# HG changeset patch
# User Ryan C. Gordon <icculus@icculus.org>
# Date 1136755095 0
# Node ID 3b8a43c428bbcbd1ee37997dc294ae3e37439e16
# Parent  cbdb2c156acac13e52ae99e03a6cb9358a1e592e
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.

diff -r cbdb2c156aca -r 3b8a43c428bb src/video/SDL_blit_A.c
--- a/src/video/SDL_blit_A.c	Sun Jan 08 17:29:19 2006 +0000
+++ b/src/video/SDL_blit_A.c	Sun Jan 08 21:18:15 2006 +0000
@@ -2145,7 +2145,8 @@
 		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
@@ -2192,7 +2193,7 @@
 		else
 #endif
 #ifdef USE_ALTIVEC_BLITTERS
-        if(SDL_HasAltiVec())
+	if(!(surface->map->dst->flags & SDL_HWSURFACE) && SDL_HasAltiVec())
             return BlitRGBtoRGBSurfaceAlphaAltivec;
         else
 #endif
@@ -2200,7 +2201,8 @@
 		}
 		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 @@
 
 	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 @@
 		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