Mercurial > sdl-ios-xcode
changeset 3899:081aecdb0911 SDL-1.2
From: Gabriel Gambetta
To: SDL Mailing List <sdl@libsdl.org>
Date: Fri, 17 Nov 2006 00:39:29 -0200
Subject: [SDL] Alpha blending bug - fixed?
It turns out mm5 never got the correct value. This failed :
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (sf->Ashift) );
mm5 got 0xFF000018 instead of 0x00000018. However I did this :
Uint32 ashift = sf->Ashift;
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (ashift) );
and everything worked fine.
The only thing I could find out was that ashift is 32-bit aligned but
sf->Ashift isn't:
printf("ashift %8X [%d]\n", &ashift, (int)(&ashift) % 4);
printf("sf->Ashift %8X [%d]\n", &sf->Ashift, (int)(&sf->Ashift) % 4);
ashift at BFF0E0C4 [0]
sf->Ashift at 08AFB9CD [1]
Could this be the problem? If it is, the fix is extremely trivial.
Should I submit a patch?
--Gabriel
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Tue, 21 Nov 2006 23:17:00 +0000 |
| parents | 899d07087694 |
| children | ce3a2bd11305 |
| files | src/video/SDL_blit_A.c |
| diffstat | 1 files changed, 2 insertions(+), 1 deletions(-) [+] |
line wrap: on
line diff
--- a/src/video/SDL_blit_A.c Tue Nov 21 20:49:35 2006 +0000 +++ b/src/video/SDL_blit_A.c Tue Nov 21 23:17:00 2006 +0000 @@ -1566,6 +1566,7 @@ int dstskip = info->d_skip >> 2; SDL_PixelFormat* sf = info->src; Uint32 amask = sf->Amask; + Uint32 ashift = sf->Ashift; __asm__ ( /* make mm6 all zeros. */ @@ -1587,7 +1588,7 @@ /* get alpha channel shift */ "movd %1, %%mm5\n\t" /* Ashift -> mm5 */ - : /* nothing */ : "m" (sf->Amask), "m" (sf->Ashift) ); + : /* nothing */ : "m" (amask), "m" (ashift) ); while(height--) {