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) { \
128 SLIST_FIRST(head) = SLIST_END(head); \
131 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
132 (elm)->field.sle_next = (slistelm)->field.sle_next; \
133 (slistelm)->field.sle_next = (elm); \
136 #define SLIST_INSERT_HEAD(head, elm, field) do { \
137 (elm)->field.sle_next = (head)->slh_first; \
138 (head)->slh_first = (elm); \
141 #define SLIST_REMOVE_NEXT(head, elm, field) do { \
142 (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
145 #define SLIST_REMOVE_HEAD(head, field) do { \
146 (head)->slh_first = (head)->slh_first->field.sle_next; \
149 #define SLIST_REMOVE(head, elm, type, field) do { \
150 if ((head)->slh_first == (elm)) { \
151 SLIST_REMOVE_HEAD((head), field); \
153 struct type *curelm = (head)->slh_first; \
155 while (curelm->field.sle_next != (elm)) \
156 curelm = curelm->field.sle_next; \
157 curelm->field.sle_next = \
158 curelm->field.sle_next->field.sle_next; \
159 _Q_INVALIDATE((elm)->field.sle_next); \
166 #define LIST_HEAD(name, type) \
168 struct type *lh_first; /* first element */ \
171 #define LIST_HEAD_INITIALIZER(head) \
174 #define LIST_ENTRY(type) \
176 struct type *le_next; /* next element */ \
177 struct type **le_prev; /* address of previous next element */ \
181 * List access methods
183 #define LIST_FIRST(head) ((head)->lh_first)
184 #define LIST_END(head) NULL
185 #define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
186 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
188 #define LIST_FOREACH(var, head, field) \
189 for((var) = LIST_FIRST(head); \
190 (var)!= LIST_END(head); \
191 (var) = LIST_NEXT(var, field))
196 #define LIST_INIT(head) do { \
197 LIST_FIRST(head) = LIST_END(head); \
200 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
201 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
202 (listelm)->field.le_next->field.le_prev = \
203 &(elm)->field.le_next; \
204 (listelm)->field.le_next = (elm); \
205 (elm)->field.le_prev = &(listelm)->field.le_next; \
208 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
209 (elm)->field.le_prev = (listelm)->field.le_prev; \
210 (elm)->field.le_next = (listelm); \
211 *(listelm)->field.le_prev = (elm); \
212 (listelm)->field.le_prev = &(elm)->field.le_next; \
215 #define LIST_INSERT_HEAD(head, elm, field) do { \
216 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
217 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
218 (head)->lh_first = (elm); \
219 (elm)->field.le_prev = &(head)->lh_first; \
222 #define LIST_REMOVE(elm, field) do { \
223 if ((elm)->field.le_next != NULL) \
224 (elm)->field.le_next->field.le_prev = \
225 (elm)->field.le_prev; \
226 *(elm)->field.le_prev = (elm)->field.le_next; \
227 _Q_INVALIDATE((elm)->field.le_prev); \
228 _Q_INVALIDATE((elm)->field.le_next); \
231 #define LIST_REPLACE(elm, elm2, field) do { \
232 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
233 (elm2)->field.le_next->field.le_prev = \
234 &(elm2)->field.le_next; \
235 (elm2)->field.le_prev = (elm)->field.le_prev; \
236 *(elm2)->field.le_prev = (elm2); \
237 _Q_INVALIDATE((elm)->field.le_prev); \
238 _Q_INVALIDATE((elm)->field.le_next); \
242 * Simple queue definitions.
244 #define SIMPLEQ_HEAD(name, type) \
246 struct type *sqh_first; /* first element */ \
247 struct type **sqh_last; /* addr of last next element */ \
250 #define SIMPLEQ_HEAD_INITIALIZER(head) \
251 { NULL, &(head).sqh_first }
253 #define SIMPLEQ_ENTRY(type) \
255 struct type *sqe_next; /* next element */ \
259 * Simple queue access methods.
