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comparison src/video/SDL_blit_A.c @ 3899:081aecdb0911 SDL-1.2

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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 571c75f3d093
children af4d584e0edb
comparison
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3898:899d07087694 3899:081aecdb0911
1564 int srcskip = info->s_skip >> 2; 1564 int srcskip = info->s_skip >> 2;
1565 Uint32 *dstp = (Uint32 *)info->d_pixels; 1565 Uint32 *dstp = (Uint32 *)info->d_pixels;
1566 int dstskip = info->d_skip >> 2; 1566 int dstskip = info->d_skip >> 2;
1567 SDL_PixelFormat* sf = info->src; 1567 SDL_PixelFormat* sf = info->src;
1568 Uint32 amask = sf->Amask; 1568 Uint32 amask = sf->Amask;
1569 Uint32 ashift = sf->Ashift;
1569 1570
1570 __asm__ ( 1571 __asm__ (
1571 /* make mm6 all zeros. */ 1572 /* make mm6 all zeros. */
1572 "pxor %%mm6, %%mm6\n" 1573 "pxor %%mm6, %%mm6\n"
1573 1574
1585 "pxor %%mm4, %%mm3\n\t" /* 0000F000 -> mm3 (~channel mask) */ 1586 "pxor %%mm4, %%mm3\n\t" /* 0000F000 -> mm3 (~channel mask) */
1586 1587
1587 /* get alpha channel shift */ 1588 /* get alpha channel shift */
1588 "movd %1, %%mm5\n\t" /* Ashift -> mm5 */ 1589 "movd %1, %%mm5\n\t" /* Ashift -> mm5 */
1589 1590
1590 : /* nothing */ : "m" (sf->Amask), "m" (sf->Ashift) ); 1591 : /* nothing */ : "m" (amask), "m" (ashift) );
1591 1592
1592 while(height--) { 1593 while(height--) {
1593 1594
1594 DUFFS_LOOP4({ 1595 DUFFS_LOOP4({
1595 Uint32 alpha; 1596 Uint32 alpha;