1 /* $OpenBSD: queue.h,v 1.32 2007/04/30 18:42:34 pedro Exp $ */
2 /* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
32 * @(#)queue.h 8.5 (Berkeley) 8/20/94
35 #ifndef _BSD_SYS_QUEUE_H_
36 #define _BSD_SYS_QUEUE_H_
39 * This file defines five types of data structures: singly-linked lists,
40 * lists, simple queues, tail queues, and circular queues.
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.
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.
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.
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.
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.
82 * For details on the use of these macros, see the queue(3) manual page.
85 #if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
86 #define _Q_INVALIDATE(a) (a) = ((void *)-1)
88 #define _Q_INVALIDATE(a)
92 * Singly-linked List definitions.
94 #define BSD_SLIST_HEAD(name, type) \
96 struct type *slh_first; /* first element */ \
99 #define BSD_SLIST_HEAD_INITIALIZER(head) \
102 #define BSD_SLIST_ENTRY(type) \
104 struct type *sle_next; /* next element */ \
108 * Singly-linked List access methods.
110 #define BSD_SLIST_FIRST(head) ((head)->slh_first)
111 #define BSD_SLIST_END(head) NULL
112 #define BSD_SLIST_EMPTY(head) (BSD_SLIST_FIRST(head) == BSD_SLIST_END(head))
113 #define BSD_SLIST_NEXT(elm, field) ((elm)->field.sle_next)
115 #define BSD_SLIST_FOREACH(var, head, field) \
116 for((var) = BSD_SLIST_FIRST(head); \
117 (var) != BSD_SLIST_END(head); \
118 (var) = BSD_SLIST_NEXT(var, field))
120 #define BSD_SLIST_FOREACH_PREVPTR(var, varp, head, field) \
121 for ((varp) = &BSD_SLIST_FIRST((head)); \
122 ((var) = *(varp)) != BSD_SLIST_END(head); \
123 (varp) = &BSD_SLIST_NEXT((var), field))
126 * Singly-linked List functions.
128 #define BSD_SLIST_INIT(head) { \
129 BSD_SLIST_FIRST(head) = BSD_SLIST_END(head); \
132 #define BSD_SLIST_INSERT_AFTER(slistelm, elm, field) do { \
133 (elm)->field.sle_next = (slistelm)->field.sle_next; \
134 (slistelm)->field.sle_next = (elm); \
137 #define BSD_SLIST_INSERT_HEAD(head, elm, field) do { \
138 (elm)->field.sle_next = (head)->slh_first; \
139 (head)->slh_first = (elm); \
142 #define BSD_SLIST_REMOVE_NEXT(head, elm, field) do { \
143 (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
146 #define BSD_SLIST_REMOVE_HEAD(head, field) do { \
147 (head)->slh_first = (head)->slh_first->field.sle_next; \
150 #define BSD_SLIST_REMOVE(head, elm, type, field) do { \
151 if ((head)->slh_first == (elm)) { \
152 BSD_SLIST_REMOVE_HEAD((head), field); \
154 struct type *curelm = (head)->slh_first; \
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); \
167 #define BSD_LIST_HEAD(name, type) \
169 struct type *lh_first; /* first element */ \
172 #define BSD_LIST_HEAD_INITIALIZER(head) \
175 #define BSD_LIST_ENTRY(type) \
177 struct type *le_next; /* next element */ \
178 struct type **le_prev; /* address of previous next element */ \
182 * List access methods
184 #define BSD_LIST_FIRST(head) ((head)->lh_first)
185 #define BSD_LIST_END(head) NULL
186 #define BSD_LIST_EMPTY(head) (BSD_LIST_FIRST(head) == BSD_LIST_END(head))
187 #define BSD_LIST_NEXT(elm, field) ((elm)->field.le_next)
189 #define BSD_LIST_FOREACH(var, head, field) \
190 for((var) = BSD_LIST_FIRST(head); \
191 (var)!= BSD_LIST_END(head); \
192 (var) = BSD_LIST_NEXT(var, field))
