1/*	$OpenBSD: queue.h,v 1.36 2012/04/11 13:29:14 naddy 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/* OPENBSD ORIGINAL: sys/sys/queue.h */
36
37#ifndef	_FAKE_QUEUE_H_
38#define	_FAKE_QUEUE_H_
39
40/*
41 * Require for OS/X and other platforms that have old/broken/incomplete
42 * <sys/queue.h>.
43 */
44#undef SLIST_HEAD
45#undef SLIST_HEAD_INITIALIZER
46#undef SLIST_ENTRY
47#undef SLIST_FOREACH_PREVPTR
48#undef SLIST_FIRST
49#undef SLIST_END
50#undef SLIST_EMPTY
51#undef SLIST_NEXT
52#undef SLIST_FOREACH
53#undef SLIST_INIT
54#undef SLIST_INSERT_AFTER
55#undef SLIST_INSERT_HEAD
56#undef SLIST_REMOVE_HEAD
57#undef SLIST_REMOVE
58#undef SLIST_REMOVE_NEXT
59#undef LIST_HEAD
60#undef LIST_HEAD_INITIALIZER
61#undef LIST_ENTRY
62#undef LIST_FIRST
63#undef LIST_END
64#undef LIST_EMPTY
65#undef LIST_NEXT
66#undef LIST_FOREACH
67#undef LIST_INIT
68#undef LIST_INSERT_AFTER
69#undef LIST_INSERT_BEFORE
70#undef LIST_INSERT_HEAD
71#undef LIST_REMOVE
72#undef LIST_REPLACE
73#undef SIMPLEQ_HEAD
74#undef SIMPLEQ_HEAD_INITIALIZER
75#undef SIMPLEQ_ENTRY
76#undef SIMPLEQ_FIRST
77#undef SIMPLEQ_END
78#undef SIMPLEQ_EMPTY
79#undef SIMPLEQ_NEXT
80#undef SIMPLEQ_FOREACH
81#undef SIMPLEQ_INIT
82#undef SIMPLEQ_INSERT_HEAD
83#undef SIMPLEQ_INSERT_TAIL
84#undef SIMPLEQ_INSERT_AFTER
85#undef SIMPLEQ_REMOVE_HEAD
86#undef TAILQ_HEAD
87#undef TAILQ_HEAD_INITIALIZER
88#undef TAILQ_ENTRY
89#undef TAILQ_FIRST
90#undef TAILQ_END
91#undef TAILQ_NEXT
92#undef TAILQ_LAST
93#undef TAILQ_PREV
94#undef TAILQ_EMPTY
95#undef TAILQ_FOREACH
96#undef TAILQ_FOREACH_REVERSE
97#undef TAILQ_INIT
98#undef TAILQ_INSERT_HEAD
99#undef TAILQ_INSERT_TAIL
100#undef TAILQ_INSERT_AFTER
101#undef TAILQ_INSERT_BEFORE
102#undef TAILQ_REMOVE
103#undef TAILQ_REPLACE
104#undef CIRCLEQ_HEAD
105#undef CIRCLEQ_HEAD_INITIALIZER
106#undef CIRCLEQ_ENTRY
107#undef CIRCLEQ_FIRST
108#undef CIRCLEQ_LAST
109#undef CIRCLEQ_END
110#undef CIRCLEQ_NEXT
111#undef CIRCLEQ_PREV
112#undef CIRCLEQ_EMPTY
113#undef CIRCLEQ_FOREACH
114#undef CIRCLEQ_FOREACH_REVERSE
115#undef CIRCLEQ_INIT
116#undef CIRCLEQ_INSERT_AFTER
117#undef CIRCLEQ_INSERT_BEFORE
118#undef CIRCLEQ_INSERT_HEAD
119#undef CIRCLEQ_INSERT_TAIL
120#undef CIRCLEQ_REMOVE
121#undef CIRCLEQ_REPLACE
122
123/*
124 * This file defines five types of data structures: singly-linked lists,
125 * lists, simple queues, tail queues, and circular queues.
