From Bug #36:

There are a couple of issues with the selection of Altivec alpha-blitting routines in CalculateAlphaBlit() in src/video/SDL_Blit_A.c. 1) There's no check for the presence of Altivec when checking if the Blit32to565PixelAlphaAltivec() routine can be selected. 2) Altivec cannot be used in video memory, and there's no check if the destination surface is a hardware surface. (Alpha-blitting to a hardware surface with GPU support is a bad idea, but somebody's bound to do it anyway.) Patch to fix these attached.
libsdl-org · Jan 8, 2006 · 7166e34 · 7166e34
1 parent 821fcee
commit 7166e34
Showing 1 changed file with 10 additions and 7 deletions.
diff --git a/src/video/SDL_blit_A.c b/src/video/SDL_blit_A.c
@@ -2145,7 +2145,8 @@ SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
 		return BlitNto1SurfaceAlphaKey;
 	    else
 #ifdef USE_ALTIVEC_BLITTERS
-        if (sf->BytesPerPixel == 4 && df->BytesPerPixel == 4 && SDL_HasAltiVec())
+	if (sf->BytesPerPixel == 4 && df->BytesPerPixel == 4 &&
+	    !(surface->map->dst->flags & SDL_HWSURFACE) && SDL_HasAltiVec())
             return Blit32to32SurfaceAlphaKeyAltivec;
         else
 #endif
@@ -2192,15 +2193,16 @@ SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
 		else
 #endif
 #ifdef USE_ALTIVEC_BLITTERS
-        if(SDL_HasAltiVec())
+	if(!(surface->map->dst->flags & SDL_HWSURFACE) && SDL_HasAltiVec())
             return BlitRGBtoRGBSurfaceAlphaAltivec;
         else
 #endif
 		    return BlitRGBtoRGBSurfaceAlpha;
 		}
 		else
 #ifdef USE_ALTIVEC_BLITTERS
-        if((sf->BytesPerPixel == 4) && SDL_HasAltiVec())
+        if((sf->BytesPerPixel == 4) &&
+	   !(surface->map->dst->flags & SDL_HWSURFACE) && SDL_HasAltiVec())
             return Blit32to32SurfaceAlphaAltivec;
         else
 #endif
@@ -2219,9 +2221,9 @@ SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
 
 	case 2:
 #ifdef USE_ALTIVEC_BLITTERS
-        if(sf->BytesPerPixel == 4 && 
+	if(sf->BytesPerPixel == 4 && !(surface->map->dst->flags & SDL_HWSURFACE) &&
            df->Gmask == 0x7e0 &&
-           df->Bmask == 0x1f)
+	   df->Bmask == 0x1f && SDL_HasAltiVec())
             return Blit32to565PixelAlphaAltivec;
         else
 #endif
@@ -2252,14 +2254,15 @@ SDL_loblit SDL_CalculateAlphaBlit(SDL_Surface *surface, int blit_index)
 		else
 #endif
 #ifdef USE_ALTIVEC_BLITTERS
-        if(SDL_HasAltiVec())
+	if(!(surface->map->dst->flags & SDL_HWSURFACE) && SDL_HasAltiVec())
             return BlitRGBtoRGBPixelAlphaAltivec;
         else
 #endif
 		    return BlitRGBtoRGBPixelAlpha;
 	    }
 #ifdef USE_ALTIVEC_BLITTERS
-        if (sf->Amask && sf->BytesPerPixel == 4 && SDL_HasAltiVec())
+        if (sf->Amask && sf->BytesPerPixel == 4 &&
+	    !(surface->map->dst->flags & SDL_HWSURFACE) && SDL_HasAltiVec())
             return Blit32to32PixelAlphaAltivec;
         else
 #endif