{
    Copyright (c) 1998-2002 by Florian Klaempfl and Peter Vreman

    Contains the base types for the i8086, i386 and x86-64 architecture

    * This code was inspired by the NASM sources
      The Netwide Assembler is Copyright (c) 1996 Simon Tatham and
      Julian Hall. All rights reserved.

    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.

 ****************************************************************************
}
{# Base unit for processor information. This unit contains
   enumerations of registers, opcodes, sizes, and other
   such things which are processor specific.
}
unit cpubase;

{$i fpcdefs.inc}

interface

uses
  globals,
  cgbase
  ;


{*****************************************************************************
                                Assembler Opcodes
*****************************************************************************}

    type
{$if defined(x86_64)}
      TAsmOp={$i x8664op.inc}
{$elseif defined(i386)}
      TAsmOp={$i i386op.inc}
{$elseif defined(i8086)}
      TAsmOp={$i i8086op.inc}
{$endif}

      { This should define the array of instructions as string }
        op2strtable=array[tasmop] of string[16];

{$ifdef i8086}
      ImmInt = SmallInt;
{$else i8086}
      ImmInt = Longint;
{$endif i8086}

    const
      { First value of opcode enumeration }
      firstop = low(tasmop);
      { Last value of opcode enumeration  }
      lastop  = high(tasmop);

{*****************************************************************************
                                  Registers
*****************************************************************************}

   const
      { Integer Super registers }
      RS_NO         = $ffffffff;
      RS_RAX        = $00;      {EAX}
      RS_RCX        = $01;      {ECX}
      RS_RDX        = $02;      {EDX}
      RS_RBX        = $03;      {EBX}
      RS_RSI        = $04;      {ESI}
      RS_RDI        = $05;      {EDI}
      RS_RBP        = $06;      {EBP}
      RS_RSP        = $07;      {ESP}
      RS_R8         = $08;      {R8}
      RS_R9         = $09;      {R9}
      RS_R10        = $0a;      {R10}
      RS_R11        = $0b;      {R11}
      RS_R12        = $0c;      {R12}
      RS_R13        = $0d;      {R13}
      RS_R14        = $0e;      {R14}
      RS_R15        = $0f;      {R15}
      { create aliases to allow code sharing between x86-64 and i386 }
      RS_EAX        = RS_RAX;
      RS_EBX        = RS_RBX;
      RS_ECX        = RS_RCX;
      RS_EDX        = RS_RDX;
      RS_ESI        = RS_RSI;
      RS_EDI        = RS_RDI;
      RS_EBP        = RS_RBP;
      RS_ESP        = RS_RSP;
      { create aliases to allow code sharing between i386 and i8086 }
      RS_AX        = RS_RAX;
      RS_BX        = RS_RBX;
      RS_CX        = RS_RCX;
      RS_DX        = RS_RDX;
      RS_SI        = RS_RSI;
      RS_DI        = RS_RDI;
      RS_BP        = RS_RBP;
      RS_SP        = RS_RSP;

      { Number of first imaginary register }
      first_int_imreg     = $10;

      { Float Super registers }
      RS_ST0        = $00;
      RS_ST1        = $01;
      RS_ST2        = $02;
      RS_ST3        = $03;
      RS_ST4        = $04;
      RS_ST5        = $05;
      RS_ST6        = $06;
      RS_ST7        = $07;
      RS_ST         = $08;

      { Number of first imaginary register }
      first_fpu_imreg     = $09;

      { MM Super registers }
      RS_XMM0        = $00;
      RS_XMM1        = $01;
      RS_XMM2        = $02;
      RS_XMM3        = $03;
      RS_XMM4        = $04;
      RS_XMM5        = $05;
      RS_XMM6        = $06;
      RS_XMM7        = $07;
      RS_XMM8        = $08;
      RS_XMM9        = $09;
      RS_XMM10       = $0a;
      RS_XMM11       = $0b;
      RS_XMM12       = $0c;
      RS_XMM13       = $0d;
      RS_XMM14       = $0e;
      RS_XMM15       = $0f;
      RS_XMM16       = $10;
      RS_XMM17       = $11;
      RS_XMM18       = $12;
      RS_XMM19       = $13;
      RS_XMM20       = $14;
      RS_XMM21       = $15;
      RS_XMM22       = $16;
      RS_XMM23       = $17;
      RS_XMM24       = $18;
      RS_XMM25       = $19;
      RS_XMM26       = $1a;
      RS_XMM27       = $1b;
      RS_XMM28       = $1c;
      RS_XMM29       = $1d;
      RS_XMM30       = $1e;
      RS_XMM31       = $1f;

