freepascal.compiler/compiler/rai386.pas

{
    $Id$
    Copyright (c) 1997-98 by Carl Eric Codere

    Does the parsing process for the intel styled inline assembler.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 ****************************************************************************
}
Unit Rai386;

{**********************************************************************}
{ WARNING                                                              }
{**********************************************************************}
{  Any modification in the order or removal of terms in the tables     }
{  in i386.pas and intasmi3.pas will BREAK the code in this unit,      }
{  unless the appropriate changes are made to this unit. Addition      }
{  of terms though, will not change the code herein.                   }
{**********************************************************************}

{--------------------------------------------------------------------}
{ LEFT TO DO:                                                        }
{--------------------------------------------------------------------}
{ o Add support for floating point opcodes.                          }
{ o Handle module overrides also... such as crt.white or             }
{    crt.delay and local typed constants.                            }
{ o Handle label references                                          }
{ o Add support for TP styled segment overrides, when the opcode     }
{    table will be completed.                                        }
{ o Add imul,shld and shrd support with references and CL            }
{    i386.pas requires to be updated to do this.                     }
{ o Support for (* *) tp styled comments, this support should be     }
{   added in asmgetchar in scanner.pas (it cannot be implemented     }
{   here without causing errors such as in :                         }
{   (* "openbrace" AComment *)                                       }
{   (presently an infinite loop will be created if a (* styled       }
{    comment is found).                                              }
{ o Bugfix of ao_imm8s for IMUL. (Currently the 3 operand imul will  }
{   be considered as invalid because I use ao_imm8 and the table     }
{   uses ao_imm8s).                                                  }
{--------------------------------------------------------------------}

Interface

uses
  tree,i386;

   function assemble: ptree;

const
 { this variable is TRUE if the lookup tables have already been setup  }
 { for fast access. On the first call to assemble the tables are setup }
 { and stay set up.                                                    }
 _asmsorted: boolean = FALSE;
 firstreg       = R_EAX;
 lastreg        = R_ST7;

type
 tiasmops = array[firstop..lastop] of string[7];
 piasmops = ^tiasmops;

var
 { sorted tables of opcodes }
 iasmops: piasmops;
 { uppercased tables of registers }
 iasmregs: array[firstreg..lastreg] of string[6];


Implementation

Uses
  aasm,globals,AsmUtils,strings,hcodegen,scanner,
  cobjects,verbose;


type
 tinteltoken = (
   AS_NONE,AS_LABEL,AS_LLABEL,AS_STRING,AS_HEXNUM,AS_OCTALNUM,
   AS_BINNUM,AS_COMMA,AS_LBRACKET,AS_RBRACKET,AS_LPAREN,
   AS_RPAREN,AS_COLON,AS_DOT,AS_PLUS,AS_MINUS,AS_STAR,AS_INTNUM,
   AS_SEPARATOR,AS_ID,AS_REGISTER,AS_OPCODE,AS_SLASH,
     {------------------ Assembler directives --------------------}
   AS_DB,AS_DW,AS_DD,AS_END,
     {------------------ Assembler Operators  --------------------}
   AS_BYTE,AS_WORD,AS_DWORD,AS_QWORD,AS_TBYTE,AS_NEAR,AS_FAR,
   AS_HIGH,AS_LOW,AS_OFFSET,AS_SEG,AS_TYPE,AS_PTR,AS_MOD,AS_SHL,AS_SHR,AS_NOT,
   AS_AND,AS_OR,AS_XOR);

   tasmkeyword = string[6];
const
   { These tokens should be modified accordingly to the modifications }
   { in the different enumerations.                                   }
   firstdirective = AS_DB;
   lastdirective  = AS_END;
   firstoperator  = AS_BYTE;
   lastoperator   = AS_XOR;
   firstsreg      = R_CS;
   lastsreg       = R_SS;
   { this is a hack to accept all opcodes }
   { in the opcode table.                 }
   { check is done until A_POPFD          }
   { otherwise no check.                  }
   lastop_in_table = A_POPFD;

       _count_asmdirectives = longint(lastdirective)-longint(firstdirective);
       _count_asmoperators  = longint(lastoperator)-longint(firstoperator);
       _count_asmprefixes   = 5;
       _count_asmspecialops = 25;
       _count_asmoverrides  = 3;

       _asmdirectives : array[0.._count_asmdirectives] of tasmkeyword =
       ('DB','DW','DD','END');

       { problems with shl,shr,not,and,or and xor, they are }
       { context sensitive.                                 }
       _asmoperators : array[0.._count_asmoperators] of tasmkeyword = (
        'BYTE','WORD','DWORD','QWORD','TBYTE','NEAR','FAR','HIGH',
        'LOW','OFFSET','SEG','TYPE','PTR','MOD','SHL','SHR','NOT','AND',
        'OR','XOR');

     {------------------ Missing opcodes from std list  ----------------}
       _asmprefixes: array[0.._count_asmprefixes] of tasmkeyword = (
       'REPNE','REPE','REP','REPZ','REPNZ','LOCK');

       _asmoverrides: array[0.._count_asmoverrides] of tasmkeyword =
       ('SEGCS','SEGDS','SEGES','SEGSS');

       _overridetokens: array[0.._count_asmoverrides] of tregister =
       (R_CS,R_DS,R_ES,R_SS);

       _prefixtokens: array[0.._count_asmprefixes] of tasmop = (
       A_REPNE,A_REPE,A_REP,A_REPE,A_REPNE,A_LOCK);

       _specialops: array[0.._count_asmspecialops] of tasmkeyword = (
       'CMPSB','CMPSW','CMPSD','INSB','INSW','INSD','OUTSB','OUTSW','OUTSD',
       'SCASB','SCASW','SCASD','STOSB','STOSW','STOSD','MOVSB','MOVSW','MOVSD',
       'LODSB','LODSW','LODSD','LOCK','SEGCS','SEGDS','SEGES','SEGSS');

       _specialopstokens: array[0.._count_asmspecialops] of tasmop = (
       A_CMPS,A_CMPS,A_CMPS,A_INS,A_INS,A_INS,A_OUTS,A_OUTS,A_OUTS,
       A_SCAS,A_SCAS,A_SCAS,A_STOS,A_STOS,A_STOS,A_MOVS,A_MOVS,A_MOVS,
       A_LODS,A_LODS,A_LODS,A_LOCK,A_NONE,A_NONE,A_NONE,A_NONE);
     {------------------------------------------------------------------}
       { register type definition table for easier searching }
       _regtypes:array[firstreg..lastreg] of longint =
       (ao_reg32,ao_reg32,ao_reg32,ao_reg32,ao_reg32,ao_reg32,ao_reg32,ao_reg32,
       ao_reg16,ao_reg16,ao_reg16,ao_reg16,ao_reg16,ao_reg16,ao_reg16,ao_reg16,
       ao_reg8,ao_reg8,ao_reg8,ao_reg8,ao_reg8,ao_reg8,ao_reg8,ao_reg8,
       ao_none,ao_sreg2,ao_sreg2,ao_sreg2,ao_sreg3,ao_sreg3,ao_sreg2,
       ao_floatacc,ao_floatacc,ao_floatreg,ao_floatreg,ao_floatreg,ao_floatreg,
       ao_floatreg,ao_floatreg,ao_floatreg);

       _regsizes: array[firstreg..lastreg] of topsize =
       (S_L,S_L,S_L,S_L,S_L,S_L,S_L,S_L,
        S_W,S_W,S_W,S_W,S_W,S_W,S_W,S_W,
        S_B,S_B,S_B,S_B,S_B,S_B,S_B,S_B,
        { segment register }
        S_W,S_W,S_W,S_W,S_W,S_W,S_W,
        { can also be S_S or S_T - must be checked at run-time }
        S_Q,S_Q,S_Q,S_Q,S_Q,S_Q,S_Q,S_Q,S_Q);

       _constsizes: array[S_NO..S_S] of longint =
       (0,ao_imm8,ao_imm16,ao_imm32,0,0,0,0,ao_imm32);




const
  newline = #10;
  firsttoken : boolean = TRUE;
  operandnum : byte = 0;
var
 { context for SHL,SHR,AND,NOT,OR,XOR operators }
 { if set to true GetToken will return these    }
 { as operators, otherwise will return these as }
 { opcodes.                                     }
 inexpression: boolean;
 p : paasmoutput;
 actasmtoken: tinteltoken;
 actasmpattern: string;
 c: char;
 Instr: TInstruction;
 labellist: TAsmLabelList;
 old_exit : pointer;


   Procedure SetupTables;
   { creates uppercased symbol tables for speed access }
   var
     i: tasmop;
     j: tregister;
   Begin
     Message(assem_d_creating_lookup_tables);
     { opcodes }
     new(iasmops);
     for i:=firstop to lastop do
      iasmops^[i] := upper(int_op2str[i]);
     { opcodes }
     for j:=firstreg to lastreg do
      iasmregs[j] := upper(int_reg2str[j]);
   end;


    procedure rai386_exit;{$ifndef FPC}far;{$endif}

      begin
         if assigned(iasmops) then
           dispose(iasmops);
         exitproc:=old_exit;
      end;


  {---------------------------------------------------------------------}
  {                     Routines for the tokenizing                     }
  {---------------------------------------------------------------------}


   function is_asmopcode(const s: string):Boolean;
  {*********************************************************************}
  { FUNCTION is_asmopcode(s: string):Boolean                            }
  {  Description: Determines if the s string is a valid opcode          }
  {  if so returns TRUE otherwise returns FALSE.                        }
  {*********************************************************************}
   var
    i: tasmop;
    j: byte;
   Begin
     is_asmopcode := FALSE;
     for i:=firstop to lastop do
     begin
       if  s = iasmops^[i] then
       begin
          is_asmopcode:=TRUE;
          exit;
       end;
     end;
     { not found yet, search for extended opcodes }
     for j:=0 to _count_asmspecialops do
     Begin
       if s = _specialops[j] then
       Begin
         is_asmopcode:=TRUE;
         exit;
       end;
     end;
   end;



   Procedure is_asmdirective(const s: string; var token: tinteltoken);
  {*********************************************************************}
  { FUNCTION is_asmdirective(s: string; var token: tinteltoken):Boolean }
  {  Description: Determines if the s string is a valid directive       }
  { (an operator can occur in operand fields, while a directive cannot) }
  {  if so returns the directive token, otherwise does not change token.}
  {*********************************************************************}
   var
    i:byte;
   Begin
     for i:=0 to _count_asmdirectives do
     begin
        if s=_asmdirectives[i] then
        begin
           token := tinteltoken(longint(firstdirective)+i);
           exit;
        end;
     end;
   end;

   Procedure is_asmoperator(const s: string; var token: tinteltoken);
  {*********************************************************************}
  { FUNCTION  is_asmoperator(s: string; var token: tinteltoken): Boolean}
  {  Description: Determines if the s string is a valid operator        }
  { (an operator can occur in operand fields, while a directive cannot) }
  {  if so returns the operator token, otherwise does not change token. }
  {*********************************************************************}
   var
    i:longint;
   Begin
     for i:=0 to _count_asmoperators do
     begin
        if s=_asmoperators[i] then
        begin
           token := tinteltoken(longint(firstoperator)+i);
           exit;
        end;
     end;
   end;





   Procedure is_register(const s: string; var token: tinteltoken);
  {*********************************************************************}
  { PROCEDURE is_register(s: string; var token: tinteltoken);           }
  {  Description: Determines if the s string is a valid register, if    }
  {  so return token equal to A_REGISTER, otherwise does not change token}
  {*********************************************************************}
   Var
    i: tregister;
   Begin
     for i:=firstreg to lastreg do
     begin
      if s=iasmregs[i] then
      begin
        token := AS_REGISTER;
        exit;
      end;
     end;
   end;




  Function GetToken: tinteltoken;
  {*********************************************************************}
  { FUNCTION GetToken: tinteltoken;                                     }
  {  Description: This routine returns intel assembler tokens and       }
  {  does some minor syntax error checking.                             }
  {*********************************************************************}
  var
   j: integer;
   token: tinteltoken;
   forcelabel: boolean;
   errorflag : boolean;
  begin
    errorflag := FALSE;
    forcelabel := FALSE;
    actasmpattern :='';
    {* INIT TOKEN TO NOTHING *}
    token := AS_NONE;
    { while space and tab , continue scan... }
    while (c in [' ',#9]) do
      c := asmgetchar;
    { Possiblities for first token in a statement:                }
    {   Local Label, Label, Directive, Prefix or Opcode....       }
    if firsttoken and not (c in [newline,#13,'{',';']) then
    begin
      firsttoken := FALSE;
      if c = '@' then
      begin
        token := AS_LLABEL;   { this is a local label }
        { Let us point to the next character }
        c := asmgetchar;
      end;



      while c in ['A'..'Z','a'..'z','0'..'9','_','@'] do
      begin
         { if there is an at_sign, then this must absolutely be a label }
         if c = '@' then forcelabel:=TRUE;
         actasmpattern := actasmpattern + c;
         c := asmgetchar;
      end;

      uppervar(actasmpattern);

      if c = ':' then
      begin
           case token of
             AS_NONE: token := AS_LABEL;
             AS_LLABEL: ; { do nothing }
           end; { end case }
           { let us point to the next character }
           c := asmgetchar;
           gettoken := token;
           exit;
      end;

      { Are we trying to create an identifier with }
      { an at-sign...?                             }
      if forcelabel then
       Message(assem_e_none_label_contain_at);

      If is_asmopcode(actasmpattern) then
      Begin
       gettoken := AS_OPCODE;
       { check if we are in an expression  }
       { then continue with asm directives }
       if not inexpression then
         exit;
      end;
      is_asmdirective(actasmpattern, token);
      if (token <> AS_NONE) then
      Begin
        gettoken := token;
        exit
      end
      else
      begin
         gettoken := AS_NONE;
         Message1(assem_e_invalid_operand,actasmpattern);
      end;
    end
    else { else firsttoken }
    { Here we must handle all possible cases                              }
    begin
      case c of

