97 lines
3.5 KiB
C
97 lines
3.5 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is the Netscape Portable Runtime (NSPR).
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998-2000
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef prsem_h___
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#define prsem_h___
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/*
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** API for counting semaphores. Semaphores are counting synchronizing
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** variables based on a lock and a condition variable. They are lightweight
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** contention control for a given count of resources.
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*/
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#include "prtypes.h"
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PR_BEGIN_EXTERN_C
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typedef struct PRSemaphore PRSemaphore;
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/*
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** Create a new semaphore object.
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*/
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NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
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/*
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** Destroy the given semaphore object.
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**
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*/
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NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
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/*
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** Wait on a Semaphore.
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**
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** This routine allows a calling thread to wait or proceed depending upon the
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** state of the semahore sem. The thread can proceed only if the counter value
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** of the semaphore sem is currently greater than 0. If the value of semaphore
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** sem is positive, it is decremented by one and the routine returns immediately
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** allowing the calling thread to continue. If the value of semaphore sem is 0,
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** the calling thread blocks awaiting the semaphore to be released by another
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** thread.
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**
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** This routine can return PR_PENDING_INTERRUPT if the waiting thread
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** has been interrupted.
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*/
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NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
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/*
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** This routine increments the counter value of the semaphore. If other threads
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** are blocked for the semaphore, then the scheduler will determine which ONE
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** thread will be unblocked.
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*/
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NSPR_API(void) PR_PostSem(PRSemaphore *sem);
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/*
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** Returns the value of the semaphore referenced by sem without affecting
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** the state of the semaphore. The value represents the semaphore vaule
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F** at the time of the call, but may not be the actual value when the
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** caller inspects it.
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*/
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NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
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PR_END_EXTERN_C
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#endif /* prsem_h___ */
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