{$if defined(x86_64)}
      RS_RFLAGS      = $06;
{$elseif defined(i386)}
      RS_EFLAGS      = $06;
{$elseif defined(i8086)}
      RS_FLAGS       = $06;
{$endif}

      { Number of first imaginary register }
{$ifdef x86_64}
      first_mm_imreg     = $10;
{$else x86_64}
      first_mm_imreg     = $08;
{$endif x86_64}

      { The subregister that specifies the entire register and an address }
{$if defined(x86_64)}
      { Hammer }
      R_SUBWHOLE    = R_SUBQ;
      R_SUBADDR     = R_SUBQ;
{$elseif defined(i386)}
      { i386 }
      R_SUBWHOLE    = R_SUBD;
      R_SUBADDR     = R_SUBD;
{$elseif defined(i8086)}
      { i8086 }
      R_SUBWHOLE    = R_SUBW;
      R_SUBADDR     = R_SUBW;
{$endif}

      { Available Registers }
{$if defined(x86_64)}
      {$i r8664con.inc}
{$elseif defined(i386)}
      {$i r386con.inc}
{$elseif defined(i8086)}
      {$i r8086con.inc}
{$endif}

    type
      { Number of registers used for indexing in tables }
{$if defined(x86_64)}
      tregisterindex=0..{$i r8664nor.inc}-1;
{$elseif defined(i386)}
      tregisterindex=0..{$i r386nor.inc}-1;
{$elseif defined(i8086)}
      tregisterindex=0..{$i r8086nor.inc}-1;
{$endif}

    const
      regnumber_table : array[tregisterindex] of tregister = (
{$if defined(x86_64)}
        {$i r8664num.inc}
{$elseif defined(i386)}
        {$i r386num.inc}
{$elseif defined(i8086)}
        {$i r8086num.inc}
{$endif}
      );

      regstabs_table : array[tregisterindex] of shortint = (
{$if defined(x86_64)}
        {$i r8664stab.inc}
{$elseif defined(i386)}
        {$i r386stab.inc}
{$elseif defined(i8086)}
        {$i r8086stab.inc}
{$endif}
      );

      regdwarf_table : array[tregisterindex] of shortint = (
{$if defined(x86_64)}
        {$i r8664dwrf.inc}
{$elseif defined(i386)}
        {$i r386dwrf.inc}
{$elseif defined(i8086)}
        {$i r8086dwrf.inc}
{$endif}
      );

{$if defined(x86_64)}
      RS_DEFAULTFLAGS = RS_RFLAGS;
      NR_DEFAULTFLAGS = NR_RFLAGS;
{$elseif defined(i386)}
      RS_DEFAULTFLAGS = RS_EFLAGS;
      NR_DEFAULTFLAGS = NR_EFLAGS;
{$elseif defined(i8086)}
      RS_DEFAULTFLAGS = RS_FLAGS;
      NR_DEFAULTFLAGS = NR_FLAGS;
{$endif}

{*****************************************************************************
                                Conditions
*****************************************************************************}

    type
      TAsmCond=(C_None,
        C_A,C_AE,C_B,C_BE,C_C,C_E,C_G,C_GE,C_L,C_LE,C_NA,C_NAE,
        C_NB,C_NBE,C_NC,C_NE,C_NG,C_NGE,C_NL,C_NLE,C_NO,C_NP,
        C_NS,C_NZ,C_O,C_P,C_PE,C_PO,C_S,C_Z
      );

    const
      cond2str:array[TAsmCond] of string[3]=('',
        'a','ae','b','be','c','e','g','ge','l','le','na','nae',
        'nb','nbe','nc','ne','ng','nge','nl','nle','no','np',
        'ns','nz','o','p','pe','po','s','z'
      );

