[fpc-pascal] Converting 32bit intel asm to Pascal or 64bit at&t asm

[Andrew Haines]

Hi,

I'm trying to convert the following 32bit asm to pascal so it's
portable. Also to 64bit asm.

It's from ACS audio component suite.

What am I doing wrong?

I tested my Pascal code with linux 32bit but the output differs from the
32bit asm. In 64bit linux it differs further but this could be from the
ACS indicator component.

I attached screenshots of the various configurations.

I am using fpc 2.5.1 for 32bit and 64bit.

Regards,

Andrew

TACSComplex = record
  Im, Re: Double;
end;


<original code>

procedure LgMagnitude(InData : PACSComplex; OutData : PDouble; DataSize,
Shift : Integer);
  var
    LogBase  : Double;
  begin
    asm
                FLD1;
                FLDL2T;
                FDIVP;
                FSTP LogBase;
                MOV EDX, DataSize;
                SHL EDX, 3;
                MOV ECX, OutData;
                ADD EDX, ECX;
                MOV EAX, InData;
      @test:    CMP EDX, ECX;
                JE @out;
                FLD QWORD[EAX];
                FMUL ST(0), ST(0);
                ADD EAX, 8;
                FLD QWORD[EAX];
                FMUL ST(0), ST(0);
                FADDP;
                FSQRT;
                FTST;
                PUSH EAX;
                FSTSW AX;
                SAHF;
                JE @skip;
                FLD LogBase;
                FXCH;
                FYL2X;
                FIADD Shift;
                FTST;
                FSTSW AX;
                SAHF;
                JAE @skip;
                FSTP QWORD[ECX];
                FLDZ;
      @skip:    POP EAX;
                ADD EAX, 8;
                FSTP QWORD[ECX];
                ADD ECX, 8;
                JMP @test;
      @out:     ;
    end;
  end;
end;

</original code>

<pascal code>
  var
    LogBase  : Double;
    i: Integer;
    Im, Re: Double;
    Tmp: Double;
  begin
    asm
      FLD1;
      FLDL2T;
      FDIVP;
      FSTP LogBase;
    end;
    for i := 0 to DataSize-1 do
    begin
      Im := InData[i].Im*InData[i].Im;
      Re := InData[i].Re*InData[i].Re;
      Tmp := sqr(Im+Re);

      if Tmp <> Im then
      begin
        //Tmp := log2(Tmp)*LogBase+Shift; // is this the same as the
following asm code?
        asm
          FLD LogBase;
          FLD Tmp;
          FYL2X;
          FIADD Shift;
          FSTP Tmp;
        end;
        if Tmp <> 0.0 then
        begin
          if 0.0 >= Tmp then
          begin
            Tmp := 0;
          end;
        end;
      end;
      OutData[i] := Tmp;
    end;
  end;
end;
</pascal code>

<64bit asm>
 SetExceptionMask([exInvalidOp, exDenormalized, exZeroDivide,
                   exOverflow, exUnderflow, exPrecision]);
    asm
                FLD1;
                FLDL2T;
                FDIVP;
                FSTP LogBase;
                MOV DataSize,  %RDX;
                SHL $3,        %RDX;
                MOV OutData,   %RCX;
                ADD %RCX,      %RDX;
                MOV InData,    %RAX;
                MOV Shift,     %rsi;
      .Ltest:   CMP %RCX,      %RDX;
                JE .Lout;
                FLD  (%RAX); //FLD QWORD[%EAX];
                FMUL %st(0), %st(0);
                ADD $8,        %RAX;
                FLD (%RAX);//FLD QWORD[EAX]; // sigsegv here with fpu
exceptions off. only happens after many iterations but seems immediate
in real time.
                FMUL %st(0), %st(0);
                FADDP;
                FSQRT;
                FTST;
                PUSH %RAX;
                FSTSW %AX; //with fpu exceptions enabled I get a FPU
exception here after some iterations but again it is immediate in realtime.

                //SAHF; // not available in amd64!
                //JE .Lskip;
                bt $14, %ax; // // copy fpu C3 flag to cpu carry flag
                JC .Lskip;

                FLD LogBase;
                FXCH;
                FYL2X;
                FIADD Shift;
                FTST;
                FSTSW %AX;

                //SAHF; // not available in amd64!
                //JAE .Lskip;
                bt $8, %ax // copy fpu C0 flag to cpu carry flag
                JNC .Lskip

                FSTP (%RCX);//FSTP QWORD[ECX];
                FLDZ;
      .Lskip:   POP %RAX;
                ADD $8,        %RAX;
                FSTP (%RCX);//FSTP QWORD[RCX];
                ADD $8, %RCX;
                JMP .Ltest;
      .Lout:     ;
    end;
end;
</64bit asm>

<<attachment: 32bit-orig-asm.png>>

<<attachment: 32bit-pascal.png>>

<<attachment: 64bit-pascal.png>>

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