         '@':   { possiblities : - local label reference , such as in jmp @local1 }
                {                - @Result, @Code or @Data special variables.     }
                            begin
                             actasmpattern := c;
                             c:= asmgetchar;
                             while c in  ['A'..'Z','a'..'z','0'..'9','_','@'] do
                             begin
                               actasmpattern := actasmpattern + c;
                               c := asmgetchar;
                             end;
                             uppervar(actasmpattern);
                             gettoken := AS_ID;
                             exit;
                            end;
      { identifier, register, opcode, prefix or directive }
         'A'..'Z','a'..'z','_': begin
                             actasmpattern := c;
                             c:= asmgetchar;
                             while c in  ['A'..'Z','a'..'z','0'..'9','_'] do
                             begin
                               actasmpattern := actasmpattern + c;
                               c := asmgetchar;
                             end;
                             uppervar(actasmpattern);

                             If is_asmopcode(actasmpattern) then
                             Begin
                                    gettoken := AS_OPCODE;
                                    { if we are not in a constant }
                                    { expression than this is an  }
                                    { opcode.                     }
                                    if  not inexpression then
                                    exit;
                             end;
                             is_register(actasmpattern, token);
                             is_asmoperator(actasmpattern,token);
                             is_asmdirective(actasmpattern,token);
                             { if found }
                             if (token <> AS_NONE) then
                             begin
                               gettoken := token;
                               exit;
                             end
                             { this is surely an identifier }
                             else
                               token := AS_ID;
                             gettoken := token;
                             exit;
                          end;
           { override operator... not supported }
           '&':       begin
                         Message(assem_w_override_op_not_supported);
                         c:=asmgetchar;
                         gettoken := AS_NONE;
                      end;
           { string or character }
           '''' :
                      begin
                         actasmpattern:='';
                         while true do
                         begin
                           if c = '''' then
                           begin
                              c:=asmgetchar;
                              if c=newline then
                              begin
                                 Message(scan_f_string_exceeds_line);
                                 break;
                              end;
                              repeat
                                  if c=''''then
                                   begin
                                       c:=asmgetchar;
                                       if c='''' then
                                        begin
                                               actasmpattern:=actasmpattern+'''';
                                               c:=asmgetchar;
                                               if c=newline then
                                               begin
                                                    Message(scan_f_string_exceeds_line);
                                                    break;
                                               end;
                                        end
                                        else break;
                                   end
                                   else
                                   begin
                                          actasmpattern:=actasmpattern+c;
                                          c:=asmgetchar;
                                          if c=newline then
                                            begin
                                               Message(scan_f_string_exceeds_line);
                                               break
                                            end;
                                   end;
                              until false; { end repeat }
                           end
                           else break; { end if }
                         end; { end while }
                   token:=AS_STRING;
                   gettoken := token;
                   exit;
                 end;
           { string or character }
           '"' :
                      begin
                         actasmpattern:='';
                         while true do
                         begin
                           if c = '"' then
                           begin
                              c:=asmgetchar;
                              if c=newline then
                              begin
                                 Message(scan_f_string_exceeds_line);
                                 break;
                              end;
                              repeat
                                  if c='"'then
                                   begin
                                       c:=asmgetchar;
                                       if c='"' then
                                        begin
                                               actasmpattern:=actasmpattern+'"';
                                               c:=asmgetchar;
                                               if c=newline then
                                               begin
                                                  Message(scan_f_string_exceeds_line);
                                                  break;
                                               end;
                                        end
                                       else break;

                                   end
                                  else
                                   begin
                                          actasmpattern:=actasmpattern+c;
                                          c:=asmgetchar;
                                          if c=newline then
                                            begin
                                               Message(scan_f_string_exceeds_line);
                                               break
                                            end;
                                   end;
                              until false; { end repeat }
                           end
                           else break; { end if }
                         end; { end while }
                   token := AS_STRING;
                   gettoken := token;
                   exit;
                 end;
           '$' :  begin
                    c:=asmgetchar;
                    while c in ['0'..'9','A'..'F','a'..'f'] do
                    begin
                      actasmpattern := actasmpattern + c;
                      c := asmgetchar;
                    end;
                   gettoken := AS_HEXNUM;
                   exit;
                  end;
           ',' : begin
                   gettoken := AS_COMMA;
                   c:=asmgetchar;
                   exit;
                 end;
           '[' : begin
                   gettoken := AS_LBRACKET;
                   c:=asmgetchar;
                   exit;
                 end;
           ']' : begin
                   gettoken := AS_RBRACKET;
                   c:=asmgetchar;
                   exit;
                 end;
           '(' : begin
                   gettoken := AS_LPAREN;
                   c:=asmgetchar;
                   exit;
                 end;
           ')' : begin
                   gettoken := AS_RPAREN;
                   c:=asmgetchar;
                   exit;
                 end;
           ':' : begin
                   gettoken := AS_COLON;
                   c:=asmgetchar;
                   exit;
                 end;
           '.' : begin
                   gettoken := AS_DOT;
                   c:=asmgetchar;
                   exit;
                 end;
           '+' : begin
                   gettoken := AS_PLUS;
                   c:=asmgetchar;
                   exit;
                 end;
           '-' : begin
                   gettoken := AS_MINUS;
                   c:=asmgetchar;
                   exit;
                 end;
           '*' : begin
                   gettoken := AS_STAR;
                   c:=asmgetchar;
                   exit;
                 end;
           '/' : begin
                   gettoken := AS_SLASH;
                   c:=asmgetchar;
                   exit;
                 end;
           '0'..'9': begin
                          { this flag indicates if there was an error  }
                          { if so, then we use a default value instead.}
                          errorflag := false;
                          actasmpattern := c;
                          c := asmgetchar;
                          { Get the possible characters }
                          while c in ['0'..'9','A'..'F','a'..'f'] do
                          begin
                            actasmpattern := actasmpattern + c;
                            c:= asmgetchar;
                          end;
                          { Get ending character }
                          uppervar(actasmpattern);
                          c:=upcase(c);
                          { possibly a binary number. }
                          if (actasmpattern[length(actasmpattern)] = 'B') and (c <> 'H') then
                          Begin
                                  { Delete the last binary specifier }
                                  delete(actasmpattern,length(actasmpattern),1);
                                  for j:=1 to length(actasmpattern) do
                                   if not (actasmpattern[j] in ['0','1']) then
                                   begin
                                       Message1(assem_e_error_in_binary_const,actasmpattern);
                                       errorflag := TRUE;
                                   end;
                                 { if error, then suppose a binary value of zero. }
                                 if errorflag then
                                   actasmpattern := '0';
                                 gettoken := AS_BINNUM;
                                 exit;
                          end
                          else
                          Begin
                             case c of
                              'O': Begin
                                      for j:=1 to length(actasmpattern) do
                                        if not (actasmpattern[j] in ['0'..'7']) then
                                        begin
                                          Message1(assem_e_error_in_octal_const,actasmpattern);
                                          errorflag := TRUE;
                                        end;
                                 { if error, then suppose an octal value of zero. }
                                     if errorflag then
                                        actasmpattern := '0';
                                      gettoken := AS_OCTALNUM;
                                      c := asmgetchar;
                                      exit;
                                    end;
                              'H': Begin
                                      for j:=1 to length(actasmpattern) do
                                        if not (actasmpattern[j] in ['0'..'9','A'..'F']) then
                                        begin
                                          Message1(assem_e_error_in_hex_const,actasmpattern);
                                          errorflag := TRUE;
                                        end;
                                 { if error, then suppose an hex value of zero. }
                                     if errorflag then
                                        actasmpattern := '0';
                                     gettoken := AS_HEXNUM;
                                     c := asmgetchar;
                                     exit;
                                   end;
                              else { must be an integer number }
                               begin
                                    for j:=1 to length(actasmpattern) do
                                     if not (actasmpattern[j] in ['0'..'9']) then
                                     begin
                                         Message1(assem_e_error_in_integer_const,actasmpattern);
                                         errorflag := TRUE;
                                     end;
                                 { if error, then suppose an int value of zero. }
                                     if errorflag then
                                        actasmpattern := '0';
                                     gettoken := AS_INTNUM;
                                     exit;
                              end;
                          end; { end case }
                      end; { end if }
                     end;
    ';','{',#13,newline : begin
                            c:=asmgetchar;
                            firsttoken := TRUE;
                            gettoken:=AS_SEPARATOR;
                           end;
            else
             Begin
               Message(scan_f_illegal_char);
             end;

      end; { end case }
    end; { end else if }
  end;

  {---------------------------------------------------------------------}
  {                     Routines for the output                         }
  {---------------------------------------------------------------------}

   { returns an appropriate ao_xxxx flag indicating the type }
   { of operand.                                             }
   function findtype(Var Opr: TOperand): longint;
   Begin
    With Opr do
    Begin
     case operandtype of
       OPR_REFERENCE:   Begin
                           if assigned(ref.symbol) then
                           { check if in local label list }
                           { if so then it is considered  }
                           { as a displacement.           }
                           Begin
                             if labellist.search(ref.symbol^) <> nil then
                               findtype := ao_disp
                             else
                               findtype := ao_mem; { probably a mem ref. }
                           end
                           else
                            findtype := ao_mem;
                        end;
       OPR_CONSTANT: Begin
                       { check if there is not already a default size }
                       if opr.size <> S_NO then
                       Begin
                          findtype := _constsizes[opr.size];
                         exit;
                       end;
                       if val < $ff then
                       Begin
                         findtype := ao_imm8;
                         opr.size := S_B;
                       end
                       else if val < $ffff then
                       Begin
                         findtype := ao_imm16;
                         opr.size := S_W;
                       end
                       else
                       Begin
                         findtype := ao_imm32;
                         opr.size := S_L;
                       end
                     end;
       OPR_REGISTER: Begin
                      findtype := _regtypes[reg];
                      exit;
                     end;
       OPR_NONE:     Begin
                       findtype := 0;
                     end;
       else
       Begin
         Message(assem_f_internal_error_in_findtype);
       end;
     end;
    end;
   end;



    Procedure ConcatLabeledInstr(var instr: TInstruction);
    Begin
       if (instr.getinstruction in [A_JO,A_JNO,A_JB,A_JC,A_JNAE,
        A_JNB,A_JNC,A_JAE,A_JE,A_JZ,A_JNE,A_JNZ,A_JBE,A_JNA,A_JNBE,
        A_JA,A_JS,A_JNS,A_JP,A_JPE,A_JNP,A_JPO,A_JL,A_JNGE,A_JNL,A_JGE,
        A_JLE,A_JNG,A_JNLE,A_JG,A_JCXZ,A_JECXZ,A_LOOP,A_LOOPZ,A_LOOPE,
        A_LOOPNZ,A_LOOPNE,A_MOV,A_JMP,A_CALL]) then
       Begin
        if instr.numops > 1 then
         Message(assem_e_invalid_labeled_opcode)
        else if instr.operands[1].operandtype <> OPR_LABINSTR then
          Message(assem_e_invalid_labeled_opcode)
        else if (instr.operands[1].operandtype = OPR_LABINSTR) and
         (instr.numops = 1) then
           if assigned(instr.operands[1].hl) then
            ConcatLabel(p,instr.getinstruction, instr.operands[1].hl)
           else
            Message(assem_f_internal_error_in_findtype);
       end
       else if instr.getinstruction = A_MOV then
       Begin
         { MOV to rel8 }
       end
       else
        Message(assem_e_invalid_operand);
    end;




   Procedure HandleExtend(var instr: TInstruction);
   { Handles MOVZX, MOVSX ... }
   var
     instruc: tasmop;
     opsize: topsize;
   Begin
      instruc:=instr.getinstruction;
      { return the old types ..}
      { these tokens still point to valid intel strings, }
      { but we must convert them to TRUE intel tokens    }
      if instruc in [A_MOVSB,A_MOVSBL,A_MOVSBW,A_MOVSWL] then
        instruc := A_MOVSX;
      if instruc in [A_MOVZB,A_MOVZWL] then
        instruc := A_MOVZX;

     With instr do

         Begin
           if operands[1].size = S_B then
           Begin
              if operands[2].size = S_L then
                 opsize := S_BL
              else
              if operands[2].size = S_W then
                 opsize := S_BW
              else
              begin
                 Message(assem_e_invalid_size_movzx);
                 exit;
              end;

           end
           else
           if operands[1].size = S_W then
           Begin
             if operands[2].size = S_L then
                opsize := S_WL
             else
             begin
                 Message(assem_e_invalid_size_movzx);
                 exit;
             end;
           end
           else
           begin
                 Message(assem_e_invalid_size_movzx);
                 exit;
           end;


           if operands[1].operandtype = OPR_REGISTER then
           Begin
              if operands[2].operandtype <> OPR_REGISTER then
               Message(assem_e_invalid_opcode)
              else
                 p^.concat(new(pai386,op_reg_reg(instruc,opsize,
                   operands[1].reg,operands[2].reg)));
           end
           else
           if operands[1].operandtype = OPR_REFERENCE then
           Begin
              if operands[2].operandtype <> OPR_REGISTER then
               Message(assem_e_invalid_opcode)
              else
                 p^.concat(new(pai386,op_ref_reg(instruc,opsize,
                   newreference(operands[1].ref),operands[2].reg)));
           end
     end; { end with }
   end;


