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 $ */
5 * Copyright (c) 1991, 1993
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32 * @(#)queue.h 8.5 (Berkeley) 8/20/94
38 * This file defines five types of data structures: singly-linked lists,
39 * lists, simple queues, tail queues, and circular queues.
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.
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.
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.
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.
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.
81 * For details on the use of these macros, see the queue(3) manual page.
84 #if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
85 #define _Q_INVALIDATE(a) (a) = ((void *)-1)
87 #define _Q_INVALIDATE(a)
91 * Singly-linked List definitions.
93 #define SLIST_HEAD(name, type) \
95 struct type *slh_first; /* first element */ \
98 #define SLIST_HEAD_INITIALIZER(head) \
101 #define SLIST_ENTRY(type) \
103 struct type *sle_next; /* next element */ \
107 * Singly-linked List access methods.
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)
114 #define SLIST_FOREACH(var, head, field) \
115 for ((var) = SLIST_FIRST(head); \
116 (var) != SLIST_END(head); \
117 (var) = SLIST_NEXT(var, field))
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))
125 * Singly-linked List functions.
127 #define SLIST_INIT(head) \
129 SLIST_FIRST(head) = SLIST_END(head); \
132 #define SLIST_INSERT_AFTER(slistelm, elm, field) \
134 (elm)->field.sle_next = (slistelm)->field.sle_next; \
135 (slistelm)->field.sle_next = (elm); \
138 #define SLIST_INSERT_HEAD(head, elm, field) \
140 (elm)->field.sle_next = (head)->slh_first; \
141 (head)->slh_first = (elm); \
144 #define SLIST_REMOVE_NEXT(head, elm, field) \
146 (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
149 #define SLIST_REMOVE_HEAD(head, field) \
151 (head)->slh_first = (head)->slh_first->field.sle_next; \
154 #define SLIST_REMOVE(head, elm, type, field) \
156 if ((head)->slh_first == (elm)) { \
157 SLIST_REMOVE_HEAD((head), field); \
159 struct type *curelm = (head)->slh_first; \
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); \
171 #define LIST_HEAD(name, type) \
173 struct type *lh_first; /* first element */ \
176 #define LIST_HEAD_INITIALIZER(head) \
179 #define LIST_ENTRY(type) \
181 struct type *le_next; /* next element */ \
182 struct type **le_prev; /* address of previous next element */ \
186 * List access methods
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)
193 #define LIST_FOREACH(var, head, field) \
194 for ((var) = LIST_FIRST(head); \
195 (var) != LIST_END(head); \
196 (var) = LIST_NEXT(var, field))
201 #define LIST_INIT(head) \
203 LIST_FIRST(head) = LIST_END(head); \
206 #define LIST_INSERT_AFTER(listelm, elm, field) \
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; \
214 #define LIST_INSERT_BEFORE(listelm, elm, field) \
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; \
222 #define LIST_INSERT_HEAD(head, elm, field) \
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; \
230 #define LIST_REMOVE(elm, field) \
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); \
239 #define LIST_REPLACE(elm, elm2, field) \
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); \
250 * Simple queue definitions.
252 #define SIMPLEQ_HEAD(name, type) \
254 struct type *sqh_first; /* first element */ \
255 struct type **sqh_last; /* addr of last next element */ \
258 #define SIMPLEQ_HEAD_INITIALIZER(head) \
259 { NULL, &(head).sqh_first }
261 #define SIMPLEQ_ENTRY(type) \
263 struct type *sqe_next; /* next element */ \
267 * Simple queue access methods.
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)
274 #define SIMPLEQ_FOREACH(var, head, field) \
275 for ((var) = SIMPLEQ_FIRST(head); \
276 (var) != SIMPLEQ_END(head); \
277 (var) = SIMPLEQ_NEXT(var, field))
280 * Simple queue functions.
282 #define SIMPLEQ_INIT(head) \
284 (head)->sqh_first = NULL; \
285 (head)->sqh_last = &(head)->sqh_first; \
288 #define SIMPLEQ_INSERT_HEAD(head, elm, field) \
290 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
291 (head)->sqh_last = &(elm)->field.sqe_next; \
292 (head)->sqh_first = (elm); \
295 #define SIMPLEQ_INSERT_TAIL(head, elm, field) \
297 (elm)->field.sqe_next = NULL; \
298 *(head)->sqh_last = (elm); \
299 (head)->sqh_last = &(elm)->field.sqe_next; \
302 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \
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); \
309 #define SIMPLEQ_REMOVE_HEAD(head, field) \
311 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
312 (head)->sqh_last = &(head)->sqh_first; \
316 * Tail queue definitions.
