Annotation of prex-old/dev/lib/queue.c, Revision 1.1.1.1
1.1 nbrk 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 <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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