1/* $NetBSD: queue.h,v 1.77 2024/05/12 10:34:56 rillig Exp $ */
2
3/*
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)queue.h 8.5 (Berkeley) 8/20/94
32 */
33
34#ifndef _SYS_QUEUE_H_
35#define _SYS_QUEUE_H_
36
37/*
38 * This file defines five types of data structures: singly-linked lists,
39 * lists, simple queues, tail queues, and circular queues.
40 *
41 * A singly-linked list is headed by a single forward pointer. The
42 * elements are singly linked for minimum space and pointer manipulation
43 * overhead at the expense of O(n) removal for arbitrary elements. New
44 * elements can be added to the list after an existing element or at the
45 * head of the list. Elements being removed from the head of the list
46 * should use the explicit macro for this purpose for optimum
47 * efficiency. A singly-linked list may only be traversed in the forward
48 * direction. Singly-linked lists are ideal for applications with large
49 * datasets and few or no removals or for implementing a LIFO queue.
50 *
51 * A list is headed by a single forward pointer (or an array of forward
52 * pointers for a hash table header). The elements are doubly linked
53 * so that an arbitrary element can be removed without a need to
54 * traverse the list. New elements can be added to the list before
55 * or after an existing element or at the head of the list. A list
56 * may only be traversed in the forward direction.
57 *
58 * A simple queue is headed by a pair of pointers, one the head of the
59 * list and the other to the tail of the list. The elements are singly
60 * linked to save space, so elements can only be removed from the
61 * head of the list. New elements can be added to the list after
62 * an existing element, at the head of the list, or at the end of the
63 * list. A simple queue may only be traversed in the forward direction.
64 *
65 * A tail queue is headed by a pair of pointers, one to the head of the
66 * list and the other to the tail of the list. The elements are doubly
67 * linked so that an arbitrary element can be removed without a need to
68 * traverse the list. New elements can be added to the list before or
69 * after an existing element, at the head of the list, or at the end of
70 * the list. A tail queue may be traversed in either direction.
71 *
72 * For details on the use of these macros, see the queue(3) manual page.
73 */
74
75/*
76 * Include the definition of NULL only on NetBSD because sys/null.h
77 * is not available elsewhere. This conditional makes the header
78 * portable and it can simply be dropped verbatim into any system.
79 * The caveat is that on other systems some other header
80 * must provide NULL before the macros can be used.
81 */
82#ifdef __NetBSD__
83#include <sys/null.h>
84#endif
85
86#if defined(_KERNEL) && defined(DIAGNOSTIC)
87#define QUEUEDEBUG 1
88#endif
89
90#if defined(QUEUEDEBUG)
91# if defined(_KERNEL)
92# define QUEUEDEBUG_ABORT(...) panic(__VA_ARGS__)
93# else
94# include <err.h>
95# define QUEUEDEBUG_ABORT(...) err(1, __VA_ARGS__)
96# endif
97#endif
98
99/*
100 * Singly-linked List definitions.
101 */
102#define SLIST_HEAD(name, type) \
103struct name { \
104 struct type *slh_first; /* first element */ \
105}
106
107#define SLIST_HEAD_INITIALIZER(head) \
108 { NULL }
109
110#define SLIST_ENTRY(type) \
111struct { \
112 struct type *sle_next; /* next element */ \
113}
114
115/*
116 * Singly-linked List access methods.
117 */
118#define SLIST_FIRST(head) ((head)->slh_first)
119#define SLIST_END(head) NULL
120#define SLIST_EMPTY(head) ((head)->slh_first == NULL)
121#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
122
123#define SLIST_FOREACH(var, head, field) \
124 for((var) = (head)->slh_first; \
125 (var) != SLIST_END(head); \
126 (var) = (var)->field.sle_next)
127
128#define SLIST_FOREACH_SAFE(var, head, field, tvar) \
129 for ((var) = SLIST_FIRST((head)); \
130 (var) != SLIST_END(head) && \
131 ((tvar) = SLIST_NEXT((var), field), 1); \
132 (var) = (tvar))
133
134/*
135 * Singly-linked List functions.