126 *
127 *
128 * A singly-linked list is headed by a single forward pointer. The elements
129 * are singly linked for minimum space and pointer manipulation overhead at
130 * the expense of O(n) removal for arbitrary elements. New elements can be
131 * added to the list after an existing element or at the head of the list.
132 * Elements being removed from the head of the list should use the explicit
133 * macro for this purpose for optimum efficiency. A singly-linked list may
134 * only be traversed in the forward direction.  Singly-linked lists are ideal
135 * for applications with large datasets and few or no removals or for
136 * implementing a LIFO queue.
137 *
138 * A list is headed by a single forward pointer (or an array of forward
139 * pointers for a hash table header). The elements are doubly linked
140 * so that an arbitrary element can be removed without a need to
141 * traverse the list. New elements can be added to the list before
142 * or after an existing element or at the head of the list. A list
143 * may only be traversed in the forward direction.
144 *
145 * A simple queue is headed by a pair of pointers, one the head of the
146 * list and the other to the tail of the list. The elements are singly
147 * linked to save space, so elements can only be removed from the
148 * head of the list. New elements can be added to the list before or after
149 * an existing element, at the head of the list, or at the end of the
150 * list. A simple queue may only be traversed in the forward direction.
151 *
152 * A tail queue is headed by a pair of pointers, one to the head of the
153 * list and the other to the tail of the list. The elements are doubly
154 * linked so that an arbitrary element can be removed without a need to
155 * traverse the list. New elements can be added to the list before or
156 * after an existing element, at the head of the list, or at the end of
157 * the list. A tail queue may be traversed in either direction.
158 *
159 * A circle queue is headed by a pair of pointers, one to the head of the
160 * list and the other to the tail of the list. The elements are doubly
161 * linked so that an arbitrary element can be removed without a need to
162 * traverse the list. New elements can be added to the list before or after
163 * an existing element, at the head of the list, or at the end of the list.
164 * A circle queue may be traversed in either direction, but has a more
165 * complex end of list detection.
166 *
167 * For details on the use of these macros, see the queue(3) manual page.
168 */
169
170#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
171#define _Q_INVALIDATE(a) (a) = ((void *)-1)
172#else
173#define _Q_INVALIDATE(a)
174#endif
175
176/*
177 * Singly-linked List definitions.
178 */
179#define SLIST_HEAD(name, type)						\
180struct name {								\
181	struct type *slh_first;	/* first element */			\
182}
183
184#define	SLIST_HEAD_INITIALIZER(head)					\
185	{ NULL }
186
187#define SLIST_ENTRY(type)						\
188struct {								\
189	struct type *sle_next;	/* next element */			\
190}
191
192/*
193 * Singly-linked List access methods.
194 */
195#define	SLIST_FIRST(head)	((head)->slh_first)
196#define	SLIST_END(head)		NULL
197#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
198#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
199
200#define	SLIST_FOREACH(var, head, field)					\
201	for((var) = SLIST_FIRST(head);					\
202	    (var) != SLIST_END(head);					\
203	    (var) = SLIST_NEXT(var, field))
204
205#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
206	for ((var) = SLIST_FIRST(head);				\
207	    (var) && ((tvar) = SLIST_NEXT(var, field), 1);		\
208	    (var) = (tvar))
209
210/*
211 * Singly-linked List functions.
