)

       -o     produce object file, filename follows

       -b     produce a raw binary file, filename may follow.  This is a 'raw'
              binary file with no header, if there's no -s option the file
              starts at location 0.

       -s     produce an ASCII symbol file, filename follows.  The format of
              this table is designed to be easy to parse for encapsulation and
              related activities in relation to binary files created with the
              -b option.  If a binary file doesn't start at location zero the
              first two items in the table are the start and end addresses of
              the binary file.

       -u     assume undefined symbols are imported-with-unspecified segment.

       -w-    allow the assembler to print warning messages.

       -t n   move all text segment data in segment n+3.

AS86 SOURCE
       Special characters

       *      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 also displayed 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
              a segment and offset. This means that the way this operator and
              the immediate prefix work are like traditional assemblers.

              Examples:
                   mov     ax,bx
                   jmp     bx
              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.

                   mov ax,#1234
              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 the third option is not strictly consistant but is in place
              mainly for asld compatibility.


                   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 correct but I tend to used the second. :-)

       Conditionals

       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

       LOC    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

       ENTRY  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.

       .ENTER 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.

       .ASCIZ Ascii string copied to output with trailing nul byte.

       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 definition

       Other useful pseudo operations.

       .ALIGN .EVEN
              Alignment

       EQU    Define label

       SET    Define re-definable label

       ORG .ORG
              Set assemble location

       BLOCK  Set assemble location and stack old one

       ENDB   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 is expected to run on (86, 186, 286, 386, 486, 586)
              instructions for cpus later than specified give a warning.

       USE32 [cpu]
              Define default operand size as 32 bit, argument is cpu type the
              code is expected to run on (86, 186, 286, 386, 486, 586)
              instructions for cpus later than specified give a warning. If
              the cpu is not mentioned the assembler ensures it is >= 80386.

       END    End of compilation for this file.

       .WARN  Switch warnings

       .LIST  Listings on/off (1,-1)

       .MACLIST
              Macro listings on/off (1,-1)

       Macros, now working, the general form is like this.

           MACRO sax
              mov ax,#?1
           MEND
           sax(1)


       Unimplemented/unused.

       IDENT  Define object identity string.

       SETDP  Set DP value on 6809

       MAP    Set binary symbol table map number.

       Registers
              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 force the 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) instructions which are shorthands for a short branch
              plus a long jump and 'BR' which is 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 BVS BR

       Intersegment
              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 ORB OUTB 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 CALL CBW CDQ CLC CLD CLI CLTS CMC CMP CMPS CMPSB CMPSD CMPSW
              CMPW CMPXCHG CSEG CWD CWDE DAA DAS DEC DIV DSEG ENTER HLT IDIV
              IMUL IN INC INS INSB INSD INSW INT INTO INVD INVLPG INW IRET
              IRETD J JA JAE JB JBE JC JCXE JCXZ JE JECXE JECXZ JG JGE JL JLE
              JMP JNA JNAE JNB JNBE JNC JNE JNG JNGE JNL JNLE JNO JNP JNS JNZ
              JO JP JPE JPO JS JZ LAHF LAR LDS LEA LEAVE LES LFS LGDT LGS LIDT
              LLDT LMSW LOCK LODB LODS LODSB LODSD LODSW LODW LOOP LOOPE
              LOOPNE LOOPNZ LOOPZ LSL LSS LTR MOV MOVS MOVSB MOVSD MOVSW MOVSX
              MOVW MOVZX MUL NEG NOP NOT OR OUT OUTS OUTSB OUTSD OUTSW OUTW
              POP POPA POPAD POPF POPFD PUSH PUSHA PUSHAD PUSHF PUSHFD RCL RCR
              RDMSR REP REPE REPNE REPNZ REPZ RET RETF RETI ROL ROR SAHF SAL
              SAR SBB SCAB SCAS SCASB SCASD SCASW SCAW SEG SETA SETAE SETB
              SETBE SETC SETE SETG SETGE SETL SETLE SETNA SETNAE SETNB SETNBE
              SETNC SETNE SETNG SETNGE SETNL SETNLE SETNO SETNP SETNS SETNZ
              SETO SETP SETPE SETPO SETS SETZ SGDT SHL SHLD SHR SHRD SIDT SLDT
              SMSW STC STD STI STOB STOS STOSB STOSD STOSW STOW STR SUB TEST
              VERR VERW WAIT WBINVD WRMSR XADD XCHG XLAT XLATB XOR

       Floating point
              F2XM1 FABS FADD FADDP FBLD FBSTP FCHS FCLEX FCOM FCOMP FCOMPP
              FCOS FDECSTP FDISI FDIV FDIVP FDIVR FDIVRP FENI FFREE FIADD
              FICOM FICOMP FIDIV FIDIVR FILD FIMUL FINCSTP FINIT FIST FISTP
              FISUB FISUBR FLD FLD1 FLDL2E FLDL2T FLDCW FLDENV FLDLG2 FLDLN2
              FLDPI FLDZ FMUL FMULP FNCLEX FNDISI FNENI FNINIT FNOP FNSAVE
              FNSTCW FNSTENV FNSTSW FPATAN FPREM FPREM1 FPTAN FRNDINT FRSTOR
              FSAVE FSCALE FSETPM FSIN FSINCOS FSQRT FST FSTCW FSTENV FSTP
              FSTSW FSUB FSUBP FSUBR FSUBRP FTST FUCOM FUCOMP FUCOMPP FWAIT
              FXAM FXCH FXTRACT FYL2X FYL2XP1

Using GASP
       The Gnu assembler preprocessor provides some reasonable implementations
       of user biased pseudo opcodes.

       It can be invoked in a form similar to:

       gasp   [-a...]  file.s [file2.s] |
              as86 [...]  - [-o obj] [-b bin]

       Be aware though that Gasp generates an error for .org commands, if
       you're not using alternate syntax you can use org instead, otherwise
       use block and endb.  The directive export is translated into .global,
       which forces an import, if you are making a file using -b use public or
       .define instead.

       The GASP list options have no support in as86.

SEE ALSO
       as(1), ld86(1), bcc(1)

BUGS
       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 characters and
       the instruction to cpu checking is not included.

       The checking for instructions that work on specific cpus is probably
       not complete, the distinction between 80186 and 80286 is especially
       problematic.

       The .text and .data pseudo operators are not useful for raw binary
       files.

       When using the org directive the assembler can generate object files
       that may break ld86(1).




                                   Mar, 1999                           as86(1)