136 */
137#define SLIST_INIT(head) do { \
138 (head)->slh_first = SLIST_END(head); \
139} while (0)
140
141#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
142 (elm)->field.sle_next = (slistelm)->field.sle_next; \
143 (slistelm)->field.sle_next = (elm); \
144} while (0)
145
146#define SLIST_INSERT_HEAD(head, elm, field) do { \
147 (elm)->field.sle_next = (head)->slh_first; \
148 (head)->slh_first = (elm); \
149} while (0)
150
151#define SLIST_REMOVE_AFTER(slistelm, field) do { \
152 (slistelm)->field.sle_next = \
153 SLIST_NEXT(SLIST_NEXT((slistelm), field), field); \
154} while (0)
155
156#define SLIST_REMOVE_HEAD(head, field) do { \
157 (head)->slh_first = (head)->slh_first->field.sle_next; \
158} while (0)
159
160#define SLIST_REMOVE(head, elm, type, field) do { \
161 if ((head)->slh_first == (elm)) { \
162 SLIST_REMOVE_HEAD((head), field); \
163 } \
164 else { \
165 struct type *curelm = (head)->slh_first; \
166 while(curelm->field.sle_next != (elm)) \
167 curelm = curelm->field.sle_next; \
168 curelm->field.sle_next = \
169 curelm->field.sle_next->field.sle_next; \
170 } \
171} while (0)
172
173
174/*
175 * List definitions.
176 */
177#define LIST_HEAD(name, type) \
178struct name { \
179 struct type *lh_first; /* first element */ \
180}
181
182#define LIST_HEAD_INITIALIZER(head) \
183 { NULL }
184
185#define LIST_ENTRY(type) \
186struct { \
187 struct type *le_next; /* next element */ \
188 struct type **le_prev; /* address of previous next element */ \
189}
190
191/*
192 * List access methods.
193 */
194#define LIST_FIRST(head) ((head)->lh_first)
195#define LIST_END(head) NULL
196#define LIST_EMPTY(head) ((head)->lh_first == LIST_END(head))
197#define LIST_NEXT(elm, field) ((elm)->field.le_next)
198
199#define LIST_FOREACH(var, head, field) \
200 for ((var) = ((head)->lh_first); \
201 (var) != LIST_END(head); \
202 (var) = ((var)->field.le_next))
203
204#define LIST_FOREACH_SAFE(var, head, field, tvar) \
205 for ((var) = LIST_FIRST((head)); \
206 (var) != LIST_END(head) && \
207 ((tvar) = LIST_NEXT((var), field), 1); \
208 (var) = (tvar))
209
210#define LIST_MOVE(head1, head2, field) do { \
211 LIST_INIT((head2)); \
212 if (!LIST_EMPTY((head1))) { \
213 (head2)->lh_first = (head1)->lh_first; \
214 (head2)->lh_first->field.le_prev = &(head2)->lh_first; \
215 LIST_INIT((head1)); \
216 } \
217} while (0)
218
219/*
220 * List functions.
221 */
222#if defined(QUEUEDEBUG)
223#define QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field) \
224 if ((head)->lh_first && \
225 (head)->lh_first->field.le_prev != &(head)->lh_first) \
226 QUEUEDEBUG_ABORT("LIST_INSERT_HEAD %p %s:%d", (head), \
227 __FILE__, __LINE__);
228#define QUEUEDEBUG_LIST_OP(elm, field) \
229 if ((elm)->field.le_next && \
230 (elm)->field.le_next->field.le_prev != \
231 &(elm)->field.le_next) \
232 QUEUEDEBUG_ABORT("LIST_* forw %p %s:%d", (elm), \
233 __FILE__, __LINE__); \
234 if (*(elm)->field.le_prev != (elm)) \
235 QUEUEDEBUG_ABORT("LIST_* back %p %s:%d", (elm), \
236 __FILE__, __LINE__);
237#define QUEUEDEBUG_LIST_POSTREMOVE(elm, field) \
