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/* ==== cond.c ============================================================
* Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
* All rights reserved.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Chris Provenzano.
* 4. The name of Chris Provenzano may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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.
*
* Description : Condition cariable functions.
*
* 1.00 93/10/28 proven
* -Started coding this file.
*/
#ifndef lint
static const char rcsid[] = "$Id: cond.c,v 1.1 1995/10/18 08:43:04 deraadt Exp $ $provenid: cond.c,v 1.16 1994/02/07 02:18:35 proven Exp $";
#endif
#include <pthread.h>
#include <errno.h>
/* ==========================================================================
* pthread_cond_init()
*
* In this implementation I don't need to allocate memory.
* ENOMEM, EAGAIN should never be returned. Arch that have
* weird constraints may need special coding.
*/
int pthread_cond_init(pthread_cond_t *cond, pthread_condattr_t *cond_attr)
{
/* Only check if attr specifies some mutex type other than fast */
if ((cond_attr) && (cond_attr->c_type != COND_TYPE_FAST)) {
if (cond_attr->c_type >= COND_TYPE_MAX) {
return(EINVAL);
}
if (cond->c_flags & COND_FLAGS_INITED) {
return(EBUSY);
}
cond->c_type = cond_attr->c_type;
} else {
cond->c_type = COND_TYPE_FAST;
}
/* Set all other paramaters */
pthread_queue_init(&cond->c_queue);
cond->c_flags |= COND_FLAGS_INITED;
cond->c_lock = SEMAPHORE_CLEAR;
return(OK);
}
/* ==========================================================================
* pthread_cond_destroy()
*/
int pthread_cond_destroy(pthread_cond_t *cond)
{
/* Only check if cond is of type other than fast */
switch(cond->c_type) {
case COND_TYPE_FAST:
break;
case COND_TYPE_STATIC_FAST:
default:
return(EINVAL);
break;
}
/* Cleanup cond, others might want to use it. */
pthread_queue_init(&cond->c_queue);
cond->c_flags |= COND_FLAGS_INITED;
cond->c_lock = SEMAPHORE_CLEAR;
cond->c_flags = 0;
return(OK);
}
/* ==========================================================================
* pthread_cond_wait()
*/
int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
semaphore *lock, *plock;
int rval;
lock = &(cond->c_lock);
while (SEMAPHORE_TEST_AND_SET(lock)) {
pthread_yield();
}
switch (cond->c_type) {
/*
* Fast condition variables do not check for any error conditions.
*/
case COND_TYPE_FAST:
case COND_TYPE_STATIC_FAST:
plock = &(pthread_run->lock);
while (SEMAPHORE_TEST_AND_SET(plock)) {
pthread_yield();
}
pthread_queue_enq(&cond->c_queue, pthread_run);
pthread_mutex_unlock(mutex);
SEMAPHORE_RESET(lock);
/* Reschedule will unlock pthread_run */
reschedule(PS_COND_WAIT);
return(pthread_mutex_lock(mutex));
break;
default:
rval = EINVAL;
break;
}
SEMAPHORE_RESET(lock);
return(rval);
}
/* ==========================================================================
* pthread_cond_signal()
*/
int pthread_cond_signal(pthread_cond_t *cond)
{
struct pthread *pthread;
semaphore *lock, *plock;
int rval;
lock = &(cond->c_lock);
while (SEMAPHORE_TEST_AND_SET(lock)) {
pthread_yield();
}
switch (cond->c_type) {
case COND_TYPE_FAST:
case COND_TYPE_STATIC_FAST:
if (pthread = pthread_queue_get(&cond->c_queue)) {
plock = &(pthread->lock);
while (SEMAPHORE_TEST_AND_SET(plock)) {
pthread_yield();
}
pthread_queue_deq(&cond->c_queue);
pthread->state = PS_RUNNING;
SEMAPHORE_RESET(plock);
}
rval = OK;
break;
default:
rval = EINVAL;
break;
}
SEMAPHORE_RESET(lock);
return(rval);
}
/* ==========================================================================
* pthread_cond_broadcast()
*
* Not much different then the above routine.
*/
int pthread_cond_broadcast(pthread_cond_t *cond)
{
struct pthread *pthread;
semaphore *lock, *plock;
int rval;
lock = &(cond->c_lock);
while (SEMAPHORE_TEST_AND_SET(lock)) {
pthread_yield();
}
switch (cond->c_type) {
case COND_TYPE_FAST:
case COND_TYPE_STATIC_FAST:
while (pthread = pthread_queue_get(&cond->c_queue)) {
plock = &(pthread->lock);
while (SEMAPHORE_TEST_AND_SET(plock)) {
pthread_yield();
}
pthread_queue_deq(&cond->c_queue);
pthread->state = PS_RUNNING;
SEMAPHORE_RESET(plock);
}
rval = OK;
break;
default:
rval = EINVAL;
break;
}
SEMAPHORE_RESET(lock);
return(rval);
}
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