2 * Copyright (c) 1991, 1993
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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 $
35 * $DragonFly: src/sys/sys/queue.h,v 1.2 2003/06/17 04:28:58 dillon Exp $
41 #include <machine/ansi.h> /* for __offsetof */
44 * This file defines five types of data structures: singly-linked lists,
45 * singly-linked tail queues, lists, tail queues, and circular queues.
47 * A singly-linked list is headed by a single forward pointer. The elements
48 * are singly linked for minimum space and pointer manipulation overhead at
49 * the expense of O(n) removal for arbitrary elements. New elements can be
50 * added to the list after an existing element or at the head of the list.
51 * Elements being removed from the head of the list should use the explicit
52 * macro for this purpose for optimum efficiency. A singly-linked list may
53 * only be traversed in the forward direction. Singly-linked lists are ideal
54 * for applications with large datasets and few or no removals or for
55 * implementing a LIFO queue.
57 * A singly-linked tail queue is headed by a pair of pointers, one to the
58 * head of the list and the other to the tail of the list. The elements are
59 * singly linked for minimum space and pointer manipulation overhead at the
60 * expense of O(n) removal for arbitrary elements. New elements can be added
61 * to the list after an existing element, at the head of the list, or at the
62 * end of the list. Elements being removed from the head of the tail queue
63 * should use the explicit macro for this purpose for optimum efficiency.
64 * A singly-linked tail queue may only be traversed in the forward direction.
65 * Singly-linked tail queues are ideal for applications with large datasets
66 * and few or no removals or for implementing a FIFO queue.
68 * A list is headed by a single forward pointer (or an array of forward
69 * pointers for a hash table header). The elements are doubly linked
70 * so that an arbitrary element can be removed without a need to
71 * traverse the list. New elements can be added to the list before
72 * or after an existing element or at the head of the list. A list
73 * may only be traversed in the forward direction.
75 * A tail queue is headed by a pair of pointers, one to the head of the
76 * list and the other to the tail of the list. The elements are doubly
77 * linked so that an arbitrary element can be removed without a need to
78 * traverse the list. New elements can be added to the list before or
79 * after an existing element, at the head of the list, or at the end of
80 * the list. A tail queue may be traversed in either direction.
82 * A circle queue is headed by a pair of pointers, one to the head of the
83 * list and the other to the tail of the list. The elements are doubly
84 * linked so that an arbitrary element can be removed without a need to
85 * traverse the list. New elements can be added to the list before or after
86 * an existing element, at the head of the list, or at the end of the list.
87 * A circle queue may be traversed in either direction, but has a more
88 * complex end of list detection.
90 * For details on the use of these macros, see the queue(3) manual page.
93 * SLIST LIST STAILQ TAILQ CIRCLEQ
95 * _HEAD_INITIALIZER + + + + +
104 * _FOREACH_REVERSE - - - + +
105 * _INSERT_HEAD + + + + +
106 * _INSERT_BEFORE - + - + +
107 * _INSERT_AFTER + + + + +
108 * _INSERT_TAIL - - + + +
109 * _REMOVE_HEAD + - + - -
115 * Singly-linked List declarations.
117 #define SLIST_HEAD(name, type) \
119 struct type *slh_first; /* first element */ \
122 #define SLIST_HEAD_INITIALIZER(head) \
125 #define SLIST_ENTRY(type) \
127 struct type *sle_next; /* next element */ \
131 * Singly-linked List functions.
133 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
135 #define SLIST_FIRST(head) ((head)->slh_first)
137 #define SLIST_FOREACH(var, head, field) \
138 for ((var) = SLIST_FIRST((head)); \
140 (var) = SLIST_NEXT((var), field))
142 #define SLIST_INIT(head) do { \
143 SLIST_FIRST((head)) = NULL; \
146 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
147 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
148 SLIST_NEXT((slistelm), field) = (elm); \
151 #define SLIST_INSERT_HEAD(head, elm, field) do { \
152 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
153 SLIST_FIRST((head)) = (elm); \
156 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
158 #define SLIST_REMOVE(head, elm, type, field) do { \
159 if (SLIST_FIRST((head)) == (elm)) { \
160 SLIST_REMOVE_HEAD((head), field); \
163 struct type *curelm = SLIST_FIRST((head)); \
164 while (SLIST_NEXT(curelm, field) != (elm)) \
165 curelm = SLIST_NEXT(curelm, field); \
166 SLIST_NEXT(curelm, field) = \
167 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
171 #define SLIST_REMOVE_HEAD(head, field) do { \
172 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
176 * Singly-linked Tail queue declarations.
