2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
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15 * This product includes software developed by the University of
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33 * @(#)queue.h 8.5 (Berkeley) 8/20/94
34 * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.7 2002/04/17 14:21:02 des Exp $
40 #include <machine/ansi.h> /* for __offsetof */
43 * This file defines five types of data structures: singly-linked lists,
44 * singly-linked tail queues, lists, tail queues, and circular queues.
46 * A singly-linked list is headed by a single forward pointer. The elements
47 * are singly linked for minimum space and pointer manipulation overhead at
48 * the expense of O(n) removal for arbitrary elements. New elements can be
49 * added to the list after an existing element or at the head of the list.
50 * Elements being removed from the head of the list should use the explicit
51 * macro for this purpose for optimum efficiency. A singly-linked list may
52 * only be traversed in the forward direction. Singly-linked lists are ideal
53 * for applications with large datasets and few or no removals or for
54 * implementing a LIFO queue.
56 * A singly-linked tail queue is headed by a pair of pointers, one to the
57 * head of the list and the other to the tail of the list. The elements are
58 * singly linked for minimum space and pointer manipulation overhead at the
59 * expense of O(n) removal for arbitrary elements. New elements can be added
60 * to the list after an existing element, at the head of the list, or at the
61 * end of the list. Elements being removed from the head of the tail queue
62 * should use the explicit macro for this purpose for optimum efficiency.
63 * A singly-linked tail queue may only be traversed in the forward direction.
64 * Singly-linked tail queues are ideal for applications with large datasets
65 * and few or no removals or for implementing a FIFO queue.
67 * A list is headed by a single forward pointer (or an array of forward
68 * pointers for a hash table header). The elements are doubly linked
69 * 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
71 * or after an existing element or at the head of the list. A list
72 * 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.
92 * SLIST LIST STAILQ TAILQ CIRCLEQ
94 * _HEAD_INITIALIZER + + + + +
103 * _FOREACH_REVERSE - - - + +
104 * _INSERT_HEAD + + + + +
105 * _INSERT_BEFORE - + - + +
106 * _INSERT_AFTER + + + + +
107 * _INSERT_TAIL - - + + +
108 * _REMOVE_HEAD + - + - -
114 * Singly-linked List declarations.
116 #define SLIST_HEAD(name, type) \
118 struct type *slh_first; /* first element */ \
121 #define SLIST_HEAD_INITIALIZER(head) \
124 #define SLIST_ENTRY(type) \
126 struct type *sle_next; /* next element */ \
130 * Singly-linked List functions.
132 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
134 #define SLIST_FIRST(head) ((head)->slh_first)
136 #define SLIST_FOREACH(var, head, field) \
137 for ((var) = SLIST_FIRST((head)); \
139 (var) = SLIST_NEXT((var), field))
141 #define SLIST_INIT(head) do { \
142 SLIST_FIRST((head)) = NULL; \
145 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
146 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
147 SLIST_NEXT((slistelm), field) = (elm); \
150 #define SLIST_INSERT_HEAD(head, elm, field) do { \
151 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
152 SLIST_FIRST((head)) = (elm); \
155 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
157 #define SLIST_REMOVE(head, elm, type, field) do { \
158 if (SLIST_FIRST((head)) == (elm)) { \
159 SLIST_REMOVE_HEAD((head), field); \
162 struct type *curelm = SLIST_FIRST((head)); \
163 while (SLIST_NEXT(curelm, field) != (elm)) \
164 curelm = SLIST_NEXT(curelm, field); \
165 SLIST_NEXT(curelm, field) = \
166 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
170 #define SLIST_REMOVE_HEAD(head, field) do { \
171 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
175 * Singly-linked Tail queue declarations.
177 #define STAILQ_HEAD(name, type) \
179 struct type *stqh_first;/* first element */ \
180 struct type **stqh_last;/* addr of last next element */ \
183 #define STAILQ_HEAD_INITIALIZER(head) \
184 { NULL, &(head).stqh_first }
186 #define STAILQ_ENTRY(type) \
188 struct type *stqe_next; /* next element */ \
192 * Singly-linked Tail queue functions.