238 (elm)->field.le_next = (void *)1L; \
239 (elm)->field.le_prev = (void *)1L;
240#else
241#define QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)
242#define QUEUEDEBUG_LIST_OP(elm, field)
243#define QUEUEDEBUG_LIST_POSTREMOVE(elm, field)
244#endif
245
246#define LIST_INIT(head) do { \
247 (head)->lh_first = LIST_END(head); \
248} while (0)
249
250#define LIST_INSERT_AFTER(listelm, elm, field) do { \
251 QUEUEDEBUG_LIST_OP((listelm), field) \
252 if (((elm)->field.le_next = (listelm)->field.le_next) != \
253 LIST_END(head)) \
254 (listelm)->field.le_next->field.le_prev = \
255 &(elm)->field.le_next; \
256 (listelm)->field.le_next = (elm); \
257 (elm)->field.le_prev = &(listelm)->field.le_next; \
258} while (0)
259
260#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
261 QUEUEDEBUG_LIST_OP((listelm), field) \
262 (elm)->field.le_prev = (listelm)->field.le_prev; \
263 (elm)->field.le_next = (listelm); \
264 *(listelm)->field.le_prev = (elm); \
265 (listelm)->field.le_prev = &(elm)->field.le_next; \
266} while (0)
267
268#define LIST_INSERT_HEAD(head, elm, field) do { \
269 QUEUEDEBUG_LIST_INSERT_HEAD((head), (elm), field) \
270 if (((elm)->field.le_next = (head)->lh_first) != LIST_END(head))\
271 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
272 (head)->lh_first = (elm); \
273 (elm)->field.le_prev = &(head)->lh_first; \
274} while (0)
275
276#define LIST_REMOVE(elm, field) do { \
277 QUEUEDEBUG_LIST_OP((elm), field) \
278 if ((elm)->field.le_next != NULL) \
279 (elm)->field.le_next->field.le_prev = \
280 (elm)->field.le_prev; \
281 *(elm)->field.le_prev = (elm)->field.le_next; \
282 QUEUEDEBUG_LIST_POSTREMOVE((elm), field) \
283} while (0)
284
285#define LIST_REPLACE(elm, elm2, field) do { \
286 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
287 (elm2)->field.le_next->field.le_prev = \
288 &(elm2)->field.le_next; \
289 (elm2)->field.le_prev = (elm)->field.le_prev; \
290 *(elm2)->field.le_prev = (elm2); \
291 QUEUEDEBUG_LIST_POSTREMOVE((elm), field) \
292} while (0)
293
294/*
295 * Simple queue definitions.
296 */
297#define SIMPLEQ_HEAD(name, type) \
298struct name { \
299 struct type *sqh_first; /* first element */ \
300 struct type **sqh_last; /* addr of last next element */ \
301}
302
303#define SIMPLEQ_HEAD_INITIALIZER(head) \
304 { NULL, &(head).sqh_first }
305
306#define SIMPLEQ_ENTRY(type) \
307struct { \
308 struct type *sqe_next; /* next element */ \
309}
310
311/*
312 * Simple queue access methods.
313 */
314#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
315#define SIMPLEQ_END(head) NULL
316#define SIMPLEQ_EMPTY(head) ((head)->sqh_first == SIMPLEQ_END(head))
317#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
318
319#define SIMPLEQ_FOREACH(var, head, field) \
320 for ((var) = ((head)->sqh_first); \
321 (var) != SIMPLEQ_END(head); \
322 (var) = ((var)->field.sqe_next))
323
324#define SIMPLEQ_FOREACH_SAFE(var, head, field, next) \
325 for ((var) = ((head)->sqh_first); \
326 (var) != SIMPLEQ_END(head) && \
327 ((next = ((var)->field.sqe_next)), 1); \
328 (var) = (next))
329
330/*
331 * Simple queue functions.
