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queue.h
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1/* $OpenBSD: queue.h,v 1.1 2007/10/26 03:14:08 niallo 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#pragma once
36
37/*
38 * This file defines five types of data structures: singly-linked lists,
39 * lists, simple queues, tail queues, and circular queues.
40 *
41 *
42 * A singly-linked list is headed by a single forward pointer. The elements
43 * are singly linked for minimum space and pointer manipulation overhead at
44 * the expense of O(n) removal for arbitrary elements. New elements can be
45 * added to the list after an existing element or at the head of the list.
46 * Elements being removed from the head of the list should use the explicit
47 * macro for this purpose for optimum efficiency. A singly-linked list may
48 * only be traversed in the forward direction. Singly-linked lists are ideal
49 * for applications with large datasets and few or no removals or for
50 * implementing a LIFO queue.
51 *
52 * A list is headed by a single forward pointer (or an array of forward
53 * pointers for a hash table header). The elements are doubly linked
54 * so that an arbitrary element can be removed without a need to
55 * traverse the list. New elements can be added to the list before
56 * or after an existing element or at the head of the list. A list
57 * may only be traversed in the forward direction.
58 *
59 * A simple queue is headed by a pair of pointers, one the head of the
60 * list and the other to the tail of the list. The elements are singly
61 * linked to save space, so elements can only be removed from the
62 * head of the list. New elements can be added to the list before or after
63 * an existing element, at the head of the list, or at the end of the
64 * list. A simple queue may only be traversed in the forward direction.
65 *
66 * A tail queue is headed by a pair of pointers, one to the head of the
67 * list and the other to the tail of the list. The elements are doubly
68 * linked so that an arbitrary element can be removed without a need to
69 * traverse the list. New elements can be added to the list before or
70 * after an existing element, at the head of the list, or at the end of
71 * the list. A tail queue may be traversed in either direction.
72 *
73 * A circle queue is headed by a pair of pointers, one to the head of the
74 * list and the other to the tail of the list. The elements are doubly
75 * linked so that an arbitrary element can be removed without a need to
76 * traverse the list. New elements can be added to the list before or after
77 * an existing element, at the head of the list, or at the end of the list.
78 * A circle queue may be traversed in either direction, but has a more
79 * complex end of list detection.
80 *
81 * For details on the use of these macros, see the queue(3) manual page.
82 */
83
84#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
85#define _Q_INVALIDATE(a) (a) = ((void *)-1)
86#else
87#define _Q_INVALIDATE(a)
88#endif
89
90/*
91 * Singly-linked List definitions.
92 */
93#define SLIST_HEAD(name, type) \
94 struct name { \
95 struct type *slh_first; /* first element */ \
96 }
97
98#define SLIST_HEAD_INITIALIZER(head) \
99 { NULL }
100
101#define SLIST_ENTRY(type) \
102 struct { \
103 struct type *sle_next; /* next element */ \
104 }
105
106/*
107 * Singly-linked List access methods.
108 */
109#define SLIST_FIRST(head) ((head)->slh_first)
110#define SLIST_END(head) NULL
111#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
112#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
113
114#define SLIST_FOREACH(var, head, field) \
115 for ((var) = SLIST_FIRST(head); \
116 (var) != SLIST_END(head); \
117 (var) = SLIST_NEXT(var, field))
118
119#define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
120 for ((varp) = &SLIST_FIRST((head)); \
121 ((var) = *(varp)) != SLIST_END(head); \
122 (varp) = &SLIST_NEXT((var), field))
123
124/*
125 * Singly-linked List functions.
126 */
127#define SLIST_INIT(head) \
128 { \
129 SLIST_FIRST(head) = SLIST_END(head); \
130 }
131
132#define SLIST_INSERT_AFTER(slistelm, elm, field) \
133 do { \
134 (elm)->field.sle_next = (slistelm)->field.sle_next; \
135 (slistelm)->field.sle_next = (elm); \
136 } while (0)
137
138#define SLIST_INSERT_HEAD(head, elm, field) \
139 do { \
140 (elm)->field.sle_next = (head)->slh_first; \
141 (head)->slh_first = (elm); \
142 } while (0)
143
144#define SLIST_REMOVE_NEXT(head, elm, field) \
145 do { \
146 (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
147 } while (0)
148
149#define SLIST_REMOVE_HEAD(head, field) \
150 do { \
151 (head)->slh_first = (head)->slh_first->field.sle_next; \
152 } while (0)
153
154#define SLIST_REMOVE(head, elm, type, field) \
155 do { \
156 if ((head)->slh_first == (elm)) { \
157 SLIST_REMOVE_HEAD((head), field); \
158 } else { \
159 struct type *curelm = (head)->slh_first; \
160 \
161 while (curelm->field.sle_next != (elm)) \
162 curelm = curelm->field.sle_next; \
163 curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \
164 _Q_INVALIDATE((elm)->field.sle_next); \
165 } \
166 } while (0)
167
168/*
169 * List definitions.