{*****************************************************************************
                                   Flags
*****************************************************************************}

    type
      TResFlags = (F_E,F_NE,F_G,F_L,F_GE,F_LE,F_C,F_NC,
                   F_A,F_AE,F_B,F_BE,
                   F_S,F_NS,F_O,F_NO,
                   { For IEEE-compliant floating-point compares,
                     same as normal counterparts but additionally check PF }
                   F_FE,F_FNE,F_FA,F_FAE,F_FB,F_FBE);

    const
      FPUFlags = [F_FE,F_FNE,F_FA,F_FAE,F_FB,F_FBE];
      FPUFlags2Flags: array[F_FE..F_FBE] of TResFlags = (
        F_E,F_NE,F_A,F_AE,F_B,F_BE
      );

{*****************************************************************************
                                 Constants
*****************************************************************************}

    const
      { declare aliases }
      LOC_SSEREGISTER = LOC_MMREGISTER;
      LOC_CSSEREGISTER = LOC_CMMREGISTER;

      max_operands = 4;
      maxfpuregs = 8;

{*****************************************************************************
                            CPU Dependent Constants
*****************************************************************************}

    {$i cpubase.inc}

const
{$ifdef x86_64}
  topsize2memsize: array[topsize] of integer =
    (0, 8,16,32,64,8,8,16,8,16,32,
     16,32,64,
     16,32,64,0,0,
     64,
     0,0,0,
     80,
     128,
     256,
     512
    );
{$else}
topsize2memsize: array[topsize] of integer =
  (0, 8,16,32,64,8,8,16,
   16,32,64,
   16,32,64,0,0,
   64,
   0,0,0,
   80,
   128,
   256,
   512
  );
{$endif}

{*****************************************************************************
                                  Helpers
*****************************************************************************}

    function cgsize2subreg(regtype: tregistertype; s:Tcgsize):Tsubregister;
    function reg2opsize(r:Tregister):topsize;
    function reg_cgsize(const reg: tregister): tcgsize;
    function is_calljmp(o:tasmop):boolean;
    procedure inverse_flags(var f: TResFlags);
    function flags_to_cond(const f: TResFlags) : TAsmCond;
    function is_segment_reg(r:tregister):boolean;
    function findreg_by_number(r:Tregister):tregisterindex;
    function std_regnum_search(const s:string):Tregister;
    function std_regname(r:Tregister):string;
    function dwarf_reg(r:tregister):shortint;
    function dwarf_reg_no_error(r:tregister):shortint;
    function eh_return_data_regno(nr: longint): longint;

    function inverse_cond(const c: TAsmCond): TAsmCond; {$ifdef USEINLINE}inline;{$endif USEINLINE}
    function conditions_equal(const c1, c2: TAsmCond): boolean; {$ifdef USEINLINE}inline;{$endif USEINLINE}

    { Checks if Subset is a subset of c (e.g. "less than" is a subset of "less than or equal" }
    function condition_in(const Subset, c: TAsmCond): Boolean;

    { checks whether two segment registers are normally equal in the current memory model }
    function segment_regs_equal(r1,r2:tregister):boolean;

    { checks whether the specified op is an x86 string instruction (e.g. cmpsb, movsd, scasw, etc.) }
    function is_x86_string_op(op: TAsmOp): boolean;
    { checks whether the specified op is an x86 parameterless string instruction
      (e.g. returns true for movsb, cmpsw, etc, but returns false for movs, cmps, etc.) }
    function is_x86_parameterless_string_op(op: TAsmOp): boolean;
    { checks whether the specified op is an x86 parameterized string instruction
      (e.g. returns true for movs, cmps, etc, but returns false for movsb, cmpsb, etc.) }
    function is_x86_parameterized_string_op(op: TAsmOp): boolean;
    function x86_parameterized_string_op_param_count(op: TAsmOp): shortint;
    function x86_param2paramless_string_op(op: TAsmOp): TAsmOp;
    function get_x86_string_op_size(op: TAsmOp): TOpSize;
    { returns the 0-based operand number (intel syntax) of the ds:[si] param of
      a x86 string instruction }
    function get_x86_string_op_si_param(op: TAsmOp):shortint;
    { returns the 0-based operand number (intel syntax) of the es:[di] param of
      a x86 string instruction }
    function get_x86_string_op_di_param(op: TAsmOp):shortint;

