1/*
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. 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. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)queue.h 8.3 (Berkeley) 12/13/93
34 */
35
36#ifndef _QUEUE_H_
37#define _QUEUE_H_
38
39/*
40 * This file defines three types of data structures: lists, tail queues,
41 * and circular queues.
42 *
43 * A list is headed by a single forward pointer (or an array of forward
44 * pointers for a hash table header). The elements are doubly linked
45 * so that an arbitrary element can be removed without a need to
46 * traverse the list. New elements can be added to the list after
47 * an existing element or at the head of the list. A list may only be
48 * traversed in the forward direction.
49 *
50 * A tail queue is headed by a pair of pointers, one to the head of the
51 * list and the other to the tail of the list. The elements are doubly
52 * linked so that an arbitrary element can be removed without a need to
53 * traverse the list. New elements can be added to the list after
54 * an existing element, at the head of the list, or at the end of the
55 * list. A tail queue may only be traversed in the forward direction.
56 *
57 * A circle queue is headed by a pair of pointers, one to the head of the
58 * list and the other to the tail of the list. The elements are doubly
59 * linked so that an arbitrary element can be removed without a need to
60 * traverse the list. New elements can be added to the list before or after
61 * an existing element, at the head of the list, or at the end of the list.
62 * A circle queue may be traversed in either direction, but has a more
63 * complex end of list detection.
64 *
65 * For details on the use of these macros, see the queue(3) manual page.
66 */
67
68/*
69 * List definitions.
70 */
71#define LIST_HEAD(name, type) \
72struct name { \
73 struct type *lh_first; /* first element */ \
74}
75
76#define LIST_ENTRY(type) \
77struct { \
78 struct type *le_next; /* next element */ \
79 struct type **le_prev; /* address of previous next element */ \
80}
81
82/*
83 * List functions.
84 */
85#define LIST_INIT(head) { \
86 (head)->lh_first = NULL; \
87}
88
89#define LIST_INSERT_AFTER(listelm, elm, field) { \
90 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
91 (listelm)->field.le_next->field.le_prev = \
92 &(elm)->field.le_next; \
93 (listelm)->field.le_next = (elm); \
94 (elm)->field.le_prev = &(listelm)->field.le_next; \
95}
96
97#define LIST_INSERT_HEAD(head, elm, field) { \
98 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
99 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
100 (head)->lh_first = (elm); \
101 (elm)->field.le_prev = &(head)->lh_first; \
102}
103
104#define LIST_REMOVE(elm, field) { \
105 if ((elm)->field.le_next != NULL) \
106 (elm)->field.le_next->field.le_prev = \
107 (elm)->field.le_prev; \
108 *(elm)->field.le_prev = (elm)->field.le_next; \
109}
110
111/*
112 * Tail queue definitions.
113 */
114#define TAILQ_HEAD(name, type) \
115struct name { \
116 struct type *tqh_first; /* first element */ \
117 struct type **tqh_last; /* addr of last next element */ \
118}
119
120#define TAILQ_ENTRY(type) \
121struct { \
122 struct type *tqe_next; /* next element */ \
123 struct type **tqe_prev; /* address of previous next element */ \
124}
125
126/*
127 * Tail queue functions.
128 */
129#define TAILQ_INIT(head) { \
130 (head)->tqh_first = NULL; \
131 (head)->tqh_last = &(head)->tqh_first; \
132}
133
134#define TAILQ_INSERT_HEAD(head, elm, field) { \
135 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
136 (elm)->field.tqe_next->field.tqe_prev = \
137 &(elm)->field.tqe_next; \
138 else \
139 (head)->tqh_last = &(elm)->field.tqe_next; \
140 (head)->tqh_first = (elm); \
141 (elm)->field.tqe_prev = &(head)->tqh_first; \
142}
143
144#define TAILQ_INSERT_TAIL(head, elm, field) { \
145 (elm)->field.tqe_next = NULL; \
146 (elm)->field.tqe_prev = (head)->tqh_last; \
147 *(head)->tqh_last = (elm); \
148 (head)->tqh_last = &(elm)->field.tqe_next; \
149}
150
151#define TAILQ_INSERT_AFTER(head, listelm, elm, field) { \
152 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
153 (elm)->field.tqe_next->field.tqe_prev = \
154 &(elm)->field.tqe_next; \
155 else \
156 (head)->tqh_last = &(elm)->field.tqe_next; \
157 (listelm)->field.tqe_next = (elm); \
158 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
159}
160
161#define TAILQ_REMOVE(head, elm, field) { \
162 if (((elm)->field.tqe_next) != NULL) \
163 (elm)->field.tqe_next->field.tqe_prev = \
164 (elm)->field.tqe_prev; \
165 else \
166 (head)->tqh_last = (elm)->field.tqe_prev; \
167 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
168}
169
170/*
171 * Circular queue definitions.
172 */
173#define CIRCLEQ_HEAD(name, type) \
174struct name { \
175 struct type *cqh_first; /* first element */ \
176 struct type *cqh_last; /* last element */ \
177}
178
179#define CIRCLEQ_ENTRY(type) \
180struct { \
181 struct type *cqe_next; /* next element */ \
182 struct type *cqe_prev; /* previous element */ \
183}
184
185/*
186 * Circular queue functions.
187 */
188#define CIRCLEQ_INIT(head) { \
189 (head)->cqh_first = (void *)(head); \
190 (head)->cqh_last = (void *)(head); \
191}
192
193#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) { \
194 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
195 (elm)->field.cqe_prev = (listelm); \
196 if ((listelm)->field.cqe_next == (void *)(head)) \
197 (head)->cqh_last = (elm); \
198 else \
199 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
200 (listelm)->field.cqe_next = (elm); \
201}
202
203#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) { \
204 (elm)->field.cqe_next = (listelm); \
205 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
206 if ((listelm)->field.cqe_prev == (void *)(head)) \
207 (head)->cqh_first = (elm); \
208 else \
209 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
210 (listelm)->field.cqe_prev = (elm); \
211}
212
213#define CIRCLEQ_INSERT_HEAD(head, elm, field) { \
214 (elm)->field.cqe_next = (head)->cqh_first; \
215 (elm)->field.cqe_prev = (void *)(head); \
216 if ((head)->cqh_last == (void *)(head)) \
217 (head)->cqh_last = (elm); \
218 else \
219 (head)->cqh_first->field.cqe_prev = (elm); \
220 (head)->cqh_first = (elm); \
221}
222
223#define CIRCLEQ_INSERT_TAIL(head, elm, field) { \
224 (elm)->field.cqe_next = (void *)(head); \
225 (elm)->field.cqe_prev = (head)->cqh_last; \
226 if ((head)->cqh_first == (void *)(head)) \
227 (head)->cqh_first = (elm); \
228 else \
229 (head)->cqh_last->field.cqe_next = (elm); \
230 (head)->cqh_last = (elm); \
231}
232
233#define CIRCLEQ_REMOVE(head, elm, field) { \
234 if ((elm)->field.cqe_next == (void *)(head)) \
235 (head)->cqh_last = (elm)->field.cqe_prev; \
236 else \
237 (elm)->field.cqe_next->field.cqe_prev = \
238 (elm)->field.cqe_prev; \
239 if ((elm)->field.cqe_prev == (void *)(head)) \
240 (head)->cqh_first = (elm)->field.cqe_next; \
241 else \
242 (elm)->field.cqe_prev->field.cqe_next = \
243 (elm)->field.cqe_next; \
244}
245#endif /* !_QUEUE_H_ */
246