SDL_SemTryWait - Attempt to lock a semaphore but don't suspend the thread.

SDL_SemTryWait  is a non-blocking varient of SDL_SemWait. If the value of the semaphore pointed to by sem
       is positive it will atomically decrement the semaphore value and  return  0,  otherwise  it  will  return
       SDL_MUTEX_TIMEOUT instead of suspending the thread.

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

       res = SDL_SemTryWait(my_sem);

       if (res == SDL_MUTEX_TIMEOUT) {
               return TRY_AGAIN;
       }
       if (res == -1) {
               return WAIT_ERROR;
       }

       ...

       SDL_SemPost(my_sem);

       SDL_SemTryWait - Attempt to lock a semaphore but don't suspend the thread.

       Returns  0 if the semaphore was successfully locked or either SDL_MUTEX_TIMEOUT or -1 if the thread would
       have suspended or there was an error, respectivly.

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

SDL_CreateSemaphore, SDL_DestroySemaphore, SDL_SemWait, SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue

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

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