Manual Pages for UNIX Operating System command usage for man SDL_SemTryWait

SDL API Reference                               SDL_SemTryWait(3)



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

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

     int SDL_SemTryWait(SDL_sem *sem);

DESCRIPTION
     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 success-
     ful call to SDL_SemPost.

RETURN VALUE
     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.

EXAMPLES
     res = SDL_SemTryWait(my_sem);

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

     ...

     SDL_SemPost(my_sem);

SEE ALSO
     SDL_CreateSemaphore,   SDL_DestroySemaphore,    SDL_SemWait,
     SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue










SDL            Last change: Tue 11 Sep 2001, 23:00              1