queue.h revision 1542
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 */
35
36#ifndef	_SYS_QUEUE_H_
37#define	_SYS_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	/* !_SYS_QUEUE_H_ */
246