194 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
196 #define STAILQ_FIRST(head) ((head)->stqh_first)
198 #define STAILQ_FOREACH(var, head, field) \
199 for((var) = STAILQ_FIRST((head)); \
201 (var) = STAILQ_NEXT((var), field))
203 #define STAILQ_INIT(head) do { \
204 STAILQ_FIRST((head)) = NULL; \
205 (head)->stqh_last = &STAILQ_FIRST((head)); \
208 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
209 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
210 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
211 STAILQ_NEXT((tqelm), field) = (elm); \
214 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
215 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
216 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
217 STAILQ_FIRST((head)) = (elm); \
220 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
221 STAILQ_NEXT((elm), field) = NULL; \
222 *(head)->stqh_last = (elm); \
223 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
226 #define STAILQ_LAST(head, type, field) \
227 (STAILQ_EMPTY(head) ? \
230 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
232 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
234 #define STAILQ_REMOVE(head, elm, type, field) do { \
235 if (STAILQ_FIRST((head)) == (elm)) { \
236 STAILQ_REMOVE_HEAD(head, field); \
239 struct type *curelm = STAILQ_FIRST((head)); \
240 while (STAILQ_NEXT(curelm, field) != (elm)) \
241 curelm = STAILQ_NEXT(curelm, field); \
242 if ((STAILQ_NEXT(curelm, field) = \
243 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
244 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
248 #define STAILQ_REMOVE_HEAD(head, field) do { \
249 if ((STAILQ_FIRST((head)) = \
250 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
251 (head)->stqh_last = &STAILQ_FIRST((head)); \
254 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
255 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
256 (head)->stqh_last = &STAILQ_FIRST((head)); \
262 #define LIST_HEAD(name, type) \
264 struct type *lh_first; /* first element */ \
267 #define LIST_HEAD_INITIALIZER(head) \
270 #define LIST_ENTRY(type) \
272 struct type *le_next; /* next element */ \
273 struct type **le_prev; /* address of previous next element */ \
280 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
282 #define LIST_FIRST(head) ((head)->lh_first)
284 #define LIST_FOREACH(var, head, field) \
285 for ((var) = LIST_FIRST((head)); \
287 (var) = LIST_NEXT((var), field))
289 #define LIST_INIT(head) do { \
290 LIST_FIRST((head)) = NULL; \
293 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
294 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
295 LIST_NEXT((listelm), field)->field.le_prev = \
296 &LIST_NEXT((elm), field); \
297 LIST_NEXT((listelm), field) = (elm); \
298 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
301 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
302 (elm)->field.le_prev = (listelm)->field.le_prev; \
303 LIST_NEXT((elm), field) = (listelm); \
304 *(listelm)->field.le_prev = (elm); \
305 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
308 #define LIST_INSERT_HEAD(head, elm, field) do { \
309 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
310 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
311 LIST_FIRST((head)) = (elm); \
312 (elm)->field.le_prev = &LIST_FIRST((head)); \
315 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
317 #define LIST_REMOVE(elm, field) do { \
318 if (LIST_NEXT((elm), field) != NULL) \
319 LIST_NEXT((elm), field)->field.le_prev = \
320 (elm)->field.le_prev; \
321 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
325 * Tail queue declarations.
327 #define TAILQ_HEAD(name, type) \
329 struct type *tqh_first; /* first element */ \
330 struct type **tqh_last; /* addr of last next element */ \
333 #define TAILQ_HEAD_INITIALIZER(head) \
334 { NULL, &(head).tqh_first }
336 #define TAILQ_ENTRY(type) \
338 struct type *tqe_next; /* next element */ \
339 struct type **tqe_prev; /* address of previous next element */ \
343 * Tail queue functions.
345 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
347 #define TAILQ_FIRST(head) ((head)->tqh_first)
349 #define TAILQ_FOREACH(var, head, field) \
350 for ((var) = TAILQ_FIRST((head)); \
352 (var) = TAILQ_NEXT((var), field))
354 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
355 for ((var) = TAILQ_LAST((head), headname); \
357 (var) = TAILQ_PREV((var), headname, field))
359 #define TAILQ_INIT(head) do { \
360 TAILQ_FIRST((head)) = NULL; \
361 (head)->tqh_last = &TAILQ_FIRST((head)); \
364 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
365 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
366 TAILQ_NEXT((elm), field)->field.tqe_prev = \
367 &TAILQ_NEXT((elm), field); \
369 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
370 TAILQ_NEXT((listelm), field) = (elm); \
371 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
374 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
375 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
376 TAILQ_NEXT((elm), field) = (listelm); \
377 *(listelm)->field.tqe_prev = (elm); \
378 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
381 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
382 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
383 TAILQ_FIRST((head))->field.tqe_prev = \
384 &TAILQ_NEXT((elm), field); \
386 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
387 TAILQ_FIRST((head)) = (elm); \
388 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
391 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
392 TAILQ_NEXT((elm), field) = NULL; \
393 (elm)->field.tqe_prev = (head)->tqh_last; \
394 *(head)->tqh_last = (elm); \
395 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
398 #define TAILQ_LAST(head, headname) \
399 (*(((struct headname *)((head)->tqh_last))->tqh_last))
401 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
403 #define TAILQ_PREV(elm, headname, field) \
404 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
406 #define TAILQ_REMOVE(head, elm, field) do { \
407 if ((TAILQ_NEXT((elm), field)) != NULL) \
408 TAILQ_NEXT((elm), field)->field.tqe_prev = \
409 (elm)->field.tqe_prev; \
411 (head)->tqh_last = (elm)->field.tqe_prev; \
412 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
416 * Circular queue declarations.
