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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 + + + +
97 * _FOREACH_FROM + + + +
98 * _FOREACH_SAFE + + + +
99 * _FOREACH_FROM_SAFE + + + +
100 * _FOREACH_REVERSE - - - +
101 * _FOREACH_REVERSE_FROM - - - +
102 * _FOREACH_REVERSE_SAFE - - - +
103 * _FOREACH_REVERSE_FROM_SAFE - - - +
104 * _INSERT_HEAD + + + +
105 * _INSERT_BEFORE - + - +
106 * _INSERT_AFTER + + + +
107 * _INSERT_TAIL - - + +
109 * _REMOVE_AFTER + - + -
110 * _REMOVE_HEAD + - + -
115 #ifdef QUEUE_MACRO_DEBUG
116 /* Store the last 2 places the queue element or head was altered */
118 unsigned long lastline;
119 unsigned long prevline;
120 const char *lastfile;
121 const char *prevfile;
124 #define TRACEBUF struct qm_trace trace;
125 #define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
126 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
127 #define QMD_SAVELINK(name, link) void **name = (void *)&(link)
129 #define QMD_TRACE_HEAD(head) do { \
130 (head)->trace.prevline = (head)->trace.lastline; \
131 (head)->trace.prevfile = (head)->trace.lastfile; \
132 (head)->trace.lastline = __LINE__; \
133 (head)->trace.lastfile = __FILE__; \
136 #define QMD_TRACE_ELEM(elem) do { \
137 (elem)->trace.prevline = (elem)->trace.lastline; \
138 (elem)->trace.prevfile = (elem)->trace.lastfile; \
139 (elem)->trace.lastline = __LINE__; \
140 (elem)->trace.lastfile = __FILE__; \
144 #define QMD_TRACE_ELEM(elem)
145 #define QMD_TRACE_HEAD(head)
146 #define QMD_SAVELINK(name, link)
148 #define TRACEBUF_INITIALIZER
150 #endif /* QUEUE_MACRO_DEBUG */
154 * In C++ there can be structure lists and class lists:
156 #define QUEUE_TYPEOF(type) type
158 #define QUEUE_TYPEOF(type) struct type
162 * Singly-linked List declarations.
164 #define SLIST_HEAD(name, type) \
166 struct type *slh_first; /* first element */ \
169 #define SLIST_CLASS_HEAD(name, type) \
171 class type *slh_first; /* first element */ \
174 #define SLIST_HEAD_INITIALIZER(head) \
177 #define SLIST_ENTRY(type) \
179 struct type *sle_next; /* next element */ \
182 #define SLIST_CLASS_ENTRY(type) \
184 class type *sle_next; /* next element */ \
188 * Singly-linked List functions.
190 #define SLIST_CONCAT(head1, head2, type, field) do { \
191 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \
192 if (curelm == NULL) { \
193 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \
195 } else if (SLIST_FIRST(head2) != NULL) { \
196 while (SLIST_NEXT(curelm, field) != NULL) \
197 curelm = SLIST_NEXT(curelm, field); \
198 SLIST_NEXT(curelm, field) = SLIST_FIRST(head2); \
203 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
205 #define SLIST_FIRST(head) ((head)->slh_first)
207 #define SLIST_FOREACH(var, head, field) \
208 for ((var) = SLIST_FIRST((head)); \
210 (var) = SLIST_NEXT((var), field))
212 #define SLIST_FOREACH_FROM(var, head, field) \
213 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
215 (var) = SLIST_NEXT((var), field))
217 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
218 for ((var) = SLIST_FIRST((head)); \
219 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
222 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
223 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
224 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
227 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
228 for ((varp) = &SLIST_FIRST((head)); \
229 ((var) = *(varp)) != NULL; \
230 (varp) = &SLIST_NEXT((var), field))
232 #define SLIST_INIT(head) do { \
233 SLIST_FIRST((head)) = NULL; \
236 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
237 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
238 SLIST_NEXT((slistelm), field) = (elm); \
241 #define SLIST_INSERT_HEAD(head, elm, field) do { \
242 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
243 SLIST_FIRST((head)) = (elm); \
246 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
248 #define SLIST_REMOVE(head, elm, type, field) do { \
249 QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
250 if (SLIST_FIRST((head)) == (elm)) { \
251 SLIST_REMOVE_HEAD((head), field); \
254 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head); \
255 while (SLIST_NEXT(curelm, field) != (elm)) \
256 curelm = SLIST_NEXT(curelm, field); \
257 SLIST_REMOVE_AFTER(curelm, field); \
262 #define SLIST_REMOVE_AFTER(elm, field) do { \
263 SLIST_NEXT(elm, field) = \
264 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
267 #define SLIST_REMOVE_HEAD(head, field) do { \
268 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
271 #define SLIST_SWAP(head1, head2, type) do { \
272 QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1); \
273 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
274 SLIST_FIRST(head2) = swap_first; \
278 * Singly-linked Tail queue declarations.