212 */
213#define	SLIST_INIT(head) {						\
214	SLIST_FIRST(head) = SLIST_END(head);				\
215}
216
217#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
218	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
219	(slistelm)->field.sle_next = (elm);				\
220} while (0)
221
222#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
223	(elm)->field.sle_next = (head)->slh_first;			\
224	(head)->slh_first = (elm);					\
225} while (0)
226
227#define	SLIST_REMOVE_AFTER(elm, field) do {				\
228	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
229} while (0)
230
231#define	SLIST_REMOVE_HEAD(head, field) do {				\
232	(head)->slh_first = (head)->slh_first->field.sle_next;		\
233} while (0)
234
235#define SLIST_REMOVE(head, elm, type, field) do {			\
236	if ((head)->slh_first == (elm)) {				\
237		SLIST_REMOVE_HEAD((head), field);			\
238	} else {							\
239		struct type *curelm = (head)->slh_first;		\
240									\
241		while (curelm->field.sle_next != (elm))			\
242			curelm = curelm->field.sle_next;		\
243		curelm->field.sle_next =				\
244		    curelm->field.sle_next->field.sle_next;		\
245		_Q_INVALIDATE((elm)->field.sle_next);			\
246	}								\
247} while (0)
248
249/*
250 * List definitions.
251 */
252#define LIST_HEAD(name, type)						\
253struct name {								\
254	struct type *lh_first;	/* first element */			\
255}
256
257#define LIST_HEAD_INITIALIZER(head)					\
258	{ NULL }
259
260#define LIST_ENTRY(type)						\
261struct {								\
262	struct type *le_next;	/* next element */			\
263	struct type **le_prev;	/* address of previous next element */	\
264}
265
266/*
267 * List access methods
268 */
269#define	LIST_FIRST(head)		((head)->lh_first)
270#define	LIST_END(head)			NULL
271#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
272#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
273
274#define LIST_FOREACH(var, head, field)					\
275	for((var) = LIST_FIRST(head);					\
276	    (var)!= LIST_END(head);					\
277	    (var) = LIST_NEXT(var, field))
278
279#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
280	for ((var) = LIST_FIRST(head);				\
281	    (var) && ((tvar) = LIST_NEXT(var, field), 1);		\
282	    (var) = (tvar))
283
284/*
285 * List functions.
286 */
287#define	LIST_INIT(head) do {						\
288	LIST_FIRST(head) = LIST_END(head);				\
289} while (0)
290
291#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
292	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
293		(listelm)->field.le_next->field.le_prev =		\
294		    &(elm)->field.le_next;				\
295	(listelm)->field.le_next = (elm);				\
296	(elm)->field.le_prev = &(listelm)->field.le_next;		\
297} while (0)
298
299#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
300	(elm)->field.le_prev = (listelm)->field.le_prev;		\
301	(elm)->field.le_next = (listelm);				\
302	*(listelm)->field.le_prev = (elm);				\
303	(listelm)->field.le_prev = &(elm)->field.le_next;		\
304} while (0)
305
306#define LIST_INSERT_HEAD(head, elm, field) do {				\
307	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
308		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
309	(head)->lh_first = (elm);					\
310	(elm)->field.le_prev = &(head)->lh_first;			\
311} while (0)
312
313#define LIST_REMOVE(elm, field) do {					\
314	if ((elm)->field.le_next != NULL)				\
315		(elm)->field.le_next->field.le_prev =			\
316		    (elm)->field.le_prev;				\
317	*(elm)->field.le_prev = (elm)->field.le_next;			\
318	_Q_INVALIDATE((elm)->field.le_prev);				\
319	_Q_INVALIDATE((elm)->field.le_next);				\
320} while (0)
321
322#define LIST_REPLACE(elm, elm2, field) do {				\
323	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
324		(elm2)->field.le_next->field.le_prev =			\
325		    &(elm2)->field.le_next;				\
326	(elm2)->field.le_prev = (elm)->field.le_prev;			\
327	*(elm2)->field.le_prev = (elm2);				\
328	_Q_INVALIDATE((elm)->field.le_prev);				\
329	_Q_INVALIDATE((elm)->field.le_next);				\
330} while (0)
331
332/*
333 * Simple queue definitions.