  Procedure ConcatOpCode(var instr: TInstruction);
  {*********************************************************************}
  { First Pass:                                                         }
  {       if instr = Lxxx with a 16bit offset, we emit an error.        }
  {       If the instruction is INS,IN,OUT,OUTS,RCL,ROL,RCR,ROR,        }
  {        SAL,SAR,SHL,SHR,SHLD,SHRD,DIV,IDIV,BT,BTC,BTR,BTS,INT,       }
  {        RET,ENTER,SCAS,CMPS,STOS,LODS,FNSTSW,FSTSW.                  }
  {         set up the optypes variables manually, as well as setting   }
  {         operand sizes.                                              }
  { Second pass:                                                        }
  {  Check if the combination of opcodes and operands are valid, using  }
  {  the opcode table.                                                  }
  { Third pass:                                                         }
  {    If there was no error on the 2nd pass  , then we check the       }
  {    following:                                                       }
  {    - If this is a 0 operand opcode                                  }
  {        we verify if it is a string opcode, if so we emit a size also}
  {        otherwise simply emit the opcode by itself.                  }
  {    - If this is a 1 operand opcode, and it is a reference, we make  }
  {      sure that the operand size is valid; we emit the opcode.       }
  {    - If this is a two operand opcode                                }
  {      o if the opcode is MOVSX or MOVZX then we handle it specially  }
  {      o we check the operand types (most important combinations):    }
  {            if reg,reg we make sure that both registers are of the   }
  {             same size.                                              }
  {            if reg,ref or ref,reg we check if the symbol name is     }
  {             assigned, if so a size must be specified and compared   }
  {             to the register size, both must be equal. If there is   }
  {             no symbol name, then we check :                         }
  {                if refsize = NO_SIZE then OPCODE_SIZE = regsize      }
  {                  else if refsize = regsize then OPCODE_SIZE = regsize}
  {                   else error.                                       }
  {                   if no_error emit the opcode.                      }
  {            if ref,const or const,ref if ref does not have any size  }
  {              then error, otherwise emit the opcode.                 }
  {    - If this is a three operand opcode:                             }
  {          imul,shld,and shrd  -> check them manually.                }
  {*********************************************************************}
  var
    fits : boolean;
    i: longint;
    opsize: topsize;
    optyp1, optyp2, optyp3: longint;
    instruc: tasmop;
  Begin
     fits := FALSE;
     for i:=1 to instr.numops do
     Begin
       case instr.operands[i].operandtype of
         OPR_REGISTER: instr.operands[i].size :=
                         _regsizes[instr.operands[i].reg];
       end; { end case }
     end; { endif }
    { setup specific instructions for first pass }
    instruc := instr.getinstruction;
    if (instruc in [A_LEA,A_LDS,A_LSS,A_LES,A_LFS,A_LGS]) then
    Begin
       if instr.operands[1].size <> S_L then
       Begin
         Message(assem_e_16bit_base_in_32bit_segment);
         exit;
       end; { endif }
    end;

    With instr do
    Begin


      for i:=1 to numops do
      Begin
         With operands[i] do
         Begin
         { check for 16-bit bases/indexes and emit an error.   }
         { we cannot only emit a warning since gas does not    }
         { accept 16-bit indexes and bases.                    }
          if (operandtype = OPR_REFERENCE) and
            ((ref.base <> R_NO) or
            (ref.index <> R_NO)) then
            Begin
            { index or base defined. }
              if (ref.base <> R_NO) then
              Begin
                if not (ref.base in
                  [R_EAX,R_EBX,R_ECX,R_EDX,R_EBP,R_ESI,R_EDI,R_ESP]) then
                    Message(assem_e_16bit_base_in_32bit_segment);
              end;
            { index or base defined. }
              if (ref.index <> R_NO) then
              Begin
                  if not (ref.index in
                    [R_EAX,R_EBX,R_ECX,R_EDX,R_EBP,R_ESI,R_EDI,R_ESP]) then
                    Message(assem_e_16bit_index_in_32bit_segment);
              end;
            end;
            { Check for constants without bases/indexes in memory }
            { references.                                         }
            if (operandtype = OPR_REFERENCE) and
               (ref.base = R_NO) and
               (ref.index = R_NO) and
               (ref.symbol = nil) and
               (ref.offset <> 0) then
               Begin
                 ref.isintvalue := TRUE;
                 Message(assem_e_const_ref_not_allowed);
               end;

              opinfo := findtype(operands[i]);

          end; { end with }
      end; {endfor}




       { TAKE CARE OF SPECIAL OPCODES, TAKE CARE OF THEM INDIVUALLY.    }
       { ALL THE REST ARE TAKEN CARE BY OPCODE TABLE AND THIRD PASS.    }
       if instruc = A_FST then
       Begin
       end
       else
       if instruc = A_FILD then
       Begin
       end
       else
       if instruc = A_FLD then
       Begin
            {A_FLDS,A_FLDL,A_FLDT}
       end
       else
       if instruc = A_FIST then
       Begin
            {A_FISTQ,A_FISTS,A_FISTL}
       end
       else
       if instruc = A_FWAIT then
        FWaitWarning
       else
       if instruc = A_MOVSX then
       Begin
         { change the instruction to conform to GAS }
         if operands[1].size = S_W then
         Begin
             addinstr(A_MOVSBW)
         end
         else
         if operands[1].size = S_L then
         Begin
             if operands[2].size = S_B then
                addinstr(A_MOVSBL)
             else
                addinstr(A_MOVSWL);
         end;
         instruc := getinstruction; { reload instruction }
       end
       else
       if instruc = A_MOVZX then
       Begin
         { change the instruction to conform to GAS }
         if operands[1].size = S_W then
         Begin
             addinstr(A_MOVZB)
         end
         else
         if operands[1].size = S_L then
         Begin
             if operands[2].size = S_B then
                addinstr(A_MOVZB)
             else
                addinstr(A_MOVZWL);
         end;
         instruc := getinstruction; { reload instruction }
       end
       else
       if (instruc in [A_BT,A_BTC,A_BTR,A_BTS]) then
       Begin
          if numops = 2 then
            Begin
                if (operands[2].operandtype = OPR_CONSTANT)
                and (operands[2].val <= $ff) then
                  Begin
                     operands[2].opinfo := ao_imm8;
                     { no operand size if using constant. }
                     operands[2].size := S_NO;
                     fits := TRUE;
                  end
            end
          else
            Begin
                Message(assem_e_invalid_opcode_and_operand);
                exit;
            end;
       end
       else
       if instruc = A_ENTER then
       Begin
          if numops =2 then
            Begin
               if (operands[1].operandtype = OPR_CONSTANT) and
                  (operands[1].val <= $ffff) then
                  Begin
                     operands[1].opinfo := ao_imm16;
                  end  { endif }
            end { endif }
          else
            Begin
                Message(assem_e_invalid_opcode_and_operand);
                exit;
            end
       end { endif }
       else
     {  Handle special opcodes for the opcode   }
     {  table. Set them up correctly.           }
       if (instruc in [A_IN,A_INS]) then
       Begin
          if numops =2 then
            Begin
              if (operands[2].operandtype = OPR_REGISTER) and (operands[2].reg = R_DX)
               then
               Begin
                  operands[2].opinfo := ao_inoutportreg;
                  if (operands[1].operandtype = OPR_REGISTER) and
                    (operands[1].reg in [R_EAX,R_AX,R_AL]) and
                    (instruc = A_IN) then
                    Begin
                       operands[1].opinfo := ao_acc;
                    end
               end
              else
              if (operands[2].operandtype = OPR_CONSTANT) and (operands[2].val <= $ff)
                and (instruc = A_IN) then
                Begin
                  operands[2].opinfo := ao_imm8;
                  operands[2].size := S_B;
                 if (operands[1].operandtype = OPR_REGISTER) and
                    (operands[1].reg in [R_EAX,R_AX,R_AL]) and
                    (instruc = A_IN) then
                    Begin
                       operands[1].opinfo := ao_acc;
                    end
                end;
            end
          else
            if not ((numops=0) and (instruc=A_INS)) then
             Begin
               Message(assem_e_invalid_opcode_and_operand);
               exit;
             end;
       end
       else
       if (instruc in [A_OUT,A_OUTS]) then
       Begin
          if numops =2 then
            Begin
              if (operands[1].operandtype = OPR_REGISTER) and (operands[1].reg = R_DX)
               then
               Begin
                  operands[1].opinfo := ao_inoutportreg;
                  if (operands[2].operandtype = OPR_REGISTER) and
                     (operands[2].reg in [R_EAX,R_AX,R_AL]) and
                     (instruc = A_OUT) then
                     Begin
                       operands[2].opinfo := ao_acc;
                       fits := TRUE;
                     end
               end
              else
              if (operands[1].operandtype = OPR_CONSTANT) and (operands[1].val <= $ff)
                and (instruc = A_OUT) then
                Begin
                  operands[1].opinfo := ao_imm8;
                  operands[1].size := S_B;
                  if (operands[2].operandtype = OPR_REGISTER) and
                     (operands[2].reg in [R_EAX,R_AX,R_AL]) and
                     (instruc = A_OUT) then
                     Begin
                       operands[2].opinfo := ao_acc;
                       fits := TRUE;
                     end
                end;
            end
          else
            if not ((numops=0) and (instruc=A_OUTS)) then
             Begin
               Message(assem_e_invalid_opcode_and_operand);
               exit;
             end;
       end
       else
       if instruc in [A_RCL,A_RCR,A_ROL,A_ROR,A_SAL,A_SAR,A_SHL,A_SHR] then
       { if RCL,ROL,... }
       Begin
          if numops =2 then
            Begin
              if (operands[2].operandtype = OPR_REGISTER) and (operands[2].reg = R_CL)
              then
              Begin
                operands[2].opinfo := ao_shiftcount
              end
              else
              if (operands[2].operandtype = OPR_CONSTANT) and
                (operands[2].val <= $ff) then
                Begin
                   operands[2].opinfo := ao_imm8;
                   operands[2].size := S_B;
                end;
            end
          else { if numops = 2 }
            Begin
                Message(assem_e_invalid_opcode_and_operand);
                exit;
            end;
       end
       { endif ROL,RCL ... }
       else
       if instruc in [A_DIV, A_IDIV] then
       Begin
          if (operands[1].operandtype = OPR_REGISTER) and
            (operands[1].reg in [R_AL,R_AX,R_EAX]) then
                operands[1].opinfo := ao_acc;
       end
       else
       if (instruc = A_FNSTSW) or (instruc = A_FSTSW) then
       Begin
          if numops = 1 then
            Begin
                if (operands[1].operandtype = OPR_REGISTER) and
                  (operands[1].reg = R_AX) then
                 operands[1].opinfo := ao_acc;
            end
          else
            Begin
              Message(assem_e_invalid_opcode_and_operand);
              exit;
            end;
       end
       else
       if (instruc = A_SHLD) or (instruc = A_SHRD) then
       { these instruction are fully parsed individually on pass three }
       { so we just do a summary checking here.                        }
       Begin
          if numops = 3 then
            Begin
                if (operands[3].operandtype = OPR_CONSTANT)
                and (operands[3].val <= $ff) then
                Begin
                   operands[3].opinfo := ao_imm8;
                   operands[3].size := S_B;
                end;
            end
          else
            Begin
                Message(assem_e_invalid_opcode_and_operand);
                exit;
            end;
       end
       else
       if instruc = A_INT then
       Begin
          if numops = 1 then
            Begin
               if (operands[1].operandtype = OPR_CONSTANT) and
                 (operands[1].val <= $ff) then
                      operands[1].opinfo := ao_imm8;
            end
       end
       else
       if instruc = A_RET then
       Begin
          if numops =1 then
            Begin
               if (operands[1].operandtype = OPR_CONSTANT) and
                  (operands[1].val <= $ffff) then
                    operands[1].opinfo := ao_imm16;
            end
       end; { endif }

       { all string instructions have default memory }
       { location which are ignored. Take care of    }
       { those.                                      }
       { Here could be added the code for segment    }
       { overrides.                                  }
       if instruc in [A_SCAS,A_CMPS,A_STOS,A_LODS] then
       Begin
          if numops =1 then
            Begin
               if (operands[1].operandtype = OPR_REFERENCE) and
                 (assigned(operands[1].ref.symbol)) then
                 Freemem(operands[1].ref.symbol,length(operands[1].ref.symbol^)+1);
               operands[1].operandtype := OPR_NONE;
               numops := 0;
            end;
       end; { endif }
       if instruc in [A_INS,A_MOVS,A_OUTS] then
       Begin
          if numops =2 then
            Begin
               if (operands[1].operandtype = OPR_REFERENCE) and
                 (assigned(operands[1].ref.symbol)) then
                 Freemem(operands[1].ref.symbol,length(operands[1].ref.symbol^)+1);
               if (operands[2].operandtype = OPR_REFERENCE) and
                 (assigned(operands[2].ref.symbol)) then
                 Freemem(operands[2].ref.symbol,length(operands[1].ref.symbol^)+1);
               operands[1].operandtype := OPR_NONE;
               operands[2].operandtype := OPR_NONE;
               numops := 0;
            end;
       end;
     { handle parameter for segment overrides }
     if instruc = A_XLAT then
     Begin
        { handle special TP syntax case for XLAT }
        { here we accept XLAT, XLATB and XLAT m8 }
        if (numops = 1) or (numops = 0) then
         Begin
               if (operands[1].operandtype = OPR_REFERENCE) and
                 (assigned(operands[1].ref.symbol)) then
                 Freemem(operands[1].ref.symbol,length(operands[1].ref.symbol^)+1);
               operands[1].operandtype := OPR_NONE;
               numops := 0;
               { always a byte for XLAT }
               instr.stropsize := S_B;
         end;
     end;



    { swap the destination and source }
    { to put in AT&T style direction  }
    { only if there are 2/3 operand   }
    { numbers.                        }
    if (instruc <> A_ENTER) then
       SwapOperands(instr);
    { copy them to local variables }
    { for faster access            }
    optyp1:=operands[1].opinfo;
    optyp2:=operands[2].opinfo;
    optyp3:=operands[3].opinfo;

    end; { end with }

    { after reading the operands }
    { search the instruction     }
    { setup startvalue from cache }
    if ins_cache[instruc]<>-1 then
       i:=ins_cache[instruc]
    else i:=0;