261 #define SIMPLEQ_FIRST(head) ((head)->sqh_first)
262 #define SIMPLEQ_END(head) NULL
263 #define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
264 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
266 #define SIMPLEQ_FOREACH(var, head, field) \
267 for((var) = SIMPLEQ_FIRST(head); \
268 (var) != SIMPLEQ_END(head); \
269 (var) = SIMPLEQ_NEXT(var, field))
272 * Simple queue functions.
274 #define SIMPLEQ_INIT(head) do { \
275 (head)->sqh_first = NULL; \
276 (head)->sqh_last = &(head)->sqh_first; \
279 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
280 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
281 (head)->sqh_last = &(elm)->field.sqe_next; \
282 (head)->sqh_first = (elm); \
285 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
286 (elm)->field.sqe_next = NULL; \
287 *(head)->sqh_last = (elm); \
288 (head)->sqh_last = &(elm)->field.sqe_next; \
291 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
292 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
293 (head)->sqh_last = &(elm)->field.sqe_next; \
294 (listelm)->field.sqe_next = (elm); \
297 #define SIMPLEQ_REMOVE_HEAD(head, field) do { \
298 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
299 (head)->sqh_last = &(head)->sqh_first; \
303 * Tail queue definitions.
305 #define TAILQ_HEAD(name, type) \
307 struct type *tqh_first; /* first element */ \
308 struct type **tqh_last; /* addr of last next element */ \
311 #define TAILQ_HEAD_INITIALIZER(head) \
312 { NULL, &(head).tqh_first }
314 #define TAILQ_ENTRY(type) \
316 struct type *tqe_next; /* next element */ \
317 struct type **tqe_prev; /* address of previous next element */ \
321 * tail queue access methods
323 #define TAILQ_FIRST(head) ((head)->tqh_first)
324 #define TAILQ_END(head) NULL
325 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
326 #define TAILQ_LAST(head, headname) \
327 (*(((struct headname *)((head)->tqh_last))->tqh_last))
329 #define TAILQ_PREV(elm, headname, field) \
330 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
331 #define TAILQ_EMPTY(head) \
332 (TAILQ_FIRST(head) == TAILQ_END(head))
334 #define TAILQ_FOREACH(var, head, field) \
335 for((var) = TAILQ_FIRST(head); \
336 (var) != TAILQ_END(head); \
337 (var) = TAILQ_NEXT(var, field))
339 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
340 for((var) = TAILQ_LAST(head, headname); \
341 (var) != TAILQ_END(head); \
342 (var) = TAILQ_PREV(var, headname, field))
345 * Tail queue functions.
347 #define TAILQ_INIT(head) do { \
348 (head)->tqh_first = NULL; \
349 (head)->tqh_last = &(head)->tqh_first; \
352 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
353 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
354 (head)->tqh_first->field.tqe_prev = \
355 &(elm)->field.tqe_next; \
357 (head)->tqh_last = &(elm)->field.tqe_next; \
358 (head)->tqh_first = (elm); \
359 (elm)->field.tqe_prev = &(head)->tqh_first; \
362 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
363 (elm)->field.tqe_next = NULL; \
364 (elm)->field.tqe_prev = (head)->tqh_last; \
365 *(head)->tqh_last = (elm); \
366 (head)->tqh_last = &(elm)->field.tqe_next; \
369 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
370 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
371 (elm)->field.tqe_next->field.tqe_prev = \
372 &(elm)->field.tqe_next; \
374 (head)->tqh_last = &(elm)->field.tqe_next; \
375 (listelm)->field.tqe_next = (elm); \
376 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
379 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
380 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
381 (elm)->field.tqe_next = (listelm); \
382 *(listelm)->field.tqe_prev = (elm); \
383 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
386 #define TAILQ_REMOVE(head, elm, field) do { \
387 if (((elm)->field.tqe_next) != NULL) \
388 (elm)->field.tqe_next->field.tqe_prev = \
389 (elm)->field.tqe_prev; \
391 (head)->tqh_last = (elm)->field.tqe_prev; \
392 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
393 _Q_INVALIDATE((elm)->field.tqe_prev); \
394 _Q_INVALIDATE((elm)->field.tqe_next); \
397 #define TAILQ_REPLACE(head, elm, elm2, field) do { \
398 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
399 (elm2)->field.tqe_next->field.tqe_prev = \
400 &(elm2)->field.tqe_next; \
402 (head)->tqh_last = &(elm2)->field.tqe_next; \
403 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
404 *(elm2)->field.tqe_prev = (elm2); \
405 _Q_INVALIDATE((elm)->field.tqe_prev); \
406 _Q_INVALIDATE((elm)->field.tqe_next); \
410 * Circular queue definitions.
