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root/bsp/drv/lib/queue.c

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DEFINITIONS

This source file includes following definitions.
  1. enqueue
  2. dequeue
  3. queue_insert
  4. queue_remove

   1 /*-
   2  * Copyright (c) 2005, Kohsuke Ohtani
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29 
  30 /*
  31  * queue.c - generic queue management library
  32  */
  33 #include <sys/queue.h>
  34 
  35 /*
  36  * Insert element at tail of queue
  37  */
  38 void
  39 enqueue(queue_t head, queue_t item)
  40 {
  41         item->next = head;
  42         item->prev = head->prev;
  43         item->prev->next = item;
  44         head->prev = item;
  45 }
  46 
  47 /*
  48  * Remove and return element of head of queue
  49  */
  50 queue_t
  51 dequeue(queue_t head)
  52 {
  53         queue_t item;
  54 
  55         if (head->next == head)
  56                 return ((queue_t)0);
  57         item = head->next;
  58         item->next->prev = head;
  59         head->next = item->next;
  60         return item;
  61 }
  62 
  63 /*
  64  * Insert element after specified element
  65  */
  66 void
  67 queue_insert(queue_t prev, queue_t item)
  68 {
  69         item->prev = prev;
  70         item->next = prev->next;
  71         prev->next->prev = item;
  72         prev->next = item;
  73 }
  74 
  75 /*
  76  * Remove specified element from queue
  77  */
  78 void
  79 queue_remove(queue_t item)
  80 {
  81         item->prev->next = item->next;
  82         item->next->prev = item->prev;
  83 }

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