freepascal.compiler/compiler/powerpc/agppcmpw.pas

{
    Copyright (c) 2002 by Florian Klaempfl

    This unit implements an asmoutput class for PowerPC with MPW syntax

    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.

 ****************************************************************************
}
{
  This unit implements an asmoutput class for PowerPC with MPW syntax
}
unit agppcmpw;

{$i fpcdefs.inc}
 { We know that use_PR is a const boolean
   but we don't care about this warning }
 {$WARN 6018 OFF}

interface

    uses
       aasmtai,aasmdata,
       globals,aasmbase,aasmcpu,assemble,
       cpubase;

    type
      TPPCMPWAssembler = class(TExternalAssembler)
        procedure WriteTree(p:TAsmList);override;
        procedure WriteAsmList;override;
        Function  DoAssemble:boolean;override;
        procedure WriteExternals;
        procedure WriteAsmFileHeader;
      private
        cur_CSECT_name: String;
        cur_CSECT_class: String;

        procedure WriteInstruction(hp : tai);
        procedure WriteProcedureHeader(var hp:tai);
        procedure WriteDataHeader(var s:string; isExported, isConst:boolean);
      end;


  implementation

    uses
      cutils,globtype,systems,cclasses,
      verbose,finput,fmodule,script,cpuinfo,
      cgbase,cgutils,
      itcpugas
      ;

    const
      line_length = 70;

      {Whether internal procedure references should be xxx[PR]: }
      use_PR = false;

      const_storage_class = '';
      var_storage_class = '';

      secnames : array[TAsmSectiontype] of string[10] = (
        '',      {none}
        '',      {user}
        'csect', {code}
        'csect', {data}
        'csect', {read only data}
        'csect', {read only data - no relocations}
        'csect', {bss} 'csect', '',
        'csect','csect','csect','csect','csect',
        'csect','csect','csect',
         '','','','','','','','','','','','','','',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        '',
        ''
      );

    type
      t64bitarray = array[0..7] of byte;
      t32bitarray = array[0..3] of byte;

    function ReplaceForbiddenChars(var s: string):Boolean;
         {Returns wheater a replacement has occured.}

        var
          i:Integer;

        {The dollar sign is not allowed in MPW PPCAsm}

    begin
      ReplaceForbiddenChars:=false;
      for i:=1 to Length(s) do
        if s[i]='$' then
          begin
            s[i]:='s';
            ReplaceForbiddenChars:=true;
          end;
    end;


{*** From here is copyed from agppcgas.pp, except where marked with CHANGED.
     Perhaps put in a third common file. ***}


    function getreferencestring(var ref : treference) : string;
    var
      s : string;
    begin
       with ref do
        begin
          if (refaddr <> addr_no) then
            InternalError(2002110301)
          else if ((offset < -32768) or (offset > 32767)) then
            InternalError(19991);


          if assigned(symbol) then
            begin
              s:= symbol.name;
              ReplaceForbiddenChars(s);
              {if symbol.typ = AT_FUNCTION then
                  ;}

              s:= s+'[TC]' {ref to TOC entry }
            end
          else
            s:= '';


          if offset<0 then
            s:=s+tostr(offset)
          else
           if (offset>0) then
            begin
              if assigned(symbol) then
               s:=s+'+'+tostr(offset)
              else
               s:=s+tostr(offset);
            end;

          if (index=NR_NO) and (base<>NR_NO) then
            begin
              if offset=0 then
                if not assigned(symbol) then
                  s:=s+'0';
              s:=s+'('+gas_regname(base)+')';
            end
          else if (index<>NR_NO) and (base<>NR_NO) and (offset=0) then
            begin
              if (offset=0) then
                s:=s+gas_regname(base)+','+gas_regname(index)
              else
                internalerror(19992);
            end
          else if (base=NR_NO) and (offset=0) then
            begin
              {Temporary fix for inline asm, where a local var is referenced.}
              //if assigned(symbol) then
              //  s:= s+'(rtoc)';
            end;
        end;
      getreferencestring:=s;
    end;