334 */
335#define SIMPLEQ_HEAD(name, type)					\
336struct name {								\
337	struct type *sqh_first;	/* first element */			\
338	struct type **sqh_last;	/* addr of last next element */		\
339}
340
341#define SIMPLEQ_HEAD_INITIALIZER(head)					\
342	{ NULL, &(head).sqh_first }
343
344#define SIMPLEQ_ENTRY(type)						\
345struct {								\
346	struct type *sqe_next;	/* next element */			\
347}
348
349/*
350 * Simple queue access methods.
351 */
352#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
353#define	SIMPLEQ_END(head)	    NULL
354#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
355#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
356
357#define SIMPLEQ_FOREACH(var, head, field)				\
358	for((var) = SIMPLEQ_FIRST(head);				\
359	    (var) != SIMPLEQ_END(head);					\
360	    (var) = SIMPLEQ_NEXT(var, field))
361
362#define	SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
363	for ((var) = SIMPLEQ_FIRST(head);				\
364	    (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1);		\
365	    (var) = (tvar))
366
367/*
368 * Simple queue functions.
369 */
370#define	SIMPLEQ_INIT(head) do {						\
371	(head)->sqh_first = NULL;					\
372	(head)->sqh_last = &(head)->sqh_first;				\
373} while (0)
374
375#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
376	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
377		(head)->sqh_last = &(elm)->field.sqe_next;		\
378	(head)->sqh_first = (elm);					\
379} while (0)
380
381#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
382	(elm)->field.sqe_next = NULL;					\
383	*(head)->sqh_last = (elm);					\
384	(head)->sqh_last = &(elm)->field.sqe_next;			\
385} while (0)
386
387#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
388	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
389		(head)->sqh_last = &(elm)->field.sqe_next;		\
390	(listelm)->field.sqe_next = (elm);				\
391} while (0)
392
393#define SIMPLEQ_REMOVE_HEAD(head, field) do {			\
394	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
395		(head)->sqh_last = &(head)->sqh_first;			\
396} while (0)
397
398#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
399	if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
400	    == NULL)							\
401		(head)->sqh_last = &(elm)->field.sqe_next;		\
402} while (0)
403
404/*
405 * Tail queue definitions.
406 */
407#define TAILQ_HEAD(name, type)						\
408struct name {								\
409	struct type *tqh_first;	/* first element */			\
410	struct type **tqh_last;	/* addr of last next element */		\
411}
412
413#define TAILQ_HEAD_INITIALIZER(head)					\
414	{ NULL, &(head).tqh_first }
415
416#define TAILQ_ENTRY(type)						\
417struct {								\
418	struct type *tqe_next;	/* next element */			\
419	struct type **tqe_prev;	/* address of previous next element */	\
420}
421
422/*
423 * tail queue access methods
424 */
425#define	TAILQ_FIRST(head)		((head)->tqh_first)
426#define	TAILQ_END(head)			NULL
427#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
428#define TAILQ_LAST(head, headname)					\
429	(*(((struct headname *)((head)->tqh_last))->tqh_last))
430/* XXX */
431#define TAILQ_PREV(elm, headname, field)				\
432	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
433#define	TAILQ_EMPTY(head)						\
434	(TAILQ_FIRST(head) == TAILQ_END(head))
435
436#define TAILQ_FOREACH(var, head, field)					\
437	for((var) = TAILQ_FIRST(head);					\
438	    (var) != TAILQ_END(head);					\
439	    (var) = TAILQ_NEXT(var, field))
440
441#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
442	for ((var) = TAILQ_FIRST(head);					\
443	    (var) != TAILQ_END(head) &&					\
444	    ((tvar) = TAILQ_NEXT(var, field), 1);			\
445	    (var) = (tvar))
446
447
448#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
449	for((var) = TAILQ_LAST(head, headname);				\
450	    (var) != TAILQ_END(head);					\
451	    (var) = TAILQ_PREV(var, headname, field))
452
453#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
454	for ((var) = TAILQ_LAST(head, headname);			\
455	    (var) != TAILQ_END(head) &&					\
456	    ((tvar) = TAILQ_PREV(var, headname, field), 1);		\
457	    (var) = (tvar))
458
459/*
460 * Tail queue functions.
