2012-11-10 17:06:01 +01:00
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/****************************************************************************
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2018-05-29 21:21:26 +02:00
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* libs/libc/sem/sem_init.c
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2012-11-10 17:06:01 +01:00
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*
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2017-10-03 20:51:15 +02:00
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* Copyright (C) 2007-2009, 2011-2012, 2016-2017 Gregory Nutt. All rights reserved.
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2012-11-10 17:06:01 +01:00
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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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2017-10-03 20:51:15 +02:00
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#include <nuttx/semaphore.h>
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2012-11-10 17:06:01 +01:00
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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2017-10-03 20:51:15 +02:00
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* Name: nxsem_init
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2012-11-10 17:06:01 +01:00
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*
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* Description:
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2019-09-08 23:59:14 +02:00
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* This function initializes the UNNAMED semaphore sem. Following a
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2017-10-03 20:51:15 +02:00
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* successful call to nxsem_init(), the semaphore may be used in subsequent
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2017-10-04 23:22:27 +02:00
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* calls to nxsem_wait(), nxsem_post(), and nxsem_trywait(). The semaphore
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2012-11-10 17:06:01 +01:00
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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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2017-10-03 23:35:24 +02:00
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* of referring to copies of sem in calls to nxsem_wait(), nxsem_trywait(),
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2017-10-04 23:22:27 +02:00
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* nxsem_post(), and nxsem_destroy() is undefined.
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2012-11-10 17:06:01 +01:00
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*
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2018-03-13 16:52:27 +01:00
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* Input Parameters:
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2012-11-10 17:06:01 +01:00
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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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2018-02-01 17:00:02 +01:00
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* Returned Value:
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2017-10-03 20:51:15 +02:00
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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2012-11-10 17:06:01 +01:00
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*
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****************************************************************************/
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2017-10-03 20:51:15 +02:00
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int nxsem_init(FAR sem_t *sem, int pshared, unsigned int value)
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2012-11-10 17:06:01 +01:00
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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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2017-10-03 20:51:15 +02:00
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if (sem != NULL && value <= SEM_VALUE_MAX)
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2012-11-10 17:06:01 +01:00
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{
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/* Initialize the seamphore count */
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2017-03-10 16:30:15 +01:00
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sem->semcount = (int16_t)value;
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2012-11-10 17:06:01 +01:00
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/* Initialize to support priority inheritance */
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#ifdef CONFIG_PRIORITY_INHERITANCE
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2017-03-10 16:30:15 +01:00
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sem->flags = 0;
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2012-11-10 17:06:01 +01:00
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# if CONFIG_SEM_PREALLOCHOLDERS > 0
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2017-03-10 16:30:15 +01:00
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sem->hhead = NULL;
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2012-11-10 17:06:01 +01:00
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# else
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2017-03-10 16:30:15 +01:00
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sem->holder[0].htcb = NULL;
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sem->holder[0].counts = 0;
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sem->holder[1].htcb = NULL;
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sem->holder[1].counts = 0;
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2012-11-10 17:06:01 +01:00
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# endif
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#endif
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return OK;
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}
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2017-10-03 20:51:15 +02:00
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return -EINVAL;
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}
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/****************************************************************************
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* Name: sem_init
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*
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* Description:
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2019-09-08 23:59:14 +02:00
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* This function initializes the UNNAMED semaphore sem. Following a
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2017-10-03 20:51:15 +02:00
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* successful call to sem_init(), the semaphore may be used in subsequent
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2017-10-05 15:59:06 +02:00
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* calls to sem_wait(), sem_post(), and sem_trywait(). The semaphore
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2017-10-03 20:51:15 +02:00
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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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2017-10-05 15:59:06 +02:00
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* sem_post(), and sem_destroy() is undefined.
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2017-10-03 20:51:15 +02:00
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*
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2018-03-13 16:52:27 +01:00
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* Input Parameters:
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2017-10-03 20:51:15 +02:00
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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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2018-02-01 17:00:02 +01:00
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* Returned Value:
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2017-10-03 20:51:15 +02:00
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* This returns zero (OK) if successful. Otherwise, -1 (ERROR) is
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* returned and the errno value is set appropriately.
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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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int ret;
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ret = nxsem_init(sem, pshared, value);
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if (ret < 0)
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2012-11-10 17:06:01 +01:00
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{
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2017-10-03 20:51:15 +02:00
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set_errno(-ret);
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ret = ERROR;
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2012-11-10 17:06:01 +01:00
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}
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2017-10-03 20:51:15 +02:00
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return ret;
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2012-11-10 17:06:01 +01:00
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}
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