178 #define STAILQ_HEAD(name, type) \
180 struct type *stqh_first;/* first element */ \
181 struct type **stqh_last;/* addr of last next element */ \
184 #define STAILQ_HEAD_INITIALIZER(head) \
185 { NULL, &(head).stqh_first }
187 #define STAILQ_ENTRY(type) \
189 struct type *stqe_next; /* next element */ \
193 * Singly-linked Tail queue functions.
195 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
197 #define STAILQ_FIRST(head) ((head)->stqh_first)
199 #define STAILQ_FOREACH(var, head, field) \
200 for((var) = STAILQ_FIRST((head)); \
202 (var) = STAILQ_NEXT((var), field))
204 #define STAILQ_INIT(head) do { \
205 STAILQ_FIRST((head)) = NULL; \
206 (head)->stqh_last = &STAILQ_FIRST((head)); \
209 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
210 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
211 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
212 STAILQ_NEXT((tqelm), field) = (elm); \
215 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
216 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
217 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
218 STAILQ_FIRST((head)) = (elm); \
221 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
222 STAILQ_NEXT((elm), field) = NULL; \
223 *(head)->stqh_last = (elm); \
224 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
227 #define STAILQ_LAST(head, type, field) \
228 (STAILQ_EMPTY(head) ? \
231 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
233 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
235 #define STAILQ_REMOVE(head, elm, type, field) do { \
236 if (STAILQ_FIRST((head)) == (elm)) { \
237 STAILQ_REMOVE_HEAD(head, field); \
240 struct type *curelm = STAILQ_FIRST((head)); \
241 while (STAILQ_NEXT(curelm, field) != (elm)) \
242 curelm = STAILQ_NEXT(curelm, field); \
243 if ((STAILQ_NEXT(curelm, field) = \
244 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
245 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
249 #define STAILQ_REMOVE_HEAD(head, field) do { \
250 if ((STAILQ_FIRST((head)) = \
251 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
252 (head)->stqh_last = &STAILQ_FIRST((head)); \
255 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
256 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
257 (head)->stqh_last = &STAILQ_FIRST((head)); \
263 #define LIST_HEAD(name, type) \
265 struct type *lh_first; /* first element */ \
268 #define LIST_HEAD_INITIALIZER(head) \
271 #define LIST_ENTRY(type) \
273 struct type *le_next; /* next element */ \
274 struct type **le_prev; /* address of previous next element */ \
281 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
283 #define LIST_FIRST(head) ((head)->lh_first)
285 #define LIST_FOREACH(var, head, field) \
286 for ((var) = LIST_FIRST((head)); \
288 (var) = LIST_NEXT((var), field))
290 #define LIST_INIT(head) do { \
291 LIST_FIRST((head)) = NULL; \
294 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
295 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
296 LIST_NEXT((listelm), field)->field.le_prev = \
297 &LIST_NEXT((elm), field); \
298 LIST_NEXT((listelm), field) = (elm); \
299 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
302 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
303 (elm)->field.le_prev = (listelm)->field.le_prev; \
304 LIST_NEXT((elm), field) = (listelm); \
305 *(listelm)->field.le_prev = (elm); \
306 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
309 #define LIST_INSERT_HEAD(head, elm, field) do { \
310 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
311 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
312 LIST_FIRST((head)) = (elm); \
313 (elm)->field.le_prev = &LIST_FIRST((head)); \
316 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
318 #define LIST_REMOVE(elm, field) do { \
319 if (LIST_NEXT((elm), field) != NULL) \
320 LIST_NEXT((elm), field)->field.le_prev = \
321 (elm)->field.le_prev; \
322 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
326 * Tail queue declarations.
328 #define TAILQ_HEAD(name, type) \
330 struct type *tqh_first; /* first element */ \
331 struct type **tqh_last; /* addr of last next element */ \
334 #define TAILQ_HEAD_INITIALIZER(head) \
335 { NULL, &(head).tqh_first }
337 #define TAILQ_ENTRY(type) \
339 struct type *tqe_next; /* next element */ \
340 struct type **tqe_prev; /* address of previous next element */ \
344 * Tail queue functions.
