/*
* 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.
*/
#include <synch/semaphore.h>
#include <synch/waitq.h>
#include <synch/spinlock.h>
#include <synch/synch.h>
#include <arch/asm.h>
#include <arch.h>
/** Initialize semaphore
*
* Initialize semaphore.
*
* @param s Semaphore.
* @param val Maximal number of threads allowed to enter critical section.
*/
void semaphore_initialize(semaphore_t *s, int val)
{
ipl_t ipl;
waitq_initialize(&s->wq);
ipl = interrupts_disable();
spinlock_lock(&s->wq.lock);
s->wq.missed_wakeups = val;
spinlock_unlock(&s->wq.lock);
interrupts_restore(ipl);
}
/** Semaphore down
*
* Semaphore down.
* Conditional mode and mode with timeout can be requested.
*
* @param s Semaphore.
* @param usec Timeout in microseconds.
* @param trydown Switches between blocking and non-blocking mode.
*
* For exact description of possible combinations of
* 'usec' and 'trydown', see comment for waitq_sleep_timeout().
*
* @return See comment for waitq_sleep_timeout().
*/
int _semaphore_down_timeout(semaphore_t *s, __u32 usec, int trydown)
{
return waitq_sleep_timeout(&s->wq, usec, trydown);
}
/** Semaphore up
*
* Semaphore up.
*
* @param s Semaphore.
*/
void semaphore_up(semaphore_t *s)
{
waitq_wakeup(&s->wq, WAKEUP_FIRST);
}