SDL_SemTryWait(3) SDL API Reference SDL_SemTryWait(3)

NAME

SDL_SemTryWait - Attempt to lock a semaphore but don't suspend the
thread.

SYNOPSIS

#include "SDL.h" #include "SDL_thread.h"

int SDL_SemTryWait(SDL_sem *sem);

DESCRIPTION

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.

RETURN VALUE

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.

EXAMPLES

res = SDL_SemTryWait(my_sem);

if (res == SDL_MUTEX_TIMEOUT) {
return TRY_AGAIN;
}
if (res == -1) {
return WAIT_ERROR;
}

...

SDL_SemPost(my_sem);

SEE ALSO

SDL_CreateSemaphore, SDL_DestroySemaphore, SDL_SemWait,
SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue

SDL Tue 11 Sep 2001, 23:00 SDL_SemTryWait(3)