346 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
348 #define TAILQ_FIRST(head) ((head)->tqh_first)
350 #define TAILQ_FOREACH(var, head, field) \
351 for ((var) = TAILQ_FIRST((head)); \
353 (var) = TAILQ_NEXT((var), field))
355 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
356 for ((var) = TAILQ_LAST((head), headname); \
358 (var) = TAILQ_PREV((var), headname, field))
360 #define TAILQ_INIT(head) do { \
361 TAILQ_FIRST((head)) = NULL; \
362 (head)->tqh_last = &TAILQ_FIRST((head)); \
365 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
366 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
367 TAILQ_NEXT((elm), field)->field.tqe_prev = \
368 &TAILQ_NEXT((elm), field); \
370 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
371 TAILQ_NEXT((listelm), field) = (elm); \
372 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
375 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
376 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
377 TAILQ_NEXT((elm), field) = (listelm); \
378 *(listelm)->field.tqe_prev = (elm); \
379 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
382 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
383 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
384 TAILQ_FIRST((head))->field.tqe_prev = \
385 &TAILQ_NEXT((elm), field); \
387 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
388 TAILQ_FIRST((head)) = (elm); \
389 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
392 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
393 TAILQ_NEXT((elm), field) = NULL; \
394 (elm)->field.tqe_prev = (head)->tqh_last; \
395 *(head)->tqh_last = (elm); \
396 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
399 #define TAILQ_LAST(head, headname) \
400 (*(((struct headname *)((head)->tqh_last))->tqh_last))
402 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
404 #define TAILQ_PREV(elm, headname, field) \
405 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
407 #define TAILQ_REMOVE(head, elm, field) do { \
408 if ((TAILQ_NEXT((elm), field)) != NULL) \
409 TAILQ_NEXT((elm), field)->field.tqe_prev = \
410 (elm)->field.tqe_prev; \
412 (head)->tqh_last = (elm)->field.tqe_prev; \
413 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
417 * Circular queue declarations.
419 #define CIRCLEQ_HEAD(name, type) \
421 struct type *cqh_first; /* first element */ \
422 struct type *cqh_last; /* last element */ \
425 #define CIRCLEQ_HEAD_INITIALIZER(head) \
426 { (void *)&(head), (void *)&(head) }
428 #define CIRCLEQ_ENTRY(type) \
430 struct type *cqe_next; /* next element */ \
431 struct type *cqe_prev; /* previous element */ \
435 * Circular queue functions.
437 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
439 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
441 #define CIRCLEQ_FOREACH(var, head, field) \
442 for ((var) = CIRCLEQ_FIRST((head)); \
443 (var) != (void *)(head) || ((var) = NULL); \
444 (var) = CIRCLEQ_NEXT((var), field))
446 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
447 for ((var) = CIRCLEQ_LAST((head)); \
448 (var) != (void *)(head) || ((var) = NULL); \
449 (var) = CIRCLEQ_PREV((var), field))
451 #define CIRCLEQ_INIT(head) do { \
452 CIRCLEQ_FIRST((head)) = (void *)(head); \
453 CIRCLEQ_LAST((head)) = (void *)(head); \
456 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
457 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \
458 CIRCLEQ_PREV((elm), field) = (listelm); \
459 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \
460 CIRCLEQ_LAST((head)) = (elm); \
462 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\
463 CIRCLEQ_NEXT((listelm), field) = (elm); \
466 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
467 CIRCLEQ_NEXT((elm), field) = (listelm); \
468 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \
469 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \
470 CIRCLEQ_FIRST((head)) = (elm); \
472 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\
473 CIRCLEQ_PREV((listelm), field) = (elm); \
476 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
477 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \
478 CIRCLEQ_PREV((elm), field) = (void *)(head); \
479 if (CIRCLEQ_LAST((head)) == (void *)(head)) \
480 CIRCLEQ_LAST((head)) = (elm); \
482 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \
483 CIRCLEQ_FIRST((head)) = (elm); \
486 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
487 CIRCLEQ_NEXT((elm), field) = (void *)(head); \
488 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \
489 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \
490 CIRCLEQ_FIRST((head)) = (elm); \
492 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \
493 CIRCLEQ_LAST((head)) = (elm); \
496 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
498 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
500 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
502 #define CIRCLEQ_REMOVE(head, elm, field) do { \
503 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \
504 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \
506 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \
507 CIRCLEQ_PREV((elm), field); \
508 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \
509 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \
511 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \
512 CIRCLEQ_NEXT((elm), field); \
518 * XXX insque() and remque() are an old way of handling certain queues.
519 * They bogusly assumes that all queue heads look alike.
523 struct quehead *qh_link;
524 struct quehead *qh_rlink;
530 insque(void *a, void *b)
532 struct quehead *element = (struct quehead *)a,
533 *head = (struct quehead *)b;
535 element->qh_link = head->qh_link;
536 element->qh_rlink = head;
537 head->qh_link = element;
538 element->qh_link->qh_rlink = element;
544 struct quehead *element = (struct quehead *)a;
546 element->qh_link->qh_rlink = element->qh_rlink;
547 element->qh_rlink->qh_link = element->qh_link;
548 element->qh_rlink = 0;
551 #else /* !__GNUC__ */
553 void insque __P((void *a, void *b));
554 void remque __P((void *a));
556 #endif /* __GNUC__ */
560 #endif /* !_SYS_QUEUE_H_ */