    function getopstr_jmp(const o:toper) : string;
    var
      hs : string;
    begin
      case o.typ of
        top_reg :
          getopstr_jmp:=gas_regname(o.reg);
        { no top_ref jumping for powerpc }
        top_const :
          getopstr_jmp:=tostr(o.val);
        top_ref :
          begin
            if o.ref^.refaddr=addr_full then
              begin
                hs:=o.ref^.symbol.name;
                ReplaceForbiddenChars(hs);
                case o.ref^.symbol.typ of
                  AT_FUNCTION:
                    begin
                      if hs[1] <> '@' then {if not local label}
                        if use_PR then
                          hs:= '.'+hs+'[PR]'
                        else
                          hs:= '.'+hs
                    end
                  else
                    ;
                end;
                if o.ref^.offset>0 then
                 hs:=hs+'+'+tostr(o.ref^.offset)
                else
                 if o.ref^.offset<0 then
                  hs:=hs+tostr(o.ref^.offset);
                getopstr_jmp:=hs;
              end
            else
              internalerror(200402263);
          end;
        top_none:
          getopstr_jmp:='';
        else
          internalerror(2002070603);
      end;
    end;

    function getopstr(const o:toper) : string;
    var
      hs : string;
    begin
      case o.typ of
        top_reg:
          getopstr:=gas_regname(o.reg);
        top_const:
          getopstr:=tostr(longint(o.val));
        top_ref:
          if o.ref^.refaddr=addr_no then
            getopstr:=getreferencestring(o.ref^)
          else
            begin
              hs:=o.ref^.symbol.name;
              ReplaceForbiddenChars(hs);
              if o.ref^.offset>0 then
               hs:=hs+'+'+tostr(o.ref^.offset)
              else
               if o.ref^.offset<0 then
                hs:=hs+tostr(o.ref^.offset);
              getopstr:=hs;
            end;
        else
          internalerror(2002070604);
      end;
    end;

    type
      topstr = string[4];

    function branchmode(o: tasmop): topstr;
      var tempstr: topstr;
      begin
        tempstr := '';
        case o of
          A_BCCTR,A_BCCTRL: tempstr := 'ctr';
          A_BCLR,A_BCLRL: tempstr := 'lr';
        end;
        case o of
          A_BL,A_BLA,A_BCL,A_BCLA,A_BCCTRL,A_BCLRL: tempstr := tempstr+'l';
        end;
        case o of
          A_BA,A_BLA,A_BCA,A_BCLA: tempstr:=tempstr+'a';
        end;
        branchmode := tempstr;
      end;

    function cond2str(op: tasmop; c: tasmcond): string;
    { note: no checking is performed whether the given combination of }
    { conditions is valid                                             }
    var
      tempstr: string;
    begin
      tempstr:=#9;
      case c.simple of
        false:
          begin
            cond2str := tempstr+gas_op2str[op];
            case c.dirhint of
              DH_None:;
              DH_Minus:
                cond2str:=cond2str+'-';
              DH_Plus:
                cond2str:=cond2str+'+';
              else
                internalerror(2003112901);
            end;
            cond2str:=cond2str+#9+tostr(c.bo)+','+tostr(c.bi)+',';
          end;
        true:
          if (op >= A_B) and (op <= A_BCLRL) then
            case c.cond of
              { unconditional branch }
              C_NONE:
                cond2str := tempstr+gas_op2str[op];
              { bdnzt etc }
              else
                begin
                  tempstr := tempstr+'b'+asmcondflag2str[c.cond]+
                              branchmode(op);
                  case c.dirhint of
                    DH_None:
                      tempstr:=tempstr+#9;
                    DH_Minus:
                      tempstr:=tempstr+('-'+#9);
                    DH_Plus:
                      tempstr:=tempstr+('+'+#9);
                    else
                      internalerror(2003112901);
                  end;
                  case c.cond of
                    C_LT..C_NU:
                      cond2str := tempstr+gas_regname(newreg(R_SPECIALREGISTER,c.cr,R_SUBWHOLE));
                    C_T,C_F,C_DNZT,C_DNZF,C_DZT,C_DZF:
                      cond2str := tempstr+tostr(c.crbit);
                    else
                      cond2str := tempstr;
                  end;
                end;
            end
          { we have a trap instruction }
          else
            begin
              internalerror(2002070601);
              { not yet implemented !!!!!!!!!!!!!!!!!!!!! }
              { case tempstr := 'tw';}
            end;
      end;
    end;