{$ifdef i8086}
    { return whether we need to add an extra FWAIT instruction before the given
      instruction, when we're targeting the i8087. This includes almost all x87
      instructions, but certain ones, which always have or have not a built in
      FWAIT prefix are excluded (e.g. FINIT,FNINIT,etc.). }
    function requires_fwait_on_8087(op: TAsmOp): boolean;
{$endif i8086}

implementation

    uses
      globtype,
      rgbase,verbose;

    const
    {$if defined(x86_64)}
      std_regname_table : TRegNameTable = (
        {$i r8664std.inc}
      );

      regnumber_index : array[tregisterindex] of tregisterindex = (
        {$i r8664rni.inc}
      );
      std_regname_index : array[tregisterindex] of tregisterindex = (
        {$i r8664sri.inc}
      );
    {$elseif defined(i386)}
      std_regname_table : TRegNameTable = (
        {$i r386std.inc}
      );

      regnumber_index : array[tregisterindex] of tregisterindex = (
        {$i r386rni.inc}
      );

      std_regname_index : array[tregisterindex] of tregisterindex = (
        {$i r386sri.inc}
      );
    {$elseif defined(i8086)}
      std_regname_table : TRegNameTable = (
        {$i r8086std.inc}
      );

      regnumber_index : array[tregisterindex] of tregisterindex = (
        {$i r8086rni.inc}
      );

      std_regname_index : array[tregisterindex] of tregisterindex = (
        {$i r8086sri.inc}
      );
    {$endif}


{*****************************************************************************
                                  Helpers
*****************************************************************************}

    function cgsize2subreg(regtype: tregistertype; s:Tcgsize):Tsubregister;
      begin
        case s of
          OS_8,OS_S8:
            cgsize2subreg:=R_SUBL;
          OS_16,OS_S16:
            cgsize2subreg:=R_SUBW;
          OS_32,OS_S32:
            cgsize2subreg:=R_SUBD;
          OS_64,OS_S64:
            cgsize2subreg:=R_SUBQ;
          OS_M64:
            cgsize2subreg:=R_SUBNONE;
          OS_F32,OS_F64,OS_C64:
            case regtype of
              R_FPUREGISTER:
                cgsize2subreg:=R_SUBWHOLE;
              R_MMREGISTER:
                case s of
                  OS_F32:
                    cgsize2subreg:=R_SUBMMS;
                  OS_F64:
                    cgsize2subreg:=R_SUBMMD;
                  else
                    internalerror(2009071901);
                end;
              else
                internalerror(2009071902);
            end;
          OS_M128:
            cgsize2subreg:=R_SUBMMX;
          OS_M256:
            cgsize2subreg:=R_SUBMMY;
          OS_M512:
            cgsize2subreg:=R_SUBMMZ;
          OS_NO:
            { error message should have been thrown already before, so avoid only
              an internal error }
            cgsize2subreg:=R_SUBNONE;
          else
            internalerror(200301231);
        end;
      end;


