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
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 SLIST_HEAD(name, type) \
96 struct type *slh_first; /* first element */ \
99 #define SLIST_HEAD_INITIALIZER(head) \
102 #define SLIST_ENTRY(type) \
104 struct type *sle_next; /* next element */ \
108 * Singly-linked List access methods.
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)
115 #define SLIST_FOREACH(var, head, field) \
116 for ((var) = SLIST_FIRST(head); \
117 (var) != SLIST_END(head); \
118 (var) = SLIST_NEXT(var, field))
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))
126 * Singly-linked List functions.
128 #define SLIST_INIT(head) \
130 SLIST_FIRST(head) = SLIST_END(head); \
133 #define SLIST_INSERT_AFTER(slistelm, elm, field) \
135 (elm)->field.sle_next = (slistelm)->field.sle_next; \
136 (slistelm)->field.sle_next = (elm); \
139 #define SLIST_INSERT_HEAD(head, elm, field) \
141 (elm)->field.sle_next = (head)->slh_first; \
142 (head)->slh_first = (elm); \
145 #define SLIST_REMOVE_NEXT(head, elm, field) \
147 (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
150 #define SLIST_REMOVE_HEAD(head, field) \
152 (head)->slh_first = (head)->slh_first->field.sle_next; \
155 #define SLIST_REMOVE(head, elm, type, field) \
157 if ((head)->slh_first == (elm)) { \
158 SLIST_REMOVE_HEAD((head), field); \
160 struct type *curelm = (head)->slh_first; \
162 while (curelm->field.sle_next != (elm)) \
163 curelm = curelm->field.sle_next; \
164 curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \
165 _Q_INVALIDATE((elm)->field.sle_next); \
172 #define LIST_HEAD(name, type) \
174 struct type *lh_first; /* first element */ \
177 #define LIST_HEAD_INITIALIZER(head) \
180 #define LIST_ENTRY(type) \
182 struct type *le_next; /* next element */ \
183 struct type **le_prev; /* address of previous next element */ \
187 * List access methods
189 #define LIST_FIRST(head) ((head)->lh_first)
190 #define LIST_END(head) NULL
191 #define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
192 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
194 #define LIST_FOREACH(var, head, field) \
195 for ((var) = LIST_FIRST(head); \
196 (var) != LIST_END(head); \
197 (var) = LIST_NEXT(var, field))
202 #define LIST_INIT(head) \
204 LIST_FIRST(head) = LIST_END(head); \
207 #define LIST_INSERT_AFTER(listelm, elm, field) \
209 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
210 (listelm)->field.le_next->field.le_prev = &(elm)->field.le_next; \
211 (listelm)->field.le_next = (elm); \
212 (elm)->field.le_prev = &(listelm)->field.le_next; \
215 #define LIST_INSERT_BEFORE(listelm, elm, field) \
217 (elm)->field.le_prev = (listelm)->field.le_prev; \
218 (elm)->field.le_next = (listelm); \
219 *(listelm)->field.le_prev = (elm); \
220 (listelm)->field.le_prev = &(elm)->field.le_next; \
223 #define LIST_INSERT_HEAD(head, elm, field) \
225 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
226 (head)->lh_first->field.le_prev = &(elm)->field.le_next; \
227 (head)->lh_first = (elm); \
228 (elm)->field.le_prev = &(head)->lh_first; \
231 #define LIST_REMOVE(elm, field) \
233 if ((elm)->field.le_next != NULL) \
234 (elm)->field.le_next->field.le_prev = (elm)->field.le_prev; \
235 *(elm)->field.le_prev = (elm)->field.le_next; \
236 _Q_INVALIDATE((elm)->field.le_prev); \
237 _Q_INVALIDATE((elm)->field.le_next); \
240 #define LIST_REPLACE(elm, elm2, field) \
242 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
243 (elm2)->field.le_next->field.le_prev = &(elm2)->field.le_next; \
244 (elm2)->field.le_prev = (elm)->field.le_prev; \
245 *(elm2)->field.le_prev = (elm2); \
246 _Q_INVALIDATE((elm)->field.le_prev); \
247 _Q_INVALIDATE((elm)->field.le_next); \
251 * Simple queue definitions.
253 #define SIMPLEQ_HEAD(name, type) \
255 struct type *sqh_first; /* first element */ \
256 struct type **sqh_last; /* addr of last next element */ \
259 #define SIMPLEQ_HEAD_INITIALIZER(head) \
260 { NULL, &(head).sqh_first }
262 #define SIMPLEQ_ENTRY(type) \
264 struct type *sqe_next; /* next element */ \
268 * Simple queue access methods.