418 #define CIRCLEQ_HEAD(name, type) \
420 struct type *cqh_first; /* first element */ \
421 struct type *cqh_last; /* last element */ \
424 #define CIRCLEQ_HEAD_INITIALIZER(head) \
425 { (void *)&(head), (void *)&(head) }
427 #define CIRCLEQ_ENTRY(type) \
429 struct type *cqe_next; /* next element */ \
430 struct type *cqe_prev; /* previous element */ \
434 * Circular queue functions.
436 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
438 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
440 #define CIRCLEQ_FOREACH(var, head, field) \
441 for ((var) = CIRCLEQ_FIRST((head)); \
442 (var) != (void *)(head) || ((var) = NULL); \
443 (var) = CIRCLEQ_NEXT((var), field))
445 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
446 for ((var) = CIRCLEQ_LAST((head)); \
447 (var) != (void *)(head) || ((var) = NULL); \
448 (var) = CIRCLEQ_PREV((var), field))
450 #define CIRCLEQ_INIT(head) do { \
451 CIRCLEQ_FIRST((head)) = (void *)(head); \
452 CIRCLEQ_LAST((head)) = (void *)(head); \
455 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
456 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \
457 CIRCLEQ_PREV((elm), field) = (listelm); \
458 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \
459 CIRCLEQ_LAST((head)) = (elm); \
461 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\
462 CIRCLEQ_NEXT((listelm), field) = (elm); \
465 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
466 CIRCLEQ_NEXT((elm), field) = (listelm); \
467 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \
468 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \
469 CIRCLEQ_FIRST((head)) = (elm); \
471 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\
472 CIRCLEQ_PREV((listelm), field) = (elm); \
475 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
476 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \
477 CIRCLEQ_PREV((elm), field) = (void *)(head); \
478 if (CIRCLEQ_LAST((head)) == (void *)(head)) \
479 CIRCLEQ_LAST((head)) = (elm); \
481 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \
482 CIRCLEQ_FIRST((head)) = (elm); \
485 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
486 CIRCLEQ_NEXT((elm), field) = (void *)(head); \
487 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \
488 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \
489 CIRCLEQ_FIRST((head)) = (elm); \
491 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \
492 CIRCLEQ_LAST((head)) = (elm); \
495 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
497 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
499 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
501 #define CIRCLEQ_REMOVE(head, elm, field) do { \
502 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \
503 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \
505 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \
506 CIRCLEQ_PREV((elm), field); \
507 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \
508 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \
510 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \
511 CIRCLEQ_NEXT((elm), field); \
517 * XXX insque() and remque() are an old way of handling certain queues.
518 * They bogusly assumes that all queue heads look alike.
522 struct quehead *qh_link;
523 struct quehead *qh_rlink;
529 insque(void *a, void *b)
531 struct quehead *element = (struct quehead *)a,
532 *head = (struct quehead *)b;
534 element->qh_link = head->qh_link;
535 element->qh_rlink = head;
536 head->qh_link = element;
537 element->qh_link->qh_rlink = element;
543 struct quehead *element = (struct quehead *)a;
545 element->qh_link->qh_rlink = element->qh_rlink;
546 element->qh_rlink->qh_link = element->qh_link;
547 element->qh_rlink = 0;
550 #else /* !__GNUC__ */
552 void insque __P((void *a, void *b));
553 void remque __P((void *a));
555 #endif /* __GNUC__ */
559 #endif /* !_SYS_QUEUE_H_ */