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29 * @(#)queue.h 8.5 (Berkeley) 8/20/94
36 #include <sys/cdefs.h>
39 * This file defines four types of data structures: singly-linked lists,
40 * singly-linked tail queues, lists and tail 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 singly-linked tail queue is headed by a pair of pointers, one to the
53 * head of the list and the other to the tail of the list. The elements are
54 * singly linked for minimum space and pointer manipulation overhead at the
55 * expense of O(n) removal for arbitrary elements. New elements can be added
56 * to the list after an existing element, at the head of the list, or at the
57 * end of the list. Elements being removed from the head of the tail queue
58 * should use the explicit macro for this purpose for optimum efficiency.
59 * A singly-linked tail queue may only be traversed in the forward direction.
60 * Singly-linked tail queues are ideal for applications with large datasets
61 * and few or no removals or for implementing a FIFO queue.
63 * A list is headed by a single forward pointer (or an array of forward
64 * pointers for a hash table header). The elements are doubly linked
65 * so that an arbitrary element can be removed without a need to
66 * traverse the list. New elements can be added to the list before
67 * or after an existing element or at the head of the list. A list
68 * may be traversed in either direction.
70 * A tail queue is headed by a pair of pointers, one to the head of the
71 * list and the other to the tail of the list. The elements are doubly
72 * linked so that an arbitrary element can be removed without a need to
73 * traverse the list. New elements can be added to the list before or
74 * after an existing element, at the head of the list, or at the end of
75 * the list. A tail queue may be traversed in either direction.
77 * For details on the use of these macros, see the queue(3) manual page.
79 * Below is a summary of implemented functions where:
80 * + means the macro is available
81 * - means the macro is not available
82 * s means the macro is available but is slow (runs in O(n) time)
84 * SLIST LIST STAILQ TAILQ
87 * _HEAD_INITIALIZER + + + +
89 * _CLASS_ENTRY + + + +
98 * _FOREACH_FROM + + + +
99 * _FOREACH_SAFE + + + +
100 * _FOREACH_FROM_SAFE + + + +
101 * _FOREACH_REVERSE - - - +
102 * _FOREACH_REVERSE_FROM - - - +
103 * _FOREACH_REVERSE_SAFE - - - +
104 * _FOREACH_REVERSE_FROM_SAFE - - - +
105 * _INSERT_HEAD + + + +
106 * _INSERT_BEFORE - + - +
107 * _INSERT_AFTER + + + +
108 * _INSERT_TAIL - - + +
110 * _REMOVE_AFTER + - + -
111 * _REMOVE_HEAD + - + -
116 #ifdef QUEUE_MACRO_DEBUG
117 /* Store the last 2 places the queue element or head was altered */
119 unsigned long lastline;
120 unsigned long prevline;
121 const char *lastfile;
122 const char *prevfile;
125 #define TRACEBUF struct qm_trace trace;
126 #define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
127 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
128 #define QMD_SAVELINK(name, link) void **name = (void *)&(link)
130 #define QMD_TRACE_HEAD(head) do { \
131 (head)->trace.prevline = (head)->trace.lastline; \
132 (head)->trace.prevfile = (head)->trace.lastfile; \
133 (head)->trace.lastline = __LINE__; \
134 (head)->trace.lastfile = __FILE__; \
137 #define QMD_TRACE_ELEM(elem) do { \
138 (elem)->trace.prevline = (elem)->trace.lastline; \
139 (elem)->trace.prevfile = (elem)->trace.lastfile; \
140 (elem)->trace.lastline = __LINE__; \
141 (elem)->trace.lastfile = __FILE__; \
145 #define QMD_TRACE_ELEM(elem)
146 #define QMD_TRACE_HEAD(head)
147 #define QMD_SAVELINK(name, link)
149 #define TRACEBUF_INITIALIZER
151 #endif /* QUEUE_MACRO_DEBUG */
155 * In C++ there can be structure lists and class lists:
157 #define QUEUE_TYPEOF(type) type
159 #define QUEUE_TYPEOF(type) struct type
163 * Singly-linked List declarations.
165 #define SLIST_HEAD(name, type) \
167 struct type *slh_first; /* first element */ \
170 #define SLIST_CLASS_HEAD(name, type) \
172 class type *slh_first; /* first element */ \
175 #define SLIST_HEAD_INITIALIZER(head) \
178 #define SLIST_ENTRY(type) \
180 struct type *sle_next; /* next element */ \
183 #define SLIST_CLASS_ENTRY(type) \
185 class type *sle_next; /* next element */ \
189 * Singly-linked List functions.