280 #define STAILQ_HEAD(name, type) \
282 struct type *stqh_first;/* first element */ \
283 struct type **stqh_last;/* addr of last next element */ \
286 #define STAILQ_CLASS_HEAD(name, type) \
288 class type *stqh_first; /* first element */ \
289 class type **stqh_last; /* addr of last next element */ \
292 #define STAILQ_HEAD_INITIALIZER(head) \
293 { NULL, &(head).stqh_first }
295 #define STAILQ_ENTRY(type) \
297 struct type *stqe_next; /* next element */ \
300 #define STAILQ_CLASS_ENTRY(type) \
302 class type *stqe_next; /* next element */ \
306 * Singly-linked Tail queue functions.
308 #define STAILQ_CONCAT(head1, head2) do { \
309 if (!STAILQ_EMPTY((head2))) { \
310 *(head1)->stqh_last = (head2)->stqh_first; \
311 (head1)->stqh_last = (head2)->stqh_last; \
312 STAILQ_INIT((head2)); \
316 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
318 #define STAILQ_FIRST(head) ((head)->stqh_first)
320 #define STAILQ_FOREACH(var, head, field) \
321 for((var) = STAILQ_FIRST((head)); \
323 (var) = STAILQ_NEXT((var), field))
325 #define STAILQ_FOREACH_FROM(var, head, field) \
326 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
328 (var) = STAILQ_NEXT((var), field))
330 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
331 for ((var) = STAILQ_FIRST((head)); \
332 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
335 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
336 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
337 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
340 #define STAILQ_INIT(head) do { \
341 STAILQ_FIRST((head)) = NULL; \
342 (head)->stqh_last = &STAILQ_FIRST((head)); \
345 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
346 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
347 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
348 STAILQ_NEXT((tqelm), field) = (elm); \
351 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
352 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
353 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
354 STAILQ_FIRST((head)) = (elm); \
357 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
358 STAILQ_NEXT((elm), field) = NULL; \
359 *(head)->stqh_last = (elm); \
360 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
363 #define STAILQ_LAST(head, type, field) \
364 (STAILQ_EMPTY((head)) ? NULL : \
365 __containerof((head)->stqh_last, \
366 QUEUE_TYPEOF(type), field.stqe_next))
368 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
370 #define STAILQ_REMOVE(head, elm, type, field) do { \
371 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
372 if (STAILQ_FIRST((head)) == (elm)) { \
373 STAILQ_REMOVE_HEAD((head), field); \
376 QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head); \
377 while (STAILQ_NEXT(curelm, field) != (elm)) \
378 curelm = STAILQ_NEXT(curelm, field); \
379 STAILQ_REMOVE_AFTER(head, curelm, field); \
384 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
385 if ((STAILQ_NEXT(elm, field) = \
386 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
387 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
390 #define STAILQ_REMOVE_HEAD(head, field) do { \
391 if ((STAILQ_FIRST((head)) = \
392 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
393 (head)->stqh_last = &STAILQ_FIRST((head)); \
396 #define STAILQ_SWAP(head1, head2, type) do { \
397 QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1); \
398 QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last; \
399 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
400 (head1)->stqh_last = (head2)->stqh_last; \
401 STAILQ_FIRST(head2) = swap_first; \
402 (head2)->stqh_last = swap_last; \
403 if (STAILQ_EMPTY(head1)) \
404 (head1)->stqh_last = &STAILQ_FIRST(head1); \
405 if (STAILQ_EMPTY(head2)) \
406 (head2)->stqh_last = &STAILQ_FIRST(head2); \
413 #define LIST_HEAD(name, type) \
415 struct type *lh_first; /* first element */ \
418 #define LIST_CLASS_HEAD(name, type) \
420 class type *lh_first; /* first element */ \
423 #define LIST_HEAD_INITIALIZER(head) \
426 #define LIST_ENTRY(type) \
428 struct type *le_next; /* next element */ \
429 struct type **le_prev; /* address of previous next element */ \
432 #define LIST_CLASS_ENTRY(type) \
434 class type *le_next; /* next element */ \
