queue.h
1/* $OpenBSD: queue.h,v 1.38 2013/07/03 15:05:21 fgsch 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#ifndef _SYS_QUEUE_H_
36#define _SYS_QUEUE_H_
37
38/*
39 * This file defines five types of data structures: singly-linked lists,
40 * lists, simple queues, tail queues, and circular queues.
41 *
42 *
43 * A singly-linked list is headed by a single forward pointer. The elements
44 * are singly linked for minimum space and pointer manipulation overhead at
45 * the expense of O(n) removal for arbitrary elements. New elements can be
46 * added to the list after an existing element or at the head of the list.
47 * Elements being removed from the head of the list should use the explicit
48 * macro for this purpose for optimum efficiency. A singly-linked list may
49 * only be traversed in the forward direction. Singly-linked lists are ideal
50 * for applications with large datasets and few or no removals or for
51 * implementing a LIFO queue.
52 *
53 * A list is headed by a single forward pointer (or an array of forward
54 * pointers for a hash table header). The elements are doubly linked
55 * so that an arbitrary element can be removed without a need to
56 * traverse the list. New elements can be added to the list before
57 * or after an existing element or at the head of the list. A list
58 * may only be traversed in the forward direction.
59 *
60 * A simple queue is headed by a pair of pointers, one the head of the
61 * list and the other to the tail of the list. The elements are singly
62 * linked to save space, so elements can only be removed from the
63 * head of the list. New elements can be added to the list before or after
64 * an existing element, at the head of the list, or at the end of the
65 * list. A simple queue may only be traversed in the forward direction.
66 *
67 * A tail queue is headed by a pair of pointers, one to the head of the
68 * list and the other to the tail of the list. The elements are doubly
69 * linked so that an arbitrary element can be removed without a need to
70 * traverse the list. New elements can be added to the list before or
71 * after an existing element, at the head of the list, or at the end of
72 * the list. A tail queue may be traversed in either direction.
73 *
74 * A circle queue is headed by a pair of pointers, one to the head of the
75 * list and the other to the tail of the list. The elements are doubly
76 * linked so that an arbitrary element can be removed without a need to
77 * traverse the list. New elements can be added to the list before or after
78 * an existing element, at the head of the list, or at the end of the list.
79 * A circle queue may be traversed in either direction, but has a more
80 * complex end of list detection.
81 *
82 * For details on the use of these macros, see the queue(3) manual page.
83 */
84
85#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
86#define _Q_INVALIDATE(a) (a) = ((void *)-1)
87#else
88#define _Q_INVALIDATE(a)
89#endif
90
91/*
92 * Singly-linked List definitions.
93 */
94#define SLIST_HEAD(name, type) \
95struct name { \
96 struct type *slh_first; /* first element */ \
97}
98
99#define SLIST_HEAD_INITIALIZER(head) \
100 { NULL }
101
102#define SLIST_ENTRY(type) \
103struct { \
104 struct type *sle_next; /* next element */ \
105}
106
107/*
108 * Singly-linked List access methods.
109 */
110#define SLIST_FIRST(head) ((head)->slh_first)
111#define SLIST_END(head) NULL
112#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
113#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
114
115#define SLIST_FOREACH(var, head, field) \
116 for((var) = SLIST_FIRST(head); \
117 (var) != SLIST_END(head); \
118 (var) = SLIST_NEXT(var, field))
119
120#define SLIST_FOREACH_SAFE(var, head, field, tvar) \
121 for ((var) = SLIST_FIRST(head); \
122 (var) && ((tvar) = SLIST_NEXT(var, field), 1); \
123 (var) = (tvar))
124
125/*
126 * Singly-linked List functions.
127 */
128#define SLIST_INIT(head) { \
129 SLIST_FIRST(head) = SLIST_END(head); \
130}
131
132#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
133 (elm)->field.sle_next = (slistelm)->field.sle_next; \
134 (slistelm)->field.sle_next = (elm); \
135} while (0)
136
137#define SLIST_INSERT_HEAD(head, elm, field) do { \
138 (elm)->field.sle_next = (head)->slh_first; \
139 (head)->slh_first = (elm); \
140} while (0)
141
142#define SLIST_REMOVE_AFTER(elm, field) do { \
143 (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
144} while (0)
145
146#define SLIST_REMOVE_HEAD(head, field) do { \
147 (head)->slh_first = (head)->slh_first->field.sle_next; \
148} while (0)
149
150#define SLIST_REMOVE(head, elm, type, field) do { \
151 if ((head)->slh_first == (elm)) { \
152 SLIST_REMOVE_HEAD((head), field); \
153 } else { \
154 struct type *curelm = (head)->slh_first; \
155 \
156 while (curelm->field.sle_next != (elm)) \
157 curelm = curelm->field.sle_next; \
158 curelm->field.sle_next = \
159 curelm->field.sle_next->field.sle_next; \
160 _Q_INVALIDATE((elm)->field.sle_next); \
161 } \
162} while (0)
163
164/*
165 * List definitions.