318 #define TAILQ_HEAD(name, type) \
320 struct type *tqh_first; /* first element */ \
321 struct type **tqh_last; /* addr of last next element */ \
324 #define TAILQ_HEAD_INITIALIZER(head) \
325 { NULL, &(head).tqh_first }
327 #define TAILQ_ENTRY(type) \
329 struct type *tqe_next; /* next element */ \
330 struct type **tqe_prev; /* address of previous next element */ \
334 * tail queue access methods
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))
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))
347 #define TAILQ_FOREACH(var, head, field) \
348 for ((var) = TAILQ_FIRST(head); \
349 (var) != TAILQ_END(head); \
350 (var) = TAILQ_NEXT(var, field))
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))
358 * Tail queue functions.
360 #define TAILQ_INIT(head) \
362 (head)->tqh_first = NULL; \
363 (head)->tqh_last = &(head)->tqh_first; \
366 #define TAILQ_INSERT_HEAD(head, elm, field) \
368 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
369 (head)->tqh_first->field.tqe_prev = &(elm)->field.tqe_next; \
371 (head)->tqh_last = &(elm)->field.tqe_next; \
372 (head)->tqh_first = (elm); \
373 (elm)->field.tqe_prev = &(head)->tqh_first; \
376 #define TAILQ_INSERT_TAIL(head, elm, field) \
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; \
384 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) \
386 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL) \
387 (elm)->field.tqe_next->field.tqe_prev = &(elm)->field.tqe_next; \
389 (head)->tqh_last = &(elm)->field.tqe_next; \
390 (listelm)->field.tqe_next = (elm); \
391 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
394 #define TAILQ_INSERT_BEFORE(listelm, elm, field) \
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; \
402 #define TAILQ_REMOVE(head, elm, field) \
404 if (((elm)->field.tqe_next) != NULL) \
405 (elm)->field.tqe_next->field.tqe_prev = (elm)->field.tqe_prev; \
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); \
413 #define TAILQ_REPLACE(head, elm, elm2, field) \
415 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
416 (elm2)->field.tqe_next->field.tqe_prev = &(elm2)->field.tqe_next; \
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); \
425 /* Swaps two consecutive elements. 'second' *MUST* follow 'first' */
426 #define TAILQ_SWAP(first, second, head, field) \
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); \
440 * Circular queue definitions.
442 #define CIRCLEQ_HEAD(name, type) \
444 struct type *cqh_first; /* first element */ \
445 struct type *cqh_last; /* last element */ \
448 #define CIRCLEQ_HEAD_INITIALIZER(head) \
451 , CIRCLEQ_END(&head) \
454 #define CIRCLEQ_ENTRY(type) \
456 struct type *cqe_next; /* next element */ \
457 struct type *cqe_prev; /* previous element */ \
461 * Circular queue access methods
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))
471 #define CIRCLEQ_FOREACH(var, head, field) \
472 for ((var) = CIRCLEQ_FIRST(head); \
473 (var) != CIRCLEQ_END(head); \
474 (var) = CIRCLEQ_NEXT(var, field))
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))
482 * Circular queue functions.
484 #define CIRCLEQ_INIT(head) \
486 (head)->cqh_first = CIRCLEQ_END(head); \
487 (head)->cqh_last = CIRCLEQ_END(head); \
490 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) \
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); \
497 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
498 (listelm)->field.cqe_next = (elm); \
501 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) \
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); \
508 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
509 (listelm)->field.cqe_prev = (elm); \
512 #define CIRCLEQ_INSERT_HEAD(head, elm, field) \
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); \
519 (head)->cqh_first->field.cqe_prev = (elm); \
520 (head)->cqh_first = (elm); \
523 #define CIRCLEQ_INSERT_TAIL(head, elm, field) \
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); \
530 (head)->cqh_last->field.cqe_next = (elm); \
531 (head)->cqh_last = (elm); \
534 #define CIRCLEQ_REMOVE(head, elm, field) \
536 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
537 (head)->cqh_last = (elm)->field.cqe_prev; \
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; \
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); \
548 #define CIRCLEQ_REPLACE(head, elm, elm2, field) \
550 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == CIRCLEQ_END(head)) \
551 (head)->cqh_last = (elm2); \
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); \
557 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
558 _Q_INVALIDATE((elm)->field.cqe_prev); \
559 _Q_INVALIDATE((elm)->field.cqe_next); \