    procedure TPPCMPWAssembler.WriteInstruction(hp : tai);
    var op: TAsmOp;
        s: string;
        i: byte;
        sep: string[3];
    begin
      op:=taicpu(hp).opcode;
      if is_calljmp(op) then
        begin
          { direct BO/BI in op[0] and op[1] not supported, put them in condition! }
          case op of
             A_B,A_BA:
               s:=#9+gas_op2str[op]+#9;
             A_BCTR,A_BCTRL,A_BLR,A_BLRL:
               s:=#9+gas_op2str[op];
             A_BL,A_BLA:
               s:=#9+gas_op2str[op]+#9;
             else
               begin
                 s:=cond2str(op,taicpu(hp).condition);
                 if (s[length(s)] <> #9) and
                    (taicpu(hp).ops>0) then
                   s := s + ',';
               end;
          end;
          if (taicpu(hp).ops>0) and (taicpu(hp).oper[0]^.typ<>top_none) then
            begin
              { first write the current contents of s, because the symbol }
              { may be 255 characters                                     }
              writer.AsmWrite(s);
              s:=getopstr_jmp(taicpu(hp).oper[0]^);
            end;
        end
      else
        { process operands }
        begin
          s:=#9+gas_op2str[op];
          if taicpu(hp).ops<>0 then
            begin
               sep:=#9;
               for i:=0 to taicpu(hp).ops-1 do
                 begin
                   s:=s+sep+getopstr(taicpu(hp).oper[i]^);
                   sep:=',';
                 end;
            end;
        end;
      writer.AsmWriteLn(s);
    end;

    {*** Until here is copyed from agppcgas.pp. ***}


    function single2str(d : single) : string;
      var
         hs : string;
         p : byte;
      begin
         str(d,hs);
      { nasm expects a lowercase e }
         p:=pos('E',hs);
         if p>0 then
          hs[p]:='e';
         p:=pos('+',hs);
         if p>0 then
          delete(hs,p,1);
         single2str:=lower(hs);
      end;

    function double2str(d : double) : string;
      var
         hs : string;
         p : byte;
      begin
         str(d,hs);
      { nasm expects a lowercase e }
         p:=pos('E',hs);
         if p>0 then
          hs[p]:='e';
         p:=pos('+',hs);
         if p>0 then
          delete(hs,p,1);
         double2str:=lower(hs);
      end;

  { convert floating point values }
  { to correct endian             }
  procedure swap64bitarray(var t: t64bitarray);
    var
     b: byte;
    begin
      b:= t[7];
      t[7] := t[0];
      t[0] := b;

      b := t[6];
      t[6] := t[1];
      t[1] := b;

      b:= t[5];
      t[5] := t[2];
      t[2] := b;

      b:= t[4];
      t[4] := t[3];
      t[3] := b;
   end;

   procedure swap32bitarray(var t: t32bitarray);
    var
     b: byte;
    begin
      b:= t[1];
      t[1]:= t[2];
      t[2]:= b;

      b:= t[0];
      t[0]:= t[3];
      t[3]:= b;
    end;

    Function PadTabs(const p:string;addch:char):string;
    var
      s : string;
      i : longint;
    begin
      i:=length(p);
      if addch<>#0 then
       begin
         inc(i);
         s:=p+addch;
       end
      else
       s:=p;
      if i<8 then
       PadTabs:=s+#9#9
      else
       PadTabs:=s+#9;
    end;

{****************************************************************************
                               PowerPC MPW Assembler
 ****************************************************************************}
    procedure TPPCMPWAssembler.WriteProcedureHeader(var hp:tai);
      {Returns the current hp where the caller should continue from}
      {For multiple entry procedures, only the last is exported as xxx[PR]
       (if use_PR is set) }

      procedure WriteExportHeader(hp:tai);

        var
          s: string;
          replaced: boolean;

      begin
        s:= tai_symbol(hp).sym.name;
        replaced:= ReplaceForbiddenChars(s);

        if not use_PR then
          begin
            writer.AsmWrite(#9'export'#9'.');
            writer.AsmWrite(s);
            if replaced then
              begin
                writer.AsmWrite(' => ''.');
                writer.AsmWrite(tai_symbol(hp).sym.name);
                writer.AsmWrite('''');
              end;
            writer.AsmLn;
          end;

        writer.AsmWrite(#9'export'#9);
        writer.AsmWrite(s);
        writer.AsmWrite('[DS]');
        if replaced then
          begin
            writer.AsmWrite(' => ''');
            writer.AsmWrite(tai_symbol(hp).sym.name);
            writer.AsmWrite('[DS]''');
          end;
        writer.AsmLn;