170 */
171#define LIST_HEAD(name, type) \
172 struct name { \
173 struct type *lh_first; /* first element */ \
174 }
175
176#define LIST_HEAD_INITIALIZER(head) \
177 { NULL }
178
179#define LIST_ENTRY(type) \
180 struct { \
181 struct type *le_next; /* next element */ \
182 struct type **le_prev; /* address of previous next element */ \
183 }
184
185/*
186 * List access methods
187 */
188#define LIST_FIRST(head) ((head)->lh_first)
189#define LIST_END(head) NULL
190#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
191#define LIST_NEXT(elm, field) ((elm)->field.le_next)
192
193#define LIST_FOREACH(var, head, field) \
194 for ((var) = LIST_FIRST(head); \
195 (var) != LIST_END(head); \
196 (var) = LIST_NEXT(var, field))
197
198/*
199 * List functions.
200 */
201#define LIST_INIT(head) \
202 do { \
203 LIST_FIRST(head) = LIST_END(head); \
204 } while (0)
205
206#define LIST_INSERT_AFTER(listelm, elm, field) \
207 do { \
208 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
209 (listelm)->field.le_next->field.le_prev = &(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) \
215 do { \
216 (elm)->field.le_prev = (listelm)->field.le_prev; \
217 (elm)->field.le_next = (listelm); \
218 *(listelm)->field.le_prev = (elm); \
219 (listelm)->field.le_prev = &(elm)->field.le_next; \
220 } while (0)
221
222#define LIST_INSERT_HEAD(head, elm, field) \
223 do { \
224 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
225 (head)->lh_first->field.le_prev = &(elm)->field.le_next; \
226 (head)->lh_first = (elm); \
227 (elm)->field.le_prev = &(head)->lh_first; \
228 } while (0)
229
230#define LIST_REMOVE(elm, field) \
231 do { \
232 if ((elm)->field.le_next != NULL) \
233 (elm)->field.le_next->field.le_prev = (elm)->field.le_prev; \
234 *(elm)->field.le_prev = (elm)->field.le_next; \
235 _Q_INVALIDATE((elm)->field.le_prev); \
236 _Q_INVALIDATE((elm)->field.le_next); \
237 } while (0)
238
239#define LIST_REPLACE(elm, elm2, field) \
240 do { \
241 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
242 (elm2)->field.le_next->field.le_prev = &(elm2)->field.le_next; \
243 (elm2)->field.le_prev = (elm)->field.le_prev; \
244 *(elm2)->field.le_prev = (elm2); \
245 _Q_INVALIDATE((elm)->field.le_prev); \
246 _Q_INVALIDATE((elm)->field.le_next); \
247 } while (0)
248
249/*
250 * Simple queue definitions.
251 */
252#define SIMPLEQ_HEAD(name, type) \
253 struct name { \
254 struct type *sqh_first; /* first element */ \
255 struct type **sqh_last; /* addr of last next element */ \
256 }
257
258#define SIMPLEQ_HEAD_INITIALIZER(head) \
259 { NULL, &(head).sqh_first }
260
261#define SIMPLEQ_ENTRY(type) \
262 struct { \
263 struct type *sqe_next; /* next element */ \
264 }
265
266/*
267 * Simple queue access methods.
268 */
269#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
270#define SIMPLEQ_END(head) NULL
271#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
272#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
273
274#define SIMPLEQ_FOREACH(var, head, field) \
275 for ((var) = SIMPLEQ_FIRST(head); \
276 (var) != SIMPLEQ_END(head); \
277 (var) = SIMPLEQ_NEXT(var, field))
278
279/*
280 * Simple queue functions.
281 */
282#define SIMPLEQ_INIT(head) \
283 do { \
284 (head)->sqh_first = NULL; \
285 (head)->sqh_last = &(head)->sqh_first; \
286 } while (0)
287
288#define SIMPLEQ_INSERT_HEAD(head, elm, field) \
289 do { \
290 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
291 (head)->sqh_last = &(elm)->field.sqe_next; \
292 (head)->sqh_first = (elm); \
293 } while (0)
294
295#define SIMPLEQ_INSERT_TAIL(head, elm, field) \
296 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) \
303 do { \
304 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \
305 (head)->sqh_last = &(elm)->field.sqe_next; \
306 (listelm)->field.sqe_next = (elm); \
307 } while (0)
308
309#define SIMPLEQ_REMOVE_HEAD(head, field) \
310 do { \
311 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
312 (head)->sqh_last = &(head)->sqh_first; \
313 } while (0)
314
315/*
316 * Tail queue definitions.
