Mercurial > sdl-ios-xcode
view src/timer/mint/SDL_vbltimer.S @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 15 Mar 2006 15:47:49 +0000 |
| parents | c9b51268668f |
| children | eb5e61b72da3 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2006 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ /* * VBL queue routine * * Patrice Mandin */ #define _vbl_queue 0x456 .text .globl _SDL_AtariVblInstall .globl _SDL_AtariVblUninstall /*--- Vector installer ---*/ _SDL_AtariVblInstall: movel sp@(4),my_vector lea _my_vbl,a0 clrw vbl_mutex /* Stop interrupts */ movew #0x2700,sr /* Read vbl_queue pointer */ movel _vbl_queue.w,a1 /* Search a free place */ moveq #7,d0 bcl_search_place: movel (a1),d1 beqs place_found addql #4,a1 dbra d0,bcl_search_place /* Not found */ moveq #1,d0 bras exit_vbl_queue /* Then install ourselves */ place_found: movel a0,(a1) moveq #0,d0 exit_vbl_queue: /* Restart interrupts */ movew #0x2300,sr rts /*--- Vector uninstaller ---*/ _SDL_AtariVblUninstall: movel sp@(4),d0 cmpl my_vector,d0 bnes badvector movel #_my_vbl,d0 /* Stop interrupts */ movew #0x2700,sr /* Read vbl_queue pointer */ movel _vbl_queue.w,a1 /* Search where we are */ moveq #7,d1 bcl2_search_place: cmpl (a1),d0 bnes next_place clrl (a1) moveq #0,d1 next_place: addql #4,a1 dbra d1,bcl2_search_place /* Restart interrupts */ movew #0x2300,sr badvector: rts /*--- Our vbl ---*/ _my_vbl: /* Verify if this is not already running */ tstw vbl_mutex bnes vbl_end notw vbl_mutex moveml d0-d7/a0-a6,sp@- movel my_vector,a0 jsr a0@ moveml sp@+,d0-d7/a0-a6 clrw vbl_mutex vbl_end: rts .data .even .comm vbl_mutex,2*1 .even .comm my_vector,4*1