        {Entry in transition vector: }
        writer.AsmWrite(#9'csect'#9); writer.AsmWrite(s); writer.AsmWriteLn('[DS]');

        writer.AsmWrite(#9'dc.l'#9'.'); writer.AsmWriteLn(s);

        writer.AsmWriteln(#9'dc.l'#9'TOC[tc0]');

        {Entry in TOC: }
        writer.AsmWriteLn(#9'toc');

        writer.AsmWrite(#9'tc'#9);
        writer.AsmWrite(s); writer.AsmWrite('[TC],');
        writer.AsmWrite(s); writer.AsmWriteln('[DS]');
      end;

    function GetAdjacentTaiSymbol(var hp:tai):Boolean;

    begin
      GetAdjacentTaiSymbol:= false;
      while assigned(hp.next) do
        case tai(hp.next).typ of
          ait_symbol:
            begin
              hp:=tai(hp.next);
              GetAdjacentTaiSymbol:= true;
              Break;
            end;
          ait_function_name:
            hp:=tai(hp.next);
          else
            begin
              //writer.AsmWriteln('  ;#*#*# ' + tostr(Ord(tai(hp.next).typ)));
              Break;
            end;
        end;
    end;

    var
      first,last: tai;
      s: string;
      replaced: boolean;


    begin
      s:= tai_symbol(hp).sym.name;
      {Write all headers}
      first:= hp;
      repeat
        WriteExportHeader(hp);
        last:= hp;
      until not GetAdjacentTaiSymbol(hp);

      {Start the section of the body of the proc: }
      s:= tai_symbol(last).sym.name;
      replaced:= ReplaceForbiddenChars(s);

      if use_PR then
        begin
          writer.AsmWrite(#9'export'#9'.'); writer.AsmWrite(s); writer.AsmWrite('[PR]');
          if replaced then
            begin
              writer.AsmWrite(' => ''.');
              writer.AsmWrite(tai_symbol(last).sym.name);
              writer.AsmWrite('[PR]''');
            end;
          writer.AsmLn;
        end;

      {Starts the section: }
      writer.AsmWrite(#9'csect'#9'.');
      writer.AsmWrite(s);
      writer.AsmWriteLn('[PR]');

      {Info for the debugger: }
      writer.AsmWrite(#9'function'#9'.');
      writer.AsmWrite(s);
      writer.AsmWriteLn('[PR]');

      {Write all labels: }
      hp:= first;
      repeat
        s:= tai_symbol(hp).sym.name;
        ReplaceForbiddenChars(s);
        writer.AsmWrite('.'); writer.AsmWrite(s); writer.AsmWriteLn(':');
      until not GetAdjacentTaiSymbol(hp);
    end;

    procedure TPPCMPWAssembler.WriteDataHeader(var s:string; isExported, isConst:boolean);
    // Returns in s the changed string
    var
      sym: string;
      replaced: boolean;

    begin
      sym:= s;
      replaced:= ReplaceForbiddenChars(s);

      if isExported then
        begin
          writer.AsmWrite(#9'export'#9);
          writer.AsmWrite(s);
          if isConst then
            writer.AsmWrite(const_storage_class)
          else
            writer.AsmWrite(var_storage_class);
          if replaced then
              begin
                writer.AsmWrite(' => ''');
                writer.AsmWrite(sym);
                writer.AsmWrite('''');
              end;
          writer.AsmLn;
        end;

      if not macos_direct_globals then
        begin
          {The actual section is here interrupted, by inserting a "tc" entry}
          writer.AsmWriteLn(#9'toc');

          writer.AsmWrite(#9'tc'#9);
          writer.AsmWrite(s);
          writer.AsmWrite('[TC], ');
          writer.AsmWrite(s);
          if isConst then
            writer.AsmWrite(const_storage_class)
          else
            writer.AsmWrite(var_storage_class);
          writer.AsmLn;

