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[3DS] Use the CondVar API for condition variables
The pthread wrapper uses semaphores to simulate condition variables, but it is easy to hit the 3DS' limit of available semaphores. libctru 2.0 supplies a lightweight condition variable API. We will use that when it exists, and backport it when it doesn't.
This commit is contained in:
Justin Weiss
parent
38ccca18f4
commit
1ee7b71884
@ -43,11 +43,107 @@ typedef uint32_t pthread_cond_t;
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typedef int pthread_condattr_t;
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#endif
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typedef struct {
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uint32_t semaphore;
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LightLock lock;
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uint32_t waiting;
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} cond_t;
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#ifndef USE_CTRULIB_2
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/* Backported CondVar API from libctru 2.0, and under its license:
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https://github.com/devkitPro/libctru
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Slightly modified for compatibility with older libctru. */
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typedef s32 CondVar;
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static INLINE Result syncArbitrateAddress(s32* addr, ArbitrationType type, s32 value)
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{
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return svcArbitrateAddress(__sync_get_arbiter(), (u32)addr, type, value, 0);
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}
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static INLINE Result syncArbitrateAddressWithTimeout(s32* addr, ArbitrationType type, s32 value, s64 timeout_ns)
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{
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return svcArbitrateAddress(__sync_get_arbiter(), (u32)addr, type, value, timeout_ns);
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}
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static INLINE void __dmb(void)
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{
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__asm__ __volatile__("mcr p15, 0, %[val], c7, c10, 5" :: [val] "r" (0) : "memory");
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}
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static INLINE void CondVar_BeginWait(CondVar* cv, LightLock* lock)
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{
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s32 val;
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do
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val = __ldrex(cv) - 1;
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while (__strex(cv, val));
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LightLock_Unlock(lock);
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}
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static INLINE bool CondVar_EndWait(CondVar* cv, s32 num_threads)
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{
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bool hasWaiters;
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s32 val;
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do {
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val = __ldrex(cv);
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hasWaiters = val < 0;
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if (hasWaiters)
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{
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if (num_threads < 0)
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val = 0;
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else if (val <= -num_threads)
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val += num_threads;
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else
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val = 0;
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}
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} while (__strex(cv, val));
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return hasWaiters;
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}
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static INLINE void CondVar_Init(CondVar* cv)
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{
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*cv = 0;
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}
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static INLINE void CondVar_Wait(CondVar* cv, LightLock* lock)
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{
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CondVar_BeginWait(cv, lock);
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syncArbitrateAddress(cv, ARBITRATION_WAIT_IF_LESS_THAN, 0);
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LightLock_Lock(lock);
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}
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static INLINE int CondVar_WaitTimeout(CondVar* cv, LightLock* lock, s64 timeout_ns)
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{
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CondVar_BeginWait(cv, lock);
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bool timedOut = false;
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Result rc = syncArbitrateAddressWithTimeout(cv, ARBITRATION_WAIT_IF_LESS_THAN_TIMEOUT, 0, timeout_ns);
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if (R_DESCRIPTION(rc) == RD_TIMEOUT)
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{
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timedOut = CondVar_EndWait(cv, 1);
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__dmb();
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}
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LightLock_Lock(lock);
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return timedOut;
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}
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static INLINE void CondVar_WakeUp(CondVar* cv, s32 num_threads)
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{
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__dmb();
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if (CondVar_EndWait(cv, num_threads))
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syncArbitrateAddress(cv, ARBITRATION_SIGNAL, num_threads);
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else
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__dmb();
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}
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static INLINE void CondVar_Signal(CondVar* cv)
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{
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CondVar_WakeUp(cv, 1);
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}
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static INLINE void CondVar_Broadcast(CondVar* cv)
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{
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CondVar_WakeUp(cv, ARBITRATION_SIGNAL_ALL);
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}
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/* End libctru 2.0 backport */
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#endif
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/* libctru threads return void but pthreads return void pointer */
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static bool mutex_inited = false;
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@ -139,8 +235,7 @@ static INLINE void pthread_exit(void *retval)
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static INLINE int pthread_detach(pthread_t thread)
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{
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/* FIXME: pthread_detach equivalent missing? */
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(void)thread;
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threadDetach((Thread)thread);
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return 0;
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}
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@ -163,13 +258,7 @@ static INLINE int pthread_mutex_trylock(pthread_mutex_t *mutex)