435 class type **le_prev; /* address of previous next element */ \
442 #if (defined(_KERNEL) && defined(INVARIANTS))
443 #define QMD_LIST_CHECK_HEAD(head, field) do { \
444 if (LIST_FIRST((head)) != NULL && \
445 LIST_FIRST((head))->field.le_prev != \
446 &LIST_FIRST((head))) \
447 panic("Bad list head %p first->prev != head", (head)); \
450 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
451 if (LIST_NEXT((elm), field) != NULL && \
452 LIST_NEXT((elm), field)->field.le_prev != \
453 &((elm)->field.le_next)) \
454 panic("Bad link elm %p next->prev != elm", (elm)); \
457 #define QMD_LIST_CHECK_PREV(elm, field) do { \
458 if (*(elm)->field.le_prev != (elm)) \
459 panic("Bad link elm %p prev->next != elm", (elm)); \
462 #define QMD_LIST_CHECK_HEAD(head, field)
463 #define QMD_LIST_CHECK_NEXT(elm, field)
464 #define QMD_LIST_CHECK_PREV(elm, field)
465 #endif /* (_KERNEL && INVARIANTS) */
467 #define LIST_CONCAT(head1, head2, type, field) do { \
468 QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1); \
469 if (curelm == NULL) { \
470 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \
471 LIST_FIRST(head2)->field.le_prev = \
472 &LIST_FIRST((head1)); \
475 } else if (LIST_FIRST(head2) != NULL) { \
476 while (LIST_NEXT(curelm, field) != NULL) \
477 curelm = LIST_NEXT(curelm, field); \
478 LIST_NEXT(curelm, field) = LIST_FIRST(head2); \
479 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
484 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
486 #define LIST_FIRST(head) ((head)->lh_first)
488 #define LIST_FOREACH(var, head, field) \
489 for ((var) = LIST_FIRST((head)); \
491 (var) = LIST_NEXT((var), field))
493 #define LIST_FOREACH_FROM(var, head, field) \
494 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
496 (var) = LIST_NEXT((var), field))
498 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
499 for ((var) = LIST_FIRST((head)); \
500 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
503 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
504 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
505 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
508 #define LIST_INIT(head) do { \
509 LIST_FIRST((head)) = NULL; \
512 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
513 QMD_LIST_CHECK_NEXT(listelm, field); \
514 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
515 LIST_NEXT((listelm), field)->field.le_prev = \
516 &LIST_NEXT((elm), field); \
517 LIST_NEXT((listelm), field) = (elm); \
518 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
521 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
522 QMD_LIST_CHECK_PREV(listelm, field); \
523 (elm)->field.le_prev = (listelm)->field.le_prev; \
524 LIST_NEXT((elm), field) = (listelm); \
525 *(listelm)->field.le_prev = (elm); \
526 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
529 #define LIST_INSERT_HEAD(head, elm, field) do { \
530 QMD_LIST_CHECK_HEAD((head), field); \
531 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
532 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
533 LIST_FIRST((head)) = (elm); \
534 (elm)->field.le_prev = &LIST_FIRST((head)); \
537 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
539 #define LIST_PREV(elm, head, type, field) \
540 ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
541 __containerof((elm)->field.le_prev, \
542 QUEUE_TYPEOF(type), field.le_next))
544 #define LIST_REMOVE(elm, field) do { \
545 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
546 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
547 QMD_LIST_CHECK_NEXT(elm, field); \
548 QMD_LIST_CHECK_PREV(elm, field); \
549 if (LIST_NEXT((elm), field) != NULL) \
550 LIST_NEXT((elm), field)->field.le_prev = \
551 (elm)->field.le_prev; \
552 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
557 #define LIST_SWAP(head1, head2, type, field) do { \
558 QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1); \
559 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
560 LIST_FIRST((head2)) = swap_tmp; \
561 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
562 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
563 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
564 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
568 * Tail queue declarations.