          {The interrupted section is here continued.}
          writer.AsmWrite(#9'csect'#9);
          writer.AsmWriteln(cur_CSECT_name+cur_CSECT_class);
          writer.AsmWrite(PadTabs(s+':',#0));
        end
      else
        begin
          writer.AsmWrite(#9'csect'#9);
          writer.AsmWrite(s);
          writer.AsmWrite('[TC]');
        end;

      writer.AsmLn;
    end;

    const
      ait_const2str:array[aitconst_32bit..aitconst_8bit] of string[8]=
        (#9'dc.l'#9,#9'dc.w'#9,#9'dc.b'#9);


    procedure TPPCMPWAssembler.WriteTree(p:TAsmList);
    var
      s        : string;
      hp       : tai;
      counter,
      lines,
      InlineLevel : longint;
      i,j,l    : longint;
      consttype : taiconst_type;
      do_line,DoNotSplitLine,
      quoted   : boolean;
      sin      : single;
      d        : double;

    begin
      if not assigned(p) then
       exit;
      InlineLevel:=0;
      { lineinfo is only needed for al_procedures (PFV) }
      do_line:=((cs_asm_source in current_settings.globalswitches) or
                (cs_lineinfo in current_settings.moduleswitches))
                 and (p=current_asmdata.asmlists[al_procedures]);
      DoNotSplitLine:=false;
      hp:=tai(p.first);
      while assigned(hp) do
       begin
         prefetch(pointer(hp.next)^);
         if not(hp.typ in SkipLineInfo) then
          begin
            current_filepos:=tailineinfo(hp).fileinfo;
            { no line info for inlined code }
            if do_line and (inlinelevel=0) and not DoNotSplitLine then
              WriteSourceLine(hp as tailineinfo);
          end;

         DoNotSplitLine:=false;

         case hp.typ of
            ait_comment:
              begin
                 writer.AsmWrite(asminfo^.comment);
                 writer.AsmWritePChar(tai_comment(hp).str);
                 writer.AsmLn;
              end;
            ait_regalloc,
            ait_tempalloc:
              ;
            ait_section:
              begin
                 {if LastSecType<>sec_none then
                  writer.AsmWriteLn('_'+asminfo^.secnames[LastSecType]+#9#9'ENDS');}

                 if tai_section(hp).sectype<>sec_none then
                  begin
                    if tai_section(hp).sectype in [sec_data,sec_rodata,sec_bss] then
                      cur_CSECT_class:= '[RW]'
                    else if tai_section(hp).sectype in [sec_code] then
                      cur_CSECT_class:= ''
                    else
                      cur_CSECT_class:= '[RO]';

                    s:= tai_section(hp).name^;
                    if s = '' then
                      InternalError(2004101001);    {Nameless sections should not occur on MPW}
                    ReplaceForbiddenChars(s);
                    cur_CSECT_name:= s;

                    writer.AsmLn;
                    writer.AsmWriteLn(#9+secnames[tai_section(hp).sectype]+' '+cur_CSECT_name+cur_CSECT_class);
                  end;
                 LastSecType:=tai_section(hp).sectype;
               end;
            ait_align:
              begin
                 case tai_align(hp).aligntype of
                   1:writer.AsmWriteLn(#9'align 0');
                   2:writer.AsmWriteLn(#9'align 1');
                   4:writer.AsmWriteLn(#9'align 2');
                   otherwise internalerror(2002110302);
                 end;
              end;
            ait_datablock: {Storage for global variables.}
              begin
                 s:= tai_datablock(hp).sym.name;

                 WriteDataHeader(s, tai_datablock(hp).is_global, false);
                 if not macos_direct_globals then
                   begin
                     writer.AsmWriteLn(#9'ds.b '+tostr(tai_datablock(hp).size));
                   end
                 else
                   begin
                     writer.AsmWriteLn(PadTabs(s+':',#0)+'ds.b '+tostr(tai_datablock(hp).size));
                     {TODO: ? PadTabs(s,#0) }
                   end;
              end;

            ait_const:
              begin
                consttype:=tai_const(hp).consttype;
                case consttype of
                   aitconst_128bit:
                      begin
                        internalerror(200404291);
                      end;
                   aitconst_64bit:
                      begin
                        if assigned(tai_const(hp).sym) then
                          internalerror(200404292);
                        writer.AsmWrite(ait_const2str[aitconst_32bit]);
                        if target_info.endian = endian_little then
                          begin
                            writer.AsmWrite(tostr(longint(lo(tai_const(hp).value))));
                            writer.AsmWrite(',');
                            writer.AsmWrite(tostr(longint(hi(tai_const(hp).value))));
                          end
                        else
                          begin
                            writer.AsmWrite(tostr(longint(hi(tai_const(hp).value))));
                            writer.AsmWrite(',');
                            writer.AsmWrite(tostr(longint(lo(tai_const(hp).value))));
                          end;
                        writer.AsmLn;
                      end;