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static INLINE int pthread_cond_wait(pthread_cond_t *cond,
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pthread_mutex_t *mutex)
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{
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cond_t *cond_data = (cond_t *)*cond;
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LightLock_Lock(&cond_data->lock);
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cond_data->waiting++;
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LightLock_Unlock(mutex);
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LightLock_Unlock(&cond_data->lock);
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svcWaitSynchronization(cond_data->semaphore, INT64_MAX);
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LightLock_Lock(mutex);
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CondVar_Wait((CondVar *)cond, (LightLock *)mutex);
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return 0;
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}
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@ -181,25 +270,22 @@ static INLINE int pthread_cond_timedwait(pthread_cond_t *cond,
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struct timeval tm;
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int retval = 0;
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cond_t *cond_data = (cond_t *)*cond;
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LightLock_Lock(&cond_data->lock);
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cond_data->waiting++;
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do {
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gettimeofday(&tm, NULL);
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now.tv_sec = tm.tv_sec;
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now.tv_nsec = tm.tv_usec * 1000;
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s64 timeout = (abstime->tv_sec - now.tv_sec) * 1000000000 + (abstime->tv_nsec - now.tv_nsec);
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gettimeofday(&tm, NULL);
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now.tv_sec = tm.tv_sec;
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now.tv_nsec = tm.tv_usec * 1000;
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s64 timeout = (abstime->tv_sec - now.tv_sec) * 1000000000 + (abstime->tv_nsec - now.tv_nsec);
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if (timeout >= 0) {
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LightLock_Unlock(mutex);
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LightLock_Unlock(&cond_data->lock);
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if (svcWaitSynchronization(cond_data->semaphore, timeout))
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if (timeout < 0)
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{
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retval = ETIMEDOUT;
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break;
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}
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LightLock_Lock(mutex);
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} else {
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retval = ETIMEDOUT;
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}
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if (!CondVar_WaitTimeout((CondVar *)cond, (LightLock *)mutex, timeout)) {
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break;
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}
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} while (1);
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return retval;
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}
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@ -207,65 +293,25 @@ static INLINE int pthread_cond_timedwait(pthread_cond_t *cond,
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static INLINE int pthread_cond_init(pthread_cond_t *cond,
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const pthread_condattr_t *attr)
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{
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cond_t *cond_data = calloc(1, sizeof(cond_t));
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if (!cond_data)
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goto error;
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if (svcCreateSemaphore(&cond_data->semaphore, 0, 1))
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goto error;
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LightLock_Init(&cond_data->lock);
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cond_data->waiting = 0;
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*cond = (pthread_cond_t)cond_data;
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CondVar_Init((CondVar *)cond);
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return 0;
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error:
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svcCloseHandle(cond_data->semaphore);
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if (cond_data)
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free(cond_data);
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return -1;
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}
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static INLINE int pthread_cond_signal(pthread_cond_t *cond)
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{
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int32_t count;
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cond_t *cond_data = (cond_t *)*cond;
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LightLock_Lock(&cond_data->lock);
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if (cond_data->waiting) {
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cond_data->waiting--;
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LightLock_Unlock(&cond_data->lock);
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svcReleaseSemaphore(&count, cond_data->semaphore, 1);
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} else {
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LightLock_Unlock(&cond_data->lock);
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}
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CondVar_Signal((CondVar *)cond);
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return 0;
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}
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static INLINE int pthread_cond_broadcast(pthread_cond_t *cond)
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{
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int32_t count;
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cond_t *cond_data = (cond_t *)*cond;
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LightLock_Lock(&cond_data->lock);
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while (cond_data->waiting) {
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cond_data->waiting--;
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LightLock_Unlock(&cond_data->lock);
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svcReleaseSemaphore(&count, cond_data->semaphore, 1);
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LightLock_Lock(&cond_data->lock);
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}
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LightLock_Unlock(&cond_data->lock);
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CondVar_Broadcast((CondVar *)cond);
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return 0;
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}
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static INLINE int pthread_cond_destroy(pthread_cond_t *cond)
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{
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if (*cond) {
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cond_t *cond_data = (cond_t *)*cond;
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svcCloseHandle(cond_data->semaphore);
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free(cond_data);
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}
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*cond = 0;
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/*Nothing to destroy*/
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return 0;
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}
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