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← Revision 7 as of 2013-08-12 05:48:11 ⇥
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| #pragma disable-camelcase ||<tablewidth="100%" style="color: #FF0000;" :> DRAFT|| |
#pragma camelcase off |
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| Use this function to *unlock a semaphore and* atomically increase the semaphore's count ,,(not blocking),,. <<Color2(green,See Remarks.)>> |
Use this function to atomically increment a semaphore's value and wake waiting threads. |
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| ||'''sem'''||^a pointer to the SDL_sem structure / semaphore to be incremented^|| | ||'''sem'''||the semaphore to increment|| |
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| Returns 0 on success ^(and increments the semaphore count)^ or a negative error code on failure *(leaving the semaphore unchanged)*; call [[SDL_GetError]]() for more information. | Returns 0 on success or a negative error code on failure ; call [[SDL_GetError]]() for more information. |
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| {{{#!highlight cpp SDL_SemPost(my_sem); }}} |
<<Include(SDL_CreateSemaphore, , , from="## Begin Semaphore Example", to="## End Semaphore Example")>> |
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| *<<BR>>[[SDL_SemPost]]() unlocks the semaphore pointed to by '''sem''' and atomically increments the semaphore's value. Threads that were blocking on the semaphore may be scheduled after this call succeeds. [[SDL_SemPost]]() should be called after a semaphore is locked by a successful call to [[SDL_SemWait]](), [[SDL_SemTryWait]]() or [[SDL_SemWaitTimeout]](). <<BR>>* <<Color2(green,Should the (not blocking) addendum from the header description be moved down here and explained more fully?)>> |
''You can add useful comments here'' |
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| .[[SDL_SemTryWait]] * .[[SDL_SemValue]] * .[[SDL_SemWait]] * .[[SDL_SemWaitTimeout]] * |
.[[SDL_CreateSemaphore]] .[[SDL_DestroySemaphore]] .[[SDL_SemTryWait]] .[[SDL_SemValue]] .[[SDL_SemWait]] .[[SDL_SemWaitTimeout]] |
SDL_SemPost
Use this function to atomically increment a semaphore's value and wake waiting threads.
Contents
Syntax
int SDL_SemPost(SDL_sem* sem)
Function Parameters
sem |
the semaphore to increment |
Return Value
Returns 0 on success or a negative error code on failure ; call SDL_GetError() for more information.
Code Examples
Typical use of semaphores:
SDL_atomic_t done;
SDL_sem *sem;
SDL_AtomicSet(&done, 0);
sem = SDL_CreateSemaphore(0);
.
.
Thread A:
while (!SDL_AtomicGet(&done)) {
add_data_to_queue();
SDL_SemPost(sem);
}
Thread B:
while (!SDL_AtomicGet(&done)) {
SDL_SemWait(sem);
if (data_available()) {
get_data_from_queue();
}
}
.
.
SDL_AtomicSet(&done, 1);
SDL_SemPost(sem);
wait_for_threads();
SDL_DestroySemaphore(sem);
Remarks
You can add useful comments here
