queue.h revision 1817 
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	8.4 (Berkeley) 1/4/94
34 * $Id$
35 */
36
37#ifndef	_SYS_QUEUE_H_
38#define	_SYS_QUEUE_H_
39
40/*
41 * This file defines three types of data structures: lists, tail queues,
42 * and circular queues.
43 *
44 * A list is headed by a single forward pointer (or an array of forward
45 * pointers for a hash table header). The elements are doubly linked
46 * so that an arbitrary element can be removed without a need to
47 * traverse the list. New elements can be added to the list after
48 * an existing element or at the head of the list. A list may only be
49 * traversed in the forward direction.
50 *
51 * A tail queue is headed by a pair of pointers, one to the head of the
52 * list and the other to the tail of the list. The elements are doubly
53 * linked so that an arbitrary element can be removed without a need to
54 * traverse the list. New elements can be added to the list after
55 * an existing element, at the head of the list, or at the end of the
56 * list. A tail queue may only be traversed in the forward direction.
57 *
58 * A circle queue is headed by a pair of pointers, one to the head of the
59 * list and the other to the tail of the list. The elements are doubly
60 * linked so that an arbitrary element can be removed without a need to
61 * traverse the list. New elements can be added to the list before or after
62 * an existing element, at the head of the list, or at the end of the list.
63 * A circle queue may be traversed in either direction, but has a more
64 * complex end of list detection.
65 *
66 * For details on the use of these macros, see the queue(3) manual page.
67 */
68
69/*
70 * List definitions.
71 */
72#define LIST_HEAD(name, type)						\
73struct name {								\
74	struct type *lh_first;	/* first element */			\
75}
76
77#define LIST_ENTRY(type)						\
78struct {								\
79	struct type *le_next;	/* next element */			\
80	struct type **le_prev;	/* address of previous next element */	\
81}
82
83/*
84 * List functions.
85 */
86#define	LIST_INIT(head) {						\
87	(head)->lh_first = NULL;					\
88}
89
90#define LIST_INSERT_AFTER(listelm, elm, field) {			\
91	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
92		(listelm)->field.le_next->field.le_prev =		\
93		    &(elm)->field.le_next;				\
94	(listelm)->field.le_next = (elm);				\
95	(elm)->field.le_prev = &(listelm)->field.le_next;		\
96}
97
98#define LIST_INSERT_HEAD(head, elm, field) {				\
99	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
100		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
101	(head)->lh_first = (elm);					\
102	(elm)->field.le_prev = &(head)->lh_first;			\
103}
104
105#define LIST_REMOVE(elm, field) {					\
106	if ((elm)->field.le_next != NULL)				\
107		(elm)->field.le_next->field.le_prev = 			\
108		    (elm)->field.le_prev;				\
109	*(elm)->field.le_prev = (elm)->field.le_next;			\
110}
111
112/*
113 * Tail queue definitions.
114 */
115#define TAILQ_HEAD(name, type)						\
116struct name {								\
117	struct type *tqh_first;	/* first element */			\
118	struct type **tqh_last;	/* addr of last next element */		\
119}
120
121#define TAILQ_ENTRY(type)						\
122struct {								\
123	struct type *tqe_next;	/* next element */			\
124	struct type **tqe_prev;	/* address of previous next element */	\
125}
126
127/*
128 * Tail queue functions.