166 */
167#define LIST_HEAD(name, type) \
168struct name { \
169 struct type *lh_first; /* first element */ \
170}
171
172#define LIST_HEAD_INITIALIZER(head) \
173 { NULL }
174
175#define LIST_ENTRY(type) \
176struct { \
177 struct type *le_next; /* next element */ \
178 struct type **le_prev; /* address of previous next element */ \
179}
180
181/*
182 * List access methods
183 */
184#define LIST_FIRST(head) ((head)->lh_first)
185#define LIST_END(head) NULL
186#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
187#define LIST_NEXT(elm, field) ((elm)->field.le_next)
188
189#define LIST_FOREACH(var, head, field) \
190 for((var) = LIST_FIRST(head); \
191 (var)!= LIST_END(head); \
192 (var) = LIST_NEXT(var, field))
193
194#define LIST_FOREACH_SAFE(var, head, field, tvar) \
195 for ((var) = LIST_FIRST(head); \
196 (var) && ((tvar) = LIST_NEXT(var, field), 1); \
197 (var) = (tvar))
198
199/*
200 * List functions.
201 */
202#define LIST_INIT(head) do { \
203 LIST_FIRST(head) = LIST_END(head); \
204} while (0)
205
206#define LIST_INSERT_AFTER(listelm, elm, field) do { \
207 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
208 (listelm)->field.le_next->field.le_prev = \
209 &(elm)->field.le_next; \
210 (listelm)->field.le_next = (elm); \
211 (elm)->field.le_prev = &(listelm)->field.le_next; \
212} while (0)
213
214#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
215 (elm)->field.le_prev = (listelm)->field.le_prev; \
216 (elm)->field.le_next = (listelm); \
217 *(listelm)->field.le_prev = (elm); \
218 (listelm)->field.le_prev = &(elm)->field.le_next; \
219} while (0)
220
221#define LIST_INSERT_HEAD(head, elm, field) do { \
222 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
223 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
224 (head)->lh_first = (elm); \
225 (elm)->field.le_prev = &(head)->lh_first; \
226} while (0)
227
228#define LIST_REMOVE(elm, field) do { \
229 if ((elm)->field.le_next != NULL) \
230 (elm)->field.le_next->field.le_prev = \
231 (elm)->field.le_prev; \
232 *(elm)->field.le_prev = (elm)->field.le_next; \
233 _Q_INVALIDATE((elm)->field.le_prev); \
234 _Q_INVALIDATE((elm)->field.le_next); \
235} while (0)
236
237#define LIST_REPLACE(elm, elm2, field) do { \
238 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
239 (elm2)->field.le_next->field.le_prev = \
240 &(elm2)->field.le_next; \
241 (elm2)->field.le_prev = (elm)->field.le_prev; \
242 *(elm2)->field.le_prev = (elm2); \
243 _Q_INVALIDATE((elm)->field.le_prev); \
244 _Q_INVALIDATE((elm)->field.le_next); \
245} while (0)
246
247/*
248 * Simple queue definitions.
249 */
250#define SIMPLEQ_HEAD(name, type) \
251struct name { \
252 struct type *sqh_first; /* first element */ \
253 struct type **sqh_last; /* addr of last next element */ \
254}
255
256#define SIMPLEQ_HEAD_INITIALIZER(head) \
257 { NULL, &(head).sqh_first }
258
259#define SIMPLEQ_ENTRY(type) \
260struct { \
261 struct type *sqe_next; /* next element */ \
262}
263
264/*
265 * Simple queue access methods.
266 */
267#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
268#define SIMPLEQ_END(head) NULL
269#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
270#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
271
272#define SIMPLEQ_FOREACH(var, head, field) \
273 for((var) = SIMPLEQ_FIRST(head); \
274 (var) != SIMPLEQ_END(head); \
275 (var) = SIMPLEQ_NEXT(var, field))
276
277#define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
278 for ((var) = SIMPLEQ_FIRST(head); \
279 (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1); \
280 (var) = (tvar))
281
282/*
283 * Simple queue functions.
