[SOLVED] Improved CPU cache usage at procedure TFPCustomImage.Assign

[lagprogramming]

packages/fcl-image/src/fpimage.inc has procedure TFPCustomImage.Assign(Source: TPersistent);

Code: Pascal  [Select][+][-]

1. Procedure TFPCustomImage.Assign(Source: TPersistent);
2.  
3. Var
4.   Src : TFPCustomImage;
5.   X,Y : Integer;
6.  
7. begin
8.   If Source is TFPCustomImage then
9.     begin
10.     Src:=TFPCustomImage(Source);
11.     // Copy extra info
12.     FExtra.Assign(Src.Fextra);
13.     // Copy palette if needed.
14.     SetSize(0,0); { avoid side-effects in descendant classes }
15.     UsePalette:=Src.UsePalette;
16.     If UsePalette then
17.       begin
18.       Palette.Count:=0;
19.       Palette.Merge(Src.Palette);
20.       end;
21.     // Copy image.
22.     SetSize(Src.Width,Src.height);
23.     If UsePalette then
24.       For x:=0 to Src.Width-1 do
25.         For y:=0 to src.Height-1 do
26.           pixels[X,Y]:=src.pixels[X,Y]
27.     else
28.       For x:=0 to Src.Width-1 do
29.         For y:=0 to src.Height-1 do
30.           self[X,Y]:=src[X,Y];
31.     end
32.   else
33.     Inherited Assign(Source);
34. end;

The following patch improves CPU cache usage by switching the x and y loops. In addition, some cosmetics: two empty lines have been removed, "Var" has been changed to "var" and "[X,Y]" has been changed to "[x,y]".

Code: Pascal  [Select][+][-]

1. diff --git a/packages/fcl-image/src/fpimage.inc b/packages/fcl-image/src/fpimage.inc
2. index 3e2075900d..54be93074c 100644
3. --- a/packages/fcl-image/src/fpimage.inc
4. +++ b/packages/fcl-image/src/fpimage.inc
5. @@ -460,11 +460,9 @@ procedure TFPCustomImage.CheckIndex (x,y:integer);
6.  end;
7.  
8.  Procedure TFPCustomImage.Assign(Source: TPersistent);
9. -
10. -Var
11. +var
12.    Src : TFPCustomImage;
13. -  X,Y : Integer;
14. -
15. +  x,y : Integer;
16.  begin
17.    If Source is TFPCustomImage then
18.      begin
19. @@ -482,13 +480,13 @@ procedure TFPCustomImage.CheckIndex (x,y:integer);
20.      // Copy image.
21.      SetSize(Src.Width,Src.height);
22.      If UsePalette then
23. -      For x:=0 to Src.Width-1 do
24. -        For y:=0 to src.Height-1 do
25. -          pixels[X,Y]:=src.pixels[X,Y]
26. +      For y:=0 to src.Height-1 do
27. +        For x:=0 to Src.Width-1 do
28. +          pixels[x,y]:=src.pixels[x,y]
29.      else
30. -      For x:=0 to Src.Width-1 do
31. -        For y:=0 to src.Height-1 do
32. -          self[X,Y]:=src[X,Y];
33. +      For y:=0 to src.Height-1 do
34. +        For x:=0 to Src.Width-1 do
35. +          self[x,y]:=src[x,y];
36.      end
37.    else
38.      Inherited Assign(Source);
39.  

[marcov]

Fixed.