129 */
130#define	TAILQ_INIT(head) {						\
131	(head)->tqh_first = NULL;					\
132	(head)->tqh_last = &(head)->tqh_first;				\
133}
134
135#define TAILQ_INSERT_HEAD(head, elm, field) {				\
136	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
137		(elm)->field.tqe_next->field.tqe_prev =			\
138		    &(elm)->field.tqe_next;				\
139	else								\
140		(head)->tqh_last = &(elm)->field.tqe_next;		\
141	(head)->tqh_first = (elm);					\
142	(elm)->field.tqe_prev = &(head)->tqh_first;			\
143}
144
145#define TAILQ_INSERT_TAIL(head, elm, field) {				\
146	(elm)->field.tqe_next = NULL;					\
147	(elm)->field.tqe_prev = (head)->tqh_last;			\
148	*(head)->tqh_last = (elm);					\
149	(head)->tqh_last = &(elm)->field.tqe_next;			\
150}
151
152#define TAILQ_INSERT_AFTER(head, listelm, elm, field) {			\
153	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
154		(elm)->field.tqe_next->field.tqe_prev = 		\
155		    &(elm)->field.tqe_next;				\
156	else								\
157		(head)->tqh_last = &(elm)->field.tqe_next;		\
158	(listelm)->field.tqe_next = (elm);				\
159	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
160}
161
162#define TAILQ_REMOVE(head, elm, field) {				\
163	if (((elm)->field.tqe_next) != NULL)				\
164		(elm)->field.tqe_next->field.tqe_prev = 		\
165		    (elm)->field.tqe_prev;				\
166	else								\
167		(head)->tqh_last = (elm)->field.tqe_prev;		\
168	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
169}
170
171/*
172 * Circular queue definitions.
173 */
174#define CIRCLEQ_HEAD(name, type)					\
175struct name {								\
176	struct type *cqh_first;		/* first element */		\
177	struct type *cqh_last;		/* last element */		\
178}
179
180#define CIRCLEQ_ENTRY(type)						\
181struct {								\
182	struct type *cqe_next;		/* next element */		\
183	struct type *cqe_prev;		/* previous element */		\
184}
185
186/*
187 * Circular queue functions.
188 */
189#define	CIRCLEQ_INIT(head) {						\
190	(head)->cqh_first = (void *)(head);				\
191	(head)->cqh_last = (void *)(head);				\
192}
193
194#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {		\
195	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
196	(elm)->field.cqe_prev = (listelm);				\
197	if ((listelm)->field.cqe_next == (void *)(head))		\
198		(head)->cqh_last = (elm);				\
199	else								\
200		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
201	(listelm)->field.cqe_next = (elm);				\
202}
203
204#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {		\
205	(elm)->field.cqe_next = (listelm);				\
206	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
207	if ((listelm)->field.cqe_prev == (void *)(head))		\
208		(head)->cqh_first = (elm);				\
209	else								\
210		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
211	(listelm)->field.cqe_prev = (elm);				\
212}
213
214#define CIRCLEQ_INSERT_HEAD(head, elm, field) {				\
215	(elm)->field.cqe_next = (head)->cqh_first;			\
216	(elm)->field.cqe_prev = (void *)(head);				\
217	if ((head)->cqh_last == (void *)(head))				\
218		(head)->cqh_last = (elm);				\
219	else								\
220		(head)->cqh_first->field.cqe_prev = (elm);		\
221	(head)->cqh_first = (elm);					\
222}
223
224#define CIRCLEQ_INSERT_TAIL(head, elm, field) {				\
225	(elm)->field.cqe_next = (void *)(head);				\
226	(elm)->field.cqe_prev = (head)->cqh_last;			\
227	if ((head)->cqh_first == (void *)(head))			\
228		(head)->cqh_first = (elm);				\
229	else								\
230		(head)->cqh_last->field.cqe_next = (elm);		\
231	(head)->cqh_last = (elm);					\
232}
233
234#define	CIRCLEQ_REMOVE(head, elm, field) {				\
235	if ((elm)->field.cqe_next == (void *)(head))			\
236		(head)->cqh_last = (elm)->field.cqe_prev;		\
237	else								\
238		(elm)->field.cqe_next->field.cqe_prev =			\
239		    (elm)->field.cqe_prev;				\
240	if ((elm)->field.cqe_prev == (void *)(head))			\
241		(head)->cqh_first = (elm)->field.cqe_next;		\
242	else								\
243		(elm)->field.cqe_prev->field.cqe_next =			\
244		    (elm)->field.cqe_next;				\
245}
246#endif	/* !_SYS_QUEUE_H_ */
247