NetBSD/lib/libpthread/pthreads/queue.c

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/* ==== queue.c ============================================================
* Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
1993-12-20 22:31:06 +03:00
* 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 : Queue functions.
*
* 1.00 93/07/15 proven
* -Started coding this file.
*/
#ifndef lint
static const char rcsid[] = "$Id: queue.c,v 1.3 1994/02/07 22:04:28 proven Exp $ $provenid: queue.c,v 1.16 1994/02/07 02:19:24 proven Exp $";
#endif
#include <pthread.h>
/*
* All routines in this file assume that the queue has been appropriatly
* locked.
*/
/* ==========================================================================
* pthread_queue_init()
*/
void pthread_queue_init(struct pthread_queue *queue)
{
queue->q_next = NULL;
queue->q_last = NULL;
queue->q_data = NULL;
}
/* ==========================================================================
* pthread_queue_enq()
*/
void pthread_queue_enq(struct pthread_queue *queue, struct pthread *thread)
{
if (queue->q_last) {
queue->q_last->next = thread;
} else {
queue->q_next = thread;
}
queue->q_last = thread;
thread->queue = queue;
thread->next = NULL;
}
/* ==========================================================================
* pthread_queue_get()
*/
struct pthread *pthread_queue_get(struct pthread_queue *queue)
{
return(queue->q_next);
}
/* ==========================================================================
* pthread_queue_deq()
*/
struct pthread *pthread_queue_deq(struct pthread_queue *queue)
{
struct pthread *thread = NULL;
if (queue->q_next) {
thread = queue->q_next;
if (!(queue->q_next = queue->q_next->next)) {
queue->q_last = NULL;
}
thread->queue = NULL;
thread->next = NULL;
}
return(thread);
}
/* ==========================================================================
* pthread_queue_remove()
*/
void pthread_queue_remove(struct pthread_queue *queue, struct pthread *thread)
{
struct pthread **current = &(queue->q_next);
struct pthread *prev = NULL;
while (*current) {
if (*current == thread) {
if ((*current)->next) {
*current = (*current)->next;
} else {
queue->q_last = prev;
*current = NULL;
}
}
prev = *current;
current = &((*current)->next);
}
thread->queue = NULL;
thread->next = NULL;
}