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

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.

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

       ...

       SDL_SemPost(my_sem);

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

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

SDL_CreateSemaphore, SDL_DestroySemaphore, SDL_SemTryWait, SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue

SDL                                          Tue 11 Sep 2001, 23:00                               SDL_SemWait(3)

#include"SDL.h"#include"SDL_thread.h"intSDL_SemWait(SDL_sem*sem);