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124 lines
4.6 KiB
124 lines
4.6 KiB
/**************************************************************************** |
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* lib/sem/sem_init.c |
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* |
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* Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**************************************************************************** |
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* Included Files |
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****************************************************************************/ |
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#include <nuttx/config.h> |
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#include <sys/types.h> |
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#include <limits.h> |
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#include <semaphore.h> |
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#include <errno.h> |
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/**************************************************************************** |
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* Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Type Declarations |
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****************************************************************************/ |
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/**************************************************************************** |
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* Global Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Function: sem_init |
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* |
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* Description: |
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* This function initializes the UNAMED semaphore sem. Following a |
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* successful call to sem_init(), the semaophore may be used in subsequent |
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* calls to sem_wait(), sem_post(), and sem_trywait(). The semaphore |
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* remains usable until it is destroyed. |
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* |
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* Only sem itself may be used for performing synchronization. The result |
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* of referring to copies of sem in calls to sem_wait(), sem_trywait(), |
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* sem_post(), and sem_destroy() is undefined. |
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* |
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* Parameters: |
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* sem - Semaphore to be initialized |
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* pshared - Process sharing (not used) |
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* value - Semaphore initialization value |
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* |
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* Return Value: |
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* 0 (OK), or -1 (ERROR) if unsuccessful. |
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* |
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* Assumptions: |
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* |
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****************************************************************************/ |
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int sem_init(FAR sem_t *sem, int pshared, unsigned int value) |
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{ |
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/* Verify that a semaphore was provided and the count is within the valid |
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* range. |
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*/ |
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if (sem && value <= SEM_VALUE_MAX) |
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{ |
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/* Initialize the seamphore count */ |
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sem->semcount = (int16_t)value; |
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/* Initialize to support priority inheritance */ |
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#ifdef CONFIG_PRIORITY_INHERITANCE |
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# if CONFIG_SEM_PREALLOCHOLDERS > 0 |
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sem->hlist.flink = NULL; |
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# endif |
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sem->hlist.holder = NULL; |
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sem->hlist.counts = 0; |
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#endif |
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return OK; |
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} |
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else |
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{ |
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set_errno(EINVAL); |
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return ERROR; |
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} |
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}
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