    function reg_cgsize(const reg: tregister): tcgsize;
      const subreg2cgsize:array[Tsubregister] of Tcgsize =
            (OS_NO,OS_8,OS_8,OS_16,OS_32,OS_64,OS_NO,OS_NO,OS_NO,OS_F32,OS_F64,OS_NO,OS_M128,OS_M256,OS_M512,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO,OS_NO);
      begin
        case getregtype(reg) of
          R_INTREGISTER :
            reg_cgsize:=subreg2cgsize[getsubreg(reg)];
          R_FPUREGISTER :
            reg_cgsize:=OS_F80;
          R_MMXREGISTER:
            reg_cgsize:=OS_M64;
          R_MMREGISTER:
            reg_cgsize:=subreg2cgsize[getsubreg(reg)];
          R_SPECIALREGISTER :
            case reg of
              NR_CS,NR_DS,NR_ES,NR_SS,NR_FS,NR_GS:
                reg_cgsize:=OS_16;
{$ifdef x86_64}
              NR_DR0..NR_TR7:
                reg_cgsize:=OS_64;
{$endif x86_64}
              else
                reg_cgsize:=OS_32
            end;
          R_ADDRESSREGISTER:
            case reg of
              NR_K0..NR_K7: reg_cgsize:=OS_64;
              else internalerror(2003031801);
            end;
          else
            internalerror(2003031801);
          end;
        end;


    function reg2opsize(r:Tregister):topsize;
      const
        subreg2opsize : array[tsubregister] of topsize =
          (S_NO,S_B,S_B,S_W,S_L,S_Q,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO,S_NO);
      begin
        reg2opsize:=S_L;
        case getregtype(r) of
          R_INTREGISTER :
            reg2opsize:=subreg2opsize[getsubreg(r)];
          R_FPUREGISTER :
            reg2opsize:=S_FL;
          R_MMXREGISTER,
          R_MMREGISTER :
            reg2opsize:=S_MD;
          R_SPECIALREGISTER :
            begin
              case r of
                NR_CS,NR_DS,NR_ES,
                NR_SS,NR_FS,NR_GS :
                  reg2opsize:=S_W;
                else
                  ;
              end;
            end;
          else
            internalerror(200303181);
        end;
      end;


    function is_calljmp(o:tasmop):boolean;
      begin
        case o of
          A_CALL,
{$if defined(i386) or defined(i8086)}
          A_JCXZ,
{$endif defined(i386) or defined(i8086)}
          A_JECXZ,
{$ifdef x86_64}
          A_JRCXZ,
{$endif x86_64}
          A_JMP,
          A_LOOP,
          A_LOOPE,
          A_LOOPNE,
          A_LOOPNZ,
          A_LOOPZ,
          A_LCALL,
          A_LJMP,
          A_Jcc :
            is_calljmp:=true;
          else
            is_calljmp:=false;
        end;
      end;


    procedure inverse_flags(var f: TResFlags);
      const
        inv_flags: array[TResFlags] of TResFlags =
          (F_NE,F_E,F_LE,F_GE,F_L,F_G,F_NC,F_C,
           F_BE,F_B,F_AE,F_A,
           F_NS,F_S,F_NO,F_O,
           F_FNE,F_FE,F_FBE,F_FB,F_FAE,F_FA);
      begin
        f:=inv_flags[f];
      end;


    function flags_to_cond(const f: TResFlags) : TAsmCond;
      const
        flags_2_cond : array[TResFlags] of TAsmCond =
          (C_E,C_NE,C_G,C_L,C_GE,C_LE,C_C,C_NC,C_A,C_AE,C_B,C_BE,C_S,C_NS,C_O,C_NO,
           C_None,C_None,C_None,C_None,C_None,C_None);
      begin
        result := flags_2_cond[f];
        if (result=C_None) then
          InternalError(2014041301);
      end;


    function is_segment_reg(r:tregister):boolean;
      begin
        case r of
          NR_CS,NR_DS,NR_ES,
          NR_SS,NR_FS,NR_GS :
            result:=true;
          else
            result:=false;
        end;
      end;


    function findreg_by_number(r:Tregister):tregisterindex;
      var
        hr : tregister;
      begin
        { for the name the sub reg doesn't matter }
        hr:=r;
        if (getregtype(hr)=R_MMREGISTER) and
           (getsubreg(hr)<>R_SUBMMY) and
           (getsubreg(hr)<>R_SUBMMZ) then
          setsubreg(hr,R_SUBMMX);