                   aitconst_uleb128bit,
                   aitconst_sleb128bit,
                   aitconst_32bit,
                   aitconst_16bit,
                   aitconst_8bit,
                   aitconst_rva_symbol :
                     begin
                       writer.AsmWrite(ait_const2str[consttype]);
                       l:=0;
                       repeat
                         if assigned(tai_const(hp).sym) then
                           begin
                             if assigned(tai_const(hp).endsym) then
                               begin
                                 if (tai_const(hp).endsym.typ = AT_FUNCTION) and use_PR then
                                   writer.AsmWrite('.');

                                 s:=tai_const(hp).endsym.name;
                                 ReplaceForbiddenChars(s);
                                 writer.AsmWrite(s);
                                 inc(l,length(s));

                                 if tai_const(hp).endsym.typ = AT_FUNCTION then
                                   begin
                                     if use_PR then
                                       writer.AsmWrite('[PR]')
                                     else
                                       writer.AsmWrite('[DS]');
                                   end;

                                 writer.AsmWrite('-');
                                 inc(l,5); {Approx 5 extra, no need to be exactly}
                               end;

                             if (tai_const(hp).sym.typ = AT_FUNCTION) and use_PR then
                               writer.AsmWrite('.');

                             s:= tai_const(hp).sym.name;
                             ReplaceForbiddenChars(s);
                             writer.AsmWrite(s);
                             inc(l,length(s));

                             if tai_const(hp).sym.typ = AT_FUNCTION then
                               begin
                                 if use_PR then
                                   writer.AsmWrite('[PR]')
                                 else
                                   writer.AsmWrite('[DS]');
                               end;
                             inc(l,5); {Approx 5 extra, no need to be exactly}

                             if tai_const(hp).value > 0 then
                               s:= '+'+tostr(tai_const(hp).value)
                             else if tai_const(hp).value < 0 then
                               s:= '-'+tostr(tai_const(hp).value)
                             else
                               s:= '';
                             if s<>'' then
                               begin
                                 writer.AsmWrite(s);
                                 inc(l,length(s));
                               end;
                           end
                         else
                           begin
                             s:= tostr(tai_const(hp).value);
                             writer.AsmWrite(s);
                             inc(l,length(s));
                           end;

                         if (l>line_length) or
                            (hp.next=nil) or
                            (tai(hp.next).typ<>ait_const) or
                            (tai_const(hp.next).consttype<>consttype) then
                           break;
                         hp:=tai(hp.next);
                         writer.AsmWrite(',');
                       until false;
                       writer.AsmLn;
                     end;
                end;
              end;

            ait_realconst:
              begin
                WriteRealConstAsBytes(tai_realconst(hp),#9'dc.b'#9,do_line);
              end;

            ait_string:
              begin
                {NOTE When a single quote char is encountered, it is
                replaced with a numeric ascii value. It could also
                have been replaced with the escape seq of double quotes.
                Backslash seems to be used as an escape char, although
                this is not mentioned in the PPCAsm documentation.}
                counter := 0;
                lines := tai_string(hp).len div line_length;
                { separate lines in different parts }
                if tai_string(hp).len > 0 then
                  begin
                    for j := 0 to lines-1 do
                      begin
                        writer.AsmWrite(#9'dc.b'#9);
                        quoted:=false;
                        for i:=counter to counter+line_length-1 do
                          begin
                            { it is an ascii character. }
                            if (ord(tai_string(hp).str[i])>31) and
                               (ord(tai_string(hp).str[i])<128) and
                               (tai_string(hp).str[i]<>'''') and
                               (tai_string(hp).str[i]<>'\') then
                              begin
                                if not(quoted) then
                                    begin
                                      if i>counter then
                                        writer.AsmWrite(',');
                                      writer.AsmWrite('''');
                                    end;
                                writer.AsmWrite(tai_string(hp).str[i]);
                                quoted:=true;
                              end { if > 31 and < 128 and ord('"') }
                            else
                              begin
                                  if quoted then
                                      writer.AsmWrite('''');
                                  if i>counter then
                                      writer.AsmWrite(',');
                                  quoted:=false;
                                  writer.AsmWrite(tostr(ord(tai_string(hp).str[i])));
                              end;
                          end; { end for i:=0 to... }
                        if quoted then writer.AsmWrite('''');
                        writer.AsmLn;
                        counter := counter+line_length;
                      end; { end for j:=0 ... }