191 #define SLIST_CONCAT(head1, head2, type, field) do { \
192 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \
193 if (curelm == NULL) { \
194 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \
196 } else if (SLIST_FIRST(head2) != NULL) { \
197 while (SLIST_NEXT(curelm, field) != NULL) \
198 curelm = SLIST_NEXT(curelm, field); \
199 SLIST_NEXT(curelm, field) = SLIST_FIRST(head2); \
204 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
206 #define SLIST_FIRST(head) ((head)->slh_first)
208 #define SLIST_FOREACH(var, head, field) \
209 for ((var) = SLIST_FIRST((head)); \
211 (var) = SLIST_NEXT((var), field))
213 #define SLIST_FOREACH_FROM(var, head, field) \
214 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
216 (var) = SLIST_NEXT((var), field))
218 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
219 for ((var) = SLIST_FIRST((head)); \
220 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
223 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
224 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
225 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
228 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
229 for ((varp) = &SLIST_FIRST((head)); \
230 ((var) = *(varp)) != NULL; \
231 (varp) = &SLIST_NEXT((var), field))
233 #define SLIST_INIT(head) do { \
234 SLIST_FIRST((head)) = NULL; \
237 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
238 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
239 SLIST_NEXT((slistelm), field) = (elm); \
242 #define SLIST_INSERT_HEAD(head, elm, field) do { \
243 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
244 SLIST_FIRST((head)) = (elm); \
247 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
249 #define SLIST_REMOVE(head, elm, type, field) do { \
250 QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
251 if (SLIST_FIRST((head)) == (elm)) { \
252 SLIST_REMOVE_HEAD((head), field); \
255 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head); \
256 while (SLIST_NEXT(curelm, field) != (elm)) \
257 curelm = SLIST_NEXT(curelm, field); \
258 SLIST_REMOVE_AFTER(curelm, field); \
263 #define SLIST_REMOVE_AFTER(elm, field) do { \
264 SLIST_NEXT(elm, field) = \
265 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
268 #define SLIST_REMOVE_HEAD(head, field) do { \
269 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
272 #define SLIST_SWAP(head1, head2, type) do { \
273 QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1); \
274 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
275 SLIST_FIRST(head2) = swap_first; \
279 * Singly-linked Tail queue declarations.
281 #define STAILQ_HEAD(name, type) \
283 struct type *stqh_first;/* first element */ \
284 struct type **stqh_last;/* addr of last next element */ \
287 #define STAILQ_CLASS_HEAD(name, type) \
289 class type *stqh_first; /* first element */ \
290 class type **stqh_last; /* addr of last next element */ \
293 #define STAILQ_HEAD_INITIALIZER(head) \
294 { NULL, &(head).stqh_first }
296 #define STAILQ_ENTRY(type) \
298 struct type *stqe_next; /* next element */ \
301 #define STAILQ_CLASS_ENTRY(type) \
303 class type *stqe_next; /* next element */ \
307 * Singly-linked Tail queue functions.
