Mercurial > sdl-ios-xcode
view test/testsem.c @ 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 | 1dd8bf30a109 |
children | d5298e8f22b3 |
line wrap: on
line source
/* Simple test of the SDL semaphore code */ #include <stdio.h> #include <stdlib.h> #include <signal.h> #include "SDL.h" #include "SDL_thread.h" #define NUM_THREADS 10 static SDL_sem *sem; int alive = 1; int ThreadFunc(void *data) { uintptr_t threadnum = (uintptr_t)data; while ( alive ) { SDL_SemWait(sem); fprintf(stderr, "Thread number %d has got the semaphore (value = %d)!\n", threadnum, SDL_SemValue(sem)); SDL_Delay(200); SDL_SemPost(sem); fprintf(stderr, "Thread number %d has released the semaphore (value = %d)!\n", threadnum, SDL_SemValue(sem)); SDL_Delay(1); /* For the scheduler */ } printf("Thread number %d exiting.\n", threadnum); return 0; } static void killed(int sig) { alive = 0; } int main(int argc, char **argv) { SDL_Thread *threads[NUM_THREADS]; uintptr_t i; int init_sem; if(argc < 2) { fprintf(stderr,"Usage: %s init_value\n", argv[0]); return(1); } /* Load the SDL library */ if ( SDL_Init(0) < 0 ) { fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError()); return(1); } signal(SIGTERM, killed); signal(SIGINT, killed); init_sem = atoi(argv[1]); sem = SDL_CreateSemaphore(init_sem); printf("Running %d threads, semaphore value = %d\n", NUM_THREADS, init_sem); /* Create all the threads */ for( i = 0; i < NUM_THREADS; ++i ) { threads[i] = SDL_CreateThread(ThreadFunc, (void*)i); } /* Wait 10 seconds */ SDL_Delay(10 * 1000); /* Wait for all threads to finish */ printf("Waiting for threads to finish\n"); alive = 0; for( i = 0; i < NUM_THREADS; ++i ) { SDL_WaitThread(threads[i], NULL); } printf("Finished waiting for threads\n"); SDL_DestroySemaphore(sem); SDL_Quit(); return(0); }