461 */
462#define	TAILQ_INIT(head) do {						\
463	(head)->tqh_first = NULL;					\
464	(head)->tqh_last = &(head)->tqh_first;				\
465} while (0)
466
467#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
468	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
469		(head)->tqh_first->field.tqe_prev =			\
470		    &(elm)->field.tqe_next;				\
471	else								\
472		(head)->tqh_last = &(elm)->field.tqe_next;		\
473	(head)->tqh_first = (elm);					\
474	(elm)->field.tqe_prev = &(head)->tqh_first;			\
475} while (0)
476
477#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
478	(elm)->field.tqe_next = NULL;					\
479	(elm)->field.tqe_prev = (head)->tqh_last;			\
480	*(head)->tqh_last = (elm);					\
481	(head)->tqh_last = &(elm)->field.tqe_next;			\
482} while (0)
483
484#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
485	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
486		(elm)->field.tqe_next->field.tqe_prev =			\
487		    &(elm)->field.tqe_next;				\
488	else								\
489		(head)->tqh_last = &(elm)->field.tqe_next;		\
490	(listelm)->field.tqe_next = (elm);				\
491	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
492} while (0)
493
494#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
495	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
496	(elm)->field.tqe_next = (listelm);				\
497	*(listelm)->field.tqe_prev = (elm);				\
498	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
499} while (0)
500
501#define TAILQ_REMOVE(head, elm, field) do {				\
502	if (((elm)->field.tqe_next) != NULL)				\
503		(elm)->field.tqe_next->field.tqe_prev =			\
504		    (elm)->field.tqe_prev;				\
505	else								\
506		(head)->tqh_last = (elm)->field.tqe_prev;		\
507	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
508	_Q_INVALIDATE((elm)->field.tqe_prev);				\
509	_Q_INVALIDATE((elm)->field.tqe_next);				\
510} while (0)
511
512#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
513	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
514		(elm2)->field.tqe_next->field.tqe_prev =		\
515		    &(elm2)->field.tqe_next;				\
516	else								\
517		(head)->tqh_last = &(elm2)->field.tqe_next;		\
518	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
519	*(elm2)->field.tqe_prev = (elm2);				\
520	_Q_INVALIDATE((elm)->field.tqe_prev);				\
521	_Q_INVALIDATE((elm)->field.tqe_next);				\
522} while (0)
523
524/*
525 * Circular queue definitions.
526 */
527#define CIRCLEQ_HEAD(name, type)					\
528struct name {								\
529	struct type *cqh_first;		/* first element */		\
530	struct type *cqh_last;		/* last element */		\
531}
532
533#define CIRCLEQ_HEAD_INITIALIZER(head)					\
534	{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
535
536#define CIRCLEQ_ENTRY(type)						\
537struct {								\
538	struct type *cqe_next;		/* next element */		\
539	struct type *cqe_prev;		/* previous element */		\
540}
541
542/*
543 * Circular queue access methods
544 */
545#define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
546#define	CIRCLEQ_LAST(head)		((head)->cqh_last)
547#define	CIRCLEQ_END(head)		((void *)(head))
548#define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
549#define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
550#define	CIRCLEQ_EMPTY(head)						\
551	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
552
553#define CIRCLEQ_FOREACH(var, head, field)				\
554	for((var) = CIRCLEQ_FIRST(head);				\
555	    (var) != CIRCLEQ_END(head);					\
556	    (var) = CIRCLEQ_NEXT(var, field))
557
558#define	CIRCLEQ_FOREACH_SAFE(var, head, field, tvar)			\
559	for ((var) = CIRCLEQ_FIRST(head);				\
560	    (var) != CIRCLEQ_END(head) &&				\
561	    ((tvar) = CIRCLEQ_NEXT(var, field), 1);			\
562	    (var) = (tvar))
563
564#define CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
565	for((var) = CIRCLEQ_LAST(head);					\
566	    (var) != CIRCLEQ_END(head);					\
567	    (var) = CIRCLEQ_PREV(var, field))
568
569#define	CIRCLEQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
570	for ((var) = CIRCLEQ_LAST(head, headname);			\
571	    (var) != CIRCLEQ_END(head) && 				\
572	    ((tvar) = CIRCLEQ_PREV(var, headname, field), 1);		\
573	    (var) = (tvar))
574
575/*
576 * Circular queue functions.
