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38 #include <kernel/OS.h>
43 ** Create a new semaphore object.
45 PR_IMPLEMENT(PRSemaphore*)
46 PR_NewSem (PRUintn value)
48 PRSemaphore *semaphore;
50 if (!_pr_initialized) _PR_ImplicitInitialization();
52 semaphore = PR_NEWZAP(PRSemaphore);
53 if (NULL != semaphore) {
54 if ((semaphore->sem = create_sem(value, "nspr_sem")) < B_NO_ERROR)
63 ** Destroy the given semaphore object.
67 PR_DestroySem (PRSemaphore *sem)
71 PR_ASSERT(sem != NULL);
72 result = delete_sem(sem->sem);
73 PR_ASSERT(result == B_NO_ERROR);
78 ** Wait on a Semaphore.
80 ** This routine allows a calling thread to wait or proceed depending upon
81 ** the state of the semahore sem. The thread can proceed only if the
82 ** counter value of the semaphore sem is currently greater than 0. If the
83 ** value of semaphore sem is positive, it is decremented by one and the
84 ** routine returns immediately allowing the calling thread to continue. If
85 ** the value of semaphore sem is 0, the calling thread blocks awaiting the
86 ** semaphore to be released by another thread.
88 ** This routine can return PR_PENDING_INTERRUPT if the waiting thread
89 ** has been interrupted.
91 PR_IMPLEMENT(PRStatus)
92 PR_WaitSem (PRSemaphore *sem)
94 PR_ASSERT(sem != NULL);
95 if (acquire_sem(sem->sem) == B_NO_ERROR)
102 ** This routine increments the counter value of the semaphore. If other
103 ** threads are blocked for the semaphore, then the scheduler will
104 ** determine which ONE thread will be unblocked.
107 PR_PostSem (PRSemaphore *sem)
111 PR_ASSERT(sem != NULL);
112 result = release_sem_etc(sem->sem, 1, B_DO_NOT_RESCHEDULE);
113 PR_ASSERT(result == B_NO_ERROR);
117 ** Returns the value of the semaphore referenced by sem without affecting
118 ** the state of the semaphore. The value represents the semaphore value
119 ** at the time of the call, but may not be the actual value when the
120 ** caller inspects it.
122 PR_IMPLEMENT(PRUintn)
123 PR_GetValueSem (PRSemaphore *sem)
127 PR_ASSERT(sem != NULL);
128 get_sem_info(sem->sem, &info);