    { this makes cpu.pp uncompilable, but i think this code should be }
    { inserted in the system unit anyways.                            }
    if (instruc >= lastop_in_table) and
       ((cs_compilesystem in aktswitches) or (opt_processors > globals.i386)) then
      begin
         Message(assem_w_opcode_not_in_table);
         fits:=true;
      end
    else while not(fits) do
      begin
       { set the instruction cache, if the instruction }
       { occurs the first time                         }
       if (it[i].i=instruc) and (ins_cache[instruc]=-1) then
           ins_cache[instruc]:=i;

       if (it[i].i=instruc) and (instr.numops=it[i].ops) then
       begin
          { first fit }
          case instr.numops of
          0 : begin
                 fits:=true;
                 break;
              end;
          1 :
              Begin
                if (optyp1 and it[i].o1)<>0 then
                Begin
                   fits:=true;
                   break;
                end;
                { I consider sign-extended 8bit value to }
                { be equal to immediate 8bit therefore   }
                { convert...                             }
                if (optyp1 = ao_imm8) then
                Begin
                  { check if this is a simple sign extend. }
                  if (it[i].o1<>ao_imm8s) then
                  Begin
                    fits:=true;
                    break;
                  end;
                end;
              end;
          2 : if ((optyp1 and it[i].o1)<>0) and
               ((optyp2 and it[i].o2)<>0) then
               Begin
                     fits:=true;
                     break;
               end
               { if the operands can be swaped }
               { then swap them                }
               else if ((it[i].m and af_d)<>0) and
               ((optyp1 and it[i].o2)<>0) and
               ((optyp2 and it[i].o1)<>0) then
               begin
                 { swap the destination and source }
                 { to put in AT&T style direction  }
{ What does this mean !!!! ???????????????????????? }
{                 if (output_format in [of_o,of_att]) then }
                 { ???????????? }
{                          SwapOperands(instr); }
                 fits:=true;
                 break;
               end;
          3 : if ((optyp1 and it[i].o1)<>0) and
               ((optyp2 and it[i].o2)<>0) and
               ((optyp3 and it[i].o3)<>0) then
               Begin
                 fits:=true;
                 break;
               end;
          end; { end case }
       end; { endif }
       if it[i].i=A_NONE then
       begin
         { NO MATCH! }
         Message(assem_e_invalid_opcode_and_operand);
         exit;
       end;
       inc(i);
      end; { end while }

  { We add the opcode to the opcode linked list }
  if fits then
  Begin
    if instr.getprefix <> A_NONE then
    Begin
      p^.concat(new(pai386,op_none(instr.getprefix,S_NO)));
    end;
    case instr.numops of
     0:
        if instr.stropsize <> S_NO then
        { is this a string operation opcode or xlat then check }
        { the size of the operation.                           }
          p^.concat(new(pai386,op_none(instruc,instr.stropsize)))
        else
          p^.concat(new(pai386,op_none(instruc,S_NO)));
     1: Begin
          case instr.operands[1].operandtype of
               { all one operand opcodes with constant have no defined sizes }
               { at least that is what it seems in the tasm 2.0 manual.      }
           OPR_CONSTANT:  p^.concat(new(pai386,op_const(instruc,
                             S_NO, instr.operands[1].val)));
               { the size of the operand can be determined by the as,nasm and }
               { tasm.                                                        }
               { Even though normally gas should not be trusted, v2.8.1       }
               { has been *extensively* tested to assure that the output      }
               { is indeed correct with the following opcodes: push,pop,inc,dec}
               { neg and not.                                                   }
           OPR_REGISTER:  p^.concat(new(pai386,op_reg(instruc,
                            S_NO,instr.operands[1].reg)));
               { this is where it gets a bit more complicated...              }
           OPR_REFERENCE:
                          if instr.operands[1].size <> S_NO then
                          Begin
                           p^.concat(new(pai386,op_ref(instruc,
                            instr.operands[1].size,newreference(instr.operands[1].ref))));
                          end
                          else
                          Begin
                              { special jmp and call case with }
                              { symbolic references.           }
                              if instruc in [A_CALL,A_JMP] then
                              Begin
                                p^.concat(new(pai386,op_ref(instruc,
                                  S_NO,newreference(instr.operands[1].ref))));
                              end
                              else
                                Message(assem_e_invalid_opcode_and_operand);
                          end;
           OPR_NONE: Begin
                       Message(assem_f_internal_error_in_concatopcode);
                     end;
          else
           Begin
            Message(assem_f_internal_error_in_concatopcode);
           end;
          end;
        end;
     2:
        Begin
           if instruc in [A_MOVSX,A_MOVZX,A_MOVSB,A_MOVSBL,A_MOVSBW,
             A_MOVSWL,A_MOVZB,A_MOVZWL] then
              { movzx and movsx }
              HandleExtend(instr)
           else
             { other instructions }
             Begin
                With instr do
                Begin
                { source }
                  opsize := operands[1].size;
                  case operands[1].operandtype of
                  { reg,reg     }
                  { reg,ref     }
                   OPR_REGISTER:
                     Begin
                       case operands[2].operandtype of
                         OPR_REGISTER:
                            { see info in ratti386.pas, about the problem }
                            { which can cause gas here.                   }
                            if (opsize = operands[2].size) then
                            begin
                               p^.concat(new(pai386,op_reg_reg(instruc,
                               opsize,operands[1].reg,operands[2].reg)));
                            end
                            else
                            { these do not require any size specification. }
                            if (instruc in [A_IN,A_OUT,A_SAL,A_SAR,A_SHL,A_SHR,A_ROL,
                               A_ROR,A_RCR,A_RCL])  then
                               { outs and ins are already taken care by }
                               { the first pass.                        }
                               p^.concat(new(pai386,op_reg_reg(instruc,
                               S_NO,operands[1].reg,operands[2].reg)))
                            else
                            Begin
                              Message(assem_e_invalid_opcode_and_operand);
                            end;
                         OPR_REFERENCE:
                           { variable name. }
                           { here we must check the instruction type }
                           { before deciding if to use and compare   }
                           { any sizes.                              }
                           if assigned(operands[2].ref.symbol) then
                           Begin
                              if (opsize = operands[2].size) or (instruc in
                               [A_RCL,A_RCR,A_ROL,A_ROR,A_SAL,A_SAR,A_SHR,A_SHL]) then
                                  p^.concat(new(pai386,op_reg_ref(instruc,
                                  opsize,operands[1].reg,newreference(operands[2].ref))))
                              else
                                  Message(assem_e_invalid_size_in_ref);
                           end
                           else
                           Begin
                              { register reference }
                              { possiblities:1) local variable which }
                              { has been replaced by bp and offset   }
                              { in this case size should be valid    }
                              {              2) Indirect register    }
                              { adressing, 1st operand determines    }
                              { size.                                }
                              if (opsize = operands[2].size) or  (operands[2].size = S_NO) then
                                  p^.concat(new(pai386,op_reg_ref(instruc,
                                  opsize,operands[1].reg,newreference(operands[2].ref))))
                              else
                                  Message(assem_e_invalid_size_in_ref);
                           end;
                        OPR_CONSTANT: { const,reg }
                               Begin  { OUT const,reg }
                                 if (instruc = A_OUT) and (opsize = S_B) then
                                   p^.concat(new(pai386,op_reg_const(instruc,
                                    opsize,operands[1].reg,operands[2].val)))
                                 else
                                    Message(assem_e_invalid_size_in_ref);
                               end;
                       else { else case }
                         Begin
                           Message(assem_f_internal_error_in_concatopcode);
                         end;
                       end; { end inner case }
                     end;
                  { const,reg   }
                  { const,const }
                  { const,ref   }
                   OPR_CONSTANT:
                      case instr.operands[2].operandtype of
                      { constant, constant does not have a specific size. }
                        OPR_CONSTANT:
                           p^.concat(new(pai386,op_const_const(instruc,
                           S_NO,operands[1].val,operands[2].val)));
                        OPR_REFERENCE:
                           Begin
                              if (operands[1].val <= $ff) and
                               (operands[2].size in [S_B,S_W,S_L,S_Q,S_S]) then
                                 p^.concat(new(pai386,op_const_ref(instruc,
                                 operands[2].size,operands[1].val,
                                 newreference(operands[2].ref))))
                              else
                              if (operands[1].val <= $ffff) and
                               (operands[2].size in [S_W,S_L,S_Q,S_S]) then
                                 p^.concat(new(pai386,op_const_ref(instruc,
                                 operands[2].size,operands[1].val,
                                 newreference(operands[2].ref))))
                              else
                              if (operands[1].val <= $7fffffff) and
                               (operands[2].size in [S_L,S_Q,S_S]) then
                                 p^.concat(new(pai386,op_const_ref(instruc,
                                 operands[2].size,operands[1].val,
                                 newreference(operands[2].ref))))
                              else
                                  Message(assem_e_invalid_size_in_ref);
                           end;
                        OPR_REGISTER:
                           Begin
                              { size of opcode determined by register }
                              if (operands[1].val <= $ff) and
                               (operands[2].size in [S_B,S_W,S_L,S_Q,S_S]) then
                                 p^.concat(new(pai386,op_const_reg(instruc,
                                 operands[2].size,operands[1].val,
                                 operands[2].reg)))
                              else
                              if (operands[1].val <= $ffff) and
                               (operands[2].size in [S_W,S_L,S_Q,S_S]) then
                                 p^.concat(new(pai386,op_const_reg(instruc,
                                 operands[2].size,operands[1].val,
                                 operands[2].reg)))
                              else
                              if (operands[1].val <= $7fffffff) and
                               (operands[2].size in [S_L,S_Q,S_S]) then
                                 p^.concat(new(pai386,op_const_reg(instruc,
                                 operands[2].size,operands[1].val,
                                 operands[2].reg)))
                              else
                               Message(assem_e_invalid_opcode_size);
                           end;
                      else
                         Begin
                           Message(assem_f_internal_error_in_concatopcode);
                         end;
                      end; { end case }
                   { ref,reg     }
                   { ref,ref     }
                   OPR_REFERENCE:
                      case instr.operands[2].operandtype of
                         OPR_REGISTER:
                            if assigned(operands[1].ref.symbol) then
                            { global variable }
                            Begin
                              if instruc in [A_LEA,A_LDS,A_LES,A_LFS,A_LGS,A_LSS]
                               then
                                 p^.concat(new(pai386,op_ref_reg(instruc,
                                 S_NO,newreference(operands[1].ref),
                                 operands[2].reg)))
                              else
                              if (opsize = operands[2].size) then
                                 p^.concat(new(pai386,op_ref_reg(instruc,
                                 opsize,newreference(operands[1].ref),
                                 operands[2].reg)))
                              else
                                Begin
                                   Message(assem_e_invalid_opcode_and_operand);
                                end;
                            end
                            else
                            Begin
                              { register reference }
                              { possiblities:1) local variable which }
                              { has been replaced by bp and offset   }
                              { in this case size should be valid    }
                              {              2) Indirect register    }
                              { adressing, 2nd operand determines    }
                              { size.                                }
                              if (opsize = operands[2].size) or (opsize = S_NO) then
                              Begin
                                 p^.concat(new(pai386,op_ref_reg(instruc,
                                 operands[2].size,newreference(operands[1].ref),
                                 operands[2].reg)));
                              end
                              else
                                  Message(assem_e_invalid_size_in_ref);
                            end;
                         OPR_REFERENCE: { special opcodes }
                            p^.concat(new(pai386,op_ref_ref(instruc,
                            opsize,newreference(operands[1].ref),
                            newreference(operands[2].ref))));
                      else
                         Begin
                           Message(assem_f_internal_error_in_concatopcode);
                         end;
                   end; { end inner case }
                  end; { end case }
                end; { end with }
             end; {end if movsx... }
        end;
     3: Begin
             { only imul, shld and shrd  }
             { middle must be a register }
             if (instruc in [A_SHLD,A_SHRD]) and (instr.operands[2].operandtype =
                OPR_REGISTER) then
             Begin
               case instr.operands[2].size of
                S_W:  if instr.operands[1].operandtype = OPR_CONSTANT then
                        Begin
                          if instr.operands[1].val <= $ff then
                            Begin
                              if instr.operands[3].size in [S_W] then
                              Begin
                                 case instr.operands[3].operandtype of
                                  OPR_REFERENCE: { MISSING !!!! } ;
                                  OPR_REGISTER:  p^.concat(new(pai386,
                                     op_const_reg_reg(instruc, S_W,
                                     instr.operands[1].val, instr.operands[2].reg,
                                     instr.operands[3].reg)));
                                 else
                                    Message(assem_e_invalid_opcode_and_operand);
                                    Message(assem_e_invalid_opcode_and_operand);
                                 end;
                              end
                              else
                                 Message(assem_e_invalid_opcode_and_operand);
                            end;
                        end
                      else
                        Message(assem_e_invalid_opcode_and_operand);
                S_L:  if instr.operands[1].operandtype = OPR_CONSTANT then
                        Begin
                          if instr.operands[1].val <= $ff then
                            Begin
                              if instr.operands[3].size in [S_L] then
                              Begin
                                 case instr.operands[3].operandtype of
                                  OPR_REFERENCE: { MISSING !!!! } ;
                                  OPR_REGISTER:  p^.concat(new(pai386,
                                     op_const_reg_reg(instruc, S_L,
                                     instr.operands[1].val, instr.operands[2].reg,
                                     instr.operands[3].reg)));
                                 else
                                   Message(assem_e_invalid_opcode_and_operand);
                                 end;
                              end
                              else
                                Message(assem_e_invalid_opcode_and_operand);
                            end;
                        end
                      else
                       Message(assem_e_invalid_opcode_and_operand);
                else
                  Message(assem_e_invalid_opcode_and_operand);
               end; { end case }
             end
             else
             if (instruc in [A_IMUL]) and (instr.operands[3].operandtype
               = OPR_REGISTER) then
             Begin
               case instr.operands[3].size of
                S_W:  if instr.operands[1].operandtype = OPR_CONSTANT then
                        Begin
                          if instr.operands[1].val <= $ffff then
                            Begin
                              if instr.operands[2].size in [S_W] then
                              Begin
                                 case instr.operands[2].operandtype of
                                  OPR_REFERENCE: { MISSING !!!! } ;
                                  OPR_REGISTER:  p^.concat(new(pai386,
                                     op_const_reg_reg(instruc, S_W,
                                     instr.operands[1].val, instr.operands[2].reg,
                                     instr.operands[3].reg)));
                                 else
                                  Message(assem_e_invalid_opcode_and_operand);
                                 end; { end case }
                              end
                              else
                                Message(assem_e_invalid_opcode_and_operand);
                            end;
                        end
                      else
                        Message(assem_e_invalid_opcode_and_operand);
                S_L:  if instr.operands[1].operandtype = OPR_CONSTANT then
                        Begin
                          if instr.operands[1].val <= $7fffffff then
                            Begin
                              if instr.operands[2].size in [S_L] then
                              Begin
                                 case instr.operands[2].operandtype of
                                  OPR_REFERENCE: { MISSING !!!! } ;
                                  OPR_REGISTER:  p^.concat(new(pai386,
                                     op_const_reg_reg(instruc, S_L,
                                     instr.operands[1].val, instr.operands[2].reg,
                                     instr.operands[3].reg)));
                                 else
                                   Message(assem_e_invalid_opcode_and_operand);
                                 end; { end case }
                              end
                              else
                               Message(assem_e_invalid_opcode_and_operand);
                            end;
                        end
                      else
                       Message(assem_e_invalid_opcode_and_operand);
                else
                  Message(assem_e_invalid_middle_sized_operand);
               end; { end case }
             end { endif }
             else
               Message(assem_e_invalid_three_operand_opcode);
        end;
  end; { end case }
 end;
 end;