        //// TG TODO check
        //if (getregtype(hr)=R_MMREGISTER) then
        // case getsubreg(hr) of
        //   R_SUBMMX: setsubreg(hr,R_SUBMMX);
        //   R_SUBMMY: setsubreg(hr,R_SUBMMY);
        //   R_SUBMMZ: setsubreg(hr,R_SUBMMZ);
        //  else setsubreg(hr,R_SUBMMX);
        // end;
        result:=findreg_by_number_table(hr,regnumber_index);
      end;


    function std_regnum_search(const s:string):Tregister;
      begin
        result:=regnumber_table[findreg_by_name_table(s,std_regname_table,std_regname_index)];
      end;


    function std_regname(r:Tregister):string;
      var
        p : tregisterindex;
      begin
        if (getregtype(r)=R_MMXREGISTER) or
          ((getregtype(r)=R_MMREGISTER) and not(getsubreg(r) in [R_SUBMMX,R_SUBMMY])) then
          r:=newreg(getregtype(r),getsupreg(r),R_SUBNONE);
        p:=findreg_by_number(r);
        if p<>0 then
          result:=std_regname_table[p]
        else
          result:=generic_regname(r);
      end;


    function inverse_cond(const c: TAsmCond): TAsmCond; {$ifdef USEINLINE}inline;{$endif USEINLINE}
      const
        inverse: array[TAsmCond] of TAsmCond=(C_None,
          C_NA,C_NAE,C_NB,C_NBE,C_NC,C_NE,C_NG,C_NGE,C_NL,C_NLE,C_A,C_AE,
          C_B,C_BE,C_C,C_E,C_G,C_GE,C_L,C_LE,C_O,C_P,
          C_S,C_Z,C_NO,C_NP,C_NP,C_P,C_NS,C_NZ
        );
      begin
        result := inverse[c];
      end;


    function conditions_equal(const c1, c2: TAsmCond): boolean; {$ifdef USEINLINE}inline;{$endif USEINLINE}
      begin
        result := c1 = c2;
      end;


    { Checks if Subset is a subset of c (e.g. "less than" is a subset of "less than or equal" }
    function condition_in(const Subset, c: TAsmCond): Boolean;
      begin
        Result := (c = C_None) or conditions_equal(Subset, c);
        if not Result then
          case Subset of
            C_A,  C_NBE:
              Result := (c in [C_A,  C_AE, C_NB, C_NBE]);
            C_AE, C_NB:
              Result := (c in [C_AE, C_NB]);
            C_B,  C_NAE:
              Result := (c in [C_B,  C_BE, C_C,  C_NA, C_NAE]);
            C_BE, C_NA:
              Result := (c in [C_BE, C_NA]);
            C_C:
              { C_B  / C_NAE: CF = 1
                C_BE / C_NA:  CF = 1 or ZF = 1 }
              Result := (c in [C_B,  C_BE, C_NA, C_NAE]);
            C_E,  C_Z:
              Result := (c in [C_AE, C_BE, C_E,  C_NA, C_NB, C_NG, C_NL]);
            C_G,  C_NLE:
              Result := (c in [C_G,  C_GE, C_NL, C_NLE]);
            C_GE, C_NL:
              Result := (c in [C_GE, C_NL]);
            C_L,  C_NGE:
              Result := (c in [C_L,  C_LE, C_NG, C_NGE]);
            C_LE, C_NG:
              Result := (c in [C_LE, C_NG]);
            C_NC:
              { C_A  / C_NBE: CF = 0 and ZF = 0; not a subset because ZF has to be zero as well
                C_AE / C_NB:  CF = 0 }
              Result := (c in [C_AE, C_NB]);
            C_NE, C_NZ:
              Result := (c in [C_NE, C_NZ, C_A,  C_B,  C_NAE,C_NBE,C_L,  C_G,  C_NLE,C_NGE]);
            C_NP, C_PO:
              Result := (c in [C_NP, C_PO]);
            C_P,  C_PE:
              Result := (c in [C_P,  C_PE]);
            else
              Result := False;
          end;
      end;

    function dwarf_reg(r:tregister):shortint;
      begin
        result:=regdwarf_table[findreg_by_number(r)];
        if result=-1 then
          internalerror(200603251);
      end;

