1 /* $OpenBSD: queue.h,v 1.30 2005/10/25 06:37:47 otto Exp $ */
2 /* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
3
4 /*
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)queue.h 8.5 (Berkeley) 8/20/94
33 */
34
35 #ifndef SM_TAILQ_H_
36 #define SM_TAILQ_H_
37
38 /*
39 * $Id: tailq.h,v 1.3 2012-01-21 00:12:14 ashish Exp $
40 *
41 * This file is a modified copy of queue.h from a BSD system:
42 * we only need tail queues here.
43 * We do not use queue.h directly because there is a conflict with
44 * some versions of that file on some OSs.
45 *
46 * A tail queue is headed by a pair of pointers, one to the head of the
47 * list and the other to the tail of the list. The elements are doubly
48 * linked so that an arbitrary element can be removed without a need to
49 * traverse the list. New elements can be added to the list before or
50 * after an existing element, at the head of the list, or at the end of
51 * the list. A tail queue may be traversed in either direction.
52 */
53
54 /*
55 * Tail queue definitions.
56 */
57 #define SM_TAILQ_HEAD(name, type) \
58 struct name { \
59 struct type *tqh_first; /* first element */ \
60 struct type **tqh_last; /* addr of last next element */ \
61 }
62
63 #define SM_TAILQ_HEAD_INITIALIZER(head) \
64 { NULL, &(head).tqh_first }
65
66 #define SM_TAILQ_ENTRY(type) \
67 struct { \
68 struct type *tqe_next; /* next element */ \
69 struct type **tqe_prev; /* address of previous next element */ \
70 }
71
72 /*
73 * tail queue access methods
74 */
75 #define SM_TAILQ_FIRST(head) ((head)->tqh_first)
76 #define SM_TAILQ_END(head) NULL
77 #define SM_TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
78 #define SM_TAILQ_LAST(head, headname) \
79 (*(((struct headname *)((head)->tqh_last))->tqh_last))
80 /* XXX */
81 #define SM_TAILQ_PREV(elm, headname, field) \
82 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
83 #define SM_TAILQ_EMPTY(head) \
84 (SM_TAILQ_FIRST(head) == SM_TAILQ_END(head))
85
86 #define SM_TAILQ_FOREACH(var, head, field) \
87 for((var) = SM_TAILQ_FIRST(head); \
88 (var) != SM_TAILQ_END(head); \
89 (var) = SM_TAILQ_NEXT(var, field))
90
91 #define SM_TAILQ_FOREACH_REVERSE(var, head, headname, field) \
92 for((var) = SM_TAILQ_LAST(head, headname); \
93 (var) != SM_TAILQ_END(head); \
94 (var) = SM_TAILQ_PREV(var, headname, field))
95
96 /*
97 * Tail queue functions.
98 */
99 #define SM_TAILQ_INIT(head) do { \
100 (head)->tqh_first = NULL; \
101 (head)->tqh_last = &(head)->tqh_first; \
102 } while (0)
103
104 #define SM_TAILQ_INSERT_HEAD(head, elm, field) do { \
105 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
106 (head)->tqh_first->field.tqe_prev = \
107 &(elm)->field.tqe_next; \
108 else \
109 (head)->tqh_last = &(elm)->field.tqe_next; \
110 (head)->tqh_first = (elm); \
111 (elm)->field.tqe_prev = &(head)->tqh_first; \
112 } while (0)
113
114 #define SM_TAILQ_INSERT_TAIL(head, elm, field) do { \
115 (elm)->field.tqe_next = NULL; \
116 (elm)->field.tqe_prev = (head)->tqh_last; \
117 *(head)->tqh_last = (elm); \
118 (head)->tqh_last = &(elm)->field.tqe_next; \
119 } while (0)
120
121 #define SM_TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
122 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
123 (elm)->field.tqe_next->field.tqe_prev = \
124 &(elm)->field.tqe_next; \
125 else \
126 (head)->tqh_last = &(elm)->field.tqe_next; \
127 (listelm)->field.tqe_next = (elm); \
128 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
129 } while (0)
130
131 #define SM_TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
132 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
133 (elm)->field.tqe_next = (listelm); \
134 *(listelm)->field.tqe_prev = (elm); \
135 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
136 } while (0)
137
138 #define SM_TAILQ_REMOVE(head, elm, field) do { \
139 if (((elm)->field.tqe_next) != NULL) \
140 (elm)->field.tqe_next->field.tqe_prev = \
141 (elm)->field.tqe_prev; \
142 else \
143 (head)->tqh_last = (elm)->field.tqe_prev; \
144 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
145 } while (0)
146
147 #define SM_TAILQ_REPLACE(head, elm, elm2, field) do { \
148 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
149 (elm2)->field.tqe_next->field.tqe_prev = \
150 &(elm2)->field.tqe_next; \
151 else \
152 (head)->tqh_last = &(elm2)->field.tqe_next; \
153 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
154 *(elm2)->field.tqe_prev = (elm2); \
155 } while (0)
156
157 #endif /* !SM_TAILQ_H_ */