SDL_Sem Wait Timeout(3) - Waikato Linux Users Group

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SDL_!SemWaitTimeout?

NAME SYNOPSIS DESCRIPTION RETURN VALUE EXAMPLES SEE ALSO

NAME

SDL_!SemWaitTimeout?- Lock a semaphore, but only wait up to a specified maximum time.

SYNOPSIS

#include

int SDL_!SemWaitTimeout?(SDL_sem *sem, Uint32 timeout);

DESCRIPTION

SDL_!SemWaitTimeout?() is a varient of SDL_!SemWait? with a maximum timeout value. If the value of the semaphore pointed to by sem is positive (greater than zero) it will atomically decrement the semaphore value and return 0, otherwise it will wait up to timeout milliseconds trying to lock the semaphore. This function is to be avoided if possible since on some platforms it is implemented by polling the semaphore every millisecond in a busy loop.

After SDL_!SemWaitTimeout?() 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 timeout period was exceeded or there was an error, respectivly.

If the semaphore was not successfully locked, the semaphore will be unchanged.

EXAMPLES

res = SDL_!SemWaitTimeout?(my_sem, WAIT_TIMEOUT_MILLISEC); if (res == SDL_MUTEX_TIMEOUT) { return TRY_AGAIN; } if (res == -1) { return WAIT_ERROR; } ... SDL_!SemPost?(my_sem);