View Source: SDL_SemTryWait(3) - Waikato Linux Users Group

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SDL_!SemTryWait
!!!SDL_!SemTryWait
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
EXAMPLES
SEE ALSO
----
!!NAME


SDL_!SemTryWait- Attempt to lock a semaphore but don't suspend the thread.
!!SYNOPSIS


__#include
__


__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__
----

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Last edited on Monday, June 3, 2002 6:53:47 pm by "perry"

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