270 #define SIMPLEQ_FIRST(head) ((head)->sqh_first)
271 #define SIMPLEQ_END(head) NULL
272 #define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
273 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
275 #define SIMPLEQ_FOREACH(var, head, field) \
276 for ((var) = SIMPLEQ_FIRST(head); \
277 (var) != SIMPLEQ_END(head); \
278 (var) = SIMPLEQ_NEXT(var, field))
281 * Simple queue functions.
283 #define SIMPLEQ_INIT(head) \
285 (head)->sqh_first = NULL; \
286 (head)->sqh_last = &(head)->sqh_first; \
289 #define SIMPLEQ_INSERT_HEAD(head, elm, field) \
291 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
292 (head)->sqh_last = &(elm)->field.sqe_next; \
293 (head)->sqh_first = (elm); \
296 #define SIMPLEQ_INSERT_TAIL(head, elm, field) \
298 (elm)->field.sqe_next = NULL; \
299 *(head)->sqh_last = (elm); \
300 (head)->sqh_last = &(elm)->field.sqe_next; \
303 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \
305 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \
306 (head)->sqh_last = &(elm)->field.sqe_next; \
307 (listelm)->field.sqe_next = (elm); \
310 #define SIMPLEQ_REMOVE_HEAD(head, field) \
312 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
313 (head)->sqh_last = &(head)->sqh_first; \
317 * Tail queue definitions.
319 #define TAILQ_HEAD(name, type) \
321 struct type *tqh_first; /* first element */ \
322 struct type **tqh_last; /* addr of last next element */ \
325 #define TAILQ_HEAD_INITIALIZER(head) \
326 { NULL, &(head).tqh_first }
328 #define TAILQ_ENTRY(type) \
330 struct type *tqe_next; /* next element */ \
331 struct type **tqe_prev; /* address of previous next element */ \
335 * tail queue access methods
337 #define TAILQ_FIRST(head) ((head)->tqh_first)
338 #define TAILQ_END(head) NULL
339 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
340 #define TAILQ_LAST(head, headname) \
341 (*(((struct headname *)((head)->tqh_last))->tqh_last))
343 #define TAILQ_PREV(elm, headname, field) \
344 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
345 #define TAILQ_EMPTY(head) \
346 (TAILQ_FIRST(head) == TAILQ_END(head))
348 #define TAILQ_FOREACH(var, head, field) \
349 for ((var) = TAILQ_FIRST(head); \
350 (var) != TAILQ_END(head); \
351 (var) = TAILQ_NEXT(var, field))
353 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
354 for ((var) = TAILQ_LAST(head, headname); \
355 (var) != TAILQ_END(head); \
356 (var) = TAILQ_PREV(var, headname, field))
359 * Tail queue functions.
361 #define TAILQ_INIT(head) \
363 (head)->tqh_first = NULL; \
364 (head)->tqh_last = &(head)->tqh_first; \
367 #define TAILQ_INSERT_HEAD(head, elm, field) \
369 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
370 (head)->tqh_first->field.tqe_prev = &(elm)->field.tqe_next; \
372 (head)->tqh_last = &(elm)->field.tqe_next; \
373 (head)->tqh_first = (elm); \
374 (elm)->field.tqe_prev = &(head)->tqh_first; \
377 #define TAILQ_INSERT_TAIL(head, elm, field) \
379 (elm)->field.tqe_next = NULL; \
380 (elm)->field.tqe_prev = (head)->tqh_last; \
381 *(head)->tqh_last = (elm); \
382 (head)->tqh_last = &(elm)->field.tqe_next; \
385 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) \
387 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL) \
388 (elm)->field.tqe_next->field.tqe_prev = &(elm)->field.tqe_next; \
390 (head)->tqh_last = &(elm)->field.tqe_next; \
391 (listelm)->field.tqe_next = (elm); \
392 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
395 #define TAILQ_INSERT_BEFORE(listelm, elm, field) \
397 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
398 (elm)->field.tqe_next = (listelm); \
399 *(listelm)->field.tqe_prev = (elm); \
400 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
403 #define TAILQ_REMOVE(head, elm, field) \
405 if (((elm)->field.tqe_next) != NULL) \
406 (elm)->field.tqe_next->field.tqe_prev = (elm)->field.tqe_prev; \
408 (head)->tqh_last = (elm)->field.tqe_prev; \
409 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
410 _Q_INVALIDATE((elm)->field.tqe_prev); \
411 _Q_INVALIDATE((elm)->field.tqe_next); \
414 #define TAILQ_REPLACE(head, elm, elm2, field) \
416 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
417 (elm2)->field.tqe_next->field.tqe_prev = &(elm2)->field.tqe_next; \
419 (head)->tqh_last = &(elm2)->field.tqe_next; \
420 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
421 *(elm2)->field.tqe_prev = (elm2); \
422 _Q_INVALIDATE((elm)->field.tqe_prev); \
423 _Q_INVALIDATE((elm)->field.tqe_next); \
427 * Circular queue definitions.
