1 /* $OpenBSD: queue.h,v 1.22 2001/06/23 04:39:35 angelos Exp $ */
2 /* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
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7 * Licensing, University of California, Berkeley, on the 22nd day of July
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39 * @(#)queue.h 8.5 (Berkeley) 8/20/94
42 #ifndef _LOCAL_SYS_QUEUE_H_
43 #define _LOCAL_SYS_QUEUE_H_
46 * This file defines five types of data structures: singly-linked lists,
47 * lists, simple queues, tail queues, and circular queues.
50 * A singly-linked list is headed by a single forward pointer. The elements
51 * are singly linked for minimum space and pointer manipulation overhead at
52 * the expense of O(n) removal for arbitrary elements. New elements can be
53 * added to the list after an existing element or at the head of the list.
54 * Elements being removed from the head of the list should use the explicit
55 * macro for this purpose for optimum efficiency. A singly-linked list may
56 * only be traversed in the forward direction. Singly-linked lists are ideal
57 * for applications with large datasets and few or no removals or for
58 * implementing a LIFO queue.
60 * A list is headed by a single forward pointer (or an array of forward
61 * pointers for a hash table header). The elements are doubly linked
62 * so that an arbitrary element can be removed without a need to
63 * traverse the list. New elements can be added to the list before
64 * or after an existing element or at the head of the list. A list
65 * may only be traversed in the forward direction.
67 * A simple queue is headed by a pair of pointers, one the head of the
68 * list and the other to the tail of the list. The elements are singly
69 * linked to save space, so elements can only be removed from the
70 * head of the list. New elements can be added to the list before or after
71 * an existing element, at the head of the list, or at the end of the
72 * list. A simple queue may only be traversed in the forward direction.
74 * A tail 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
78 * after an existing element, at the head of the list, or at the end of
79 * the list. A tail queue may be traversed in either direction.
81 * A circle queue is headed by a pair of pointers, one to the head of the
82 * list and the other to the tail of the list. The elements are doubly
83 * linked so that an arbitrary element can be removed without a need to
84 * traverse the list. New elements can be added to the list before or after
85 * an existing element, at the head of the list, or at the end of the list.
86 * A circle queue may be traversed in either direction, but has a more
87 * complex end of list detection.
89 * For details on the use of these macros, see the queue(3) manual page.
93 * Singly-linked List definitions.
95 #define SLIST_HEAD(name, type) \
97 struct type *slh_first; /* first element */ \
100 #define SLIST_HEAD_INITIALIZER(head) \
103 #define SLIST_ENTRY(type) \
105 struct type *sle_next; /* next element */ \
109 * Singly-linked List access methods.
111 #define SLIST_FIRST(head) ((head)->slh_first)
112 #define SLIST_END(head) NULL
113 #define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
114 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
116 #define SLIST_FOREACH(var, head, field) \
117 for((var) = SLIST_FIRST(head); \
118 (var) != SLIST_END(head); \
119 (var) = SLIST_NEXT(var, field))
121 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
122 for((var) = SLIST_FIRST(head); \
123 (var) != SLIST_END(head) && \
124 ((tvar) = SLIST_NEXT(var, field), 1); \
128 * Singly-linked List functions.
130 #define SLIST_INIT(head) { \
131 SLIST_FIRST(head) = SLIST_END(head); \
134 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
135 (elm)->field.sle_next = (slistelm)->field.sle_next; \
136 (slistelm)->field.sle_next = (elm); \
139 #define SLIST_INSERT_HEAD(head, elm, field) do { \
140 (elm)->field.sle_next = (head)->slh_first; \
141 (head)->slh_first = (elm); \
144 #define SLIST_REMOVE_HEAD(head, field) do { \
145 (head)->slh_first = (head)->slh_first->field.sle_next; \
148 #define SLIST_REMOVE(head, elm, type, field) do { \
149 if ((head)->slh_first == (elm)) { \
150 SLIST_REMOVE_HEAD((head), field); \
153 struct type *curelm = (head)->slh_first; \
154 while( curelm->field.sle_next != (elm) ) \
155 curelm = curelm->field.sle_next; \
156 curelm->field.sle_next = \
157 curelm->field.sle_next->field.sle_next; \
164 #define LIST_HEAD(name, type) \
166 struct type *lh_first; /* first element */ \
169 #define LIST_HEAD_INITIALIZER(head) \
172 #define LIST_ENTRY(type) \
174 struct type *le_next; /* next element */ \
175 struct type **le_prev; /* address of previous next element */ \
179 * List access methods
181 #define LIST_FIRST(head) ((head)->lh_first)
182 #define LIST_END(head) NULL
183 #define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
184 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
186 #define LIST_FOREACH(var, head, field) \
187 for((var) = LIST_FIRST(head); \
188 (var)!= LIST_END(head); \
189 (var) = LIST_NEXT(var, field))
191 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
192 for((var) = LIST_FIRST(head); \
193 (var)!= LIST_END(head) && \
194 ((tvar) = LIST_NEXT(var, field), 1); \
201 #define LIST_INIT(head) do { \
202 LIST_FIRST(head) = LIST_END(head); \
205 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
206 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
207 (listelm)->field.le_next->field.le_prev = \
208 &(elm)->field.le_next; \
209 (listelm)->field.le_next = (elm); \
210 (elm)->field.le_prev = &(listelm)->field.le_next; \
213 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
214 (elm)->field.le_prev = (listelm)->field.le_prev; \
215 (elm)->field.le_next = (listelm); \
216 *(listelm)->field.le_prev = (elm); \
217 (listelm)->field.le_prev = &(elm)->field.le_next; \
220 #define LIST_INSERT_HEAD(head, elm, field) do { \
221 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
222 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
223 (head)->lh_first = (elm); \
224 (elm)->field.le_prev = &(head)->lh_first; \
227 #define LIST_REMOVE(elm, field) do { \
228 if ((elm)->field.le_next != NULL) \
229 (elm)->field.le_next->field.le_prev = \
230 (elm)->field.le_prev; \
231 *(elm)->field.le_prev = (elm)->field.le_next; \
234 #define LIST_REPLACE(elm, elm2, field) do { \
235 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
236 (elm2)->field.le_next->field.le_prev = \
237 &(elm2)->field.le_next; \
238 (elm2)->field.le_prev = (elm)->field.le_prev; \
239 *(elm2)->field.le_prev = (elm2); \
243 * Simple queue definitions.
