SDL Library Documentation
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SDL_SemWait

Name

SDL_SemWait -- Lock a semaphore and suspend the thread if the semaphore value is zero.

Synopsis

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

int SDL_SemWait(SDL_sem *sem);

Description

SDL_SemWait() suspends the calling thread until either the semaphore pointed to by sem has a positive value, the call is interrupted by a signal or error. If the call is successful it will atomically decrement the semaphore value.

After SDL_SemWait() is successful, the semaphore can be released and its count atomically incremented by a successful call to SDL_SemPost.

Return Value

Returns 0 if successful or -1 if there was an error (leaving the semaphore unchanged).

Examples

if (SDL_SemWait(my_sem) == -1) {
        return WAIT_FAILED;
}

...

SDL_SemPost(my_sem);

See Also

SDL_CreateSemaphore, SDL_DestroySemaphore, SDL_SemTryWait, SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue

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