scoutos / prex-0.9.0 / bsp / drv / lib / queue.c @ 03e9c04a
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/*-
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* Copyright (c) 2005, Kohsuke Ohtani
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* queue.c - generic queue management library
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*/
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#include <sys/queue.h> |
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/*
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* Insert element at tail of queue
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*/
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void
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enqueue(queue_t head, queue_t item) |
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{ |
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item->next = head; |
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item->prev = head->prev; |
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item->prev->next = item; |
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head->prev = item; |
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} |
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/*
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* Remove and return element of head of queue
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*/
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queue_t |
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dequeue(queue_t head) |
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{ |
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queue_t item; |
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if (head->next == head)
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return ((queue_t)0); |
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item = head->next; |
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item->next->prev = head; |
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head->next = item->next; |
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return item;
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} |
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/*
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* Insert element after specified element
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*/
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void
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queue_insert(queue_t prev, queue_t item) |
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{ |
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item->prev = prev; |
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item->next = prev->next; |
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prev->next->prev = item; |
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prev->next = item; |
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} |
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/*
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* Remove specified element from queue
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*/
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void
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queue_remove(queue_t item) |
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{ |
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item->prev->next = item->next; |
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item->next->prev = item->prev; |
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} |