  {---------------------------------------------------------------------}
  {                     Routines for the parsing                        }
  {---------------------------------------------------------------------}

     procedure consume(t : tinteltoken);

     begin
       if t<>actasmtoken then
         Message(assem_e_syntax_error);
       actasmtoken:=gettoken;
       { if the token must be ignored, then }
       { get another token to parse.        }
       if actasmtoken = AS_NONE then
          actasmtoken := gettoken;
      end;





   function findregister(const s : string): tregister;
  {*********************************************************************}
  { FUNCTION findregister(s: string):tasmop;                            }
  {  Description: Determines if the s string is a valid register,       }
  {  if so returns correct tregister token, or R_NO if not found.       }
  {*********************************************************************}
   var
    i: tregister;
   begin
     findregister := R_NO;
     for i:=firstreg to lastreg do
       if s = iasmregs[i] then
       Begin
         findregister := i;
         exit;
       end;
   end;


   function findoverride(const s: string; var reg:tregister): boolean;
   var
    i: byte;
   begin
     findoverride := FALSE;
     reg := R_NO;
     for i:=0 to _count_asmoverrides do
     Begin
       if s = _asmoverrides[i] then
       begin
          reg := _overridetokens[i];
          findoverride := TRUE;
          exit;
       end;
     end;
   end;

   function findprefix(const s: string; var token: tasmop): boolean;
   var i: byte;
   Begin
     findprefix := FALSE;
     for i:=0 to _count_asmprefixes do
     Begin
       if s = _asmprefixes[i] then
       begin
          token := _prefixtokens[i];
          findprefix := TRUE;
          exit;
       end;
     end;
   end;


   function findsegment(const s:string): tregister;
  {*********************************************************************}
  { FUNCTION findsegment(s: string):tasmop;                             }
  {  Description: Determines if the s string is a valid segment register}
  {  if so returns correct tregister token, or R_NO if not found.       }
  {*********************************************************************}
   var
    i: tregister;
   Begin
     findsegment := R_DEFAULT_SEG;
     for i:=firstsreg to lastsreg do
       if s = iasmregs[i] then
       Begin
         findsegment := i;
         exit;
       end;
   end;

   function findopcode(const s: string): tasmop;
  {*********************************************************************}
  { FUNCTION findopcode(s: string): tasmop;                             }
  {  Description: Determines if the s string is a valid opcode          }
  {  if so returns correct tasmop token.                                }
  {*********************************************************************}
   var
    i: tasmop;
    j: byte;
   Begin
     findopcode := A_NONE;
     for i:=firstop to lastop do
       if  s = iasmops^[i] then
       begin
          findopcode:=i;
          exit;
       end;
     { not found yet, search for extended opcodes }
     { now, in this case, we must use the suffix  }
     { to determine the size of the instruction   }
     for j:=0 to _count_asmspecialops do
     Begin
       if s = _specialops[j] then
       Begin
         findopcode := _specialopstokens[j];
         { set the size }
         case s[length(s)] of
         'B': instr.stropsize := S_B;
         'D': instr.stropsize := S_L;
         'W': instr.stropsize := S_W;
         end;
         exit;
       end;
     end;
   end;






   Function CheckPrefix(prefix: tasmop; opcode:tasmop): Boolean;
   { Checks if the prefix is valid with the following instruction }
   { return false if not, otherwise true                          }
   Begin
     CheckPrefix := TRUE;
     Case prefix of
       A_REP,A_REPNE,A_REPE: if not (opcode in [A_SCAS,A_INS,A_OUTS,A_MOVS,
                             A_CMPS,A_LODS,A_STOS]) then
                             Begin
                               CheckPrefix := FALSE;
                               exit;
                             end;
       A_LOCK: if not (opcode in [A_BT,A_BTS,A_BTR,A_BTC,A_XCHG,A_ADD,A_OR,
                        A_ADC,A_SBB,A_AND,A_SUB,A_XOR,A_NOT,A_NEG,A_INC,A_DEC]) then
                  Begin
                     CheckPrefix := FALSE;
                     Exit;
                  end;
       A_NONE: exit; { no prefix here }

     else
       CheckPrefix := FALSE;
     end; { end case }
   end;


  Procedure InitAsmRef(var instr: TInstruction);
  {*********************************************************************}
  {  Description: This routine first check if the instruction is of     }
  {  type OPR_NONE, or OPR_REFERENCE , if not it gives out an error.    }
  {  If the operandtype = OPR_NONE or <> OPR_REFERENCE then it sets up  }
  {  the operand type to OPR_REFERENCE, as well as setting up the ref   }
  {  to point to the default segment.                                   }
  {*********************************************************************}
   Begin
     With instr do
     Begin
        case operands[operandnum].operandtype of
          OPR_REFERENCE: exit;
          OPR_NONE: ;
        else
          Message(assem_e_invalid_operand_type);
        end;
        operands[operandnum].operandtype := OPR_REFERENCE;
        operands[operandnum].ref.segment := R_DEFAULT_SEG;
     end;
   end;

   Function CheckOverride(segreg: tregister; var instr: TInstruction): Boolean;
   { Check if the override is valid, and if so then }
   { update the instr variable accordingly.         }
   Begin
     CheckOverride := FALSE;
     if instr.getinstruction in [A_MOVS,A_XLAT,A_CMPS] then
     Begin
       CheckOverride := TRUE;
       Message(assem_e_segment_override_not_supported);
     end
   end;




  Function CalculateExpression(expression: string): longint;
  var
    expr: TExprParse;
  Begin
   expr.Init;
   CalculateExpression := expr.Evaluate(expression);
   expr.Done;
  end;







  Function BuildRefExpression: longint;
  {*********************************************************************}
  { FUNCTION BuildExpression: longint                                   }
  {  Description: This routine calculates a constant expression to      }
  {  a given value. The return value is the value calculated from       }
  {  the expression.                                                    }
  { The following tokens (not strings) are recognized:                  }
  {    (,),SHL,SHR,/,*,NOT,OR,XOR,AND,MOD,+/-,numbers,ID to constants.  }
  {*********************************************************************}
  { ENTRY: On entry the token should be any valid expression token.     }
  { EXIT:  On Exit the token points to any token after the closing      }
  {         RBRACKET                                                    }
  { ERROR RECOVERY: Tries to find COMMA or SEPARATOR token by consuming }
  {  invalid tokens.                                                    }
  {*********************************************************************}
  var tempstr: string;
      expr: string;
    l : longint;
    errorflag : boolean;
  Begin
    errorflag := FALSE;
    tempstr := '';
    expr := '';
    { tell tokenizer that we are in }
    { an expression.                }
    inexpression := TRUE;
    Repeat
      Case actasmtoken of
      AS_LPAREN: Begin
                  Consume(AS_LPAREN);
                  expr := expr + '(';
                end;
      AS_RPAREN: Begin
                  Consume(AS_RPAREN);
                  expr := expr + ')';
                end;
      AS_SHL:    Begin
                  Consume(AS_SHL);
                  expr := expr + '<';
                end;
      AS_SHR:    Begin
                  Consume(AS_SHR);
                  expr := expr + '>';
                end;
      AS_SLASH:  Begin
                  Consume(AS_SLASH);
                  expr := expr + '/';
                end;
      AS_MOD:    Begin
                  Consume(AS_MOD);
                  expr := expr + '%';
                end;
      AS_STAR:   Begin
                  Consume(AS_STAR);
                  expr := expr + '*';
                end;
      AS_PLUS:   Begin
                  Consume(AS_PLUS);
                  expr := expr + '+';
                end;
      AS_MINUS:  Begin
                  Consume(AS_MINUS);
                  expr := expr + '-';
                end;
      AS_AND:    Begin
                  Consume(AS_AND);
                  expr := expr + '&';
                end;
      AS_NOT:    Begin
                  Consume(AS_NOT);
                  expr := expr + '~';
                end;
      AS_XOR:    Begin
                  Consume(AS_XOR);
                  expr := expr + '^';
                end;
      AS_OR:     Begin
                  Consume(AS_OR);
                  expr := expr + '|';
                end;
      { End of reference }
      AS_RBRACKET: Begin
                     if not ErrorFlag then
                        BuildRefExpression := CalculateExpression(expr)
                     else
                        BuildRefExpression := 0;
                     Consume(AS_RBRACKET);
                     { no longer in an expression }
                     inexpression := FALSE;
                     exit;
                  end;
      AS_ID:
                Begin
                  if NOT SearchIConstant(actasmpattern,l) then
                  Begin
                    Message1(assem_e_invalid_const_symbol,actasmpattern);
                    l := 0;
                  end;
                  str(l, tempstr);
                  expr := expr + tempstr;
                  Consume(AS_ID);
                end;
      AS_INTNUM:  Begin
                   expr := expr + actasmpattern;
                   Consume(AS_INTNUM);
                 end;
      AS_BINNUM:  Begin
                      tempstr := BinaryToDec(actasmpattern);
                      if tempstr = '' then
                       Message(assem_f_error_converting_bin);
                      expr:=expr+tempstr;
                      Consume(AS_BINNUM);
                 end;

      AS_HEXNUM: Begin
                    tempstr := HexToDec(actasmpattern);
                    if tempstr = '' then
                     Message(assem_f_error_converting_hex);
                    expr:=expr+tempstr;
                    Consume(AS_HEXNUM);
                end;
      AS_OCTALNUM: Begin
                    tempstr := OctalToDec(actasmpattern);
                    if tempstr = '' then
                     Message(assem_f_error_converting_octal);
                    expr:=expr+tempstr;
                    Consume(AS_OCTALNUM);
                  end;
      else
        Begin
          { write error only once. }
          if not errorflag then
           Message(assem_e_invalid_constant_expression);
          BuildRefExpression := 0;
          if actasmtoken in [AS_COMMA,AS_SEPARATOR] then exit;
          { consume tokens until we find COMMA or SEPARATOR }
          Consume(actasmtoken);
          errorflag := TRUE;
        end;
      end;
    Until false;
  end;



  Procedure BuildRecordOffset(var instr: TInstruction; varname: string);
  {*********************************************************************}
  { PROCEDURE BuildRecordOffset(var Instr: TInstruction)                }
  { Description: This routine takes care of field specifiers of records }
  {  and/or variables in asm operands. It updates the offset accordingly}
  {*********************************************************************}
  { ENTRY: On entry the token should be DOT.                            }
  {    name: should be the name of the variable to be expanded. '' if   }
  {     no variabled specified.                                         }
  { EXIT:  On Exit the token points to SEPARATOR or COMMA.              }
  { ERROR RECOVERY: Tries to find COMMA or SEPARATOR token by consuming }
  {  invalid tokens.                                                    }
  {*********************************************************************}
  var
    firstpass: boolean;
    offset: longint;
    basetypename : string;
  Begin
    basetypename := '';
    firstpass := TRUE;
    { // .ID[REG].ID ...   // }
    { // .ID.ID...         // }
    Consume(AS_DOT);
    Repeat
      case actasmtoken of
        AS_ID: Begin
                  InitAsmRef(instr);
                  { // var_name.typefield.typefield // }
                  if (varname <> '') then
                  Begin
                    if not GetVarOffset(varname,actasmpattern,offset) then
                    Begin
                      Message1(assem_e_unknown_id,actasmpattern);
                    end
                    else
                      Inc(instr.operands[operandnum].ref.offset,Offset);
                  end
                  else
                 {    [ref].var_name.typefield.typefield ...                }
                 {    [ref].var_name[reg]                                   }
                  if not assigned(instr.operands[operandnum].ref.symbol) and
                    firstpass then
                  Begin
                     if not CreateVarInstr(instr,actasmpattern,operandnum) then
                     Begin
                       { type field ? }
                       basetypename := actasmpattern;
                     end
                     else
                       varname := actasmpattern;
                    end
                  else
                  if firstpass then
                 {    [ref].typefield.typefield ...                         }
                 {    where the first typefield must specifiy the base      }
                 {    object or record type.                                }
                  Begin
                     basetypename := actasmpattern;
                  end
                  else
                 {    [ref].typefield.typefield ...                         }
                 {  basetpyename is already set up... now look for fields.  }
                  Begin
                     if not GetTypeOffset(basetypename,actasmpattern,Offset) then
                     Begin
                      Message1(assem_e_unknown_id,actasmpattern);
                     end
                     else
                       Inc(instr.operands[operandnum].ref.offset,Offset);
                  end;
                  Consume(AS_ID);
                 { Take care of index register on this variable }
                 if actasmtoken = AS_LBRACKET then
                 Begin
                   Consume(AS_LBRACKET);
                   Case actasmtoken of
                     AS_REGISTER: Begin
                                   if instr.operands[operandnum].ref.index <> R_NO then
                                    Message(assem_e_defining_index_more_than_once);
                                   instr.operands[operandnum].ref.index :=
                                      findregister(actasmpattern);
                                   Consume(AS_REGISTER);
                                  end;
                    else
                     Begin
                      { add offsets , assuming these are constant expressions... }
                      Inc(instr.operands[operandnum].ref.offset,BuildRefExpression);
                     end;
                   end;
                   Consume(AS_RBRACKET);
                 end;
                 { Here we should either have AS_DOT, AS_SEPARATOR or AS_COMMA }
                 if actasmtoken = AS_DOT then
                    Consume(AS_DOT);
                 firstpass := FALSE;
                 Offset := 0;
              end;
        AS_SEPARATOR: exit;
        AS_COMMA: exit;
      else
       Begin
         Message(assem_e_invalid_field_specifier);
         Consume(actasmtoken);
         firstpass := FALSE;
       end;
      end; { end case }
    Until (actasmtoken = AS_SEPARATOR) or (actasmtoken = AS_COMMA);
  end;


