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queue.h
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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 $ */
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_PREVPTR(var, varp, head, field) \
121 for ((varp) = &SLIST_FIRST((head)); \
122 ((var) = *(varp)) != SLIST_END(head); \
123 (varp) = &SLIST_NEXT((var), field))
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_NEXT(head, 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/*
195 * List functions.
196 */
197#define LIST_INIT(head) do { \
198 LIST_FIRST(head) = LIST_END(head); \
199} while (0)
200
201#define 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; \
207} while (0)
208
209#define 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; \
214} while (0)
215
216#define 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; \
221} while (0)
222
223#define 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); \
230} while (0)
231
232#define 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); \
240} while (0)
241
242/*
243 * Simple queue definitions.
244 */
245#define SIMPLEQ_HEAD(name, type) \
246struct name { \
247 struct type *sqh_first; /* first element */ \
248 struct type **sqh_last; /* addr of last next element */ \
249}
250
251#define SIMPLEQ_HEAD_INITIALIZER(head) \
252 { NULL, &(head).sqh_first }
253
254#define SIMPLEQ_ENTRY(type) \
255struct { \
256 struct type *sqe_next; /* next element */ \
257}
258
259/*
260 * Simple queue access methods.
261 */
262#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
263#define SIMPLEQ_END(head) NULL
264#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
265#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
266
267#define SIMPLEQ_FOREACH(var, head, field) \
268 for((var) = SIMPLEQ_FIRST(head); \
269 (var) != SIMPLEQ_END(head); \
270 (var) = SIMPLEQ_NEXT(var, field))
271
272/*
273 * Simple queue functions.
274 */
275#define SIMPLEQ_INIT(head) do { \
276 (head)->sqh_first = NULL; \
277 (head)->sqh_last = &(head)->sqh_first; \
278} while (0)
279
280#define 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); \
284} while (0)
285
286#define 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; \
290} while (0)
291
292#define 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); \
296} while (0)
297
298#define 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; \
301} while (0)
302
303/*
304 * Tail queue definitions.
305 */
306#define TAILQ_HEAD(name, type) \
307struct name { \
308 struct type *tqh_first; /* first element */ \
309 struct type **tqh_last; /* addr of last next element */ \
310}
311
312#define TAILQ_HEAD_INITIALIZER(head) \
313 { NULL, &(head).tqh_first }
314
315#define TAILQ_ENTRY(type) \
316struct { \
317 struct type *tqe_next; /* next element */ \
318 struct type **tqe_prev; /* address of previous next element */ \
319}
320
321/*
322 * tail queue access methods
323 */
324#define TAILQ_FIRST(head) ((head)->tqh_first)
325#define TAILQ_END(head) NULL
326#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
327#define TAILQ_LAST(head, headname) \
328 (*(((struct headname *)((head)->tqh_last))->tqh_last))
329/* XXX */
330#define TAILQ_PREV(elm, headname, field) \
331 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
332#define TAILQ_EMPTY(head) \
333 (TAILQ_FIRST(head) == TAILQ_END(head))
334
335#define TAILQ_FOREACH(var, head, field) \
336 for((var) = TAILQ_FIRST(head); \
337 (var) != TAILQ_END(head); \
338 (var) = TAILQ_NEXT(var, field))
339
340#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
341 for((var) = TAILQ_LAST(head, headname); \
342 (var) != TAILQ_END(head); \
343 (var) = TAILQ_PREV(var, headname, field))
344
345/*
346 * Tail queue functions.
347 */
348#define TAILQ_INIT(head) do { \
349 (head)->tqh_first = NULL; \
350 (head)->tqh_last = &(head)->tqh_first; \
351} while (0)
352
353#define 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; \
357 else \
358 (head)->tqh_last = &(elm)->field.tqe_next; \
359 (head)->tqh_first = (elm); \
360 (elm)->field.tqe_prev = &(head)->tqh_first; \
361} while (0)
362
363#define 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; \
368} while (0)
369
370#define 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; \
374 else \
375 (head)->tqh_last = &(elm)->field.tqe_next; \
376 (listelm)->field.tqe_next = (elm); \
377 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
378} while (0)
379
380#define 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; \
385} while (0)
386
387#define 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; \
391 else \
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); \
396} while (0)
397
398#define 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; \
402 else \
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); \
408} while (0)
409
410/*
411 * Circular queue definitions.
