sdl_createsemaphore(3) [redhat man page]

SDL_CreateSemaphore(3)						 SDL API Reference					    SDL_CreateSemaphore(3)

NAME

       SDL_CreateSemaphore- Creates a new semaphore and assigns an initial value to it.

SYNOPSIS

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

       SDL_sem *SDL_CreateSemaphore(Uint32 initial_value);

DESCRIPTION

       SDL_CreateSemaphore()  creates  a new semaphore and initializes it with the value initial_value. Each locking operation on the semaphore by
       SDL_SemWait, SDL_SemTryWait or SDL_SemWaitTimeout will atomically decrement the semaphore value. The locking operation will be  blocked	if
       the  semaphore  value  is  not  positive  (greater than zero). Each unlock operation by SDL_SemPost will atomically increment the semaphore
       value.

RETURN VALUE

       Returns a pointer to an initialized semaphore or NULL if there was an error.

EXAMPLES

       SDL_sem *my_sem;

       my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE);

       if (my_sem == NULL) {
	       return CREATE_SEM_FAILED;
       }

SEE ALSO

       SDL_DestroySemaphore, SDL_SemWait, SDL_SemTryWait, SDL_SemWaitTimeout, SDL_SemPost, SDL_SemValue

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

SDL_SemWaitTimeout(3)						 SDL API Reference					     SDL_SemWaitTimeout(3)

NAME

       SDL_SemWaitTimeout- Lock a semaphore, but only wait up to a specified maximum time.

SYNOPSIS

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

       int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout);

DESCRIPTION

       SDL_SemWaitTimeout()  is a varient of SDL_SemWait with a maximum timeout value. If the value of the semaphore pointed to by sem is positive
       (greater than zero) it will atomically decrement the semaphore value and return 0, otherwise it will wait up to timeout milliseconds trying
       to  lock the semaphore. This function is to be avoided if possible since on some platforms it is implemented by polling the semaphore every
       millisecond in a busy loop.

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

RETURN VALUE

       Returns	0  if  the  semaphore was successfully locked or either SDL_MUTEX_TIMEOUT or -1 if the timeout period was exceeded or there was an
       error, respectivly.

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

EXAMPLES

       res = SDL_SemWaitTimeout(my_sem, WAIT_TIMEOUT_MILLISEC);

       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_SemTryWait, SDL_SemPost, SDL_SemValue

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