forked from Archive/PX4-Autopilot
126 lines
4.6 KiB
C
126 lines
4.6 KiB
C
/****************************************************************************
|
|
* libc/sem/sem_init.c
|
|
*
|
|
* Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <gnutt@nuttx.org>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <sys/types.h>
|
|
#include <limits.h>
|
|
#include <semaphore.h>
|
|
#include <errno.h>
|
|
|
|
/****************************************************************************
|
|
* Definitions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Type Declarations
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Global Variables
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Variables
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Function: sem_init
|
|
*
|
|
* Description:
|
|
* This function initializes the UNAMED semaphore sem. Following a
|
|
* successful call to sem_init(), the semaophore may be used in subsequent
|
|
* calls to sem_wait(), sem_post(), and sem_trywait(). The semaphore
|
|
* remains usable until it is destroyed.
|
|
*
|
|
* Only sem itself may be used for performing synchronization. The result
|
|
* of referring to copies of sem in calls to sem_wait(), sem_trywait(),
|
|
* sem_post(), and sem_destroy() is undefined.
|
|
*
|
|
* Parameters:
|
|
* sem - Semaphore to be initialized
|
|
* pshared - Process sharing (not used)
|
|
* value - Semaphore initialization value
|
|
*
|
|
* Return Value:
|
|
* 0 (OK), or -1 (ERROR) if unsuccessful.
|
|
*
|
|
* Assumptions:
|
|
*
|
|
****************************************************************************/
|
|
|
|
int sem_init(FAR sem_t *sem, int pshared, unsigned int value)
|
|
{
|
|
/* Verify that a semaphore was provided and the count is within the valid
|
|
* range.
|
|
*/
|
|
|
|
if (sem && value <= SEM_VALUE_MAX)
|
|
{
|
|
/* Initialize the seamphore count */
|
|
|
|
sem->semcount = (int16_t)value;
|
|
|
|
/* Initialize to support priority inheritance */
|
|
|
|
#ifdef CONFIG_PRIORITY_INHERITANCE
|
|
# if CONFIG_SEM_PREALLOCHOLDERS > 0
|
|
sem->hhead = NULL;
|
|
# else
|
|
sem->holder.htcb = NULL;
|
|
sem->holder.counts = 0;
|
|
# endif
|
|
#endif
|
|
return OK;
|
|
}
|
|
else
|
|
{
|
|
set_errno(EINVAL);
|
|
return ERROR;
|
|
}
|
|
}
|