412 */
413#define CIRCLEQ_HEAD(name, type) \
414struct name { \
415 struct type *cqh_first; /* first element */ \
416 struct type *cqh_last; /* last element */ \
417}
418
419#define CIRCLEQ_HEAD_INITIALIZER(head) \
420 { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
421
422#define CIRCLEQ_ENTRY(type) \
423struct { \
424 struct type *cqe_next; /* next element */ \
425 struct type *cqe_prev; /* previous element */ \
426}
427
428/*
429 * Circular queue access methods
430 */
431#define CIRCLEQ_FIRST(head) ((head)->cqh_first)
432#define CIRCLEQ_LAST(head) ((head)->cqh_last)
433#define CIRCLEQ_END(head) ((void *)(head))
434#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
435#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
436#define CIRCLEQ_EMPTY(head) \
437 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
438
439#define CIRCLEQ_FOREACH(var, head, field) \
440 for((var) = CIRCLEQ_FIRST(head); \
441 (var) != CIRCLEQ_END(head); \
442 (var) = CIRCLEQ_NEXT(var, field))
443
444#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
445 for((var) = CIRCLEQ_LAST(head); \
446 (var) != CIRCLEQ_END(head); \
447 (var) = CIRCLEQ_PREV(var, field))
448
449/*
450 * Circular queue functions.
451 */
452#define CIRCLEQ_INIT(head) do { \
453 (head)->cqh_first = CIRCLEQ_END(head); \
454 (head)->cqh_last = CIRCLEQ_END(head); \
455} while (0)
456
457#define 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 == CIRCLEQ_END(head)) \
461 (head)->cqh_last = (elm); \
462 else \
463 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
464 (listelm)->field.cqe_next = (elm); \
465} while (0)
466
467#define 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 == CIRCLEQ_END(head)) \
471 (head)->cqh_first = (elm); \
472 else \
473 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
474 (listelm)->field.cqe_prev = (elm); \
475} while (0)
476
477#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
478 (elm)->field.cqe_next = (head)->cqh_first; \
479 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
480 if ((head)->cqh_last == CIRCLEQ_END(head)) \
481 (head)->cqh_last = (elm); \
482 else \
483 (head)->cqh_first->field.cqe_prev = (elm); \
484 (head)->cqh_first = (elm); \
485} while (0)
486
487#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
488 (elm)->field.cqe_next = CIRCLEQ_END(head); \
489 (elm)->field.cqe_prev = (head)->cqh_last; \
490 if ((head)->cqh_first == CIRCLEQ_END(head)) \
491 (head)->cqh_first = (elm); \
492 else \
493 (head)->cqh_last->field.cqe_next = (elm); \
494 (head)->cqh_last = (elm); \
495} while (0)
496
497#define CIRCLEQ_REMOVE(head, elm, field) do { \
498 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
499 (head)->cqh_last = (elm)->field.cqe_prev; \
500 else \
501 (elm)->field.cqe_next->field.cqe_prev = \
502 (elm)->field.cqe_prev; \
503 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
504 (head)->cqh_first = (elm)->field.cqe_next; \
505 else \
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); \
510} while (0)
511
512#define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
513 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
514 CIRCLEQ_END(head)) \
515 (head).cqh_last = (elm2); \
516 else \
517 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
518 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
519 CIRCLEQ_END(head)) \
520 (head).cqh_first = (elm2); \
521 else \
522 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
523 _Q_INVALIDATE((elm)->field.cqe_prev); \
524 _Q_INVALIDATE((elm)->field.cqe_next); \
525} while (0)
526
527#endif /* !_SYS_QUEUE_H_ */
528
529