317 */
318#define TAILQ_HEAD(name, type) \
319 struct name { \
320 struct type *tqh_first; /* first element */ \
321 struct type **tqh_last; /* addr of last next element */ \
322 }
323
324#define TAILQ_HEAD_INITIALIZER(head) \
325 { NULL, &(head).tqh_first }
326
327#define TAILQ_ENTRY(type) \
328 struct { \
329 struct type *tqe_next; /* next element */ \
330 struct type **tqe_prev; /* address of previous next element */ \
331 }
332
333/*
334 * tail queue access methods
335 */
336#define TAILQ_FIRST(head) ((head)->tqh_first)
337#define TAILQ_END(head) NULL
338#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
339#define TAILQ_LAST(head, headname) \
340 (*(((struct headname *)((head)->tqh_last))->tqh_last))
341/* XXX */
342#define TAILQ_PREV(elm, headname, field) \
343 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
344#define TAILQ_EMPTY(head) \
345 (TAILQ_FIRST(head) == TAILQ_END(head))
346
347#define TAILQ_FOREACH(var, head, field) \
348 for ((var) = TAILQ_FIRST(head); \
349 (var) != TAILQ_END(head); \
350 (var) = TAILQ_NEXT(var, field))
351
352#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
353 for ((var) = TAILQ_LAST(head, headname); \
354 (var) != TAILQ_END(head); \
355 (var) = TAILQ_PREV(var, headname, field))
356
357/*
358 * Tail queue functions.
359 */
360#define TAILQ_INIT(head) \
361 do { \
362 (head)->tqh_first = NULL; \
363 (head)->tqh_last = &(head)->tqh_first; \
364 } while (0)
365
366#define TAILQ_INSERT_HEAD(head, elm, field) \
367 do { \
368 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
369 (head)->tqh_first->field.tqe_prev = &(elm)->field.tqe_next; \
370 else \
371 (head)->tqh_last = &(elm)->field.tqe_next; \
372 (head)->tqh_first = (elm); \
373 (elm)->field.tqe_prev = &(head)->tqh_first; \
374 } while (0)
375
376#define TAILQ_INSERT_TAIL(head, elm, field) \
377 do { \
378 (elm)->field.tqe_next = NULL; \
379 (elm)->field.tqe_prev = (head)->tqh_last; \
380 *(head)->tqh_last = (elm); \
381 (head)->tqh_last = &(elm)->field.tqe_next; \
382 } while (0)
383
384#define TAILQ_INSERT_AFTER(head, listelm, elm, field) \
385 do { \
386 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL) \
387 (elm)->field.tqe_next->field.tqe_prev = &(elm)->field.tqe_next; \
388 else \
389 (head)->tqh_last = &(elm)->field.tqe_next; \
390 (listelm)->field.tqe_next = (elm); \
391 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
392 } while (0)
393
394#define TAILQ_INSERT_BEFORE(listelm, elm, field) \
395 do { \
396 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
397 (elm)->field.tqe_next = (listelm); \
398 *(listelm)->field.tqe_prev = (elm); \
399 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
400 } while (0)
401
402#define TAILQ_REMOVE(head, elm, field) \
403 do { \
404 if (((elm)->field.tqe_next) != NULL) \
405 (elm)->field.tqe_next->field.tqe_prev = (elm)->field.tqe_prev; \
406 else \
407 (head)->tqh_last = (elm)->field.tqe_prev; \
408 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
409 _Q_INVALIDATE((elm)->field.tqe_prev); \
410 _Q_INVALIDATE((elm)->field.tqe_next); \
411 } while (0)
412
413#define TAILQ_REPLACE(head, elm, elm2, field) \
414 do { \
415 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
416 (elm2)->field.tqe_next->field.tqe_prev = &(elm2)->field.tqe_next; \
417 else \
418 (head)->tqh_last = &(elm2)->field.tqe_next; \
419 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
420 *(elm2)->field.tqe_prev = (elm2); \
421 _Q_INVALIDATE((elm)->field.tqe_prev); \
422 _Q_INVALIDATE((elm)->field.tqe_next); \
423 } while (0)
424
425/* Swaps two consecutive elements. 'second' *MUST* follow 'first' */
426#define TAILQ_SWAP(first, second, head, field) \
427 do { \
428 *((first)->field.tqe_prev) = (second); \
429 (second)->field.tqe_prev = (first)->field.tqe_prev; \
430 (first)->field.tqe_prev = &((second)->field.tqe_next); \
431 (first)->field.tqe_next = (second)->field.tqe_next; \
432 if ((second)->field.tqe_next) \
433 (second)->field.tqe_next->field.tqe_prev = &((first)->field.tqe_next); \
434 (second)->field.tqe_next = first; \
435 if ((head)->tqh_last == &((second)->field.tqe_next)) \
436 (head)->tqh_last = &((first)->field.tqe_next); \
437 } while (0)
438
439/*
440 * Circular queue definitions.
