1 /* $OpenBSD: queue.h,v 1.16 2000/09/07 19:47:59 art Exp $ */
2 /* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
3
4 /*
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)queue.h 8.5 (Berkeley) 8/20/94
33 */
34
35 #ifndef _SYS_QUEUE_H_
36 #define _SYS_QUEUE_H_
37
38 /*
39 * This file defines five types of data structures: singly-linked lists,
40 * lists, simple queues, tail queues, and circular queues.
41 *
42 *
43 * A singly-linked list is headed by a single forward pointer. The elements
44 * are singly linked for minimum space and pointer manipulation overhead at
45 * the expense of O(n) removal for arbitrary elements. New elements can be
46 * added to the list after an existing element or at the head of the list.
47 * Elements being removed from the head of the list should use the explicit
48 * macro for this purpose for optimum efficiency. A singly-linked list may
49 * only be traversed in the forward direction. Singly-linked lists are ideal
50 * for applications with large datasets and few or no removals or for
51 * implementing a LIFO queue.
52 *
53 * A list is headed by a single forward pointer (or an array of forward
54 * pointers for a hash table header). The elements are doubly linked
55 * so that an arbitrary element can be removed without a need to
56 * traverse the list. New elements can be added to the list before
57 * or after an existing element or at the head of the list. A list
58 * may only be traversed in the forward direction.
59 *
60 * A simple queue is headed by a pair of pointers, one the head of the
61 * list and the other to the tail of the list. The elements are singly
62 * linked to save space, so elements can only be removed from the
63 * head of the list. New elements can be added to the list before or after
64 * an existing element, at the head of the list, or at the end of the
65 * list. A simple queue may only be traversed in the forward direction.
66 *
67 * A tail queue is headed by a pair of pointers, one to the head of the
68 * list and the other to the tail of the list. The elements are doubly
69 * linked so that an arbitrary element can be removed without a need to
70 * traverse the list. New elements can be added to the list before or
71 * after an existing element, at the head of the list, or at the end of
72 * the list. A tail queue may be traversed in either direction.
73 *
74 * A circle queue is headed by a pair of pointers, one to the head of the
75 * list and the other to the tail of the list. The elements are doubly
76 * linked so that an arbitrary element can be removed without a need to
77 * traverse the list. New elements can be added to the list before or after
78 * an existing element, at the head of the list, or at the end of the list.
79 * A circle queue may be traversed in either direction, but has a more
80 * complex end of list detection.
81 *
82 * For details on the use of these macros, see the queue(3) manual page.
83 */
84
85 /*
86 * Singly-linked List definitions.
87 */
88 #define SLIST_HEAD(name, type) \
89 struct name { \
90 struct type *slh_first; /* first element */ \
91 }
92
93 #define SLIST_HEAD_INITIALIZER(head) \
94 { NULL }
95
96 #ifndef WIN32
97 #define SLIST_ENTRY(type) \
98 struct { \
99 struct type *sle_next; /* next element */ \
100 }
101 #endif
102
103 /*
104 * Singly-linked List access methods.
105 */
106 #define SLIST_FIRST(head) ((head)->slh_first)
107 #define SLIST_END(head) NULL
108 #define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
109 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
110
111 #define SLIST_FOREACH(var, head, field) \
112 for((var) = SLIST_FIRST(head); \
113 (var) != SLIST_END(head); \
114 (var) = SLIST_NEXT(var, field))
115
116 /*
117 * Singly-linked List functions.
118 */
119 #define SLIST_INIT(head) { \
120 SLIST_FIRST(head) = SLIST_END(head); \
121 }
122
123 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
124 (elm)->field.sle_next = (slistelm)->field.sle_next; \
125 (slistelm)->field.sle_next = (elm); \
126 } while (0)
127
128 #define SLIST_INSERT_HEAD(head, elm, field) do { \
129 (elm)->field.sle_next = (head)->slh_first; \
130 (head)->slh_first = (elm); \
131 } while (0)
132
133 #define SLIST_REMOVE_HEAD(head, field) do { \
134 (head)->slh_first = (head)->slh_first->field.sle_next; \
135 } while (0)
136
137 /*
138 * List definitions.