284 */
285#define SIMPLEQ_INIT(head) do { \
286 (head)->sqh_first = NULL; \
287 (head)->sqh_last = &(head)->sqh_first; \
288} while (0)
289
290#define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
291 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
292 (head)->sqh_last = &(elm)->field.sqe_next; \
293 (head)->sqh_first = (elm); \
294} while (0)
295
296#define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
297 (elm)->field.sqe_next = NULL; \
298 *(head)->sqh_last = (elm); \
299 (head)->sqh_last = &(elm)->field.sqe_next; \
300} while (0)
301
302#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
303 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
304 (head)->sqh_last = &(elm)->field.sqe_next; \
305 (listelm)->field.sqe_next = (elm); \
306} while (0)
307
308#define SIMPLEQ_REMOVE_HEAD(head, field) do { \
309 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
310 (head)->sqh_last = &(head)->sqh_first; \
311} while (0)
312
313#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do { \
314 if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
315 == NULL) \
316 (head)->sqh_last = &(elm)->field.sqe_next; \
317} while (0)
318
319/*
320 * XOR Simple queue definitions.
321 */
322#define XSIMPLEQ_HEAD(name, type) \
323struct name { \
324 struct type *sqx_first; /* first element */ \
325 struct type **sqx_last; /* addr of last next element */ \
326 unsigned long sqx_cookie; \
327}
328
329#define XSIMPLEQ_ENTRY(type) \
330struct { \
331 struct type *sqx_next; /* next element */ \
332}
333
334/*
335 * XOR Simple queue access methods.
336 */
337#define XSIMPLEQ_XOR(head, ptr) ((__typeof(ptr))((head)->sqx_cookie ^ \
338 (unsigned long)(ptr)))
339#define XSIMPLEQ_FIRST(head) XSIMPLEQ_XOR(head, ((head)->sqx_first))
340#define XSIMPLEQ_END(head) NULL
341#define XSIMPLEQ_EMPTY(head) (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
342#define XSIMPLEQ_NEXT(head, elm, field) XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
343
344
345#define XSIMPLEQ_FOREACH(var, head, field) \
346 for ((var) = XSIMPLEQ_FIRST(head); \
347 (var) != XSIMPLEQ_END(head); \
348 (var) = XSIMPLEQ_NEXT(head, var, field))
349
350#define XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
351 for ((var) = XSIMPLEQ_FIRST(head); \
352 (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1); \
353 (var) = (tvar))
354
355/*
356 * XOR Simple queue functions.
357 */
358#define XSIMPLEQ_INIT(head) do { \
359 arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); \
360 (head)->sqx_first = XSIMPLEQ_XOR(head, NULL); \
361 (head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
362} while (0)
363
364#define XSIMPLEQ_INSERT_HEAD(head, elm, field) do { \
365 if (((elm)->field.sqx_next = (head)->sqx_first) == \
366 XSIMPLEQ_XOR(head, NULL)) \
367 (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
368 (head)->sqx_first = XSIMPLEQ_XOR(head, (elm)); \
369} while (0)
370
371#define XSIMPLEQ_INSERT_TAIL(head, elm, field) do { \
372 (elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL); \
373 *(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); \
374 (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
375} while (0)
376
377#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
378 if (((elm)->field.sqx_next = (listelm)->field.sqx_next) == \
379 XSIMPLEQ_XOR(head, NULL)) \
380 (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
381 (listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm)); \
382} while (0)
383
384#define XSIMPLEQ_REMOVE_HEAD(head, field) do { \
385 if (((head)->sqx_first = XSIMPLEQ_XOR(head, \
386 (head)->sqx_first)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) \
387 (head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
388} while (0)
389
390#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) do { \
391 if (((elm)->field.sqx_next = XSIMPLEQ_XOR(head, \
392 (elm)->field.sqx_next)->field.sqx_next) \
393 == XSIMPLEQ_XOR(head, NULL)) \
394 (head)->sqx_last = \
395 XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
396} while (0)
397
398
399/*
400 * Tail queue definitions.
