michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include <kernel/OS.h>
michael@0: 
michael@0: #include "primpl.h"
michael@0: 
michael@0: /*
michael@0: ** Create a new semaphore object.
michael@0: */
michael@0: PR_IMPLEMENT(PRSemaphore*)
michael@0:     PR_NewSem (PRUintn value)
michael@0: {
michael@0: 	PRSemaphore *semaphore;
michael@0: 
michael@0: 	if (!_pr_initialized) _PR_ImplicitInitialization();
michael@0: 
michael@0: 	semaphore = PR_NEWZAP(PRSemaphore);
michael@0: 	if (NULL != semaphore) {
michael@0: 		if ((semaphore->sem = create_sem(value, "nspr_sem")) < B_NO_ERROR)
michael@0: 			return NULL;
michael@0: 		else 
michael@0: 			return semaphore;
michael@0: 	}
michael@0: 	return NULL;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Destroy the given semaphore object.
michael@0: **
michael@0: */
michael@0: PR_IMPLEMENT(void)
michael@0:     PR_DestroySem (PRSemaphore *sem)
michael@0: {
michael@0: 	status_t result;
michael@0: 
michael@0: 	PR_ASSERT(sem != NULL);
michael@0: 	result = delete_sem(sem->sem);
michael@0: 	PR_ASSERT(result == B_NO_ERROR);
michael@0: 	PR_DELETE(sem);
michael@0: } 
michael@0: 
michael@0: /*
michael@0: ** Wait on a Semaphore.
michael@0: ** 
michael@0: ** This routine allows a calling thread to wait or proceed depending upon
michael@0: ** the state of the semahore sem. The thread can proceed only if the
michael@0: ** counter value of the semaphore sem is currently greater than 0. If the
michael@0: ** value of semaphore sem is positive, it is decremented by one and the
michael@0: ** routine returns immediately allowing the calling thread to continue. If
michael@0: ** the value of semaphore sem is 0, the calling thread blocks awaiting the
michael@0: ** semaphore to be released by another thread.
michael@0: ** 
michael@0: ** This routine can return PR_PENDING_INTERRUPT if the waiting thread 
michael@0: ** has been interrupted.
michael@0: */
michael@0: PR_IMPLEMENT(PRStatus)
michael@0:     PR_WaitSem (PRSemaphore *sem)
michael@0: {
michael@0: 	PR_ASSERT(sem != NULL);
michael@0: 	if (acquire_sem(sem->sem) == B_NO_ERROR)
michael@0: 		return PR_SUCCESS;
michael@0: 	else
michael@0: 		return PR_FAILURE;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** This routine increments the counter value of the semaphore. If other
michael@0: ** threads are blocked for the semaphore, then the scheduler will
michael@0: ** determine which ONE thread will be unblocked.
michael@0: */
michael@0: PR_IMPLEMENT(void)
michael@0:     PR_PostSem (PRSemaphore *sem)
michael@0: {
michael@0: 	status_t result;
michael@0: 
michael@0: 	PR_ASSERT(sem != NULL);
michael@0: 	result = release_sem_etc(sem->sem, 1, B_DO_NOT_RESCHEDULE);
michael@0: 	PR_ASSERT(result == B_NO_ERROR);
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Returns the value of the semaphore referenced by sem without affecting
michael@0: ** the state of the semaphore.  The value represents the semaphore value
michael@0: ** at the time of the call, but may not be the actual value when the
michael@0: ** caller inspects it.
michael@0: */
michael@0: PR_IMPLEMENT(PRUintn)
michael@0:     PR_GetValueSem (PRSemaphore *sem)
michael@0: {
michael@0: 	sem_info	info;
michael@0: 
michael@0: 	PR_ASSERT(sem != NULL);
michael@0: 	get_sem_info(sem->sem, &info);
michael@0: 	return info.count;
michael@0: }