SDL_SemTryWait — Attempt to lock a semaphore but don't suspend the thread.
#include "SDL.h" #include "SDL_thread.h"
int
SDL_SemTryWait( |
SDL_sem *sem); |
SDL_SemTryWait is a
non-blocking varient of SDL_SemWait. If the value of the semaphore
pointed to by sem is
positive it will atomically decrement the semaphore value and
return 0, otherwise it will return SDL_MUTEX_TIMEOUT instead of suspending the
thread.
After SDL_SemTryWait is
successful, the semaphore can be released and its count
atomically incremented by a successful call to SDL_SemPost.
Returns 0 if the semaphore
was successfully locked or either SDL_MUTEX_TIMEOUT or -1 if the thread would have
suspended or there was an error, respectivly.
If the semaphore was not successfully locked, the semaphore will be unchanged.
res = SDL_SemTryWait(my_sem);
if (res == SDL_MUTEX_TIMEOUT) {
return TRY_AGAIN;
}
if (res == -1) {
return WAIT_ERROR;
}
...
SDL_SemPost(my_sem);
SDL_CreateSemaphore(3), SDL_DestroySemaphore(3), SDL_SemWait(3), SDL_SemWaitTimeout(3), SDL_SemPost(3), SDL_SemValue(3)
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This manual page is taken from the SDL library, licensed under GNU LGPL. |