332 */
333#define SIMPLEQ_INIT(head) do { \
334 (head)->sqh_first = NULL; \
335 (head)->sqh_last = &(head)->sqh_first; \
336} while (0)
337
338#define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
339 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
340 (head)->sqh_last = &(elm)->field.sqe_next; \
341 (head)->sqh_first = (elm); \
342} while (0)
343
344#define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
345 (elm)->field.sqe_next = NULL; \
346 *(head)->sqh_last = (elm); \
347 (head)->sqh_last = &(elm)->field.sqe_next; \
348} while (0)
349
350#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
351 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
352 (head)->sqh_last = &(elm)->field.sqe_next; \
353 (listelm)->field.sqe_next = (elm); \
354} while (0)
355
356#define SIMPLEQ_REMOVE_HEAD(head, field) do { \
357 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
358 (head)->sqh_last = &(head)->sqh_first; \
359} while (0)
360
361#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do { \
362 if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
363 == NULL) \
364 (head)->sqh_last = &(elm)->field.sqe_next; \
365} while (0)
366
367#define SIMPLEQ_REMOVE(head, elm, type, field) do { \
368 if ((head)->sqh_first == (elm)) { \
369 SIMPLEQ_REMOVE_HEAD((head), field); \
370 } else { \
371 struct type *curelm = (head)->sqh_first; \
372 while (curelm->field.sqe_next != (elm)) \
373 curelm = curelm->field.sqe_next; \
374 if ((curelm->field.sqe_next = \
375 curelm->field.sqe_next->field.sqe_next) == NULL) \
376 (head)->sqh_last = &(curelm)->field.sqe_next; \
377 } \
378} while (0)
379
380#define SIMPLEQ_CONCAT(head1, head2) do { \
381 if (!SIMPLEQ_EMPTY((head2))) { \
382 *(head1)->sqh_last = (head2)->sqh_first; \
383 (head1)->sqh_last = (head2)->sqh_last; \
384 SIMPLEQ_INIT((head2)); \
385 } \
386} while (0)
387
388#define SIMPLEQ_LAST(head, type, field) \
389 (SIMPLEQ_EMPTY((head)) ? \
390 NULL : \
391 ((struct type *)(void *) \
392 ((char *)((head)->sqh_last) - offsetof(struct type, field))))
393
394/*
395 * Tail queue definitions.
396 */
397#define _TAILQ_HEAD(name, type, qual) \
398struct name { \
399 qual type *tqh_first; /* first element */ \
400 qual type *qual *tqh_last; /* addr of last next element */ \
401}
402#define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type,)
403
404#define TAILQ_HEAD_INITIALIZER(head) \
405 { TAILQ_END(head), &(head).tqh_first }
406
407#define _TAILQ_ENTRY(type, qual) \
408struct { \
409 qual type *tqe_next; /* next element */ \
410 qual type *qual *tqe_prev; /* address of previous next element */\
411}
412#define TAILQ_ENTRY(type) _TAILQ_ENTRY(struct type,)
413
414/*
415 * Tail queue access methods.
416 */
417#define TAILQ_FIRST(head) ((head)->tqh_first)
418#define TAILQ_END(head) (NULL)
419#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
420#define TAILQ_LAST(head, headname) \
421 (*(((struct headname *)(void *)((head)->tqh_last))->tqh_last))
422#define TAILQ_PREV(elm, headname, field) \
423 (*(((struct headname *)(void *)((elm)->field.tqe_prev))->tqh_last))
424#define TAILQ_EMPTY(head) (TAILQ_FIRST(head) == TAILQ_END(head))
425
426
427#define TAILQ_FOREACH(var, head, field) \
428 for ((var) = ((head)->tqh_first); \
429 (var) != TAILQ_END(head); \
430 (var) = ((var)->field.tqe_next))
431
432#define TAILQ_FOREACH_SAFE(var, head, field, next) \
433 for ((var) = ((head)->tqh_first); \
434 (var) != TAILQ_END(head) && \
435 ((next) = TAILQ_NEXT(var, field), 1); (var) = (next))
436
437#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
438 for ((var) = TAILQ_LAST((head), headname); \
439 (var) != TAILQ_END(head); \
440 (var) = TAILQ_PREV((var), headname, field))
441
442#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, prev) \
443 for ((var) = TAILQ_LAST((head), headname); \
444 (var) != TAILQ_END(head) && \
445 ((prev) = TAILQ_PREV((var), headname, field), 1); (var) = (prev))
446
447/*
448 * Tail queue functions.
