1 /*
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * @(#)queue.h 8.5 (Berkeley) 8/20/94
27 * $FreeBSD: src/sys/sys/queue.h,v 1.38 2000/05/26 02:06:56 jake Exp $
28 */
29
30 #ifndef _SYS_QUEUE_H_
31 #define _SYS_QUEUE_H_
32
33 /*
34 * This file defines five types of data structures: singly-linked lists,
35 * singly-linked tail queues, lists, tail queues, and circular queues.
36 *
37 * A singly-linked list is headed by a single forward pointer. The elements
38 * are singly linked for minimum space and pointer manipulation overhead at
39 * the expense of O(n) removal for arbitrary elements. New elements can be
40 * added to the list after an existing element or at the head of the list.
41 * Elements being removed from the head of the list should use the explicit
42 * macro for this purpose for optimum efficiency. A singly-linked list may
43 * only be traversed in the forward direction. Singly-linked lists are ideal
44 * for applications with large datasets and few or no removals or for
45 * implementing a LIFO queue.
46 *
47 * A singly-linked tail queue is headed by a pair of pointers, one to the
48 * head of the list and the other to the tail of the list. The elements are
49 * singly linked for minimum space and pointer manipulation overhead at the
50 * expense of O(n) removal for arbitrary elements. New elements can be added
51 * to the list after an existing element, at the head of the list, or at the
52 * end of the list. Elements being removed from the head of the tail queue
53 * should use the explicit macro for this purpose for optimum efficiency.
54 * A singly-linked tail queue may only be traversed in the forward direction.
55 * Singly-linked tail queues are ideal for applications with large datasets
56 * and few or no removals or for implementing a FIFO queue.
57 *
58 * A list is headed by a single forward pointer (or an array of forward
59 * pointers for a hash table header). The elements are doubly linked
60 * so that an arbitrary element can be removed without a need to
61 * traverse the list. New elements can be added to the list before
62 * or after an existing element or at the head of the list. A list
63 * 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 * A circle queue is headed by a pair of pointers, one to the head of the
73 * list and the other to the tail of the list. The elements are doubly
74 * linked so that an arbitrary element can be removed without a need to
75 * traverse the list. New elements can be added to the list before or after
76 * an existing element, at the head of the list, or at the end of the list.
77 * A circle queue may be traversed in either direction, but has a more
78 * complex end of list detection.
79 *
80 * For details on the use of these macros, see the queue(3) manual page.
81 *
82 *
83 * SLIST LIST STAILQ TAILQ CIRCLEQ
84 * _HEAD + + + + +
85 * _HEAD_INITIALIZER + + + + +
86 * _ENTRY + + + + +
87 * _INIT + + + + +
88 * _EMPTY + + + + +
89 * _FIRST + + + + +
90 * _NEXT + + + + +
91 * _PREV - - - + +
92 * _LAST - - + + +
93 * _FOREACH + + + + +
94 * _FOREACH_REVERSE - - - + +
95 * _INSERT_HEAD + + + + +
96 * _INSERT_BEFORE - + - + +
97 * _INSERT_AFTER + + + + +
98 * _INSERT_TAIL - - + + +
99 * _REMOVE_HEAD + - + - -
100 * _REMOVE + + + + +
101 *
102 */
103
104 /*
105 * Singly-linked List declarations.
106 */
107 #define SLIST_HEAD(name, type) \
108 struct name { \
109 struct type *slh_first; /* first element */ \
110 }
111
112 #define SLIST_HEAD_INITIALIZER(head) \
113 { NULL }
114
115 #define SLIST_ENTRY(type) \
116 struct { \
117 struct type *sle_next; /* next element */ \
118 }
119
120 /*
121 * Singly-linked List functions.
122 */
123 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
124
125 #define SLIST_FIRST(head) ((head)->slh_first)
126
127 #define SLIST_FOREACH(var, head, field) \
128 for ((var) = SLIST_FIRST((head)); \
129 (var); \
130 (var) = SLIST_NEXT((var), field))
131
132 #define SLIST_INIT(head) do { \
133 SLIST_FIRST((head)) = NULL; \
134 } while (0)
135
136 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
137 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
138 SLIST_NEXT((slistelm), field) = (elm); \
139 } while (0)
140
141 #define SLIST_INSERT_HEAD(head, elm, field) do { \
142 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
143 SLIST_FIRST((head)) = (elm); \
144 } while (0)
145
146 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
147
148 #define SLIST_REMOVE(head, elm, type, field) do { \
149 if (SLIST_FIRST((head)) == (elm)) { \
150 SLIST_REMOVE_HEAD((head), field); \
151 } \
152 else { \
153 struct type *curelm = SLIST_FIRST((head)); \
154 while (SLIST_NEXT(curelm, field) != (elm)) \
155 curelm = SLIST_NEXT(curelm, field); \
156 SLIST_NEXT(curelm, field) = \
157 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
158 } \
159 } while (0)
160
161 #define SLIST_REMOVE_HEAD(head, field) do { \
162 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
163 } while (0)
164
165 /*
166 * Singly-linked Tail queue declarations.
