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