309 #define STAILQ_CONCAT(head1, head2) do { \
310 if (!STAILQ_EMPTY((head2))) { \
311 *(head1)->stqh_last = (head2)->stqh_first; \
312 (head1)->stqh_last = (head2)->stqh_last; \
313 STAILQ_INIT((head2)); \
317 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
319 #define STAILQ_FIRST(head) ((head)->stqh_first)
321 #define STAILQ_FOREACH(var, head, field) \
322 for((var) = STAILQ_FIRST((head)); \
324 (var) = STAILQ_NEXT((var), field))
326 #define STAILQ_FOREACH_FROM(var, head, field) \
327 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
329 (var) = STAILQ_NEXT((var), field))
331 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
332 for ((var) = STAILQ_FIRST((head)); \
333 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
336 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
337 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
338 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
341 #define STAILQ_INIT(head) do { \
342 STAILQ_FIRST((head)) = NULL; \
343 (head)->stqh_last = &STAILQ_FIRST((head)); \
346 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
347 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
348 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
349 STAILQ_NEXT((tqelm), field) = (elm); \
352 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
353 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
354 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
355 STAILQ_FIRST((head)) = (elm); \
358 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
359 STAILQ_NEXT((elm), field) = NULL; \
360 *(head)->stqh_last = (elm); \
361 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
364 #define STAILQ_LAST(head, type, field) \
365 (STAILQ_EMPTY((head)) ? NULL : \
366 __containerof((head)->stqh_last, \
367 QUEUE_TYPEOF(type), field.stqe_next))
369 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
371 #define STAILQ_REMOVE(head, elm, type, field) do { \
372 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
373 if (STAILQ_FIRST((head)) == (elm)) { \
374 STAILQ_REMOVE_HEAD((head), field); \
377 QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head); \
378 while (STAILQ_NEXT(curelm, field) != (elm)) \
379 curelm = STAILQ_NEXT(curelm, field); \
380 STAILQ_REMOVE_AFTER(head, curelm, field); \
385 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
386 if ((STAILQ_NEXT(elm, field) = \
387 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
388 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
391 #define STAILQ_REMOVE_HEAD(head, field) do { \
392 if ((STAILQ_FIRST((head)) = \
393 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
394 (head)->stqh_last = &STAILQ_FIRST((head)); \
397 #define STAILQ_SWAP(head1, head2, type) do { \
398 QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1); \
399 QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last; \
400 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
401 (head1)->stqh_last = (head2)->stqh_last; \
402 STAILQ_FIRST(head2) = swap_first; \
403 (head2)->stqh_last = swap_last; \
404 if (STAILQ_EMPTY(head1)) \
405 (head1)->stqh_last = &STAILQ_FIRST(head1); \
406 if (STAILQ_EMPTY(head2)) \
407 (head2)->stqh_last = &STAILQ_FIRST(head2); \
414 #define LIST_HEAD(name, type) \
416 struct type *lh_first; /* first element */ \
419 #define LIST_CLASS_HEAD(name, type) \
421 class type *lh_first; /* first element */ \
424 #define LIST_HEAD_INITIALIZER(head) \
427 #define LIST_ENTRY(type) \
429 struct type *le_next; /* next element */ \
430 struct type **le_prev; /* address of previous next element */ \
433 #define LIST_CLASS_ENTRY(type) \
435 class type *le_next; /* next element */ \
436 class type **le_prev; /* address of previous next element */ \
443 #if (defined(_KERNEL) && defined(INVARIANTS))
444 #define QMD_LIST_CHECK_HEAD(head, field) do { \
445 if (LIST_FIRST((head)) != NULL && \
446 LIST_FIRST((head))->field.le_prev != \
447 &LIST_FIRST((head))) \
448 panic("Bad list head %p first->prev != head", (head)); \
451 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
452 if (LIST_NEXT((elm), field) != NULL && \
453 LIST_NEXT((elm), field)->field.le_prev != \
454 &((elm)->field.le_next)) \
455 panic("Bad link elm %p next->prev != elm", (elm)); \
458 #define QMD_LIST_CHECK_PREV(elm, field) do { \
459 if (*(elm)->field.le_prev != (elm)) \
460 panic("Bad link elm %p prev->next != elm", (elm)); \
463 #define QMD_LIST_CHECK_HEAD(head, field)
464 #define QMD_LIST_CHECK_NEXT(elm, field)
465 #define QMD_LIST_CHECK_PREV(elm, field)
466 #endif /* (_KERNEL && INVARIANTS) */
468 #define LIST_CONCAT(head1, head2, type, field) do { \
469 QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1); \
470 if (curelm == NULL) { \
471 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \
472 LIST_FIRST(head2)->field.le_prev = \
473 &LIST_FIRST((head1)); \
476 } else if (LIST_FIRST(head2) != NULL) { \
477 while (LIST_NEXT(curelm, field) != NULL) \
478 curelm = LIST_NEXT(curelm, field); \
479 LIST_NEXT(curelm, field) = LIST_FIRST(head2); \
