/**************************************************************************** * lib/sem/sem_init.c * * Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include /**************************************************************************** * 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) { if (sem && value <= SEM_VALUE_MAX) { sem->semcount = (int16_t)value; #ifdef CONFIG_PRIORITY_INHERITANCE #if CONFIG_SEM_PREALLOCHOLDERS > 0 sem->hlist.flink = NULL; #endif sem->hlist.holder = NULL; sem->hlist.counts = 0; #endif return OK; } else { errno = -EINVAL; return ERROR; } }