                  { do last line of lines }
                  if counter < tai_string(hp).len then
                    writer.AsmWrite(#9'dc.b'#9);
                  quoted:=false;
                  for i:=counter to tai_string(hp).len-1 do
                    begin
                      { it is an ascii character. }
                      if (ord(tai_string(hp).str[i])>31) and
                         (ord(tai_string(hp).str[i])<128) and
                         (tai_string(hp).str[i]<>'''') and
                         (tai_string(hp).str[i]<>'\') then
                        begin
                          if not(quoted) then
                            begin
                              if i>counter then
                                writer.AsmWrite(',');
                              writer.AsmWrite('''');
                            end;
                          writer.AsmWrite(tai_string(hp).str[i]);
                          quoted:=true;
                        end { if > 31 and < 128 and " }
                      else
                        begin
                          if quoted then
                            writer.AsmWrite('''');
                          if i>counter then
                            writer.AsmWrite(',');
                          quoted:=false;
                          writer.AsmWrite(tostr(ord(tai_string(hp).str[i])));
                        end;
                    end; { end for i:=0 to... }
                  if quoted then
                    writer.AsmWrite('''');
                end;
                writer.AsmLn;
              end;
            ait_label:
              begin
                 if tai_label(hp).labsym.is_used then
                  begin
                    s:= tai_label(hp).labsym.name;
                    if s[1] = '@' then
                      begin
                        ReplaceForbiddenChars(s);
                        //Local labels:
                        writer.AsmWriteLn(s+':')
                      end
                    else
                      begin
                        //Procedure entry points:
                        if not macos_direct_globals then
                          begin
                            WriteDataHeader(s, tai_label(hp).labsym.bind in [AB_GLOBAL,AB_PRIVATE_EXTERN], true);
                          end
                        else
                          begin
                            ReplaceForbiddenChars(s);
                            writer.AsmWrite(#9'csect'#9); writer.AsmWrite(s);
                            writer.AsmWriteLn('[TC]');

                            writer.AsmWriteLn(PadTabs(s+':',#0));
                          end;
                      end;
                  end;
               end;
             ait_symbol:
               begin
                  if tai_symbol(hp).sym.typ=AT_FUNCTION then
                    WriteProcedureHeader(hp)
                  else if tai_symbol(hp).sym.typ=AT_DATA then
                    begin
                       s:= tai_symbol(hp).sym.name;
                       WriteDataHeader(s, tai_symbol(hp).is_global, true);
                       if macos_direct_globals then
                         begin
                           writer.AsmWrite(s);
                           writer.AsmWriteLn(':');
                         end;
                    end
                  else
                    InternalError(2003071301);
                end;
              ait_symbol_end:
                ;
              ait_instruction:
                WriteInstruction(hp);
              ait_stab,
              ait_force_line,
              ait_function_name : ;
              ait_cutobject :
                begin
                  InternalError(2004101101);  {Smart linking is done transparently by the MPW linker.}
                end;
              ait_marker :
                 begin
                   if tai_marker(hp).kind=mark_NoLineInfoStart then
                     inc(InlineLevel)
                   else if tai_marker(hp).kind=mark_NoLineInfoEnd then
                     dec(InlineLevel);
                 end;
              ait_directive :
                if tai_directive(hp).directive=asd_cpu then
                  begin
                    writer.AsmWrite(asminfo^.comment+' CPU ');
                    if tai_directive(hp).name<>'' then
                      writer.AsmWrite(tai_directive(hp).name);
                    writer.AsmLn;
                  end
                else
                  internalerror(2016022601);
         else
          internalerror(2002110303);
         end;
         hp:=tai(hp.next);
       end;
    end;

    var
      currentasmlist : TExternalAssembler;

    procedure writeexternal(p:tasmsymbol);

      var
        s:string;
        replaced: boolean;

      begin
        if tasmsymbol(p).bind=AB_EXTERNAL then
          begin
            //Writeln('ZZZ ',p.name,' ',p.classname,' ',Ord(tasmsymbol(p).typ));
            s:= p.name;
            replaced:= ReplaceForbiddenChars(s);

            with currentasmlist do
              case tasmsymbol(p).typ of
                AT_FUNCTION:
                  begin
                    writer.AsmWrite(#9'import'#9'.');
                    writer.AsmWrite(s);
                    if use_PR then
                     writer.AsmWrite('[PR]');