    function dwarf_reg_no_error(r:tregister):shortint;
      begin
        result:=regdwarf_table[findreg_by_number(r)];
      end;


    function eh_return_data_regno(nr: longint): longint;
      begin
         case nr of
           0: result:=0;
{$ifdef x86_64}
           1: result:=1;
{$else}
           1: result:=2;
{$endif}
           else
             result:=-1;
         end;
      end;


    function segment_regs_equal(r1, r2: tregister): boolean;
      begin
        if not is_segment_reg(r1) or not is_segment_reg(r2) then
          internalerror(2013062301);
        { every segment register is equal to itself }
        if r1=r2 then
          exit(true);
{$if defined(i8086)}
        case current_settings.x86memorymodel of
          mm_tiny:
            begin
              { CS=DS=SS }
              if ((r1=NR_CS) or (r1=NR_DS) or (r1=NR_SS)) and
                 ((r2=NR_CS) or (r2=NR_DS) or (r2=NR_SS)) then
                exit(true);
              { the remaining are distinct from each other }
              exit(false);
            end;
          mm_small,mm_medium:
            begin
              { DS=SS }
              if ((r1=NR_DS) or (r1=NR_SS)) and
                 ((r2=NR_DS) or (r2=NR_SS)) then
                exit(true);
              { the remaining are distinct from each other }
              exit(false);
            end;
          mm_compact,mm_large,mm_huge:
            { all segment registers are different in these models }
            exit(false);
        end;
{$elseif defined(i386) or defined(x86_64)}
        { DS=SS=ES }
        if ((r1=NR_DS) or (r1=NR_SS) or (r1=NR_ES)) and
           ((r2=NR_DS) or (r2=NR_SS) or (r2=NR_ES)) then
          exit(true);
        { the remaining are distinct from each other }
        exit(false);
{$endif}
      end;


    function is_x86_string_op(op: TAsmOp): boolean;
      begin
        case op of
{$ifdef x86_64}
          A_MOVSQ,
          A_CMPSQ,
          A_SCASQ,
          A_LODSQ,
          A_STOSQ,
{$endif x86_64}
          A_MOVSB,A_MOVSW,A_MOVSD,
          A_CMPSB,A_CMPSW,A_CMPSD,
          A_SCASB,A_SCASW,A_SCASD,
          A_LODSB,A_LODSW,A_LODSD,
          A_STOSB,A_STOSW,A_STOSD,
          A_INSB, A_INSW, A_INSD,
          A_OUTSB,A_OUTSW,A_OUTSD,
          A_MOVS,A_CMPS,A_SCAS,A_LODS,A_STOS,A_INS,A_OUTS:
            result:=true;
          else
            result:=false;
        end;
      end;


    function is_x86_parameterless_string_op(op: TAsmOp): boolean;
      begin
        case op of
{$ifdef x86_64}
          A_MOVSQ,
          A_CMPSQ,
          A_SCASQ,
          A_LODSQ,
          A_STOSQ,
{$endif x86_64}
          A_MOVSB,A_MOVSW,A_MOVSD,
          A_CMPSB,A_CMPSW,A_CMPSD,
          A_SCASB,A_SCASW,A_SCASD,
          A_LODSB,A_LODSW,A_LODSD,
          A_STOSB,A_STOSW,A_STOSD,
          A_INSB, A_INSW, A_INSD,
          A_OUTSB,A_OUTSW,A_OUTSD:
            result:=true;
          else
            result:=false;
        end;
      end;


    function is_x86_parameterized_string_op(op: TAsmOp): boolean;
      begin
        case op of
          A_MOVS,A_CMPS,A_SCAS,A_LODS,A_STOS,A_INS,A_OUTS:
            result:=true;
          else
            result:=false;
        end;
      end;


    function x86_parameterized_string_op_param_count(op: TAsmOp): shortint;
      begin
        case op of
          A_MOVS,A_CMPS,A_INS,A_OUTS:
            result:=2;
          A_SCAS,A_LODS,A_STOS:
            result:=1;
          else
            internalerror(2017101203);
        end;
      end;


