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. |