197 #define BSD_LIST_INIT(head) do { \
198 BSD_LIST_FIRST(head) = BSD_LIST_END(head); \
201 #define BSD_LIST_INSERT_AFTER(listelm, elm, field) do { \
202 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
203 (listelm)->field.le_next->field.le_prev = \
204 &(elm)->field.le_next; \
205 (listelm)->field.le_next = (elm); \
206 (elm)->field.le_prev = &(listelm)->field.le_next; \
209 #define BSD_LIST_INSERT_BEFORE(listelm, elm, field) do { \
210 (elm)->field.le_prev = (listelm)->field.le_prev; \
211 (elm)->field.le_next = (listelm); \
212 *(listelm)->field.le_prev = (elm); \
213 (listelm)->field.le_prev = &(elm)->field.le_next; \
216 #define BSD_LIST_INSERT_HEAD(head, elm, field) do { \
217 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
218 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
219 (head)->lh_first = (elm); \
220 (elm)->field.le_prev = &(head)->lh_first; \
223 #define BSD_LIST_REMOVE(elm, field) do { \
224 if ((elm)->field.le_next != NULL) \
225 (elm)->field.le_next->field.le_prev = \
226 (elm)->field.le_prev; \
227 *(elm)->field.le_prev = (elm)->field.le_next; \
228 _Q_INVALIDATE((elm)->field.le_prev); \
229 _Q_INVALIDATE((elm)->field.le_next); \
232 #define BSD_LIST_REPLACE(elm, elm2, field) do { \
233 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
234 (elm2)->field.le_next->field.le_prev = \
235 &(elm2)->field.le_next; \
236 (elm2)->field.le_prev = (elm)->field.le_prev; \
237 *(elm2)->field.le_prev = (elm2); \
238 _Q_INVALIDATE((elm)->field.le_prev); \
239 _Q_INVALIDATE((elm)->field.le_next); \
243 * Simple queue definitions.
245 #define BSD_SIMPLEQ_HEAD(name, type) \
247 struct type *sqh_first; /* first element */ \
248 struct type **sqh_last; /* addr of last next element */ \
251 #define BSD_SIMPLEQ_HEAD_INITIALIZER(head) \
252 { NULL, &(head).sqh_first }
254 #define BSD_SIMPLEQ_ENTRY(type) \
256 struct type *sqe_next; /* next element */ \
260 * Simple queue access methods.
262 #define BSD_SIMPLEQ_FIRST(head) ((head)->sqh_first)
263 #define BSD_SIMPLEQ_END(head) NULL
264 #define BSD_SIMPLEQ_EMPTY(head) (BSD_SIMPLEQ_FIRST(head) == BSD_SIMPLEQ_END(head))
265 #define BSD_SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
267 #define BSD_SIMPLEQ_FOREACH(var, head, field) \
268 for((var) = BSD_SIMPLEQ_FIRST(head); \
269 (var) != BSD_SIMPLEQ_END(head); \
270 (var) = BSD_SIMPLEQ_NEXT(var, field))
273 * Simple queue functions.
275 #define BSD_SIMPLEQ_INIT(head) do { \
276 (head)->sqh_first = NULL; \
277 (head)->sqh_last = &(head)->sqh_first; \
280 #define BSD_SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
281 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
282 (head)->sqh_last = &(elm)->field.sqe_next; \
283 (head)->sqh_first = (elm); \
286 #define BSD_SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
287 (elm)->field.sqe_next = NULL; \
288 *(head)->sqh_last = (elm); \
289 (head)->sqh_last = &(elm)->field.sqe_next; \
292 #define BSD_SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
293 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
294 (head)->sqh_last = &(elm)->field.sqe_next; \
295 (listelm)->field.sqe_next = (elm); \
298 #define BSD_SIMPLEQ_REMOVE_HEAD(head, field) do { \
299 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
300 (head)->sqh_last = &(head)->sqh_first; \
304 * Tail queue definitions.