570 #define TAILQ_HEAD(name, type) \
572 struct type *tqh_first; /* first element */ \
573 struct type **tqh_last; /* addr of last next element */ \
577 #define TAILQ_CLASS_HEAD(name, type) \
579 class type *tqh_first; /* first element */ \
580 class type **tqh_last; /* addr of last next element */ \
584 #define TAILQ_HEAD_INITIALIZER(head) \
585 { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
587 #define TAILQ_ENTRY(type) \
589 struct type *tqe_next; /* next element */ \
590 struct type **tqe_prev; /* address of previous next element */ \
594 #define TAILQ_CLASS_ENTRY(type) \
596 class type *tqe_next; /* next element */ \
597 class type **tqe_prev; /* address of previous next element */ \
602 * Tail queue functions.
604 #if (defined(_KERNEL) && defined(INVARIANTS))
605 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
606 if (!TAILQ_EMPTY(head) && \
607 TAILQ_FIRST((head))->field.tqe_prev != \
608 &TAILQ_FIRST((head))) \
609 panic("Bad tailq head %p first->prev != head", (head)); \
612 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
613 if (*(head)->tqh_last != NULL) \
614 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
617 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
618 if (TAILQ_NEXT((elm), field) != NULL && \
619 TAILQ_NEXT((elm), field)->field.tqe_prev != \
620 &((elm)->field.tqe_next)) \
621 panic("Bad link elm %p next->prev != elm", (elm)); \
624 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
625 if (*(elm)->field.tqe_prev != (elm)) \
626 panic("Bad link elm %p prev->next != elm", (elm)); \
629 #define QMD_TAILQ_CHECK_HEAD(head, field)
630 #define QMD_TAILQ_CHECK_TAIL(head, headname)
631 #define QMD_TAILQ_CHECK_NEXT(elm, field)
632 #define QMD_TAILQ_CHECK_PREV(elm, field)
633 #endif /* (_KERNEL && INVARIANTS) */
635 #define TAILQ_CONCAT(head1, head2, field) do { \
636 if (!TAILQ_EMPTY(head2)) { \
637 *(head1)->tqh_last = (head2)->tqh_first; \
638 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
639 (head1)->tqh_last = (head2)->tqh_last; \
640 TAILQ_INIT((head2)); \
641 QMD_TRACE_HEAD(head1); \
642 QMD_TRACE_HEAD(head2); \
646 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
648 #define TAILQ_FIRST(head) ((head)->tqh_first)
650 #define TAILQ_FOREACH(var, head, field) \
651 for ((var) = TAILQ_FIRST((head)); \
653 (var) = TAILQ_NEXT((var), field))
655 #define TAILQ_FOREACH_FROM(var, head, field) \
656 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
658 (var) = TAILQ_NEXT((var), field))
660 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
661 for ((var) = TAILQ_FIRST((head)); \
662 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
665 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
666 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
667 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
670 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
671 for ((var) = TAILQ_LAST((head), headname); \
673 (var) = TAILQ_PREV((var), headname, field))
675 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
676 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
678 (var) = TAILQ_PREV((var), headname, field))
680 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
681 for ((var) = TAILQ_LAST((head), headname); \
682 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
685 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
686 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
