sys/lib/queue.c

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This source file includes following definitions.
enqueue
dequeue
queue_insert
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 
  34 #include <kernel.h>
  35 
  36 /*
  37  * Insert element at tail of queue
  38  */
  39 void
  40 enqueue(queue_t head, queue_t item)
  41 {
  42 
  43         item->next = head;
  44         item->prev = head->prev;
  45         item->prev->next = item;
  46         head->prev = item;
  47 }
  48 
  49 /*
  50  * Remove and return element of head of queue
  51  */
  52 queue_t
  53 dequeue(queue_t head)
  54 {
  55         queue_t item;
  56 
  57         if (head->next == head)
  58                 return ((queue_t)0);
  59         item = head->next;
  60         item->next->prev = head;
  61         head->next = item->next;
  62         return item;
  63 }
  64 
  65 /*
  66  * Insert element after specified element
  67  */
  68 void
  69 queue_insert(queue_t prev, queue_t item)
  70 {
  71 
  72         item->prev = prev;
  73         item->next = prev->next;
  74         prev->next->prev = item;
  75         prev->next = item;
  76 }
  77 
  78 /*
  79  * Remove specified element from queue
  80  */
  81 void
  82 queue_remove(queue_t item)
  83 {
  84 
  85         item->prev->next = item->next;
  86         item->next->prev = item->prev;
  87 }
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root/sys/lib/queue.c

DEFINITIONS