167 */
168 #define STAILQ_HEAD(name, type) \
169 struct name { \
170 struct type *stqh_first;/* first element */ \
171 struct type **stqh_last;/* addr of last next element */ \
172 }
173
174 #define STAILQ_HEAD_INITIALIZER(head) \
175 { NULL, &(head).stqh_first }
176
177 #define STAILQ_ENTRY(type) \
178 struct { \
179 struct type *stqe_next; /* next element */ \
180 }
181
182 /*
183 * Singly-linked Tail queue functions.
184 */
185 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
186
187 #define STAILQ_FIRST(head) ((head)->stqh_first)
188
189 #define STAILQ_FOREACH(var, head, field) \
190 for((var) = STAILQ_FIRST((head)); \
191 (var); \
192 (var) = STAILQ_NEXT((var), field))
193
194 #define STAILQ_INIT(head) do { \
195 STAILQ_FIRST((head)) = NULL; \
196 (head)->stqh_last = &STAILQ_FIRST((head)); \
197 } while (0)
198
199 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
200 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
201 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
202 STAILQ_NEXT((tqelm), field) = (elm); \
203 } while (0)
204
205 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
206 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
207 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
208 STAILQ_FIRST((head)) = (elm); \
209 } while (0)
210
211 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
212 STAILQ_NEXT((elm), field) = NULL; \
213 STAILQ_LAST((head)) = (elm); \
214 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
215 } while (0)
216
217 #define STAILQ_LAST(head) (*(head)->stqh_last)
218
219 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
220
221 #define STAILQ_REMOVE(head, elm, type, field) do { \
222 if (STAILQ_FIRST((head)) == (elm)) { \
223 STAILQ_REMOVE_HEAD(head, field); \
224 } \
225 else { \
226 struct type *curelm = STAILQ_FIRST((head)); \
227 while (STAILQ_NEXT(curelm, field) != (elm)) \
228 curelm = STAILQ_NEXT(curelm, field); \
229 if ((STAILQ_NEXT(curelm, field) = \
230 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
231 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
232 } \
233 } while (0)
234
235 #define STAILQ_REMOVE_HEAD(head, field) do { \
236 if ((STAILQ_FIRST((head)) = \
237 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
238 (head)->stqh_last = &STAILQ_FIRST((head)); \
239 } while (0)
240
241 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
242 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
243 (head)->stqh_last = &STAILQ_FIRST((head)); \
244 } while (0)
245
246 /*
247 * List declarations.
248 */
249 #define BSD_LIST_HEAD(name, type) \
250 struct name { \
251 struct type *lh_first; /* first element */ \
252 }
253
254 #define LIST_HEAD_INITIALIZER(head) \
255 { NULL }
256
257 #define LIST_ENTRY(type) \
258 struct { \
259 struct type *le_next; /* next element */ \
260 struct type **le_prev; /* address of previous next element */ \
261 }
262
263 /*
264 * List functions.
265 */
266
267 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
268
269 #define LIST_FIRST(head) ((head)->lh_first)
270
271 #define LIST_FOREACH(var, head, field) \
272 for ((var) = LIST_FIRST((head)); \
273 (var); \
274 (var) = LIST_NEXT((var), field))
275
276 #define LIST_INIT(head) do { \
277 LIST_FIRST((head)) = NULL; \
278 } while (0)
279
280 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
281 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
282 LIST_NEXT((listelm), field)->field.le_prev = \
283 &LIST_NEXT((elm), field); \
284 LIST_NEXT((listelm), field) = (elm); \
285 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
286 } while (0)
287
288 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
289 (elm)->field.le_prev = (listelm)->field.le_prev; \
290 LIST_NEXT((elm), field) = (listelm); \
291 *(listelm)->field.le_prev = (elm); \
292 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
293 } while (0)
294
295 #define LIST_INSERT_HEAD(head, elm, field) do { \
296 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
297 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
298 LIST_FIRST((head)) = (elm); \
299 (elm)->field.le_prev = &LIST_FIRST((head)); \
300 } while (0)
301
302 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
303
304 #define LIST_REMOVE(elm, field) do { \
305 if (LIST_NEXT((elm), field) != NULL) \
306 LIST_NEXT((elm), field)->field.le_prev = \
307 (elm)->field.le_prev; \
308 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
309 } while (0)
310
311 /*
312 * Tail queue declarations.
313 */
314 #define TAILQ_HEAD(name, type) \
315 struct name { \
316 struct type *tqh_first; /* first element */ \
317 struct type **tqh_last; /* addr of last next element */ \
318 }
319
320 #define TAILQ_HEAD_INITIALIZER(head) \
321 { NULL, &(head).tqh_first }
322
323 #define TAILQ_ENTRY(type) \
324 struct { \
325 struct type *tqe_next; /* next element */ \
326 struct type **tqe_prev; /* address of previous next element */ \
327 }
328
329 /*
330 * Tail queue functions.
