File: [local] / prex-old / sys / lib / queue.c (download)
Revision 1.1.1.1 (vendor branch), Tue Jun 3 09:38:46 2008 UTC (16 years, 2 months ago) by nbrk
Branch: MAIN, KOHSUKE
CVS Tags: PREX_0_8_BASE, PREX_0_7_BASE, HEAD Changes since 1.1: +0 -0 lines
Yeah, this is an initial import of Prex, portable real-time microkernel
operating system. I wanna hack it for non-profit but fun, so let it in.
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/*-
* Copyright (c) 2005, Kohsuke Ohtani
* 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. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
/*
* queue.c - generic queue management library
*/
#include <queue.h>
/*
* Insert element at tail of queue
*/
void
enqueue(queue_t head, queue_t item)
{
item->next = head;
item->prev = head->prev;
item->prev->next = item;
head->prev = item;
}
/*
* Remove and return element of head of queue
*/
queue_t
dequeue(queue_t head)
{
queue_t item;
if (head->next == head)
return ((queue_t)0);
item = head->next;
item->next->prev = head;
head->next = item->next;
return item;
}
/*
* Insert element after specified element
*/
void
queue_insert(queue_t prev, queue_t item)
{
item->prev = prev;
item->next = prev->next;
prev->next->prev = item;
prev->next = item;
}
/*
* Remove specified element from queue
*/
void
queue_remove(queue_t item)
{
item->prev->next = item->next;
item->next->prev = item->prev;
}