401 */
402#define TAILQ_HEAD(name, type) \
403struct name { \
404 struct type *tqh_first; /* first element */ \
405 struct type **tqh_last; /* addr of last next element */ \
406}
407
408#define TAILQ_HEAD_INITIALIZER(head) \
409 { NULL, &(head).tqh_first }
410
411#define TAILQ_ENTRY(type) \
412struct { \
413 struct type *tqe_next; /* next element */ \
414 struct type **tqe_prev; /* address of previous next element */ \
415}
416
417/*
418 * tail queue access methods
419 */
420#define TAILQ_FIRST(head) ((head)->tqh_first)
421#define TAILQ_END(head) NULL
422#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
423#define TAILQ_LAST(head, headname) \
424 (*(((struct headname *)((head)->tqh_last))->tqh_last))
425/* XXX */
426#define TAILQ_PREV(elm, headname, field) \
427 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
428#define TAILQ_EMPTY(head) \
429 (TAILQ_FIRST(head) == TAILQ_END(head))
430
431#define TAILQ_FOREACH(var, head, field) \
432 for((var) = TAILQ_FIRST(head); \
433 (var) != TAILQ_END(head); \
434 (var) = TAILQ_NEXT(var, field))
435
436#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
437 for ((var) = TAILQ_FIRST(head); \
438 (var) != TAILQ_END(head) && \
439 ((tvar) = TAILQ_NEXT(var, field), 1); \
440 (var) = (tvar))
441
442
443#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
444 for((var) = TAILQ_LAST(head, headname); \
445 (var) != TAILQ_END(head); \
446 (var) = TAILQ_PREV(var, headname, field))
447
448#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
449 for ((var) = TAILQ_LAST(head, headname); \
450 (var) != TAILQ_END(head) && \
451 ((tvar) = TAILQ_PREV(var, headname, field), 1); \
452 (var) = (tvar))
453
454/*
455 * Tail queue functions.
456 */
457#define TAILQ_INIT(head) do { \
458 (head)->tqh_first = NULL; \
459 (head)->tqh_last = &(head)->tqh_first; \
460} while (0)
461
462#define TAILQ_INSERT_HEAD(head, elm, field) do { \
463 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
464 (head)->tqh_first->field.tqe_prev = \
465 &(elm)->field.tqe_next; \
466 else \
467 (head)->tqh_last = &(elm)->field.tqe_next; \
468 (head)->tqh_first = (elm); \
469 (elm)->field.tqe_prev = &(head)->tqh_first; \
470} while (0)
471
472#define TAILQ_INSERT_TAIL(head, elm, field) do { \
473 (elm)->field.tqe_next = NULL; \
474 (elm)->field.tqe_prev = (head)->tqh_last; \
475 *(head)->tqh_last = (elm); \
476 (head)->tqh_last = &(elm)->field.tqe_next; \
477} while (0)
478
479#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
480 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
481 (elm)->field.tqe_next->field.tqe_prev = \
482 &(elm)->field.tqe_next; \
483 else \
484 (head)->tqh_last = &(elm)->field.tqe_next; \
485 (listelm)->field.tqe_next = (elm); \
486 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
487} while (0)
488
489#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
490 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
491 (elm)->field.tqe_next = (listelm); \
492 *(listelm)->field.tqe_prev = (elm); \
493 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
494} while (0)
495
496#define TAILQ_REMOVE(head, elm, field) do { \
497 if (((elm)->field.tqe_next) != NULL) \
498 (elm)->field.tqe_next->field.tqe_prev = \
499 (elm)->field.tqe_prev; \
500 else \
501 (head)->tqh_last = (elm)->field.tqe_prev; \
502 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
503 _Q_INVALIDATE((elm)->field.tqe_prev); \
504 _Q_INVALIDATE((elm)->field.tqe_next); \
505} while (0)
506
507#define TAILQ_REPLACE(head, elm, elm2, field) do { \
508 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
509 (elm2)->field.tqe_next->field.tqe_prev = \
510 &(elm2)->field.tqe_next; \
511 else \
512 (head)->tqh_last = &(elm2)->field.tqe_next; \
513 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
514 *(elm2)->field.tqe_prev = (elm2); \
515 _Q_INVALIDATE((elm)->field.tqe_prev); \
516 _Q_INVALIDATE((elm)->field.tqe_next); \
517} while (0)
518
519/*
520 * Circular queue definitions.
