/*
* Copyright (c) 2001-2004 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/** @addtogroup kernel_sync
* @{
*/
/**
* @file
* @brief Semaphores.
*/
#include <synch/semaphore.h>
#include <synch/waitq.h>
#include <synch/spinlock.h>
#include <arch/asm.h>
#include <arch.h>
/** Initialize semaphore
*
* Initialize semaphore.
*
* @param sem Semaphore.
* @param val Maximal number of threads allowed to enter critical section.
*
*/
void semaphore_initialize(semaphore_t *sem, int val)
{
waitq_initialize_with_count(&sem->wq, val);
}
errno_t semaphore_trydown(semaphore_t *sem)
{
return semaphore_down_timeout(sem, 0);
}
/** Semaphore down with timeout
*
* @param sem Semaphore.
* @param usec Timeout in microseconds.
*
* @return See comment for waitq_sleep_timeout().
*
*/
errno_t semaphore_down_timeout(semaphore_t *sem, uint32_t usec)
{
errno_t rc = waitq_sleep_timeout(&sem->wq, usec);
assert(rc == EOK || rc == ETIMEOUT || rc == EAGAIN);
return rc;
}
void semaphore_down(semaphore_t *sem)
{
errno_t rc = waitq_sleep(&sem->wq);
assert(rc == EOK);
}
/** Semaphore up
*
* Semaphore up.
*
* @param s Semaphore.
*
*/
void semaphore_up(semaphore_t *sem)
{
waitq_wake_one(&sem->wq);
}
/** @}
*/