  Function BuildExpression: longint;
  {*********************************************************************}
  { FUNCTION BuildExpression: longint                                   }
  {  Description: This routine calculates a constant expression to      }
  {  a given value. The return value is the value calculated from       }
  {  the expression.                                                    }
  { The following tokens (not strings) are recognized:                  }
  {    (,),SHL,SHR,/,*,NOT,OR,XOR,AND,MOD,+/-,numbers,ID to constants.  }
  {*********************************************************************}
  { ENTRY: On entry the token should be any valid expression token.     }
  { EXIT:  On Exit the token points to either COMMA or SEPARATOR        }
  { ERROR RECOVERY: Tries to find COMMA or SEPARATOR token by consuming }
  {  invalid tokens.                                                    }
  {*********************************************************************}
  var expr: string;
      tempstr: string;
      l : longint;
      errorflag: boolean;
  Begin
    errorflag := FALSE;
    expr := '';
    tempstr := '';
    { tell tokenizer that we are in an expression. }
    inexpression := TRUE;
    Repeat
      Case actasmtoken of
      AS_LPAREN: Begin
                  Consume(AS_LPAREN);
                  expr := expr + '(';
                end;
      AS_RPAREN: Begin
                  Consume(AS_RPAREN);
                  expr := expr + ')';
                end;
      AS_SHL:    Begin
                  Consume(AS_SHL);
                  expr := expr + '<';
                end;
      AS_SHR:    Begin
                  Consume(AS_SHR);
                  expr := expr + '>';
                end;
      AS_SLASH:  Begin
                  Consume(AS_SLASH);
                  expr := expr + '/';
                end;
      AS_MOD:    Begin
                  Consume(AS_MOD);
                  expr := expr + '%';
                end;
      AS_STAR:   Begin
                  Consume(AS_STAR);
                  expr := expr + '*';
                end;
      AS_PLUS:   Begin
                  Consume(AS_PLUS);
                  expr := expr + '+';
                end;
      AS_MINUS:  Begin
                  Consume(AS_MINUS);
                  expr := expr + '-';
                end;
      AS_AND:    Begin
                  Consume(AS_AND);
                  expr := expr + '&';
                end;
      AS_NOT:    Begin
                  Consume(AS_NOT);
                  expr := expr + '~';
                end;
      AS_XOR:    Begin
                  Consume(AS_XOR);
                  expr := expr + '^';
                end;
      AS_OR:     Begin
                  Consume(AS_OR);
                  expr := expr + '|';
                end;
      AS_ID:    Begin
                  if NOT SearchIConstant(actasmpattern,l) then
                  Begin
                    Message1(assem_e_invalid_const_symbol,actasmpattern);
                    l := 0;
                  end;
                  str(l, tempstr);
                  expr := expr + tempstr;
                  Consume(AS_ID);
                end;
      AS_INTNUM:  Begin
                   expr := expr + actasmpattern;
                   Consume(AS_INTNUM);
                 end;
      AS_BINNUM:  Begin
                      tempstr := BinaryToDec(actasmpattern);
                      if tempstr = '' then
                       Message(assem_f_error_converting_bin);
                      expr:=expr+tempstr;
                      Consume(AS_BINNUM);
                 end;

      AS_HEXNUM: Begin
                    tempstr := HexToDec(actasmpattern);
                    if tempstr = '' then
                     Message(assem_f_error_converting_hex);
                    expr:=expr+tempstr;
                    Consume(AS_HEXNUM);
                end;
      AS_OCTALNUM: Begin
                    tempstr := OctalToDec(actasmpattern);
                    if tempstr = '' then
                     Message(assem_f_error_converting_octal);
                    expr:=expr+tempstr;
                    Consume(AS_OCTALNUM);
                  end;
      { go to next term }
      AS_COMMA: Begin
                  if not ErrorFlag then
                    BuildExpression := CalculateExpression(expr)
                  else
                    BuildExpression := 0;
                  inexpression := FALSE;
                  Exit;
               end;
      { go to next symbol }
      AS_SEPARATOR: Begin
                      if not ErrorFlag then
                        BuildExpression := CalculateExpression(expr)
                      else
                        BuildExpression := 0;
                      inexpression := FALSE;
                      Exit;
                   end;
      else
        Begin
          { only write error once. }
          if not errorflag then
           Message(assem_e_invalid_constant_expression);
          { consume tokens until we find COMMA or SEPARATOR }
          Consume(actasmtoken);
          errorflag := TRUE;
        End;
      end;
    Until false;
  end;




  Procedure BuildScaling(Var instr: TInstruction);
  {*********************************************************************}
  {  Takes care of parsing expression starting from the scaling value   }
  {  up to and including possible field specifiers.                     }
  { EXIT CONDITION:  On exit the routine should point to  AS_SEPARATOR  }
  { or AS_COMMA. On entry should point to AS_STAR token.                }
  {*********************************************************************}
  var str:string;
      l: longint;
      code: integer;
  Begin
     Consume(AS_STAR);
     if (instr.operands[operandnum].ref.scalefactor <> 0)
     and (instr.operands[operandnum].ref.scalefactor <> 1) then
     Begin
         Message(assem_f_internal_error_in_buildscale);
     end;
     case actasmtoken of
        AS_INTNUM: str := actasmpattern;
        AS_HEXNUM: str := HexToDec(actasmpattern);
        AS_BINNUM: str := BinaryToDec(actasmpattern);
        AS_OCTALNUM: str := OctalToDec(actasmpattern);
     else
        Message(assem_e_syntax_error);
     end;
     val(str, l, code);
     if code <> 0 then
       Message(assem_e_invalid_scaling_factor);
     if ((l = 2) or (l = 4) or (l = 8) or (l = 1)) and (code = 0) then
     begin
        instr.operands[operandnum].ref.scalefactor := l;
     end
     else
     Begin
        Message(assem_e_invalid_scaling_value);
        instr.operands[operandnum].ref.scalefactor := 0;
     end;
     if instr.operands[operandnum].ref.index = R_NO then
     Begin
        Message(assem_e_scaling_value_only_allowed_with_index);
        instr.operands[operandnum].ref.scalefactor := 0;
     end;
    { Consume the scaling number }
    Consume(actasmtoken);
    case actasmtoken of
        { //  [...*SCALING-expr] ... // }
        AS_MINUS: Begin
                    if instr.operands[operandnum].ref.offset <> 0 then
                     Message(assem_f_internal_error_in_buildscale);
                    instr.operands[operandnum].ref.offset :=
                        BuildRefExpression;
                  end;
        { //  [...*SCALING+expr] ... // }
        AS_PLUS: Begin
                    if instr.operands[operandnum].ref.offset <> 0 then
                     Message(assem_f_internal_error_in_buildscale);
                    instr.operands[operandnum].ref.offset :=
                         BuildRefExpression;
                    end;
        { //  [...*SCALING] ... // }
        AS_RBRACKET: Consume(AS_RBRACKET);
    else
       Message(assem_e_invalid_scaling_value);
    end;
    { // .Field.Field ... or separator/comma // }
    Case actasmtoken of
     AS_DOT: BuildRecordOffset(instr,'');
     AS_COMMA, AS_SEPARATOR: ;
    else
      Message(assem_e_syntax_error);
    end;
  end;



  Procedure BuildReference(var instr: TInstruction);
  {*********************************************************************}
  { EXIT CONDITION:  On exit the routine should point to either the     }
  {       AS_COMMA or AS_SEPARATOR token.                               }
  {   On entry: contains the register after the opening bracket if any. }
  {*********************************************************************}
  var
    reg:string;
    segreg: boolean;
    negative: boolean;
    expr: string;
  Begin
     expr := '';
     if instr.operands[operandnum].operandtype <> OPR_REFERENCE then
     Begin
       Message(assem_e_syn_no_ref_with_brackets);
       InitAsmRef(instr);
       consume(AS_REGISTER);
     end
     else
     Begin
       { save the reg }
       reg := actasmpattern;
       { is the syntax of the form: [REG:REG...] }
       consume(AS_REGISTER);
       if actasmtoken = AS_COLON then
       begin
         segreg := TRUE;
         Message(assem_e_expression_form_not_supported);
         if instr.operands[operandnum].ref.segment <> R_NO then
          Message(assem_e_defining_seg_more_than_once);
         instr.operands[operandnum].ref.segment := findsegment(reg);
         { Here we should process the syntax of the form   }
         { [reg:reg...]                                    }
         {!!!!!!!!!!!!!!!!!!!!!!!!                         }
       end
       { This is probably of the following syntax: }
       { SREG:[REG...] where SReg: is optional.    }
       { Therefore we immediately say that reg     }
       { is the base.                              }
       else
       Begin
         if instr.operands[operandnum].ref.base <> R_NO then
          Message(assem_e_defining_base_more_than_once);
         instr.operands[operandnum].ref.base := findregister(reg);
       end;
       { we process this type of syntax immediately... }
       case actasmtoken of

          { //  REG:[REG].Field.Field ...     // }
          { //  REG:[REG].Field[REG].Field... // }
         AS_RBRACKET: Begin
                       Consume(AS_RBRACKET);
                       { check for record fields }
                       if actasmtoken = AS_DOT then
                          BuildRecordOffset(instr,'');
                       if (actasmtoken = AS_SEPARATOR) or (actasmtoken = AS_COMMA) then
                         exit
                       else
                         Message(assem_e_syn_reference);
                     end;
          { //  REG:[REG +/- ...].Field.Field ... // }
         AS_PLUS,AS_MINUS: Begin
                            if actasmtoken = AS_MINUS then
                            Begin
                               expr := '-';
                               negative := TRUE
                            end
                            else
                            Begin
                               negative := FALSE;
                               expr := '+';
                            end;
                            Consume(actasmtoken);
                            { // REG:[REG+REG+/-...].Field.Field // }
                            if actasmtoken = AS_REGISTER then
                            Begin
                              if negative then
                                Message(assem_e_negative_index_register);
                              if instr.operands[operandnum].ref.index <> R_NO then
                                Message(assem_e_defining_index_more_than_once);
                              instr.operands[operandnum].ref.index := findregister(actasmpattern);
                              Consume(AS_REGISTER);
                              case actasmtoken of
                                AS_RBRACKET: { // REG:[REG+REG].Field.Field... // }
                                            Begin
                                              Consume(AS_RBRACKET);
                                              Case actasmtoken of
                                                 AS_DOT: BuildRecordOffset(instr,'');
                                                 AS_COMMA,AS_SEPARATOR: exit;
                                              else
                                                Message(assem_e_syntax_error);
                                              end
                                             end;
                                AS_PLUS,AS_MINUS: { // REG:[REG+REG+/-expr].Field.Field... // }
                                                Begin
                                                  if instr.operands[operandnum].ref.offset <> 0 then
                                                   Message(assem_f_internal_error_in_buildreference);
                                                  instr.operands[operandnum].ref.offset :=
                                                      BuildRefExpression;
                                                  case actasmtoken of
                                                    AS_DOT: BuildRecordOffset(instr,'');
                                                    AS_COMMA,AS_SEPARATOR: ;
                                                  else
                                                    Message(assem_e_syntax_error);
                                                  end; { end case }
                                                end;
                                AS_STAR: Begin  { // REG:[REG+REG*SCALING...].Field.Field... // }
                                             BuildScaling(instr);
                                         end;
                                else
                                Begin
                                  Message(assem_e_syntax_error);
                                end;
                              end; { end case }
                            end
                            else if actasmtoken = AS_STAR then
                            { // REG:[REG*SCALING ... ]     // }
                            Begin
                              BuildScaling(instr);
                            end
                            else
                            { // REG:[REG+expr].Field.Field // }
                             Begin
                               if instr.operands[operandnum].ref.offset <> 0 then
                                Message(assem_f_internal_error_in_buildreference);
                               instr.operands[operandnum].ref.offset := BuildRefExpression;
                               case actasmtoken of
                                  AS_DOT: BuildRecordOffset(instr,'');
                                  AS_COMMA,AS_SEPARATOR: ;
                                else
                                  Message(assem_e_syntax_error);
                               end; { end case }
                             end; { end if }
                         end; { end this case }
     { //  REG:[REG*scaling] ... // }
         AS_STAR: Begin
                     BuildScaling(instr);
                 end;
       end;
     end; { end outer if }
  end;