441 */
442#define CIRCLEQ_HEAD(name, type) \
443 struct name { \
444 struct type *cqh_first; /* first element */ \
445 struct type *cqh_last; /* last element */ \
446 }
447
448#define CIRCLEQ_HEAD_INITIALIZER(head) \
449 { \
450 CIRCLEQ_END(&head) \
451 , CIRCLEQ_END(&head) \
452 }
453
454#define CIRCLEQ_ENTRY(type) \
455 struct { \
456 struct type *cqe_next; /* next element */ \
457 struct type *cqe_prev; /* previous element */ \
458 }
459
460/*
461 * Circular queue access methods
462 */
463#define CIRCLEQ_FIRST(head) ((head)->cqh_first)
464#define CIRCLEQ_LAST(head) ((head)->cqh_last)
465#define CIRCLEQ_END(head) ((void *)(head))
466#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
467#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
468#define CIRCLEQ_EMPTY(head) \
469 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
470
471#define CIRCLEQ_FOREACH(var, head, field) \
472 for ((var) = CIRCLEQ_FIRST(head); \
473 (var) != CIRCLEQ_END(head); \
474 (var) = CIRCLEQ_NEXT(var, field))
475
476#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
477 for ((var) = CIRCLEQ_LAST(head); \
478 (var) != CIRCLEQ_END(head); \
479 (var) = CIRCLEQ_PREV(var, field))
480
481/*
482 * Circular queue functions.
483 */
484#define CIRCLEQ_INIT(head) \
485 do { \
486 (head)->cqh_first = CIRCLEQ_END(head); \
487 (head)->cqh_last = CIRCLEQ_END(head); \
488 } while (0)
489
490#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) \
491 do { \
492 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
493 (elm)->field.cqe_prev = (listelm); \
494 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
495 (head)->cqh_last = (elm); \
496 else \
497 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
498 (listelm)->field.cqe_next = (elm); \
499 } while (0)
500
501#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) \
502 do { \
503 (elm)->field.cqe_next = (listelm); \
504 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
505 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
506 (head)->cqh_first = (elm); \
507 else \
508 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
509 (listelm)->field.cqe_prev = (elm); \
510 } while (0)
511
512#define CIRCLEQ_INSERT_HEAD(head, elm, field) \
513 do { \
514 (elm)->field.cqe_next = (head)->cqh_first; \
515 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
516 if ((head)->cqh_last == CIRCLEQ_END(head)) \
517 (head)->cqh_last = (elm); \
518 else \
519 (head)->cqh_first->field.cqe_prev = (elm); \
520 (head)->cqh_first = (elm); \
521 } while (0)
522
523#define CIRCLEQ_INSERT_TAIL(head, elm, field) \
524 do { \
525 (elm)->field.cqe_next = CIRCLEQ_END(head); \
526 (elm)->field.cqe_prev = (head)->cqh_last; \
527 if ((head)->cqh_first == CIRCLEQ_END(head)) \
528 (head)->cqh_first = (elm); \
529 else \
530 (head)->cqh_last->field.cqe_next = (elm); \
531 (head)->cqh_last = (elm); \
532 } while (0)
533
534#define CIRCLEQ_REMOVE(head, elm, field) \
535 do { \
536 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
537 (head)->cqh_last = (elm)->field.cqe_prev; \
538 else \
539 (elm)->field.cqe_next->field.cqe_prev = (elm)->field.cqe_prev; \
540 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
541 (head)->cqh_first = (elm)->field.cqe_next; \
542 else \
543 (elm)->field.cqe_prev->field.cqe_next = (elm)->field.cqe_next; \
544 _Q_INVALIDATE((elm)->field.cqe_prev); \
545 _Q_INVALIDATE((elm)->field.cqe_next); \
546 } while (0)
547
548#define CIRCLEQ_REPLACE(head, elm, elm2, field) \
549 do { \
550 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == CIRCLEQ_END(head)) \
551 (head)->cqh_last = (elm2); \
552 else \
553 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
554 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == CIRCLEQ_END(head)) \
555 (head)->cqh_first = (elm2); \
556 else \
557 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
558 _Q_INVALIDATE((elm)->field.cqe_prev); \
559 _Q_INVALIDATE((elm)->field.cqe_next); \
560 } while (0)