412 #define CIRCLEQ_HEAD(name, type) \
414 struct type *cqh_first; /* first element */ \
415 struct type *cqh_last; /* last element */ \
418 #define CIRCLEQ_HEAD_INITIALIZER(head) \
419 { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
421 #define CIRCLEQ_ENTRY(type) \
423 struct type *cqe_next; /* next element */ \
424 struct type *cqe_prev; /* previous element */ \
428 * Circular queue access methods
430 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
431 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
432 #define CIRCLEQ_END(head) ((void *)(head))
433 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
434 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
435 #define CIRCLEQ_EMPTY(head) \
436 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
438 #define CIRCLEQ_FOREACH(var, head, field) \
439 for((var) = CIRCLEQ_FIRST(head); \
440 (var) != CIRCLEQ_END(head); \
441 (var) = CIRCLEQ_NEXT(var, field))
443 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
444 for((var) = CIRCLEQ_LAST(head); \
445 (var) != CIRCLEQ_END(head); \
446 (var) = CIRCLEQ_PREV(var, field))
449 * Circular queue functions.
451 #define CIRCLEQ_INIT(head) do { \
452 (head)->cqh_first = CIRCLEQ_END(head); \
453 (head)->cqh_last = CIRCLEQ_END(head); \
456 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
457 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
458 (elm)->field.cqe_prev = (listelm); \
459 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
460 (head)->cqh_last = (elm); \
462 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
463 (listelm)->field.cqe_next = (elm); \
466 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
467 (elm)->field.cqe_next = (listelm); \
468 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
469 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
470 (head)->cqh_first = (elm); \
472 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
473 (listelm)->field.cqe_prev = (elm); \
476 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
477 (elm)->field.cqe_next = (head)->cqh_first; \
478 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
479 if ((head)->cqh_last == CIRCLEQ_END(head)) \
480 (head)->cqh_last = (elm); \
482 (head)->cqh_first->field.cqe_prev = (elm); \
483 (head)->cqh_first = (elm); \
486 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
487 (elm)->field.cqe_next = CIRCLEQ_END(head); \
488 (elm)->field.cqe_prev = (head)->cqh_last; \
489 if ((head)->cqh_first == CIRCLEQ_END(head)) \
490 (head)->cqh_first = (elm); \
492 (head)->cqh_last->field.cqe_next = (elm); \
493 (head)->cqh_last = (elm); \
496 #define CIRCLEQ_REMOVE(head, elm, field) do { \
497 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
498 (head)->cqh_last = (elm)->field.cqe_prev; \
500 (elm)->field.cqe_next->field.cqe_prev = \
501 (elm)->field.cqe_prev; \
502 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
503 (head)->cqh_first = (elm)->field.cqe_next; \
505 (elm)->field.cqe_prev->field.cqe_next = \
506 (elm)->field.cqe_next; \
507 _Q_INVALIDATE((elm)->field.cqe_prev); \
508 _Q_INVALIDATE((elm)->field.cqe_next); \
511 #define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
512 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
514 (head)->cqh_last = (elm2); \
516 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
517 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
519 (head)->cqh_first = (elm2); \
521 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
522 _Q_INVALIDATE((elm)->field.cqe_prev); \
523 _Q_INVALIDATE((elm)->field.cqe_next); \