text: /****************************************************************************
   *
   * Copyright 2016 Samsung Electronics All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied. See the License for the specific
   * language governing permissions and limitations under the License.
   *
   ****************************************************************************/
  /****************************************************************************
   * libc/sem/sem_init.c
   *
   *   Copyright (C) 2007-2009, 2011-2012, 2016 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 <tinyara/config.h>
  
  #include <sys/types.h>
  #include <limits.h>
  #include <semaphore.h>
  #include <errno.h>
  
  #ifdef CONFIG_SEMAPHORE_HISTORY
  #include <tinyara/debug/sysdbg.h>
  #endif
  
  /****************************************************************************
   * 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;
  #ifdef CONFIG_SEMAPHORE_HISTORY
  		save_semaphore_history(sem, (void *)NULL, SEM_INIT);
  #endif
  
  		sem->flags = FLAGS_INITIALIZED;
  
  		/* Initialize to support priority inheritance */
  
  #ifdef CONFIG_PRIORITY_INHERITANCE
  		sem->flags &= ~(PRIOINHERIT_FLAGS_DISABLE);
  #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;
  	}
  }
  