306 #define BSD_TAILQ_HEAD(name, type) \
308 struct type *tqh_first; /* first element */ \
309 struct type **tqh_last; /* addr of last next element */ \
312 #define BSD_TAILQ_HEAD_INITIALIZER(head) \
313 { NULL, &(head).tqh_first }
315 #define BSD_TAILQ_ENTRY(type) \
317 struct type *tqe_next; /* next element */ \
318 struct type **tqe_prev; /* address of previous next element */ \
322 * tail queue access methods
324 #define BSD_TAILQ_FIRST(head) ((head)->tqh_first)
325 #define BSD_TAILQ_END(head) NULL
326 #define BSD_TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
327 #define BSD_TAILQ_LAST(head, headname) \
328 (*(((struct headname *)((head)->tqh_last))->tqh_last))
330 #define BSD_TAILQ_PREV(elm, headname, field) \
331 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
332 #define BSD_TAILQ_EMPTY(head) \
333 (BSD_TAILQ_FIRST(head) == BSD_TAILQ_END(head))
335 #define BSD_TAILQ_FOREACH(var, head, field) \
336 for((var) = BSD_TAILQ_FIRST(head); \
337 (var) != BSD_TAILQ_END(head); \
338 (var) = BSD_TAILQ_NEXT(var, field))
340 #define BSD_TAILQ_FOREACH_REVERSE(var, head, headname, field) \
341 for((var) = BSD_TAILQ_LAST(head, headname); \
342 (var) != BSD_TAILQ_END(head); \
343 (var) = BSD_TAILQ_PREV(var, headname, field))
346 * Tail queue functions.
348 #define BSD_TAILQ_INIT(head) do { \
349 (head)->tqh_first = NULL; \
350 (head)->tqh_last = &(head)->tqh_first; \
353 #define BSD_TAILQ_INSERT_HEAD(head, elm, field) do { \
354 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
355 (head)->tqh_first->field.tqe_prev = \
356 &(elm)->field.tqe_next; \
358 (head)->tqh_last = &(elm)->field.tqe_next; \
359 (head)->tqh_first = (elm); \
360 (elm)->field.tqe_prev = &(head)->tqh_first; \
363 #define BSD_TAILQ_INSERT_TAIL(head, elm, field) do { \
364 (elm)->field.tqe_next = NULL; \
365 (elm)->field.tqe_prev = (head)->tqh_last; \
366 *(head)->tqh_last = (elm); \
367 (head)->tqh_last = &(elm)->field.tqe_next; \
370 #define BSD_TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
371 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
372 (elm)->field.tqe_next->field.tqe_prev = \
373 &(elm)->field.tqe_next; \
375 (head)->tqh_last = &(elm)->field.tqe_next; \
376 (listelm)->field.tqe_next = (elm); \
377 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
380 #define BSD_TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
381 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
382 (elm)->field.tqe_next = (listelm); \
383 *(listelm)->field.tqe_prev = (elm); \
384 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
387 #define BSD_TAILQ_REMOVE(head, elm, field) do { \
388 if (((elm)->field.tqe_next) != NULL) \
389 (elm)->field.tqe_next->field.tqe_prev = \
390 (elm)->field.tqe_prev; \
392 (head)->tqh_last = (elm)->field.tqe_prev; \
393 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
394 _Q_INVALIDATE((elm)->field.tqe_prev); \
395 _Q_INVALIDATE((elm)->field.tqe_next); \
398 #define BSD_TAILQ_REPLACE(head, elm, elm2, field) do { \
399 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
400 (elm2)->field.tqe_next->field.tqe_prev = \
401 &(elm2)->field.tqe_next; \
403 (head)->tqh_last = &(elm2)->field.tqe_next; \
404 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
405 *(elm2)->field.tqe_prev = (elm2); \
406 _Q_INVALIDATE((elm)->field.tqe_prev); \
407 _Q_INVALIDATE((elm)->field.tqe_next); \
411 * Circular queue definitions.
