Talk:Improving language shootout results

This gives about 15% improvement on Mac OS X 10.5, fpc 2.2.4 over the present version in the shootout:

The most important tricks are conversion of the multiplication for Cx and Cy in the loops into additions, actually manually in line merging the inlined function and save some assignements there. A real boost would be to use 128 bit xmm registers and instructions for Cx, Cy, Zr, Zi, Tr, Ti as well as threads for the quad core shootout, as some of the competitors do.

program mandelbrot2;

var

 n: longint;
 TextBuf: array[0..$FFF] of byte;
 OutFile: PText;

procedure run; const

 Limit: double = 4.0;
 two: double = 2.0;

var

 i, index1, index2, bits, bit: longint;
 Zr, Zi, Ti, Tr: double;
 Cx, Cy, Step: double;

begin

 Step := two/n;
 Cy := -1.0;
 for index1 := 1 to n do
 begin
   Cx := -1.5;
   bits := 255;
   bit  := 128;
   for index2 := 1 to n do
   begin
     Ti := Cy * Cy;
     Tr := Cx * Cx;
     if (Tr + Ti >= limit) then
       bits := bits xor bit
     else
     begin
       Zi := (Cx + Cx + 1.0) * Cy;
       Zr := Tr - Ti + Cx;
       Ti := Zi * Zi;
       Tr := Zr * Zr;
       if (Tr + Ti >= limit) then
         bits := bits xor bit
       else
       begin
         for i := 3 to 50 do
         begin
           Zi := Zr*Zi + Zr*Zi + Cy;
           Zr := Tr - Ti + Cx;
           Ti := Zi * Zi;
           Tr := Zr * Zr;
           if (Tr + Ti >= limit) then
           begin
             bits := bits xor bit;
             break;
           end;
         end;
       end;
     end;
     if bit > 1 then
       bit := bit shr 1
     else
     begin
       write(OutFile^, chr(bits));
       bits := 255;
       bit  := 128;
     end;
     Cx := Cx + Step;
   end;
   if bit < 128 then
     write(OutFile^, chr(bits xor ((bit shl 1) - 1)));
   Cy := Cy + Step;
 end;

end;

begin

 OutFile := @Output;
 SetTextBuf(OutFile^, TextBuf);

 Val(ParamStr(1), n);
 writeln(OutFile^, 'P4');
 writeln(OutFile^, n,' ',n);

 run;

end.