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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 355632dca928
children
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<HTML
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>SDL_CreateMutex</TITLE
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>SDL_CreateMutex</H1
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>Name</H2
>SDL_CreateMutex&nbsp;--&nbsp;Create a mutex</DIV
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><PRE
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>#include "SDL.h"
#include "SDL_thread.h"</PRE
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><CODE
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>SDL_mutex *<B
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>SDL_CreateMutex</B
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>(void);</CODE
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>Description</H2
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>Create a new, unlocked mutex.</P
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><H2
>Examples</H2
><PRE
CLASS="PROGRAMLISTING"
>SDL_mutex *mut;

mut=SDL_CreateMutex();
.
.
if(SDL_mutexP(mut)==-1){
  fprintf(stderr, "Couldn't lock mutex\n");
  exit(-1);
}
.
/* Do stuff while mutex is locked */
.
.
if(SDL_mutexV(mut)==-1){
  fprintf(stderr, "Couldn't unlock mutex\n");
  exit(-1);
}

SDL_DestroyMutex(mut);&#13;</PRE
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>SDL_mutexP</TT
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>SDL_mutexV</TT
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