480 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
485 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
487 #define LIST_FIRST(head) ((head)->lh_first)
489 #define LIST_FOREACH(var, head, field) \
490 for ((var) = LIST_FIRST((head)); \
492 (var) = LIST_NEXT((var), field))
494 #define LIST_FOREACH_FROM(var, head, field) \
495 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
497 (var) = LIST_NEXT((var), field))
499 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
500 for ((var) = LIST_FIRST((head)); \
501 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
504 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
505 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
506 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
509 #define LIST_INIT(head) do { \
510 LIST_FIRST((head)) = NULL; \
513 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
514 QMD_LIST_CHECK_NEXT(listelm, field); \
515 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
516 LIST_NEXT((listelm), field)->field.le_prev = \
517 &LIST_NEXT((elm), field); \
518 LIST_NEXT((listelm), field) = (elm); \
519 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
522 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
523 QMD_LIST_CHECK_PREV(listelm, field); \
524 (elm)->field.le_prev = (listelm)->field.le_prev; \
525 LIST_NEXT((elm), field) = (listelm); \
526 *(listelm)->field.le_prev = (elm); \
527 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
530 #define LIST_INSERT_HEAD(head, elm, field) do { \
531 QMD_LIST_CHECK_HEAD((head), field); \
532 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
533 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
534 LIST_FIRST((head)) = (elm); \
535 (elm)->field.le_prev = &LIST_FIRST((head)); \
538 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
540 #define LIST_PREV(elm, head, type, field) \
541 ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
542 __containerof((elm)->field.le_prev, \
543 QUEUE_TYPEOF(type), field.le_next))
545 #define LIST_REMOVE(elm, field) do { \
546 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
547 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
548 QMD_LIST_CHECK_NEXT(elm, field); \
549 QMD_LIST_CHECK_PREV(elm, field); \
550 if (LIST_NEXT((elm), field) != NULL) \
551 LIST_NEXT((elm), field)->field.le_prev = \
552 (elm)->field.le_prev; \
553 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
558 #define LIST_SWAP(head1, head2, type, field) do { \
559 QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1); \
560 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
561 LIST_FIRST((head2)) = swap_tmp; \
562 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
563 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
564 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
565 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
569 * Tail queue declarations.
571 #define TAILQ_HEAD(name, type) \
573 struct type *tqh_first; /* first element */ \
574 struct type **tqh_last; /* addr of last next element */ \
578 #define TAILQ_CLASS_HEAD(name, type) \
580 class type *tqh_first; /* first element */ \
581 class type **tqh_last; /* addr of last next element */ \
585 #define TAILQ_HEAD_INITIALIZER(head) \
586 { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
588 #define TAILQ_ENTRY(type) \
590 struct type *tqe_next; /* next element */ \
591 struct type **tqe_prev; /* address of previous next element */ \
595 #define TAILQ_CLASS_ENTRY(type) \
597 class type *tqe_next; /* next element */ \
598 class type **tqe_prev; /* address of previous next element */ \
603 * Tail queue functions.
605 #if (defined(_KERNEL) && defined(INVARIANTS))
606 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
607 if (!TAILQ_EMPTY(head) && \
608 TAILQ_FIRST((head))->field.tqe_prev != \
609 &TAILQ_FIRST((head))) \
610 panic("Bad tailq head %p first->prev != head", (head)); \
613 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
614 if (*(head)->tqh_last != NULL) \
615 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
618 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
619 if (TAILQ_NEXT((elm), field) != NULL && \
620 TAILQ_NEXT((elm), field)->field.tqe_prev != \
621 &((elm)->field.tqe_next)) \
622 panic("Bad link elm %p next->prev != elm", (elm)); \
625 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
626 if (*(elm)->field.tqe_prev != (elm)) \
627 panic("Bad link elm %p prev->next != elm", (elm)); \
630 #define QMD_TAILQ_CHECK_HEAD(head, field)
631 #define QMD_TAILQ_CHECK_TAIL(head, headname)
632 #define QMD_TAILQ_CHECK_NEXT(elm, field)
633 #define QMD_TAILQ_CHECK_PREV(elm, field)
634 #endif /* (_KERNEL && INVARIANTS) */
636 #define TAILQ_CONCAT(head1, head2, field) do { \
637 if (!TAILQ_EMPTY(head2)) { \
638 *(head1)->tqh_last = (head2)->tqh_first; \
639 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
640 (head1)->tqh_last = (head2)->tqh_last; \
641 TAILQ_INIT((head2)); \
642 QMD_TRACE_HEAD(head1); \
643 QMD_TRACE_HEAD(head2); \
647 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
