/****************************************************************************
* 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;
}
}