245 #define SIMPLEQ_HEAD(name, type) \
247 struct type *sqh_first; /* first element */ \
248 struct type **sqh_last; /* addr of last next element */ \
251 #define SIMPLEQ_HEAD_INITIALIZER(head) \
252 { NULL, &(head).sqh_first }
254 #define SIMPLEQ_ENTRY(type) \
256 struct type *sqe_next; /* next element */ \
260 * Simple queue access methods.
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)
267 #define SIMPLEQ_FOREACH(var, head, field) \
268 for((var) = SIMPLEQ_FIRST(head); \
269 (var) != SIMPLEQ_END(head); \
270 (var) = SIMPLEQ_NEXT(var, field))
272 #define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
273 for((var) = SIMPLEQ_FIRST(head); \
274 (var) != SIMPLEQ_END(head) && \
275 ((tvar) = SIMPLEQ_NEXT(var, field), 1); \
279 * Simple queue functions.
281 #define SIMPLEQ_INIT(head) do { \
282 (head)->sqh_first = NULL; \
283 (head)->sqh_last = &(head)->sqh_first; \
286 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
287 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
288 (head)->sqh_last = &(elm)->field.sqe_next; \
289 (head)->sqh_first = (elm); \
292 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
293 (elm)->field.sqe_next = NULL; \
294 *(head)->sqh_last = (elm); \
295 (head)->sqh_last = &(elm)->field.sqe_next; \
298 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
299 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
300 (head)->sqh_last = &(elm)->field.sqe_next; \
301 (listelm)->field.sqe_next = (elm); \
304 #define SIMPLEQ_REMOVE_HEAD(head, elm, field) do { \
305 if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) \
306 (head)->sqh_last = &(head)->sqh_first; \
310 * Tail queue definitions.
312 #define TAILQ_HEAD(name, type) \
314 struct type *tqh_first; /* first element */ \
315 struct type **tqh_last; /* addr of last next element */ \
318 #define TAILQ_HEAD_INITIALIZER(head) \
319 { NULL, &(head).tqh_first }
321 #define TAILQ_ENTRY(type) \
323 struct type *tqe_next; /* next element */ \
324 struct type **tqe_prev; /* address of previous next element */ \
328 * tail queue access methods
330 #define TAILQ_FIRST(head) ((head)->tqh_first)
331 #define TAILQ_END(head) NULL
332 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
333 #define TAILQ_LAST(head, headname) \
334 (*(((struct headname *)((head)->tqh_last))->tqh_last))
336 #define TAILQ_PREV(elm, headname, field) \
337 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
338 #define TAILQ_EMPTY(head) \
339 (TAILQ_FIRST(head) == TAILQ_END(head))
341 #define TAILQ_FOREACH(var, head, field) \
342 for((var) = TAILQ_FIRST(head); \
343 (var) != TAILQ_END(head); \
344 (var) = TAILQ_NEXT(var, field))
346 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
347 for((var) = TAILQ_FIRST(head); \
348 (var) != TAILQ_END(head) && \
349 ((tvar) = TAILQ_NEXT(var, field), 1); \
352 #define TAILQ_FOREACH_REVERSE(var, head, field, headname) \
353 for((var) = TAILQ_LAST(head, headname); \
354 (var) != TAILQ_END(head); \
355 (var) = TAILQ_PREV(var, headname, field))
357 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, field, headname, tvar) \
358 for((var) = TAILQ_LAST(head, headname); \
359 (var) != TAILQ_END(head) && \
360 ((tvar) = TAILQ_PREV(var, headname, field), 1); \
364 * Tail queue functions.