331 */
332 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
333
334 #define TAILQ_FIRST(head) ((head)->tqh_first)
335
336 #define TAILQ_FOREACH(var, head, field) \
337 for ((var) = TAILQ_FIRST((head)); \
338 (var); \
339 (var) = TAILQ_NEXT((var), field))
340
341 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
342 for ((var) = TAILQ_LAST((head), headname); \
343 (var); \
344 (var) = TAILQ_PREV((var), headname, field))
345
346 #define TAILQ_INIT(head) do { \
347 TAILQ_FIRST((head)) = NULL; \
348 (head)->tqh_last = &TAILQ_FIRST((head)); \
349 } while (0)
350
351 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
352 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
353 TAILQ_NEXT((elm), field)->field.tqe_prev = \
354 &TAILQ_NEXT((elm), field); \
355 else \
356 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
357 TAILQ_NEXT((listelm), field) = (elm); \
358 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
359 } while (0)
360
361 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
362 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
363 TAILQ_NEXT((elm), field) = (listelm); \
364 *(listelm)->field.tqe_prev = (elm); \
365 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
366 } while (0)
367
368 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
369 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
370 TAILQ_FIRST((head))->field.tqe_prev = \
371 &TAILQ_NEXT((elm), field); \
372 else \
373 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
374 TAILQ_FIRST((head)) = (elm); \
375 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
376 } while (0)
377
378 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
379 TAILQ_NEXT((elm), field) = NULL; \
380 (elm)->field.tqe_prev = (head)->tqh_last; \
381 *(head)->tqh_last = (elm); \
382 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
383 } while (0)
384
385 #define TAILQ_LAST(head, headname) \
386 (*(((struct headname *)((head)->tqh_last))->tqh_last))
387
388 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
389
390 #define TAILQ_PREV(elm, headname, field) \
391 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
392
393 #define TAILQ_REMOVE(head, elm, field) do { \
394 if ((TAILQ_NEXT((elm), field)) != NULL) \
395 TAILQ_NEXT((elm), field)->field.tqe_prev = \
396 (elm)->field.tqe_prev; \
397 else \
398 (head)->tqh_last = (elm)->field.tqe_prev; \
399 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
400 } while (0)
401
402 /*
403 * Circular queue declarations.
404 */
405 #define CIRCLEQ_HEAD(name, type) \
406 struct name { \
407 struct type *cqh_first; /* first element */ \
408 struct type *cqh_last; /* last element */ \
409 }
410
411 #define CIRCLEQ_HEAD_INITIALIZER(head) \
412 { (void *)&(head), (void *)&(head) }
413
414 #define CIRCLEQ_ENTRY(type) \
415 struct { \
416 struct type *cqe_next; /* next element */ \
417 struct type *cqe_prev; /* previous element */ \
418 }
419
420 /*
421 * Circular queue functions.
422 */
423 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
424
425 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
426
427 #define CIRCLEQ_FOREACH(var, head, field) \
428 for ((var) = CIRCLEQ_FIRST((head)); \
429 (var) != (void *)(head); \
430 (var) = CIRCLEQ_NEXT((var), field))
431
432 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
433 for ((var) = CIRCLEQ_LAST((head)); \
434 (var) != (void *)(head); \
435 (var) = CIRCLEQ_PREV((var), field))
436
437 #define CIRCLEQ_INIT(head) do { \
438 CIRCLEQ_FIRST((head)) = (void *)(head); \
439 CIRCLEQ_LAST((head)) = (void *)(head); \
440 } while (0)
441
442 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
443 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \
444 CIRCLEQ_PREV((elm), field) = (listelm); \
445 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \
446 CIRCLEQ_LAST((head)) = (elm); \
447 else \
448 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\
449 CIRCLEQ_NEXT((listelm), field) = (elm); \
450 } while (0)
451
452 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
453 CIRCLEQ_NEXT((elm), field) = (listelm); \
454 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \
455 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \
456 CIRCLEQ_FIRST((head)) = (elm); \
457 else \
458 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\
459 CIRCLEQ_PREV((listelm), field) = (elm); \
460 } while (0)
461
462 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
463 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \
464 CIRCLEQ_PREV((elm), field) = (void *)(head); \
465 if (CIRCLEQ_LAST((head)) == (void *)(head)) \
466 CIRCLEQ_LAST((head)) = (elm); \
467 else \
468 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \
469 CIRCLEQ_FIRST((head)) = (elm); \
470 } while (0)
471
472 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
473 CIRCLEQ_NEXT((elm), field) = (void *)(head); \
474 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \
475 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \
476 CIRCLEQ_FIRST((head)) = (elm); \
477 else \
478 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \
479 CIRCLEQ_LAST((head)) = (elm); \
480 } while (0)
481
482 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
483
484 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
485
486 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
487
488 #define CIRCLEQ_REMOVE(head, elm, field) do { \
489 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \
490 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \
491 else \
492 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \
493 CIRCLEQ_PREV((elm), field); \
494 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \
495 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \
496 else \
497 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \
498 CIRCLEQ_NEXT((elm), field); \
499 } while (0)
500
501 #endif /* !_SYS_QUEUE_H_ */