|
Size: 2272
Comment: update content - standard return value
|
Size: 2237
Comment: update content - pointers, structs
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 16: | Line 16: |
| ||'''sem'''||^a pointer to the SDL_sem structure / semaphore to be decremented^|| | ||'''sem'''||^the SDL_sem to be decremented^|| |
DRAFT |
SDL_SemTryWait
Use this function to as a non-blocking variant of alternative to SDL_SemWait() -or- ...*to attempt to lock a semaphore but don't not suspend the thread*.
Contents
Syntax
int SDL_SemTryWait(SDL_sem* sem)
Function Parameters
sem |
the SDL_sem to be decremented |
Return Value
Returns 0 if the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait would block, or a negative error code on failure; call SDL_GetError() for more information.
-or-
*
green
Returns 0 if the semaphore was successfully locked (and decremented), SDL_MUTEX_TIMEDOUT if the thread would have suspended, or a negative error code on failure.
If the semaphore was not successfully locked, the semaphore will be unchanged.
*
Code Examples
*
res = SDL_SemTryWait(my_sem);
if (res == SDL_MUTEX_TIMEDOUT) {
return TRY_AGAIN;
}
if (res == -1) {
return WAIT_ERROR;
}
...
SDL_SemPost(my_sem);
*
Remarks
You can add useful comments here
*
SDL_SemTryWait() is a non-blocking variant 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_TIMEDOUT 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().
*
green