  Procedure BuildBracketExpression(var Instr: TInstruction; var_prefix: boolean);
  {*********************************************************************}
  { PROCEDURE BuildBracketExpression                                    }
  {  Description: This routine builds up an expression after a LBRACKET }
  {  token is encountered.                                              }
  {   On entry actasmtoken should be equal to AS_LBRACKET.              }
  {  var_prefix : Should be set to true if variable identifier has      }
  {    been defined, such as in ID[                                     }
  {*********************************************************************}
  { EXIT CONDITION:  On exit the routine should point to either the     }
  {       AS_COMMA or AS_SEPARATOR token.                               }
  {*********************************************************************}
  var
    l:longint;
  Begin
     Consume(AS_LBRACKET);
     initAsmRef(instr);
     Case actasmtoken of
         { // Constant reference expression OR variable reference expression // }
         AS_ID: Begin
                if actasmpattern[1] = '@' then
                 Message(assem_e_local_symbol_not_allowed_as_ref);
                if SearchIConstant(actasmpattern,l) then
                 Begin
                   { if there was a variable prefix then }
                   { add to offset                       }
                   If var_prefix then
                    Begin
                        Inc(instr.operands[operandnum].ref.offset,  BuildRefExpression);
                    end
                   else
                     instr.operands[operandnum].ref.offset :=BuildRefExpression;
                   if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                      Message(assem_e_invalid_operand_in_bracket_expression);
                 end
                else if NOT var_prefix then
                 Begin
                    InitAsmRef(instr);
                    if not CreateVarInstr(instr,actasmpattern,operandnum) then
                     Message1(assem_e_unknown_id,actasmpattern);
                    Consume(AS_ID);
                   { is there a constant expression following }
                   { the variable name?                       }
                   if actasmtoken <> AS_RBRACKET then
                    Begin
                      Inc(instr.operands[operandnum].ref.offset, BuildRefExpression);
                    end
                   else
                      Consume(AS_RBRACKET);
                 end
                 else
                   Message1(assem_e_invalid_symbol_name,actasmpattern);
                end;
               { Here we handle the special case in tp where   }
               { the + operator is allowed with reg and var    }
               { references, such as in mov al, byte ptr [+bx] }
         AS_PLUS: Begin
                   Consume(AS_PLUS);
                   Case actasmtoken of
                     AS_REGISTER: Begin
                                   BuildReference(instr);
                                 end;
                     AS_ID: Begin
                             if actasmpattern[1] = '@' then
                               Message(assem_e_local_symbol_not_allowed_as_ref);
                             if SearchIConstant(actasmpattern,l) then
                               Begin
                                 { if there was a variable prefix then }
                                 { add to offset                       }
                                 If var_prefix then
                                  Begin
                                    Inc(instr.operands[operandnum].ref.offset,
                                     BuildRefExpression);
                                  end
                                 else
                                   instr.operands[operandnum].ref.offset :=
                                    BuildRefExpression;
                                 if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                                   Message(assem_e_invalid_operand_in_bracket_expression);
                               end
                             else if NOT var_prefix then
                               Begin
                               InitAsmRef(instr);
                               if not CreateVarInstr(instr,actasmpattern,operandnum) then
                                Message1(assem_e_unknown_id,actasmpattern);
                               Consume(AS_ID);
                               { is there a constant expression following }
                               { the variable name?                       }
                                 if actasmtoken <> AS_RBRACKET then
                                   Begin
                                    Inc(instr.operands[operandnum].ref.offset,
                                      BuildRefExpression);
                                   end
                                 else
                                   Consume(AS_RBRACKET);
                               end
                             else
                               Message1(assem_e_invalid_symbol_name,actasmpattern);
                           end;
                     { // Constant reference expression //  }
                   AS_INTNUM,AS_BINNUM,AS_OCTALNUM,
                   AS_HEXNUM: Begin
                               { if there was a variable prefix then }
                               { add to offset instead.              }
                               If var_prefix then
                                Begin
                                  Inc(instr.operands[operandnum].ref.offset,  BuildRefExpression);
                                end
                               else
                               Begin
                                 instr.operands[operandnum].ref.offset :=BuildRefExpression;
                               end;
                               if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                                  Message(assem_e_invalid_operand_in_bracket_expression);
                             end;
                    else
                      Message(assem_e_syntax_error);
                   end;
                 end;
         { // Constant reference expression //  }
         AS_MINUS,AS_NOT,AS_LPAREN:
                     Begin
                       { if there was a variable prefix then }
                       { add to offset instead.              }
                       If var_prefix then
                         Begin
                              Inc(instr.operands[operandnum].ref.offset,  BuildRefExpression);
                         end
                        else
                         Begin
                           instr.operands[operandnum].ref.offset :=BuildRefExpression;
                         end;
                       if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                          Message(assem_e_invalid_operand_in_bracket_expression);
                     end;
         { // Constant reference expression //  }
         AS_INTNUM,AS_OCTALNUM,AS_BINNUM,AS_HEXNUM: Begin
                       { if there was a variable prefix then }
                       { add to offset instead.              }
                       If var_prefix then
                         Begin
                              Inc(instr.operands[operandnum].ref.offset,  BuildRefExpression);
                         end
                        else
                         Begin
                           instr.operands[operandnum].ref.offset :=BuildRefExpression;
                         end;
                       if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                          Message(assem_e_invalid_operand_in_bracket_expression);
                   end;
         { // Variable reference expression // }
         AS_REGISTER: BuildReference(instr);
     else
       Begin
         Message(assem_e_invalid_reference_syntax);
         while (actasmtoken <> AS_SEPARATOR) do
           Consume(actasmtoken);
       end;
     end; { end case }
  end;


  Procedure BuildOperand(var instr: TInstruction);
  {*********************************************************************}
  { EXIT CONDITION:  On exit the routine should point to either the     }
  {       AS_COMMA or AS_SEPARATOR token.                               }
  {*********************************************************************}
  var
    tempstr: string;
    expr: string;
    lab: Pasmlabel;
    l : longint;
    hl: plabel;
  Begin
   tempstr := '';
   expr := '';
   case actasmtoken of
   { // Constant expression //  }
     AS_PLUS,AS_MINUS,AS_NOT,AS_LPAREN:
                                  Begin
                                     if not (instr.operands[operandnum].operandtype in [OPR_NONE,OPR_CONSTANT]) then
                                        Message(assem_e_invalid_operand_type);
                                     instr.operands[operandnum].operandtype := OPR_CONSTANT;
                                     instr.operands[operandnum].val :=BuildExpression;
                                   end;
   { // Constant expression //  }
     AS_STRING:   Begin
                    if not (instr.operands[operandnum].operandtype in [OPR_NONE]) then
                       Message(assem_e_invalid_operand_type);
                    instr.operands[operandnum].operandtype := OPR_CONSTANT;
                    if not PadZero(actasmpattern,4) then
                     Message1(assem_e_invalid_string_as_opcode_operand,actasmpattern);
                    instr.operands[operandnum].val :=
                      ord(actasmpattern[4]) + ord(actasmpattern[3]) shl 8 +
                       Ord(actasmpattern[2]) shl 16 + ord(actasmpattern[1])
                        shl 24;
                    Consume(AS_STRING);
                    Case actasmtoken of
                       AS_COMMA, AS_SEPARATOR: ;
                    else
                      Message(assem_e_invalid_string_expression);
                    end; { end case }
                 end;
   { // Constant expression //  }
     AS_INTNUM,AS_BINNUM,
     AS_OCTALNUM,
     AS_HEXNUM:     Begin
                      if not (instr.operands[operandnum].operandtype in [OPR_NONE,OPR_CONSTANT]) then
                         Message(assem_e_invalid_operand_type);
                      instr.operands[operandnum].operandtype := OPR_CONSTANT;
                      instr.operands[operandnum].val :=BuildExpression;
                    end;
   { // A constant expression, or a Variable ref. // }
     AS_ID:  Begin
              if actasmpattern[1] = '@' then
              { // Label or Special symbol reference // }
              Begin
                 if actasmpattern = '@RESULT' then
                   Begin
                      InitAsmRef(instr);
                      SetUpResult(instr,operandnum);
                   end
                 else
                  if (actasmpattern = '@CODE') or (actasmpattern = '@DATA') then
                      Message(assem_w_CODE_and_DATA_not_supported)
                   else
                  Begin
                    delete(actasmpattern,1,1);
                    if actasmpattern = '' then
                      Message(assem_e_null_label_ref_not_allowed);
                    lab := labellist.search(actasmpattern);
                    { check if the label is already defined   }
                    { if so, we then check if the plabel is   }
                    { non-nil, if so we add it to instruction }
                    if assigned(lab) then
                     Begin
                     if assigned(lab^.lab) then
                       Begin
                         instr.operands[operandnum].operandtype := OPR_LABINSTR;
                         instr.operands[operandnum].hl := lab^.lab;
                         instr.labeled := TRUE;
                       end;
                     end
                    else
                    { the label does not exist, create it }
                    { emit the opcode, but set that the   }
                    { label has not been emitted          }
                     Begin
                        getlabel(hl);
                        labellist.insert(actasmpattern,hl,FALSE);
                        instr.operands[operandnum].operandtype := OPR_LABINSTR;
                        instr.operands[operandnum].hl := hl;
                        instr.labeled := TRUE;
                     end;
                  end;
                Consume(AS_ID);
                if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                Begin
                  Message(assem_e_syntax_error);
                end;
              end
              { probably a variable or normal expression }
              { or a procedure (such as in CALL ID)      }
              else
               Begin
                   { is it a constant ? }
                   if SearchIConstant(actasmpattern,l) then
                   Begin
                      if not (instr.operands[operandnum].operandtype in [OPR_NONE,OPR_CONSTANT]) then
                       Message(assem_e_invalid_operand_type);
                      instr.operands[operandnum].operandtype := OPR_CONSTANT;
                      instr.operands[operandnum].val :=BuildExpression;
                    end
                   else { is it a label variable ? }
                    Begin
                     { // ID[ , ID.Field.Field or simple ID // }
                     { check if this is a label, if so then }
                     { emit it as a label.                  }
                     if SearchLabel(actasmpattern,hl) then
                     Begin
                        instr.operands[operandnum].operandtype := OPR_LABINSTR;
                        instr.operands[operandnum].hl := hl;
                        instr.labeled := TRUE;
                        Consume(AS_ID);
                        if not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) then
                          Message(assem_e_syntax_error);
                     end
                     else
                     { is it a normal variable ? }
                     Begin
                      initAsmRef(instr);
                      if not CreateVarInstr(instr,actasmpattern,operandnum) then
                      Begin
                         { not a variable.. }
                         { check special variables.. }
                         if actasmpattern = 'SELF' then
                          { special self variable }
                         Begin
                           if assigned(procinfo._class) then
                             Begin
                               instr.operands[operandnum].ref.offset := procinfo.ESI_offset;
                               instr.operands[operandnum].ref.base := procinfo.framepointer;
                             end
                           else
                             Message(assem_e_cannot_use_SELF_outside_a_method);
                         end
                         else
                           Message1(assem_e_unknown_id,actasmpattern);
                      end;
                      expr := actasmpattern;
                      Consume(AS_ID);
                      case actasmtoken of
                           AS_LBRACKET: { indexing }
                                        BuildBracketExpression(instr,TRUE);
                           AS_DOT: BuildRecordOffset(instr,expr);

                           AS_SEPARATOR,AS_COMMA: ;
                      else
                           Message(assem_e_syntax_error);
                      end;
                     end;
                    end;
               end;
            end;
   { // Register, a variable reference or a constant reference // }
     AS_REGISTER: Begin
                   { save the type of register used. }
                   tempstr := actasmpattern;
                   Consume(AS_REGISTER);
                   if actasmtoken = AS_COLON then
                   Begin
                      Consume(AS_COLON);
                      if actasmtoken <> AS_LBRACKET then
                        Message(assem_e_syn_start_with_bracket)
                      else
                      Begin
                        initAsmRef(instr);
                        instr.operands[operandnum].ref.segment := findsegment(tempstr);
                        BuildBracketExpression(instr,false);
                      end;
                   end
                   { // Simple register // }
                   else if (actasmtoken = AS_SEPARATOR) or (actasmtoken = AS_COMMA) then
                   Begin
                        if not (instr.operands[operandnum].operandtype in [OPR_NONE,OPR_REGISTER]) then
                         Message(assem_e_invalid_operand_type);
                        instr.operands[operandnum].operandtype := OPR_REGISTER;
                        instr.operands[operandnum].reg := findregister(tempstr);
                   end
                   else
                    Message1(assem_e_syn_register,tempstr);
                 end;
    { // a variable reference, register ref. or a constant reference // }
     AS_LBRACKET: Begin
                   BuildBracketExpression(instr,false);
                 end;
    { // Unsupported // }
     AS_SEG,AS_OFFSET: Begin
                         Message(assem_e_SEG_and_OFFSET_not_supported);
                         Consume(actasmtoken);
                         { error recovery }
                         While not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) do
                           Consume(actasmtoken);
                       end;
     AS_SEPARATOR, AS_COMMA: ;
    else
      Message(assem_e_syn_opcode_operand);
  end; { end case }
 end;


  Procedure BuildConstant(maxvalue: longint);
  {*********************************************************************}
  { PROCEDURE BuildConstant                                             }
  {  Description: This routine takes care of parsing a DB,DD,or DW      }
  {  line and adding those to the assembler node. Expressions, range-   }
  {  checking are fullly taken care of.                                 }
  {   maxvalue: $ff -> indicates that this is a DB node.                }
  {             $ffff -> indicates that this is a DW node.              }
  {             $ffffffff -> indicates that this is a DD node.          }
  {*********************************************************************}
  { EXIT CONDITION:  On exit the routine should point to AS_SEPARATOR.  }
  {*********************************************************************}
  var
   strlength: byte;
   expr: string;
   value : longint;
  Begin
      strlength := 0; { assume it is a DB }
      Repeat
        Case actasmtoken of
          AS_STRING: Begin
                      if maxvalue = $ffff then
                         strlength := 2
                      else if maxvalue = $ffffffff then
                         strlength := 4;
                      if strlength <> 0 then
                      { DD and DW cases }
                      Begin
                         if Not PadZero(actasmpattern,strlength) then
                          Message(scan_f_string_exceeds_line);
                      end;
                      expr := actasmpattern;
                      Consume(AS_STRING);
                      Case actasmtoken of
                       AS_COMMA: Consume(AS_COMMA);
                       AS_SEPARATOR: ;
                      else
                       Message(assem_e_invalid_string_expression);
                      end; { end case }
                      ConcatString(p,expr);
                    end;
          AS_INTNUM,AS_BINNUM,
          AS_OCTALNUM,AS_HEXNUM:
                    Begin
                      value:=BuildExpression;
                      ConcatConstant(p,value,maxvalue);
                    end;
          AS_ID:
                     Begin
                      value:=BuildExpression;
                      if value > maxvalue then
                      Begin
                         Message(assem_e_expression_out_of_bounds);
                         { assuming a value of maxvalue }
                         value := maxvalue;
                      end;
                      ConcatConstant(p,value,maxvalue);
                  end;
          { These terms can start an assembler expression }
          AS_PLUS,AS_MINUS,AS_LPAREN,AS_NOT: Begin
                                          value := BuildExpression;
                                          ConcatConstant(p,value,maxvalue);
                                         end;
          AS_COMMA:  BEGIN
                       Consume(AS_COMMA);
                     END;
          AS_SEPARATOR: ;

        else
         Begin
           Message(assem_f_internal_error_in_buildconstant);
         end;
    end; { end case }
   Until actasmtoken = AS_SEPARATOR;
  end;