    function x86_param2paramless_string_op(op: TAsmOp): TAsmOp;
      begin
        case op of
          A_MOVSB,A_MOVSW,A_MOVSD{$ifdef x86_64},A_MOVSQ{$endif}:
            result:=A_MOVS;
          A_CMPSB,A_CMPSW,A_CMPSD{$ifdef x86_64},A_CMPSQ{$endif}:
            result:=A_CMPS;
          A_SCASB,A_SCASW,A_SCASD{$ifdef x86_64},A_SCASQ{$endif}:
            result:=A_SCAS;
          A_LODSB,A_LODSW,A_LODSD{$ifdef x86_64},A_LODSQ{$endif}:
            result:=A_LODS;
          A_STOSB,A_STOSW,A_STOSD{$ifdef x86_64},A_STOSQ{$endif}:
            result:=A_STOS;
          A_INSB, A_INSW, A_INSD:
            result:=A_INS;
          A_OUTSB,A_OUTSW,A_OUTSD:
            result:=A_OUTS;
          else
            internalerror(2017101201);
        end;
      end;


    function get_x86_string_op_size(op: TAsmOp): TOpSize;
      begin
        case op of
          A_MOVSB,A_CMPSB,A_SCASB,A_LODSB,A_STOSB,A_INSB,A_OUTSB:
            result:=S_B;
          A_MOVSW,A_CMPSW,A_SCASW,A_LODSW,A_STOSW,A_INSW,A_OUTSW:
            result:=S_W;
          A_MOVSD,A_CMPSD,A_SCASD,A_LODSD,A_STOSD,A_INSD,A_OUTSD:
            result:=S_L;
{$ifdef x86_64}
          A_MOVSQ,A_CMPSQ,A_SCASQ,A_LODSQ,A_STOSQ:
            result:=S_Q;
{$endif x86_64}
          else
            internalerror(2017101202);
        end;
      end;


    function get_x86_string_op_si_param(op: TAsmOp):shortint;
      begin
        case op of
          A_MOVS,A_OUTS:
            result:=1;
          A_CMPS,A_LODS:
            result:=0;
          A_SCAS,A_STOS,A_INS:
            result:=-1;
          else
            internalerror(2017101102);
        end;
      end;


    function get_x86_string_op_di_param(op: TAsmOp):shortint;
      begin
        case op of
          A_MOVS,A_SCAS,A_STOS,A_INS:
            result:=0;
          A_CMPS:
            result:=1;
          A_LODS,A_OUTS:
            result:=-1;
          else
            internalerror(2017101204);
        end;
      end;


{$ifdef i8086}
    function requires_fwait_on_8087(op: TAsmOp): boolean;
      begin
        case op of
            A_F2XM1,A_FABS,A_FADD,A_FADDP,A_FBLD,A_FBSTP,A_FCHS,A_FCOM,A_FCOMP,
            A_FCOMPP,A_FDECSTP,A_FDIV,A_FDIVP,A_FDIVR,A_FDIVRP,
            A_FFREE,A_FIADD,A_FICOM,A_FICOMP,A_FIDIV,A_FIDIVR,A_FILD,
            A_FIMUL,A_FINCSTP,A_FIST,A_FISTP,A_FISUB,A_FISUBR,A_FLD,A_FLD1,
            A_FLDCW,A_FLDENV,A_FLDL2E,A_FLDL2T,A_FLDLG2,A_FLDLN2,A_FLDPI,A_FLDZ,
            A_FMUL,A_FMULP,A_FNOP,A_FPATAN,A_FPREM,A_FPTAN,A_FRNDINT,
            A_FRSTOR,A_FSCALE,A_FSQRT,A_FST,
            A_FSTP,A_FSUB,A_FSUBP,A_FSUBR,A_FSUBRP,A_FTST,
            A_FXAM,A_FXCH,A_FXTRACT,A_FYL2X,A_FYL2XP1:
              result:=true;
          else
            result:=false;
        end;
      end;
{$endif i8086}


end.