brauche kleine Hilfe in ASM, Flaschenhals

[Amateurprofi]

Und so geht es noch simpler und schneller.

Delphi-Quellcode:

function xSmallToDouble(CodZahl: Integer): Double;
const scale:array[0..7] of double=
     (1/100,1/10000,1/1000000,1.0,1/100,1/10000,1/1000000,1.0);
begin
  if CodZahl>=0 then result:=(CodZahl and $9FFFFFFF)*scale[CodZahl shr 29]
   else result:=(CodZahl or $60000000)*scale[CodZahl shr 29];
end;

Diese Funktion braucht durchschnittlich 53 CPU-Ticks.
Die von negaH schon sehr schön konstruierte Lösung braucht durchschnittlich 88 CPU-Ticks.
Die Resultate sind bei beiden Funktionen identisch (getestet für alle 2^32-1 möglichen Integer-Werte)

Die Ticks wurden so ermittelt.

Delphi-Quellcode:

PROCEDURE TMain.Test;
var v:double; i:integer; q1,q2,qs,qe,tsdelay:int64;
FUNCTION TimeStamp:int64;
asm
   rdtsc
end;
FUNCTION TimeStampDelay:int64;
var i:integer; ts0,ts1:int64;
begin
   result:=maxint;
   for i:=1 to 3 do begin
      ts0:=TimeStamp;
      ts1:=TimeStamp;
      dec(ts1,ts0);
      if ts1<result then result:=ts1;
   end;
end;
begin
   tsdelay:=TimeStampDelay;
    q1:=High(int64);
   for i:=1 to 10 do begin
      qs:=TimeStamp;
      v:=SmallToDouble($FFFFFFFF);
      v:=SmallToDouble($EFFFFFFF);
      v:=SmallToDouble($DFFFFFFF);
      v:=SmallToDouble($CFFFFFFF);
      v:=SmallToDouble($BFFFFFFF);
      v:=SmallToDouble($AFFFFFFF);
      v:=SmallToDouble($9FFFFFFF);
      v:=SmallToDouble($8FFFFFFF);
      v:=SmallToDouble($7FFFFFFF);
      v:=SmallToDouble($6FFFFFFF);
      v:=SmallToDouble($5FFFFFFF);
      v:=SmallToDouble($4FFFFFFF);
      v:=SmallToDouble($3FFFFFFF);
      v:=SmallToDouble($2FFFFFFF);
      v:=SmallToDouble($1FFFFFFF);
      v:=SmallToDouble($0FFFFFFF);
      qe:=TimeStamp;
      dec(qe,qs);
      if qe<q1 then q1:=qe;
   end;
   dec(q1,tsdelay);
   q2:=High(int64);
   for i:=1 to 10 do begin
      qs:=TimeStamp;
      v:=xSmallToDouble($FFFFFFFF);
      v:=xSmallToDouble($EFFFFFFF);
      v:=xSmallToDouble($DFFFFFFF);
      v:=xSmallToDouble($CFFFFFFF);
      v:=xSmallToDouble($BFFFFFFF);
      v:=xSmallToDouble($AFFFFFFF);
      v:=xSmallToDouble($9FFFFFFF);
      v:=xSmallToDouble($8FFFFFFF);
      v:=xSmallToDouble($7FFFFFFF);
      v:=xSmallToDouble($6FFFFFFF);
      v:=xSmallToDouble($5FFFFFFF);
      v:=xSmallToDouble($4FFFFFFF);
      v:=xSmallToDouble($3FFFFFFF);
      v:=xSmallToDouble($2FFFFFFF);
      v:=xSmallToDouble($1FFFFFFF);
      v:=xSmallToDouble($0FFFFFFF);
      qe:=TimeStamp;
      dec(qe,qs);
      if qe<q2 then q2:=qe;
   end;
   dec(q2,tsdelay);
   showmessage(inttostr(q1 div 16)+#13+inttostr(q2 div 16));
end;