413 #define BSD_CIRCLEQ_HEAD(name, type) \
415 struct type *cqh_first; /* first element */ \
416 struct type *cqh_last; /* last element */ \
419 #define BSD_CIRCLEQ_HEAD_INITIALIZER(head) \
420 { BSD_CIRCLEQ_END(&head), BSD_CIRCLEQ_END(&head) }
422 #define BSD_CIRCLEQ_ENTRY(type) \
424 struct type *cqe_next; /* next element */ \
425 struct type *cqe_prev; /* previous element */ \
429 * Circular queue access methods
431 #define BSD_CIRCLEQ_FIRST(head) ((head)->cqh_first)
432 #define BSD_CIRCLEQ_LAST(head) ((head)->cqh_last)
433 #define BSD_CIRCLEQ_END(head) ((void *)(head))
434 #define BSD_CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
435 #define BSD_CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
436 #define BSD_CIRCLEQ_EMPTY(head) \
437 (BSD_CIRCLEQ_FIRST(head) == BSD_CIRCLEQ_END(head))
439 #define BSD_CIRCLEQ_FOREACH(var, head, field) \
440 for((var) = BSD_CIRCLEQ_FIRST(head); \
441 (var) != BSD_CIRCLEQ_END(head); \
442 (var) = BSD_CIRCLEQ_NEXT(var, field))
444 #define BSD_CIRCLEQ_FOREACH_REVERSE(var, head, field) \
445 for((var) = BSD_CIRCLEQ_LAST(head); \
446 (var) != BSD_CIRCLEQ_END(head); \
447 (var) = BSD_CIRCLEQ_PREV(var, field))
450 * Circular queue functions.
452 #define BSD_CIRCLEQ_INIT(head) do { \
453 (head)->cqh_first = BSD_CIRCLEQ_END(head); \
454 (head)->cqh_last = BSD_CIRCLEQ_END(head); \
457 #define BSD_CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
458 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
459 (elm)->field.cqe_prev = (listelm); \
460 if ((listelm)->field.cqe_next == BSD_CIRCLEQ_END(head)) \
461 (head)->cqh_last = (elm); \
463 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
464 (listelm)->field.cqe_next = (elm); \
467 #define BSD_CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
468 (elm)->field.cqe_next = (listelm); \
469 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
470 if ((listelm)->field.cqe_prev == BSD_CIRCLEQ_END(head)) \
471 (head)->cqh_first = (elm); \
473 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
474 (listelm)->field.cqe_prev = (elm); \
477 #define BSD_CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
478 (elm)->field.cqe_next = (head)->cqh_first; \
479 (elm)->field.cqe_prev = BSD_CIRCLEQ_END(head); \
480 if ((head)->cqh_last == BSD_CIRCLEQ_END(head)) \
481 (head)->cqh_last = (elm); \
483 (head)->cqh_first->field.cqe_prev = (elm); \
484 (head)->cqh_first = (elm); \
487 #define BSD_CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
488 (elm)->field.cqe_next = BSD_CIRCLEQ_END(head); \
489 (elm)->field.cqe_prev = (head)->cqh_last; \
490 if ((head)->cqh_first == BSD_CIRCLEQ_END(head)) \
491 (head)->cqh_first = (elm); \
493 (head)->cqh_last->field.cqe_next = (elm); \
494 (head)->cqh_last = (elm); \
497 #define BSD_CIRCLEQ_REMOVE(head, elm, field) do { \
498 if ((elm)->field.cqe_next == BSD_CIRCLEQ_END(head)) \
499 (head)->cqh_last = (elm)->field.cqe_prev; \
501 (elm)->field.cqe_next->field.cqe_prev = \
502 (elm)->field.cqe_prev; \
503 if ((elm)->field.cqe_prev == BSD_CIRCLEQ_END(head)) \
504 (head)->cqh_first = (elm)->field.cqe_next; \
506 (elm)->field.cqe_prev->field.cqe_next = \
507 (elm)->field.cqe_next; \
508 _Q_INVALIDATE((elm)->field.cqe_prev); \
509 _Q_INVALIDATE((elm)->field.cqe_next); \
512 #define BSD_CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
513 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
514 BSD_CIRCLEQ_END(head)) \
515 (head).cqh_last = (elm2); \
517 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
518 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
519 BSD_CIRCLEQ_END(head)) \
520 (head).cqh_first = (elm2); \
522 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
523 _Q_INVALIDATE((elm)->field.cqe_prev); \
524 _Q_INVALIDATE((elm)->field.cqe_next); \
527 #endif /* !_BSD_SYS_QUEUE_H_ */