SDL_Sem Try Wait(3) - Waikato Linux Users Group

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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);