429 #define CIRCLEQ_HEAD(name, type) \
431 struct type *cqh_first; /* first element */ \
432 struct type *cqh_last; /* last element */ \
435 #define CIRCLEQ_HEAD_INITIALIZER(head) \
438 , CIRCLEQ_END(&head) \
441 #define CIRCLEQ_ENTRY(type) \
443 struct type *cqe_next; /* next element */ \
444 struct type *cqe_prev; /* previous element */ \
448 * Circular queue access methods
450 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
451 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
452 #define CIRCLEQ_END(head) ((void *)(head))
453 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
454 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
455 #define CIRCLEQ_EMPTY(head) \
456 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
458 #define CIRCLEQ_FOREACH(var, head, field) \
459 for ((var) = CIRCLEQ_FIRST(head); \
460 (var) != CIRCLEQ_END(head); \
461 (var) = CIRCLEQ_NEXT(var, field))
463 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
464 for ((var) = CIRCLEQ_LAST(head); \
465 (var) != CIRCLEQ_END(head); \
466 (var) = CIRCLEQ_PREV(var, field))
469 * Circular queue functions.
471 #define CIRCLEQ_INIT(head) \
473 (head)->cqh_first = CIRCLEQ_END(head); \
474 (head)->cqh_last = CIRCLEQ_END(head); \
477 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) \
479 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
480 (elm)->field.cqe_prev = (listelm); \
481 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
482 (head)->cqh_last = (elm); \
484 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
485 (listelm)->field.cqe_next = (elm); \
488 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) \
490 (elm)->field.cqe_next = (listelm); \
491 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
492 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
493 (head)->cqh_first = (elm); \
495 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
496 (listelm)->field.cqe_prev = (elm); \
499 #define CIRCLEQ_INSERT_HEAD(head, elm, field) \
501 (elm)->field.cqe_next = (head)->cqh_first; \
502 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
503 if ((head)->cqh_last == CIRCLEQ_END(head)) \
504 (head)->cqh_last = (elm); \
506 (head)->cqh_first->field.cqe_prev = (elm); \
507 (head)->cqh_first = (elm); \
510 #define CIRCLEQ_INSERT_TAIL(head, elm, field) \
512 (elm)->field.cqe_next = CIRCLEQ_END(head); \
513 (elm)->field.cqe_prev = (head)->cqh_last; \
514 if ((head)->cqh_first == CIRCLEQ_END(head)) \
515 (head)->cqh_first = (elm); \
517 (head)->cqh_last->field.cqe_next = (elm); \
518 (head)->cqh_last = (elm); \
521 #define CIRCLEQ_REMOVE(head, elm, field) \
523 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
524 (head)->cqh_last = (elm)->field.cqe_prev; \
526 (elm)->field.cqe_next->field.cqe_prev = (elm)->field.cqe_prev; \
527 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
528 (head)->cqh_first = (elm)->field.cqe_next; \
530 (elm)->field.cqe_prev->field.cqe_next = (elm)->field.cqe_next; \
531 _Q_INVALIDATE((elm)->field.cqe_prev); \
532 _Q_INVALIDATE((elm)->field.cqe_next); \
535 #define CIRCLEQ_REPLACE(head, elm, elm2, field) \
537 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == CIRCLEQ_END(head)) \
538 (head)->cqh_last = (elm2); \
540 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
541 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == CIRCLEQ_END(head)) \
542 (head)->cqh_first = (elm2); \
544 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
545 _Q_INVALIDATE((elm)->field.cqe_prev); \
546 _Q_INVALIDATE((elm)->field.cqe_next); \
549 #endif /* !_SYS_QUEUE_H_ */