139 */
140 #define LIST_HEAD(name, type) \
141 struct name { \
142 struct type *lh_first; /* first element */ \
143 }
144
145 #define LIST_HEAD_INITIALIZER(head) \
146 { NULL }
147
148 #define LIST_ENTRY(type) \
149 struct { \
150 struct type *le_next; /* next element */ \
151 struct type **le_prev; /* address of previous next element */ \
152 }
153
154 /*
155 * List access methods
156 */
157 #define LIST_FIRST(head) ((head)->lh_first)
158 #define LIST_END(head) NULL
159 #define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
160 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
161
162 #define LIST_FOREACH(var, head, field) \
163 for((var) = LIST_FIRST(head); \
164 (var)!= LIST_END(head); \
165 (var) = LIST_NEXT(var, field))
166
167 /*
168 * List functions.
169 */
170 #define LIST_INIT(head) do { \
171 LIST_FIRST(head) = LIST_END(head); \
172 } while (0)
173
174 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
175 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
176 (listelm)->field.le_next->field.le_prev = \
177 &(elm)->field.le_next; \
178 (listelm)->field.le_next = (elm); \
179 (elm)->field.le_prev = &(listelm)->field.le_next; \
180 } while (0)
181
182 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
183 (elm)->field.le_prev = (listelm)->field.le_prev; \
184 (elm)->field.le_next = (listelm); \
185 *(listelm)->field.le_prev = (elm); \
186 (listelm)->field.le_prev = &(elm)->field.le_next; \
187 } while (0)
188
189 #define LIST_INSERT_HEAD(head, elm, field) do { \
190 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
191 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
192 (head)->lh_first = (elm); \
193 (elm)->field.le_prev = &(head)->lh_first; \
194 } while (0)
195
196 #define LIST_REMOVE(elm, field) do { \
197 if ((elm)->field.le_next != NULL) \
198 (elm)->field.le_next->field.le_prev = \
199 (elm)->field.le_prev; \
200 *(elm)->field.le_prev = (elm)->field.le_next; \
201 } while (0)
202
203 #define LIST_REPLACE(elm, elm2, field) do { \
204 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
205 (elm2)->field.le_next->field.le_prev = \
206 &(elm2)->field.le_next; \
207 (elm2)->field.le_prev = (elm)->field.le_prev; \
208 *(elm2)->field.le_prev = (elm2); \
209 } while (0)
210
211 /*
212 * Simple queue definitions.
213 */
214 #define SIMPLEQ_HEAD(name, type) \
215 struct name { \
216 struct type *sqh_first; /* first element */ \
217 struct type **sqh_last; /* addr of last next element */ \
218 }
219
220 #define SIMPLEQ_HEAD_INITIALIZER(head) \
221 { NULL, &(head).sqh_first }
222
223 #define SIMPLEQ_ENTRY(type) \
224 struct { \
225 struct type *sqe_next; /* next element */ \
226 }
227
228 /*
229 * Simple queue access methods.
230 */
231 #define SIMPLEQ_FIRST(head) ((head)->sqh_first)
232 #define SIMPLEQ_END(head) NULL
233 #define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
234 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
235
236 #define SIMPLEQ_FOREACH(var, head, field) \
237 for((var) = SIMPLEQ_FIRST(head); \
238 (var) != SIMPLEQ_END(head); \
239 (var) = SIMPLEQ_NEXT(var, field))
240
241 /*
242 * Simple queue functions.