449 */
450#if defined(QUEUEDEBUG)
451#define QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field) \
452 if ((head)->tqh_first && \
453 (head)->tqh_first->field.tqe_prev != &(head)->tqh_first) \
454 QUEUEDEBUG_ABORT("TAILQ_INSERT_HEAD %p %s:%d", (head), \
455 __FILE__, __LINE__);
456#define QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field) \
457 if (*(head)->tqh_last != NULL) \
458 QUEUEDEBUG_ABORT("TAILQ_INSERT_TAIL %p %s:%d", (head), \
459 __FILE__, __LINE__);
460#define QUEUEDEBUG_TAILQ_OP(elm, field) \
461 if ((elm)->field.tqe_next && \
462 (elm)->field.tqe_next->field.tqe_prev != \
463 &(elm)->field.tqe_next) \
464 QUEUEDEBUG_ABORT("TAILQ_* forw %p %s:%d", (elm), \
465 __FILE__, __LINE__); \
466 if (*(elm)->field.tqe_prev != (elm)) \
467 QUEUEDEBUG_ABORT("TAILQ_* back %p %s:%d", (elm), \
468 __FILE__, __LINE__);
469#define QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field) \
470 if ((elm)->field.tqe_next == NULL && \
471 (head)->tqh_last != &(elm)->field.tqe_next) \
472 QUEUEDEBUG_ABORT("TAILQ_PREREMOVE head %p elm %p %s:%d",\
473 (head), (elm), __FILE__, __LINE__);
474#define QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field) \
475 (elm)->field.tqe_next = (void *)1L; \
476 (elm)->field.tqe_prev = (void *)1L;
477#else
478#define QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)
479#define QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)
480#define QUEUEDEBUG_TAILQ_OP(elm, field)
481#define QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)
482#define QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)
483#endif
484
485#define TAILQ_INIT(head) do { \
486 (head)->tqh_first = TAILQ_END(head); \
487 (head)->tqh_last = &(head)->tqh_first; \
488} while (0)
489
490#define TAILQ_INSERT_HEAD(head, elm, field) do { \
491 QUEUEDEBUG_TAILQ_INSERT_HEAD((head), (elm), field) \
492 if (((elm)->field.tqe_next = (head)->tqh_first) != TAILQ_END(head))\
493 (head)->tqh_first->field.tqe_prev = \
494 &(elm)->field.tqe_next; \
495 else \
496 (head)->tqh_last = &(elm)->field.tqe_next; \
497 (head)->tqh_first = (elm); \
498 (elm)->field.tqe_prev = &(head)->tqh_first; \
499} while (0)
500
501#define TAILQ_INSERT_TAIL(head, elm, field) do { \
502 QUEUEDEBUG_TAILQ_INSERT_TAIL((head), (elm), field) \
503 (elm)->field.tqe_next = TAILQ_END(head); \
504 (elm)->field.tqe_prev = (head)->tqh_last; \
505 *(head)->tqh_last = (elm); \
506 (head)->tqh_last = &(elm)->field.tqe_next; \
507} while (0)
508
509#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
510 QUEUEDEBUG_TAILQ_OP((listelm), field) \
511 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != \
512 TAILQ_END(head)) \
513 (elm)->field.tqe_next->field.tqe_prev = \
514 &(elm)->field.tqe_next; \
515 else \
516 (head)->tqh_last = &(elm)->field.tqe_next; \
517 (listelm)->field.tqe_next = (elm); \
518 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
519} while (0)
520
521#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
522 QUEUEDEBUG_TAILQ_OP((listelm), field) \
523 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
524 (elm)->field.tqe_next = (listelm); \
525 *(listelm)->field.tqe_prev = (elm); \
526 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
527} while (0)
528
529#define TAILQ_REMOVE(head, elm, field) do { \
530 QUEUEDEBUG_TAILQ_PREREMOVE((head), (elm), field) \
531 QUEUEDEBUG_TAILQ_OP((elm), field) \
532 if (((elm)->field.tqe_next) != TAILQ_END(head)) \
533 (elm)->field.tqe_next->field.tqe_prev = \
534 (elm)->field.tqe_prev; \
535 else \
536 (head)->tqh_last = (elm)->field.tqe_prev; \
537 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
538 QUEUEDEBUG_TAILQ_POSTREMOVE((elm), field); \
539} while (0)
540
541#define TAILQ_REPLACE(head, elm, elm2, field) do { \
542 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != \
543 TAILQ_END(head)) \
544 (elm2)->field.tqe_next->field.tqe_prev = \
545 &(elm2)->field.tqe_next; \
546 else \
547 (head)->tqh_last = &(elm2)->field.tqe_next; \
548 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
549 *(elm2)->field.tqe_prev = (elm2); \
550 QUEUEDEBUG_TAILQ_POSTREMOVE((elm), field); \
551} while (0)
552
553#define TAILQ_CONCAT(head1, head2, field) do { \
554 if (!TAILQ_EMPTY(head2)) { \
555 *(head1)->tqh_last = (head2)->tqh_first; \
556 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
557 (head1)->tqh_last = (head2)->tqh_last; \
558 TAILQ_INIT((head2)); \
559 } \
560} while (0)
561
562/*
563 * Singly-linked Tail queue declarations.
