Wait until a semaphore has a positive value and then decrements it.
int SDL_SemWait(SDL_sem * sem);
the semaphore wait on
Returns 0 on success or a negative error code on failure; call SDL_GetError() for more information.
This function suspends the calling thread until either the semaphore pointed to by
sem has a positive value or the call is interrupted by a signal or error. If the call is successful it will atomically decrement the semaphore value.
This function is the equivalent of calling SDL_SemWaitTimeout() with a time length of
This function is available since SDL 2.0.0.