                    if replaced then
                     begin
                       writer.AsmWrite(' <= ''.');
                       writer.AsmWrite(p.name);
                       if use_PR then
                         writer.AsmWrite('[PR]''')
                       else
                         writer.AsmWrite('''');
                     end;
                    writer.AsmLn;

                    writer.AsmWrite(#9'import'#9);
                    writer.AsmWrite(s);
                    writer.AsmWrite('[DS]');
                    if replaced then
                     begin
                       writer.AsmWrite(' <= ''');
                       writer.AsmWrite(p.name);
                       writer.AsmWrite('[DS]''');
                     end;
                    writer.AsmLn;

                    writer.AsmWriteLn(#9'toc');

                    writer.AsmWrite(#9'tc'#9);
                    writer.AsmWrite(s);
                    writer.AsmWrite('[TC],');
                    writer.AsmWrite(s);
                    writer.AsmWriteLn('[DS]');
                  end;
                AT_DATA:
                  begin
                    writer.AsmWrite(#9'import'#9);
                    writer.AsmWrite(s);
                    writer.AsmWrite(var_storage_class);
                    if replaced then
                      begin
                        writer.AsmWrite(' <= ''');
                        writer.AsmWrite(p.name);
                        writer.AsmWrite('''');
                      end;
                    writer.AsmLn;

                    writer.AsmWriteLn(#9'toc');
                    writer.AsmWrite(#9'tc'#9);
                    writer.AsmWrite(s);
                    writer.AsmWrite('[TC],');
                    writer.AsmWrite(s);
                    writer.AsmWriteLn(var_storage_class);
                  end
                else
                  InternalError(2003090901);
              end;
          end;
      end;

    procedure TPPCMPWAssembler.WriteExternals;
      var
        i : longint;
      begin
        currentasmlist:=self;
//        current_asmdata.asmsymboldict.foreach_static(@writeexternal,nil);
        for i:=0 to current_asmdata.AsmSymbolDict.Count-1 do
          begin
            writeexternal(tasmsymbol(current_asmdata.AsmSymbolDict[i]));
          end;
     end;


    function TPPCMPWAssembler.DoAssemble : boolean;
    begin
      DoAssemble:=Inherited DoAssemble;
    end;

    procedure TPPCMPWAssembler.WriteAsmFileHeader;

    begin
      writer.AsmWriteLn(#9'string asis');  {Interpret strings just to be the content between the quotes.}
      writer.AsmWriteLn(#9'aligning off'); {We do our own aligning.}
      writer.AsmLn;
    end;

    procedure TPPCMPWAssembler.WriteAsmList;
    var
      hal : tasmlisttype;
    begin
{$ifdef EXTDEBUG}
      if assigned(current_module.mainsource) then
       comment(v_info,'Start writing MPW-styled assembler output for '+current_module.mainsource^);
{$endif}

      WriteAsmFileHeader;
      WriteExternals;

      for hal:=low(TasmlistType) to high(TasmlistType) do
        begin
          writer.AsmWriteLn(asminfo^.comment+'Begin asmlist '+AsmListTypeStr[hal]);
          writetree(current_asmdata.asmlists[hal]);
          writer.AsmWriteLn(asminfo^.comment+'End asmlist '+AsmListTypeStr[hal]);
        end;

      writer.AsmWriteLn(#9'end');
      writer.AsmLn;

{$ifdef EXTDEBUG}
      if assigned(current_module.mainsource) then
       comment(v_info,'Done writing MPW-styled assembler output for '+current_module.mainsource^);
{$endif EXTDEBUG}
   end;

{*****************************************************************************
                                  Initialize
*****************************************************************************}

    const
       as_powerpc_mpw_info : tasminfo =
          (
            id           : as_powerpc_mpw;
            idtxt  : 'MPW';
            asmbin : 'PPCAsm';
            asmcmd : '-case on $ASM $EXTRAOPT -o $OBJ';
            supported_targets : [system_powerpc_macos];
            flags : [af_needar,af_smartlink_sections,af_labelprefix_only_inside_procedure];
            labelprefix : '@';
            comment : '; ';
            dollarsign: 's';
          );

initialization
  RegisterAssembler(as_powerpc_mpw_info,TPPCMPWAssembler);
end.