687 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
690 #define TAILQ_INIT(head) do { \
691 TAILQ_FIRST((head)) = NULL; \
692 (head)->tqh_last = &TAILQ_FIRST((head)); \
693 QMD_TRACE_HEAD(head); \
696 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
697 QMD_TAILQ_CHECK_NEXT(listelm, field); \
698 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
699 TAILQ_NEXT((elm), field)->field.tqe_prev = \
700 &TAILQ_NEXT((elm), field); \
702 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
703 QMD_TRACE_HEAD(head); \
705 TAILQ_NEXT((listelm), field) = (elm); \
706 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
707 QMD_TRACE_ELEM(&(elm)->field); \
708 QMD_TRACE_ELEM(&(listelm)->field); \
711 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
712 QMD_TAILQ_CHECK_PREV(listelm, field); \
713 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
714 TAILQ_NEXT((elm), field) = (listelm); \
715 *(listelm)->field.tqe_prev = (elm); \
716 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
717 QMD_TRACE_ELEM(&(elm)->field); \
718 QMD_TRACE_ELEM(&(listelm)->field); \
721 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
722 QMD_TAILQ_CHECK_HEAD(head, field); \
723 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
724 TAILQ_FIRST((head))->field.tqe_prev = \
725 &TAILQ_NEXT((elm), field); \
727 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
728 TAILQ_FIRST((head)) = (elm); \
729 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
730 QMD_TRACE_HEAD(head); \
731 QMD_TRACE_ELEM(&(elm)->field); \
734 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
735 QMD_TAILQ_CHECK_TAIL(head, field); \
736 TAILQ_NEXT((elm), field) = NULL; \
737 (elm)->field.tqe_prev = (head)->tqh_last; \
738 *(head)->tqh_last = (elm); \
739 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
740 QMD_TRACE_HEAD(head); \
741 QMD_TRACE_ELEM(&(elm)->field); \
744 #define TAILQ_LAST(head, headname) \
745 (*(((struct headname *)((head)->tqh_last))->tqh_last))
747 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
749 #define TAILQ_PREV(elm, headname, field) \
750 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
752 #define TAILQ_REMOVE(head, elm, field) do { \
753 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
754 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
755 QMD_TAILQ_CHECK_NEXT(elm, field); \
756 QMD_TAILQ_CHECK_PREV(elm, field); \
757 if ((TAILQ_NEXT((elm), field)) != NULL) \
758 TAILQ_NEXT((elm), field)->field.tqe_prev = \
759 (elm)->field.tqe_prev; \
761 (head)->tqh_last = (elm)->field.tqe_prev; \
762 QMD_TRACE_HEAD(head); \
764 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
767 QMD_TRACE_ELEM(&(elm)->field); \
770 #define TAILQ_SWAP(head1, head2, type, field) do { \
771 QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first; \
772 QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last; \
773 (head1)->tqh_first = (head2)->tqh_first; \
774 (head1)->tqh_last = (head2)->tqh_last; \
775 (head2)->tqh_first = swap_first; \
776 (head2)->tqh_last = swap_last; \
777 if ((swap_first = (head1)->tqh_first) != NULL) \
778 swap_first->field.tqe_prev = &(head1)->tqh_first; \
780 (head1)->tqh_last = &(head1)->tqh_first; \
781 if ((swap_first = (head2)->tqh_first) != NULL) \
782 swap_first->field.tqe_prev = &(head2)->tqh_first; \
784 (head2)->tqh_last = &(head2)->tqh_first; \
787 #endif /* !_SYS_QUEUE_H_ */