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