  Procedure BuildOpCode;
  {*********************************************************************}
  { PROCEDURE BuildOpcode;                                              }
  {  Description: Parses the intel opcode and operands, and writes it   }
  {  in the TInstruction object.                                        }
  {*********************************************************************}
  { EXIT CONDITION:  On exit the routine should point to AS_SEPARATOR.  }
  { On ENTRY: Token should point to AS_OPCODE                           }
  {*********************************************************************}
  var asmtok: tasmop;
      op: tasmop;
      expr: string;
      segreg: tregister;
  Begin
    expr := '';
    asmtok := A_NONE; { assmume no prefix          }
    segreg := R_NO;   { assume no segment override }

    { //  prefix seg opcode               // }
    { //  prefix opcode                   // }
    if findprefix(actasmpattern,asmtok) then
    Begin
     { standard opcode prefix }
     if asmtok <> A_NONE then
       instr.addprefix(asmtok);
     Consume(AS_OPCODE);
     if findoverride(actasmpattern,segreg) then
     Begin
       Consume(AS_OPCODE);
       Message(assem_w_repeat_prefix_and_seg_override);
     end;
    end
    else
    { //  seg prefix opcode               // }
    { //  seg opcode                      // }
    if findoverride(actasmpattern,segreg) then
    Begin
      Consume(AS_OPCODE);
      if findprefix(actasmpattern,asmtok) then
      Begin
     { standard opcode prefix }
        Message(assem_w_repeat_prefix_and_seg_override);
        if asmtok <> A_NONE then
          instr.addprefix(asmtok);
        Consume(AS_OPCODE);
      end;
    end;
    { //  opcode                          // }
    if (actasmtoken <> AS_OPCODE) then
    Begin
      Message(assem_e_invalid_or_missing_opcode);
      { error recovery }
      While not (actasmtoken in [AS_SEPARATOR,AS_COMMA]) do
         Consume(actasmtoken);
      exit;
    end
    else
    Begin
      op := findopcode(actasmpattern);
      instr.addinstr(op);
      { // Valid combination of prefix and instruction ? // }
      if (asmtok <> A_NONE) and (NOT CheckPrefix(asmtok,op)) then
        Message1(assem_e_invalid_prefix_and_opcode,actasmpattern);
      { // Valid combination of segment override // }
      if (segreg <> R_NO) and (NOT CheckOverride(segreg,instr)) then
        Message1(assem_e_invalid_override_and_opcode,actasmpattern);
      Consume(AS_OPCODE);
      { // Zero operand opcode ? // }
      if actasmtoken = AS_SEPARATOR then
        exit
      else
       operandnum := 1;
    end;

    While actasmtoken <> AS_SEPARATOR do
    Begin
       case actasmtoken of
         { //  Operand delimiter // }
         AS_COMMA: Begin
                  if operandnum > MaxOperands then
                    Message(assem_e_too_many_operands)
                  else
                    Inc(operandnum);
                  Consume(AS_COMMA);
                end;
         { // Typecast, Constant Expression, Type Specifier // }
         AS_DWORD,AS_BYTE,AS_WORD,AS_TBYTE,AS_QWORD: Begin
                                  Case actasmtoken of
                                   AS_DWORD: instr.operands[operandnum].size := S_L;
                                   AS_WORD:  instr.operands[operandnum].size := S_W;
                                   AS_BYTE:  instr.operands[operandnum].size := S_B;
                                   AS_QWORD: instr.operands[operandnum].size := S_Q;
                                   AS_TBYTE: instr.operands[operandnum].size := S_X;
                                  end;
                                  Consume(actasmtoken);
                                  Case actasmtoken of
                                  { // Reference // }
                                  AS_PTR: Begin
                                           initAsmRef(instr);
                                           Consume(AS_PTR);
                                           BuildOperand(instr);
                                         end;
                                  { // Possibly a typecast or a constant // }
                                  { // expression.                       // }
                                  AS_LPAREN: Begin
                                              if actasmtoken = AS_ID then
                                              Begin
                                                { Case vartype of                }
                                                {  LOCAL: Replace by offset and  }
                                                {         BP in treference.      }
                                                {  GLOBAL: Replace by mangledname}
                                                {    in symbol of treference     }
                                                { Check if next token = RPAREN   }
                                                { otherwise syntax error.        }
                                                initAsmRef(instr);
                                                if not CreateVarInstr(instr,actasmpattern,
                                                   operandnum) then
                                                Begin
                                                   Message1(assem_e_unknown_id,actasmpattern);
                                                end;
                                              end
                                              else
                                               begin
                                                 instr.operands[operandnum].operandtype := OPR_CONSTANT;
                                                 instr.operands[operandnum].val := BuildExpression;
                                               end;
                                            end;
                                  else
                                    BuildOperand(instr);
                                  end; { end case }
                            end;
         { // Type specifier // }
         AS_NEAR,AS_FAR: Begin
                          if actasmtoken = AS_NEAR then
                            Message(assem_w_near_ignored)
                          else
                            Message(assem_w_far_ignored);
                          Consume(actasmtoken);
                          if actasmtoken = AS_PTR then
                           begin
                             initAsmRef(instr);
                             Consume(AS_PTR);
                           end;
                           BuildOperand(instr);
                       end;
         { // End of asm operands for this opcode // }
         AS_SEPARATOR: ;
         { // Constant expression // }
         AS_LPAREN: Begin
                      instr.operands[operandnum].operandtype := OPR_CONSTANT;
                      instr.operands[operandnum].val := BuildExpression;
                    end;
       else
         BuildOperand(instr);
     end; { end case }
    end; { end while }
  end;


  Function Assemble: Ptree;
  {*********************************************************************}
  { PROCEDURE Assemble;                                                 }
  {  Description: Parses the intel assembler syntax, parsing is done    }
  {  according to the rules in the Turbo Pascal manual.                 }
  {*********************************************************************}
  Var
   hl: plabel;
   labelptr: pasmlabel;
  Begin
    Message(assem_d_start_intel);
    inexpression := FALSE;
    firsttoken := TRUE;
    operandnum := 0;
    { sets up all opcode and register tables in uppercase }
    if not _asmsorted then
    Begin
      SetupTables;
      _asmsorted := TRUE;
    end;
    p:=new(paasmoutput,init);
    { setup label linked list }
    labellist.init;
    c:=asmgetchar;
    actasmtoken:=gettoken;
    while actasmtoken<>AS_END do
    Begin
      case actasmtoken of
        AS_LLABEL: Begin
                    labelptr := labellist.search(actasmpattern);
                    if not assigned(labelptr) then
                    Begin
                        getlabel(hl);
                        labellist.insert(actasmpattern,hl,TRUE);
                        ConcatLabel(p,A_LABEL,hl);
                    end
                    else
                    { the label has already been inserted into the  }
                    { label list, either as an intruction label (in }
                    { this case it has not been emitted), or as a   }
                    { duplicate local symbol (in this case it has   }
                    { already been emitted).                        }
                    Begin
                       if labelptr^.emitted then
                        Message1(assem_e_dup_local_sym,'@'+labelptr^.name^)
                       else
                        Begin
                          if assigned(labelptr^.lab) then
                            ConcatLabel(p,A_LABEL,labelptr^.lab);
                          labelptr^.emitted := TRUE;
                        end;
                    end;
                    Consume(AS_LLABEL);
                  end;
        AS_LABEL: Begin
                     if SearchLabel(actasmpattern,hl) then
                       ConcatLabel(p,A_LABEL, hl)
                     else
                       Message1(assem_e_unknown_label_identifer,actasmpattern);
                     Consume(AS_LABEL);
                 end;
        AS_DW:    Begin
                   Consume(AS_DW);
                   BuildConstant($ffff);
                 end;

        AS_DB:   Begin
                  Consume(AS_DB);
                  BuildConstant($ff);
                end;
        AS_DD:   Begin
                 Consume(AS_DD);
                 BuildConstant($ffffffff);
                end;
        AS_OPCODE: Begin
                   instr.init;
                   BuildOpcode;
                   instr.numops := operandnum;
                   if instr.labeled then
                     ConcatLabeledInstr(instr)
                   else
                     ConcatOpCode(instr);
                  end;
        AS_SEPARATOR:Begin
                     Consume(AS_SEPARATOR);
                     { let us go back to the first operand }
                     operandnum := 0;
                    end;
        AS_END: ; { end assembly block }
    else
      Begin
         Message(assem_e_assemble_node_syntax_error);
         { error recovery }
         Consume(actasmtoken);
      end;
    end; { end case }
  end; { end while }
  { check if there were undefined symbols.   }
  { if so, then list each of those undefined }
  { labels.                                  }
  if assigned(labellist.First) then
  Begin
    labelptr := labellist.First;
    if labellist.First <> nil then
    Begin
      { first label }
      if not labelptr^.emitted then
       Message1(assem_e_unknown_local_sym,'@'+labelptr^.name^);
      { other labels ... }
      While (labelptr^.Next <> nil) do
       Begin
          labelptr := labelptr^.Next;
          if not labelptr^.emitted then
           Message1(assem_e_unknown_local_sym,'@'+labelptr^.name^);
      end;
    end;
  end;
  assemble := genasmnode(p);
  labellist.done;
  Message(assem_d_finish_intel);
end;


Begin
   old_exit:=exitproc;
   exitproc:=@rai386_exit;
end.
{
  $Log$
  Revision 1.2  1998-03-31 15:21:01  florian
    * fix of out (intel syntax) applied

  Revision 1.1.1.1  1998/03/25 11:18:15  root
  * Restored version

  Revision 1.19  1998/03/24 21:48:34  florian
    * just a couple of fixes applied:
         - problem with fixed16 solved
         - internalerror 10005 problem fixed
         - patch for assembler reading
         - small optimizer fix
         - mem is now supported

  Revision 1.18  1998/03/10 01:17:26  peter
    * all files have the same header
    * messages are fully implemented, EXTDEBUG uses Comment()
    + AG... files for the Assembler generation

  Revision 1.17  1998/03/09 12:58:12  peter
    * FWait warning is only showed for Go32V2 and $E+
    * opcode tables moved to i386.pas/m68k.pas to reduce circular uses (and
      for m68k the same tables are removed)
    + $E for i386

  Revision 1.16  1998/03/04 17:33:56  michael
  + Changed ifdef FPK to ifdef FPC

  Revision 1.15  1998/03/03 22:38:26  peter
    * the last 3 files

  Revision 1.14  1998/03/02 01:49:15  peter
    * renamed target_DOS to target_GO32V1
    + new verbose system, merged old errors and verbose units into one new
      verbose.pas, so errors.pas is obsolete

  Revision 1.13  1998/02/13 10:35:38  daniel
  * Made Motorola version compilable.
  * Fixed optimizer

  Revision 1.12  1998/02/12 11:50:36  daniel
  Yes! Finally! After three retries, my patch!

  Changes:

  Complete rewrite of psub.pas.
  Added support for DLL's.
  Compiler requires less memory.
  Platform units for each platform.

  Revision 1.11  1998/02/07 18:02:36  carl
    + fwait warning for emulation

  Revision 1.10  1998/01/19 03:11:40  carl
    * bugfix number 78

  Revision 1.9  1998/01/09 19:22:51  carl
  * bugfix of __ID variable names

  Revision 1.8  1997/12/09 14:00:25  carl
  * bugfix of intr reg,reg instructions, size must always be specified
    under gas (ref: DJGPP FAQ)
  * bugfix of concatopcode with fits init twice!
  + unknown instr. only poermitted when compiling system unit and/or
    target processor > i386

  Revision 1.7  1997/12/04 12:20:50  pierre
    +* MMX instructions added to att output with a warning that
       GNU as version >= 2.81 is needed
       bug in reading of reals under att syntax corrected

  Revision 1.6  1997/11/28 18:14:45  pierre
   working version with several bug fixes

  Revision 1.5  1997/11/28 15:43:20  florian
  Fixed stack ajustment bug, 0.9.8 compiles now 0.9.8 without problems.

  Revision 1.4  1997/11/28 15:31:59  carl
  * uncommented firstop and lastop. (otherwise can cause bugs)

  Revision 1.3  1997/11/28 14:26:22  florian
  Fixed some bugs

  Revision 1.2  1997/11/28 12:03:53  michael
  Changed comment delimiters to braces, causes problems with 0.9.1
  Changed use of ord to typecast with longint.
  Made boolean expressions non-redundant.

  Revision 1.1.1.1  1997/11/27 08:33:00  michael
  FPC Compiler CVS start


  Pre-CVS log:

  CEC   Carl-Eric Codere
  FK    Florian Klaempfl
  PM    Pierre Muller
  +     feature added
  -     removed
  *     bug fixed or changed

  9th november 1997:
   + first working version with main distribution line of FPC (CEC)
 12th november 1997:
   * bugfix of CALL and JMP with symbolic references. (CEC)
 13th november 1997:
   * too many bugfixes/improvements to name... (CEC)
   * Fixed range check, line numbering, missing operand checking
     bugs - range checking must be off to compile under tp. (CEC)
   + speed improvement of 30% over old version with global look up tables.
 14th november 1997:
   + added support for record/object offsets. (CEC)
   * fixed bug regarding ENTER and push imm8 instruction(CEC)
   + fixed conflicts with fpu instructions. (CEC).

}