521 */
522#define CIRCLEQ_HEAD(name, type) \
523struct name { \
524 struct type *cqh_first; /* first element */ \
525 struct type *cqh_last; /* last element */ \
526}
527
528#define CIRCLEQ_HEAD_INITIALIZER(head) \
529 { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
530
531#define CIRCLEQ_ENTRY(type) \
532struct { \
533 struct type *cqe_next; /* next element */ \
534 struct type *cqe_prev; /* previous element */ \
535}
536
537/*
538 * Circular queue access methods
539 */
540#define CIRCLEQ_FIRST(head) ((head)->cqh_first)
541#define CIRCLEQ_LAST(head) ((head)->cqh_last)
542#define CIRCLEQ_END(head) ((void *)(head))
543#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
544#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
545#define CIRCLEQ_EMPTY(head) \
546 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
547
548#define CIRCLEQ_FOREACH(var, head, field) \
549 for((var) = CIRCLEQ_FIRST(head); \
550 (var) != CIRCLEQ_END(head); \
551 (var) = CIRCLEQ_NEXT(var, field))
552
553#define CIRCLEQ_FOREACH_SAFE(var, head, field, tvar) \
554 for ((var) = CIRCLEQ_FIRST(head); \
555 (var) != CIRCLEQ_END(head) && \
556 ((tvar) = CIRCLEQ_NEXT(var, field), 1); \
557 (var) = (tvar))
558
559#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
560 for((var) = CIRCLEQ_LAST(head); \
561 (var) != CIRCLEQ_END(head); \
562 (var) = CIRCLEQ_PREV(var, field))
563
564#define CIRCLEQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
565 for ((var) = CIRCLEQ_LAST(head, headname); \
566 (var) != CIRCLEQ_END(head) && \
567 ((tvar) = CIRCLEQ_PREV(var, headname, field), 1); \
568 (var) = (tvar))
569
570/*
571 * Circular queue functions.
572 */
573#define CIRCLEQ_INIT(head) do { \
574 (head)->cqh_first = CIRCLEQ_END(head); \
575 (head)->cqh_last = CIRCLEQ_END(head); \
576} while (0)
577
578#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
579 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
580 (elm)->field.cqe_prev = (listelm); \
581 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
582 (head)->cqh_last = (elm); \
583 else \
584 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
585 (listelm)->field.cqe_next = (elm); \
586} while (0)
587
588#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
589 (elm)->field.cqe_next = (listelm); \
590 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
591 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
592 (head)->cqh_first = (elm); \
593 else \
594 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
595 (listelm)->field.cqe_prev = (elm); \
596} while (0)
597
598#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
599 (elm)->field.cqe_next = (head)->cqh_first; \
600 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
601 if ((head)->cqh_last == CIRCLEQ_END(head)) \
602 (head)->cqh_last = (elm); \
603 else \
604 (head)->cqh_first->field.cqe_prev = (elm); \
605 (head)->cqh_first = (elm); \
606} while (0)
607
608#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
609 (elm)->field.cqe_next = CIRCLEQ_END(head); \
610 (elm)->field.cqe_prev = (head)->cqh_last; \
611 if ((head)->cqh_first == CIRCLEQ_END(head)) \
612 (head)->cqh_first = (elm); \
613 else \
614 (head)->cqh_last->field.cqe_next = (elm); \
615 (head)->cqh_last = (elm); \
616} while (0)
617
618#define CIRCLEQ_REMOVE(head, elm, field) do { \
619 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
620 (head)->cqh_last = (elm)->field.cqe_prev; \
621 else \
622 (elm)->field.cqe_next->field.cqe_prev = \
623 (elm)->field.cqe_prev; \
624 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
625 (head)->cqh_first = (elm)->field.cqe_next; \
626 else \
627 (elm)->field.cqe_prev->field.cqe_next = \
628 (elm)->field.cqe_next; \
629 _Q_INVALIDATE((elm)->field.cqe_prev); \
630 _Q_INVALIDATE((elm)->field.cqe_next); \
631} while (0)
632
633#define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
634 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
635 CIRCLEQ_END(head)) \
636 (head)->cqh_last = (elm2); \
637 else \
638 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
639 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
640 CIRCLEQ_END(head)) \
641 (head)->cqh_first = (elm2); \
642 else \
643 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
644 _Q_INVALIDATE((elm)->field.cqe_prev); \
645 _Q_INVALIDATE((elm)->field.cqe_next); \
646} while (0)
647
648#endif /* !_SYS_QUEUE_H_ */