649 #define TAILQ_FIRST(head) ((head)->tqh_first)
651 #define TAILQ_FOREACH(var, head, field) \
652 for ((var) = TAILQ_FIRST((head)); \
654 (var) = TAILQ_NEXT((var), field))
656 #define TAILQ_FOREACH_FROM(var, head, field) \
657 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
659 (var) = TAILQ_NEXT((var), field))
661 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
662 for ((var) = TAILQ_FIRST((head)); \
663 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
666 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
667 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
668 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
671 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
672 for ((var) = TAILQ_LAST((head), headname); \
674 (var) = TAILQ_PREV((var), headname, field))
676 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
677 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
679 (var) = TAILQ_PREV((var), headname, field))
681 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
682 for ((var) = TAILQ_LAST((head), headname); \
683 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
686 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
687 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
688 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
691 #define TAILQ_INIT(head) do { \
692 TAILQ_FIRST((head)) = NULL; \
693 (head)->tqh_last = &TAILQ_FIRST((head)); \
694 QMD_TRACE_HEAD(head); \
697 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
698 QMD_TAILQ_CHECK_NEXT(listelm, field); \
699 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
700 TAILQ_NEXT((elm), field)->field.tqe_prev = \
701 &TAILQ_NEXT((elm), field); \
703 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
704 QMD_TRACE_HEAD(head); \
706 TAILQ_NEXT((listelm), field) = (elm); \
707 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
708 QMD_TRACE_ELEM(&(elm)->field); \
709 QMD_TRACE_ELEM(&(listelm)->field); \
712 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
713 QMD_TAILQ_CHECK_PREV(listelm, field); \
714 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
715 TAILQ_NEXT((elm), field) = (listelm); \
716 *(listelm)->field.tqe_prev = (elm); \
717 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
718 QMD_TRACE_ELEM(&(elm)->field); \
719 QMD_TRACE_ELEM(&(listelm)->field); \
722 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
723 QMD_TAILQ_CHECK_HEAD(head, field); \
724 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
725 TAILQ_FIRST((head))->field.tqe_prev = \
726 &TAILQ_NEXT((elm), field); \
728 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
729 TAILQ_FIRST((head)) = (elm); \
730 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
731 QMD_TRACE_HEAD(head); \
732 QMD_TRACE_ELEM(&(elm)->field); \
735 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
736 QMD_TAILQ_CHECK_TAIL(head, field); \
737 TAILQ_NEXT((elm), field) = NULL; \
738 (elm)->field.tqe_prev = (head)->tqh_last; \
739 *(head)->tqh_last = (elm); \
740 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
741 QMD_TRACE_HEAD(head); \
742 QMD_TRACE_ELEM(&(elm)->field); \
745 #define TAILQ_LAST(head, headname) \
746 (*(((struct headname *)((head)->tqh_last))->tqh_last))
749 * The FAST function is fast in that it causes no data access other
750 * then the access to the head. The standard LAST function above
751 * will cause a data access of both the element you want and
752 * the previous element. FAST is very useful for instances when
753 * you may want to prefetch the last data element.
755 #define TAILQ_LAST_FAST(head, type, field) \
756 (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
758 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
760 #define TAILQ_PREV(elm, headname, field) \
761 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
763 #define TAILQ_REMOVE(head, elm, field) do { \
764 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
765 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
766 QMD_TAILQ_CHECK_NEXT(elm, field); \
767 QMD_TAILQ_CHECK_PREV(elm, field); \
768 if ((TAILQ_NEXT((elm), field)) != NULL) \
769 TAILQ_NEXT((elm), field)->field.tqe_prev = \
770 (elm)->field.tqe_prev; \
772 (head)->tqh_last = (elm)->field.tqe_prev; \
773 QMD_TRACE_HEAD(head); \
775 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
778 QMD_TRACE_ELEM(&(elm)->field); \
781 #define TAILQ_SWAP(head1, head2, type, field) do { \
782 QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first; \
783 QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last; \
784 (head1)->tqh_first = (head2)->tqh_first; \
785 (head1)->tqh_last = (head2)->tqh_last; \
786 (head2)->tqh_first = swap_first; \
787 (head2)->tqh_last = swap_last; \
788 if ((swap_first = (head1)->tqh_first) != NULL) \
789 swap_first->field.tqe_prev = &(head1)->tqh_first; \
791 (head1)->tqh_last = &(head1)->tqh_first; \
792 if ((swap_first = (head2)->tqh_first) != NULL) \
793 swap_first->field.tqe_prev = &(head2)->tqh_first; \
795 (head2)->tqh_last = &(head2)->tqh_first; \
798 #endif /* !_SYS_QUEUE_H_ */