564 */
565#define STAILQ_HEAD(name, type) \
566struct name { \
567 struct type *stqh_first; /* first element */ \
568 struct type **stqh_last; /* addr of last next element */ \
569}
570
571#define STAILQ_HEAD_INITIALIZER(head) \
572 { NULL, &(head).stqh_first }
573
574#define STAILQ_ENTRY(type) \
575struct { \
576 struct type *stqe_next; /* next element */ \
577}
578
579/*
580 * Singly-linked Tail queue access methods.
581 */
582#define STAILQ_FIRST(head) ((head)->stqh_first)
583#define STAILQ_END(head) NULL
584#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
585#define STAILQ_EMPTY(head) (STAILQ_FIRST(head) == STAILQ_END(head))
586
587/*
588 * Singly-linked Tail queue functions.
589 */
590#define STAILQ_INIT(head) do { \
591 (head)->stqh_first = NULL; \
592 (head)->stqh_last = &(head)->stqh_first; \
593} while (0)
594
595#define STAILQ_INSERT_HEAD(head, elm, field) do { \
596 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \
597 (head)->stqh_last = &(elm)->field.stqe_next; \
598 (head)->stqh_first = (elm); \
599} while (0)
600
601#define STAILQ_INSERT_TAIL(head, elm, field) do { \
602 (elm)->field.stqe_next = NULL; \
603 *(head)->stqh_last = (elm); \
604 (head)->stqh_last = &(elm)->field.stqe_next; \
605} while (0)
606
607#define STAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
608 if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\
609 (head)->stqh_last = &(elm)->field.stqe_next; \
610 (listelm)->field.stqe_next = (elm); \
611} while (0)
612
613#define STAILQ_REMOVE_HEAD(head, field) do { \
614 if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \
615 (head)->stqh_last = &(head)->stqh_first; \
616} while (0)
617
618#define STAILQ_REMOVE(head, elm, type, field) do { \
619 if ((head)->stqh_first == (elm)) { \
620 STAILQ_REMOVE_HEAD((head), field); \
621 } else { \
622 struct type *curelm = (head)->stqh_first; \
623 while (curelm->field.stqe_next != (elm)) \
624 curelm = curelm->field.stqe_next; \
625 if ((curelm->field.stqe_next = \
626 curelm->field.stqe_next->field.stqe_next) == NULL) \
627 (head)->stqh_last = &(curelm)->field.stqe_next; \
628 } \
629} while (0)
630
631#define STAILQ_FOREACH(var, head, field) \
632 for ((var) = ((head)->stqh_first); \
633 (var); \
634 (var) = ((var)->field.stqe_next))
635
636#define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
637 for ((var) = STAILQ_FIRST((head)); \
638 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
639 (var) = (tvar))
640
641#define STAILQ_CONCAT(head1, head2) do { \
642 if (!STAILQ_EMPTY((head2))) { \
643 *(head1)->stqh_last = (head2)->stqh_first; \
644 (head1)->stqh_last = (head2)->stqh_last; \
645 STAILQ_INIT((head2)); \
646 } \
647} while (0)
648
649#define STAILQ_LAST(head, type, field) \
650 (STAILQ_EMPTY((head)) ? \
651 NULL : \
652 ((struct type *)(void *) \
653 ((char *)((head)->stqh_last) - offsetof(struct type, field))))
654
655#endif /* !_SYS_QUEUE_H_ */