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	8.5 (Berkeley) 8/20/94
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 before
47 * or after an existing element or at the head of the list. A list
48 * may only be 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 before or
54 * after an existing element, at the head of the list, or at the end of
55 * the 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_BEFORE(listelm, elm, field) {			\
98	(elm)->field.le_prev = (listelm)->field.le_prev;		\
99	(elm)->field.le_next = (listelm);				\
100	*(listelm)->field.le_prev = (elm);				\
101	(listelm)->field.le_prev = &(elm)->field.le_next;		\
102}
103
104#define LIST_INSERT_HEAD(head, elm, field) {				\
105	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
106		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
107	(head)->lh_first = (elm);					\
108	(elm)->field.le_prev = &(head)->lh_first;			\
109}
110
111#define LIST_REMOVE(elm, field) {					\
112	if ((elm)->field.le_next != NULL)				\
113		(elm)->field.le_next->field.le_prev = 			\
114		    (elm)->field.le_prev;				\
115	*(elm)->field.le_prev = (elm)->field.le_next;			\
116}
117
118/*
119 * Tail queue definitions.
120 */
121#define TAILQ_HEAD(name, type)						\
122struct name {								\
123	struct type *tqh_first;	/* first element */			\
124	struct type **tqh_last;	/* addr of last next element */		\
125}
126
127#define TAILQ_ENTRY(type)						\
128struct {								\
129	struct type *tqe_next;	/* next element */			\
130	struct type **tqe_prev;	/* address of previous next element */	\
131}
132
133/*
134 * Tail queue functions.
135 */
136#define	TAILQ_INIT(head) {						\
137	(head)->tqh_first = NULL;					\
138	(head)->tqh_last = &(head)->tqh_first;				\
139}
140
141#define TAILQ_INSERT_HEAD(head, elm, field) {				\
142	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
143		(head)->tqh_first->field.tqe_prev =			\
144		    &(elm)->field.tqe_next;				\
145	else								\
146		(head)->tqh_last = &(elm)->field.tqe_next;		\
147	(head)->tqh_first = (elm);					\
148	(elm)->field.tqe_prev = &(head)->tqh_first;			\
149}
150
151#define TAILQ_INSERT_TAIL(head, elm, field) {				\
152	(elm)->field.tqe_next = NULL;					\
153	(elm)->field.tqe_prev = (head)->tqh_last;			\
154	*(head)->tqh_last = (elm);					\
155	(head)->tqh_last = &(elm)->field.tqe_next;			\
156}
157
158#define TAILQ_INSERT_AFTER(head, listelm, elm, field) {			\
159	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
160		(elm)->field.tqe_next->field.tqe_prev = 		\
161		    &(elm)->field.tqe_next;				\
162	else								\
163		(head)->tqh_last = &(elm)->field.tqe_next;		\
164	(listelm)->field.tqe_next = (elm);				\
165	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
166}
167
168#define	TAILQ_INSERT_BEFORE(listelm, elm, field) {			\
169	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
170	(elm)->field.tqe_next = (listelm);				\
171	*(listelm)->field.tqe_prev = (elm);				\
172	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
173}
174
175#define TAILQ_REMOVE(head, elm, field) {				\
176	if (((elm)->field.tqe_next) != NULL)				\
177		(elm)->field.tqe_next->field.tqe_prev = 		\
178		    (elm)->field.tqe_prev;				\
179	else								\
180		(head)->tqh_last = (elm)->field.tqe_prev;		\
181	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
182}
183
184/*
185 * Circular queue definitions.
186 */
187#define CIRCLEQ_HEAD(name, type)					\
188struct name {								\
189	struct type *cqh_first;		/* first element */		\
190	struct type *cqh_last;		/* last element */		\
191}
192
193#define CIRCLEQ_ENTRY(type)						\
194struct {								\
195	struct type *cqe_next;		/* next element */		\
196	struct type *cqe_prev;		/* previous element */		\
197}
198
199/*
200 * Circular queue functions.
201 */
202#define	CIRCLEQ_INIT(head) {						\
203	(head)->cqh_first = (void *)(head);				\
204	(head)->cqh_last = (void *)(head);				\
205}
206
207#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {		\
208	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
209	(elm)->field.cqe_prev = (listelm);				\
210	if ((listelm)->field.cqe_next == (void *)(head))		\
211		(head)->cqh_last = (elm);				\
212	else								\
213		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
214	(listelm)->field.cqe_next = (elm);				\
215}
216
217#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {		\
218	(elm)->field.cqe_next = (listelm);				\
219	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
220	if ((listelm)->field.cqe_prev == (void *)(head))		\
221		(head)->cqh_first = (elm);				\
222	else								\
223		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
224	(listelm)->field.cqe_prev = (elm);				\
225}
226
227#define CIRCLEQ_INSERT_HEAD(head, elm, field) {				\
228	(elm)->field.cqe_next = (head)->cqh_first;			\
229	(elm)->field.cqe_prev = (void *)(head);				\
230	if ((head)->cqh_last == (void *)(head))				\
231		(head)->cqh_last = (elm);				\
232	else								\
233		(head)->cqh_first->field.cqe_prev = (elm);		\
234	(head)->cqh_first = (elm);					\
235}
236
237#define CIRCLEQ_INSERT_TAIL(head, elm, field) {				\
238	(elm)->field.cqe_next = (void *)(head);				\
239	(elm)->field.cqe_prev = (head)->cqh_last;			\
240	if ((head)->cqh_first == (void *)(head))			\
241		(head)->cqh_first = (elm);				\
242	else								\
243		(head)->cqh_last->field.cqe_next = (elm);		\
244	(head)->cqh_last = (elm);					\
245}
246
247#define	CIRCLEQ_REMOVE(head, elm, field) {				\
248	if ((elm)->field.cqe_next == (void *)(head))			\
249		(head)->cqh_last = (elm)->field.cqe_prev;		\
250	else								\
251		(elm)->field.cqe_next->field.cqe_prev =			\
252		    (elm)->field.cqe_prev;				\
253	if ((elm)->field.cqe_prev == (void *)(head))			\
254		(head)->cqh_first = (elm)->field.cqe_next;		\
255	else								\
256		(elm)->field.cqe_prev->field.cqe_next =			\
257		    (elm)->field.cqe_next;				\
258}
259#endif	/* !_SYS_QUEUE_H_ */
260