577 */
578#define	CIRCLEQ_INIT(head) do {						\
579	(head)->cqh_first = CIRCLEQ_END(head);				\
580	(head)->cqh_last = CIRCLEQ_END(head);				\
581} while (0)
582
583#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
584	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
585	(elm)->field.cqe_prev = (listelm);				\
586	if ((listelm)->field.cqe_next == CIRCLEQ_END(head))		\
587		(head)->cqh_last = (elm);				\
588	else								\
589		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
590	(listelm)->field.cqe_next = (elm);				\
591} while (0)
592
593#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
594	(elm)->field.cqe_next = (listelm);				\
595	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
596	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))		\
597		(head)->cqh_first = (elm);				\
598	else								\
599		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
600	(listelm)->field.cqe_prev = (elm);				\
601} while (0)
602
603#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
604	(elm)->field.cqe_next = (head)->cqh_first;			\
605	(elm)->field.cqe_prev = CIRCLEQ_END(head);			\
606	if ((head)->cqh_last == CIRCLEQ_END(head))			\
607		(head)->cqh_last = (elm);				\
608	else								\
609		(head)->cqh_first->field.cqe_prev = (elm);		\
610	(head)->cqh_first = (elm);					\
611} while (0)
612
613#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
614	(elm)->field.cqe_next = CIRCLEQ_END(head);			\
615	(elm)->field.cqe_prev = (head)->cqh_last;			\
616	if ((head)->cqh_first == CIRCLEQ_END(head))			\
617		(head)->cqh_first = (elm);				\
618	else								\
619		(head)->cqh_last->field.cqe_next = (elm);		\
620	(head)->cqh_last = (elm);					\
621} while (0)
622
623#define	CIRCLEQ_REMOVE(head, elm, field) do {				\
624	if ((elm)->field.cqe_next == CIRCLEQ_END(head))			\
625		(head)->cqh_last = (elm)->field.cqe_prev;		\
626	else								\
627		(elm)->field.cqe_next->field.cqe_prev =			\
628		    (elm)->field.cqe_prev;				\
629	if ((elm)->field.cqe_prev == CIRCLEQ_END(head))			\
630		(head)->cqh_first = (elm)->field.cqe_next;		\
631	else								\
632		(elm)->field.cqe_prev->field.cqe_next =			\
633		    (elm)->field.cqe_next;				\
634	_Q_INVALIDATE((elm)->field.cqe_prev);				\
635	_Q_INVALIDATE((elm)->field.cqe_next);				\
636} while (0)
637
638#define CIRCLEQ_REPLACE(head, elm, elm2, field) do {			\
639	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==		\
640	    CIRCLEQ_END(head))						\
641		(head).cqh_last = (elm2);				\
642	else								\
643		(elm2)->field.cqe_next->field.cqe_prev = (elm2);	\
644	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==		\
645	    CIRCLEQ_END(head))						\
646		(head).cqh_first = (elm2);				\
647	else								\
648		(elm2)->field.cqe_prev->field.cqe_next = (elm2);	\
649	_Q_INVALIDATE((elm)->field.cqe_prev);				\
650	_Q_INVALIDATE((elm)->field.cqe_next);				\
651} while (0)
652
653#endif	/* !_FAKE_QUEUE_H_ */
654