243 */
244 #define SIMPLEQ_INIT(head) do { \
245 (head)->sqh_first = NULL; \
246 (head)->sqh_last = &(head)->sqh_first; \
247 } while (0)
248
249 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
250 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
251 (head)->sqh_last = &(elm)->field.sqe_next; \
252 (head)->sqh_first = (elm); \
253 } while (0)
254
255 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
256 (elm)->field.sqe_next = NULL; \
257 *(head)->sqh_last = (elm); \
258 (head)->sqh_last = &(elm)->field.sqe_next; \
259 } while (0)
260
261 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
262 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
263 (head)->sqh_last = &(elm)->field.sqe_next; \
264 (listelm)->field.sqe_next = (elm); \
265 } while (0)
266
267 #define SIMPLEQ_REMOVE_HEAD(head, elm, field) do { \
268 if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) \
269 (head)->sqh_last = &(head)->sqh_first; \
270 } while (0)
271
272 /*
273 * Tail queue definitions.
274 */
275 #define TAILQ_HEAD(name, type) \
276 struct name { \
277 struct type *tqh_first; /* first element */ \
278 struct type **tqh_last; /* addr of last next element */ \
279 }
280
281 #define TAILQ_HEAD_INITIALIZER(head) \
282 { NULL, &(head).tqh_first }
283
284 #define TAILQ_ENTRY(type) \
285 struct { \
286 struct type *tqe_next; /* next element */ \
287 struct type **tqe_prev; /* address of previous next element */ \
288 }
289
290 /*
291 * tail queue access methods
292 */
293 #define TAILQ_FIRST(head) ((head)->tqh_first)
294 #define TAILQ_END(head) NULL
295 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
296 #define TAILQ_LAST(head, headname) \
297 (*(((struct headname *)((head)->tqh_last))->tqh_last))
298 /* XXX */
299 #define TAILQ_PREV(elm, headname, field) \
300 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
301 #define TAILQ_EMPTY(head) \
302 (TAILQ_FIRST(head) == TAILQ_END(head))
303
304 #define TAILQ_FOREACH(var, head, field) \
305 for((var) = TAILQ_FIRST(head); \
306 (var) != TAILQ_END(head); \
307 (var) = TAILQ_NEXT(var, field))
308
309 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
310 for((var) = TAILQ_LAST(head, headname); \
311 (var) != TAILQ_END(head); \
312 (var) = TAILQ_PREV(var, headname, field))
313
314 /*
315 * Tail queue functions.
316 */
317 #define TAILQ_INIT(head) do { \
318 (head)->tqh_first = NULL; \
319 (head)->tqh_last = &(head)->tqh_first; \
320 } while (0)
321
322 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
323 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
324 (head)->tqh_first->field.tqe_prev = \
325 &(elm)->field.tqe_next; \
326 else \
327 (head)->tqh_last = &(elm)->field.tqe_next; \
328 (head)->tqh_first = (elm); \
329 (elm)->field.tqe_prev = &(head)->tqh_first; \
330 } while (0)
331
332 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
333 (elm)->field.tqe_next = NULL; \
334 (elm)->field.tqe_prev = (head)->tqh_last; \
335 *(head)->tqh_last = (elm); \
336 (head)->tqh_last = &(elm)->field.tqe_next; \
337 } while (0)
338
339 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
340 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
341 (elm)->field.tqe_next->field.tqe_prev = \
342 &(elm)->field.tqe_next; \
343 else \
344 (head)->tqh_last = &(elm)->field.tqe_next; \
345 (listelm)->field.tqe_next = (elm); \
346 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
347 } while (0)
348
349 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
350 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
351 (elm)->field.tqe_next = (listelm); \
352 *(listelm)->field.tqe_prev = (elm); \
353 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
354 } while (0)
355
356 #define TAILQ_REMOVE(head, elm, field) do { \
357 if (((elm)->field.tqe_next) != NULL) \
358 (elm)->field.tqe_next->field.tqe_prev = \
359 (elm)->field.tqe_prev; \
360 else \
361 (head)->tqh_last = (elm)->field.tqe_prev; \
362 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
363 } while (0)
364
365 #define TAILQ_REPLACE(head, elm, elm2, field) do { \
366 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
367 (elm2)->field.tqe_next->field.tqe_prev = \
368 &(elm2)->field.tqe_next; \
369 else \
370 (head)->tqh_last = &(elm2)->field.tqe_next; \
371 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
372 *(elm2)->field.tqe_prev = (elm2); \
373 } while (0)
374
375 /*
376 * Circular queue definitions.