366 #define TAILQ_INIT(head) do { \
367 (head)->tqh_first = NULL; \
368 (head)->tqh_last = &(head)->tqh_first; \
371 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
372 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
373 (head)->tqh_first->field.tqe_prev = \
374 &(elm)->field.tqe_next; \
376 (head)->tqh_last = &(elm)->field.tqe_next; \
377 (head)->tqh_first = (elm); \
378 (elm)->field.tqe_prev = &(head)->tqh_first; \
381 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
382 (elm)->field.tqe_next = NULL; \
383 (elm)->field.tqe_prev = (head)->tqh_last; \
384 *(head)->tqh_last = (elm); \
385 (head)->tqh_last = &(elm)->field.tqe_next; \
388 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
389 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
390 (elm)->field.tqe_next->field.tqe_prev = \
391 &(elm)->field.tqe_next; \
393 (head)->tqh_last = &(elm)->field.tqe_next; \
394 (listelm)->field.tqe_next = (elm); \
395 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
398 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
399 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
400 (elm)->field.tqe_next = (listelm); \
401 *(listelm)->field.tqe_prev = (elm); \
402 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
405 #define TAILQ_REMOVE(head, elm, field) do { \
406 if (((elm)->field.tqe_next) != NULL) \
407 (elm)->field.tqe_next->field.tqe_prev = \
408 (elm)->field.tqe_prev; \
410 (head)->tqh_last = (elm)->field.tqe_prev; \
411 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
414 #define TAILQ_REPLACE(head, elm, elm2, field) do { \
415 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
416 (elm2)->field.tqe_next->field.tqe_prev = \
417 &(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); \
425 * Circular queue definitions.
427 #define CIRCLEQ_HEAD(name, type) \
429 struct type *cqh_first; /* first element */ \
430 struct type *cqh_last; /* last element */ \
433 #define CIRCLEQ_HEAD_INITIALIZER(head) \
434 { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
436 #define CIRCLEQ_ENTRY(type) \
438 struct type *cqe_next; /* next element */ \
439 struct type *cqe_prev; /* previous element */ \
443 * Circular queue access methods
445 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
446 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
447 #define CIRCLEQ_END(head) ((void *)(head))
448 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
449 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
450 #define CIRCLEQ_EMPTY(head) \
451 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
453 #define CIRCLEQ_FOREACH(var, head, field) \
454 for((var) = CIRCLEQ_FIRST(head); \
455 (var) != CIRCLEQ_END(head); \
456 (var) = CIRCLEQ_NEXT(var, field))
458 #define CIRCLEQ_FOREACH_SAFE(var, head, field, tvar) \
459 for((var) = CIRCLEQ_FIRST(head); \
460 (var) != CIRCLEQ_END(head) && \
461 ((tvar) = CIRCLEQ_NEXT(var, field), 1); \
464 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
465 for((var) = CIRCLEQ_LAST(head); \
466 (var) != CIRCLEQ_END(head); \
467 (var) = CIRCLEQ_PREV(var, field))
469 #define CIRCLEQ_FOREACH_REVERSE_SAFE(var, head, field, tvar) \
470 for((var) = CIRCLEQ_LAST(head); \
471 (var) != CIRCLEQ_END(head) && \
472 ((tvar) = CIRCLEQ_PREV(var, field), 1); \
476 * Circular queue functions.
478 #define CIRCLEQ_INIT(head) do { \
479 (head)->cqh_first = CIRCLEQ_END(head); \
480 (head)->cqh_last = CIRCLEQ_END(head); \
483 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
484 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
485 (elm)->field.cqe_prev = (listelm); \
486 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
487 (head)->cqh_last = (elm); \
489 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
490 (listelm)->field.cqe_next = (elm); \
493 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
494 (elm)->field.cqe_next = (listelm); \
495 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
496 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
497 (head)->cqh_first = (elm); \
499 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
500 (listelm)->field.cqe_prev = (elm); \
503 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
504 (elm)->field.cqe_next = (head)->cqh_first; \
505 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
506 if ((head)->cqh_last == CIRCLEQ_END(head)) \
507 (head)->cqh_last = (elm); \
509 (head)->cqh_first->field.cqe_prev = (elm); \
510 (head)->cqh_first = (elm); \
513 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
514 (elm)->field.cqe_next = CIRCLEQ_END(head); \
515 (elm)->field.cqe_prev = (head)->cqh_last; \
516 if ((head)->cqh_first == CIRCLEQ_END(head)) \
517 (head)->cqh_first = (elm); \
519 (head)->cqh_last->field.cqe_next = (elm); \
520 (head)->cqh_last = (elm); \
523 #define CIRCLEQ_REMOVE(head, elm, field) do { \
524 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
525 (head)->cqh_last = (elm)->field.cqe_prev; \
527 (elm)->field.cqe_next->field.cqe_prev = \
528 (elm)->field.cqe_prev; \
529 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
530 (head)->cqh_first = (elm)->field.cqe_next; \
532 (elm)->field.cqe_prev->field.cqe_next = \
533 (elm)->field.cqe_next; \
536 #define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
537 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
539 (head).cqh_last = (elm2); \
541 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
542 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
544 (head).cqh_first = (elm2); \
546 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
549 #endif /* !_LOCAL_SYS_QUEUE_H_ */