[patch] osdteletext-0.4.2 page render speed up

[udo_richter at gmx.de (Udo Richter)]

Hi list,

Since osdteletext page drawing is rather slow on my C3-600, I 
investigated the page rendering speed of osdteletext-0.4.2. Average 
rendering time is 0.74s, dividing down to 0.11s rendering, 0.45s 
scaling, 0.09s osd drawing and 0.11s screen update. (numbers might be 
slightly off due to additional debug output)

After a rewrite of the scaler, the scaling is down to 0.1s, speeding up 
screen update from 0.74s to 0.39s - a noticeable improvement. ;)

The attached patch adds the new scaling code.

Cheers,

Udo
-------------- next part --------------
diff -aur osdteletext-0.4.2/txtbitmap.c osdteletext-0.4.2-mod/txtbitmap.c
--- osdteletext-0.4.2/txtbitmap.c	2005-03-03 17:51:00.000000000 +0100
+++ osdteletext-0.4.2-mod/txtbitmap.c	2005-03-08 18:45:15.000000000 +0100
@@ -74,6 +74,39 @@
    cBitmap *bitmap=new cBitmap(wneu, hneu, depth);
    Display::SetBitmapPalette(*bitmap);
    
+#if 1   
+   // Scale rule:
+   // xsrc=x0 + xdst*walt/wneu
+   // ysrc=y0 + ydst*halt/hneu
+
+   int xsrc,xdst,xfrac,ysrc,ydst,yfrac;
+   // exact src coordinate is floor(xsrc+xfrac/wneu),floor(ysrc+yfrac/hneu) 
+   ysrc=y0;
+   ydst=0;
+   yfrac=0;
+   while (ydst<hneu) {
+	   xsrc=x0;
+	   xdst=0;
+	   xfrac=0;
+	   while (xdst<wneu) {
+		   bitmap->SetIndex(xdst,ydst,*(oldBitmap->Data(xsrc, ysrc)) ); 
+		   xdst++;
+		   xfrac+=walt;
+		   while (xfrac>=wneu) {
+			   xfrac-=wneu;
+			   xsrc++;
+		   }
+	   }
+	   ydst++;
+	   yfrac+=halt;
+	   while (yfrac>=hneu) {
+		   yfrac-=hneu;
+		   ysrc++;
+	   }
+			   
+   }
+	   
+#else   
    int/*float*/ oldX=0, oldY=0;
    for (float x=0;x<wneu;x++)
       for (float y=0;y<hneu;y++) {
@@ -84,6 +117,7 @@
          oldY=(int)(((halt*10000/hneu)*y/10000));
          bitmap->SetIndex((int)x,(int)y,*(oldBitmap->Data(oldX+x0, oldY+y0)) );
       }
+#endif
    return bitmap;
          
 }