377 */
378 #define CIRCLEQ_HEAD(name, type) \
379 struct name { \
380 struct type *cqh_first; /* first element */ \
381 struct type *cqh_last; /* last element */ \
382 }
383
384 #define CIRCLEQ_HEAD_INITIALIZER(head) \
385 { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
386
387 #define CIRCLEQ_ENTRY(type) \
388 struct { \
389 struct type *cqe_next; /* next element */ \
390 struct type *cqe_prev; /* previous element */ \
391 }
392
393 /*
394 * Circular queue access methods
395 */
396 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
397 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
398 #define CIRCLEQ_END(head) ((void *)(head))
399 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
400 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
401 #define CIRCLEQ_EMPTY(head) \
402 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
403
404 #define CIRCLEQ_FOREACH(var, head, field) \
405 for((var) = CIRCLEQ_FIRST(head); \
406 (var) != CIRCLEQ_END(head); \
407 (var) = CIRCLEQ_NEXT(var, field))
408
409 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
410 for((var) = CIRCLEQ_LAST(head); \
411 (var) != CIRCLEQ_END(head); \
412 (var) = CIRCLEQ_PREV(var, field))
413
414 /*
415 * Circular queue functions.
416 */
417 #define CIRCLEQ_INIT(head) do { \
418 (head)->cqh_first = CIRCLEQ_END(head); \
419 (head)->cqh_last = CIRCLEQ_END(head); \
420 } while (0)
421
422 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
423 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
424 (elm)->field.cqe_prev = (listelm); \
425 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
426 (head)->cqh_last = (elm); \
427 else \
428 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
429 (listelm)->field.cqe_next = (elm); \
430 } while (0)
431
432 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
433 (elm)->field.cqe_next = (listelm); \
434 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
435 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
436 (head)->cqh_first = (elm); \
437 else \
438 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
439 (listelm)->field.cqe_prev = (elm); \
440 } while (0)
441
442 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
443 (elm)->field.cqe_next = (head)->cqh_first; \
444 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
445 if ((head)->cqh_last == CIRCLEQ_END(head)) \
446 (head)->cqh_last = (elm); \
447 else \
448 (head)->cqh_first->field.cqe_prev = (elm); \
449 (head)->cqh_first = (elm); \
450 } while (0)
451
452 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
453 (elm)->field.cqe_next = CIRCLEQ_END(head); \
454 (elm)->field.cqe_prev = (head)->cqh_last; \
455 if ((head)->cqh_first == CIRCLEQ_END(head)) \
456 (head)->cqh_first = (elm); \
457 else \
458 (head)->cqh_last->field.cqe_next = (elm); \
459 (head)->cqh_last = (elm); \
460 } while (0)
461
462 #define CIRCLEQ_REMOVE(head, elm, field) do { \
463 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
464 (head)->cqh_last = (elm)->field.cqe_prev; \
465 else \
466 (elm)->field.cqe_next->field.cqe_prev = \
467 (elm)->field.cqe_prev; \
468 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
469 (head)->cqh_first = (elm)->field.cqe_next; \
470 else \
471 (elm)->field.cqe_prev->field.cqe_next = \
472 (elm)->field.cqe_next; \
473 } while (0)
474
475 #define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
476 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
477 CIRCLEQ_END(head)) \
478 (head).cqh_last = (elm2); \
479 else \
480 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
481 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
482 CIRCLEQ_END(head)) \
483 (head).cqh_first = (elm2); \
484 else \
485 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
486 } while (0)
487
488 #endif /* !_SYS_QUEUE_H_ */