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 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)queue.h 8.5 (Berkeley) 8/20/94
34 * $FreeBSD: src/sys/sys/queue.h,v 1.44 2001/09/28 00:05:11 luigi Exp $
35 */
36
37 #ifndef _SYS_QUEUE_H_
38 #define _SYS_QUEUE_H_
39
40 #include <stddef.h> /* for offsetof() */
41
42 /*
43 * This file defines five types of data structures: singly-linked lists,
44 * singly-linked tail queues, lists, tail queues, and circular queues.
45 *
46 * A singly-linked list is headed by a single forward pointer. The elements
47 * are singly linked for minimum space and pointer manipulation overhead at
48 * the expense of O(n) removal for arbitrary elements. New elements can be
49 * added to the list after an existing element or at the head of the list.
50 * Elements being removed from the head of the list should use the explicit
51 * macro for this purpose for optimum efficiency. A singly-linked list may
52 * only be traversed in the forward direction. Singly-linked lists are ideal
53 * for applications with large datasets and few or no removals or for
54 * implementing a LIFO queue.
55 *
56 * A singly-linked tail queue is headed by a pair of pointers, one to the
57 * head of the list and the other to the tail of the list. The elements are
58 * singly linked for minimum space and pointer manipulation overhead at the
59 * expense of O(n) removal for arbitrary elements. New elements can be added
60 * to the list after an existing element, at the head of the list, or at the
61 * end of the list. Elements being removed from the head of the tail queue
62 * should use the explicit macro for this purpose for optimum efficiency.
63 * A singly-linked tail queue may only be traversed in the forward direction.
64 * Singly-linked tail queues are ideal for applications with large datasets
65 * and few or no removals or for implementing a FIFO queue.
66 *
67 * A list is headed by a single forward pointer (or an array of forward
68 * pointers for a hash table header). The elements are doubly linked
69 * 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
71 * or after an existing element or at the head of the list. A list
72 * may only be traversed in the forward direction.
73 *
74 * A tail 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
78 * after an existing element, at the head of the list, or at the end of
79 * the list. A tail queue may be traversed in either direction.
80 *
81 * For details on the use of these macros, see the queue(3) manual page.
82 *
83 *
84 * SLIST LIST STAILQ TAILQ
85 * _HEAD + + + +
86 * _HEAD_INITIALIZER + + + +
87 * _ENTRY + + + +
88 * _INIT + + + +
89 * _EMPTY + + + +
90 * _FIRST + + + +
91 * _NEXT + + + +
92 * _PREV - - - +
93 * _LAST - - + +
94 * _FOREACH + + + +
95 * _FOREACH_REVERSE - - - +
96 * _INSERT_HEAD + + + +
97 * _INSERT_BEFORE - + - +
98 * _INSERT_AFTER + + + +
99 * _INSERT_TAIL - - + +
100 * _REMOVE_HEAD + - + -
101 * _REMOVE + + + +
102 *
103 */
104
105 /*
106 * Singly-linked List declarations.
107 */
108 #define SLIST_HEAD(name, type) \
109 struct name { \
110 struct type *slh_first; /* first element */ \
111 }
112
113 #define SLIST_HEAD_INITIALIZER(head) \
114 { NULL }
115
116 #define SLIST_ENTRY(type) \
117 struct { \
118 struct type *sle_next; /* next element */ \
119 }
120
121 /*
122 * Singly-linked List functions.
123 */
124 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
125
126 #define SLIST_FIRST(head) ((head)->slh_first)
127
128 #define SLIST_FOREACH(var, head, field) \
129 for ((var) = SLIST_FIRST((head)); \
130 (var); \
131 (var) = SLIST_NEXT((var), field))
132
133 #define SLIST_INIT(head) do { \
134 SLIST_FIRST((head)) = NULL; \
135 } while (0)
136
137 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
138 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
139 SLIST_NEXT((slistelm), field) = (elm); \
140 } while (0)
141
142 #define SLIST_INSERT_HEAD(head, elm, field) do { \
143 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
144 SLIST_FIRST((head)) = (elm); \
145 } while (0)
146
147 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
148
149 #define SLIST_REMOVE(head, elm, type, field) do { \
150 if (SLIST_FIRST((head)) == (elm)) { \
151 SLIST_REMOVE_HEAD((head), field); \
152 } \
153 else { \
154 struct type *curelm = SLIST_FIRST((head)); \
155 while (SLIST_NEXT(curelm, field) != (elm)) \
156 curelm = SLIST_NEXT(curelm, field); \
157 SLIST_NEXT(curelm, field) = \
158 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
159 } \
160 } while (0)
161
162 #define SLIST_REMOVE_HEAD(head, field) do { \
163 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
164 } while (0)
165
166 /*
167 * Singly-linked Tail queue declarations.
168 */
169 #define STAILQ_HEAD(name, type) \
170 struct name { \
171 struct type *stqh_first;/* first element */ \
172 struct type **stqh_last;/* addr of last next element */ \
173 }
174
175 #define STAILQ_HEAD_INITIALIZER(head) \
176 { NULL, &(head).stqh_first }
177
178 #define STAILQ_ENTRY(type) \
179 struct { \
180 struct type *stqe_next; /* next element */ \
181 }
182
183 /*
184 * Singly-linked Tail queue functions.
185 */
186 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
187
188 #define STAILQ_FIRST(head) ((head)->stqh_first)
189
190 #define STAILQ_FOREACH(var, head, field) \
191 for((var) = STAILQ_FIRST((head)); \
192 (var); \
193 (var) = STAILQ_NEXT((var), field))
194
195 #define STAILQ_INIT(head) do { \
196 STAILQ_FIRST((head)) = NULL; \
197 (head)->stqh_last = &STAILQ_FIRST((head)); \
198 } while (0)
199
200 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
201 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
202 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
203 STAILQ_NEXT((tqelm), field) = (elm); \
204 } while (0)
205
206 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
207 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
208 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
209 STAILQ_FIRST((head)) = (elm); \
210 } while (0)
211
212 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
213 STAILQ_NEXT((elm), field) = NULL; \
214 *(head)->stqh_last = (elm); \
215 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
216 } while (0)
217
218 #define STAILQ_LAST(head, type, field) \
219 (STAILQ_EMPTY(head) ? \
220 NULL : \
221 ((struct type *) \
222 ((char *)((head)->stqh_last) - offsetof(struct type, field))))
223
224 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
225
226 #define STAILQ_REMOVE(head, elm, type, field) do { \
227 if (STAILQ_FIRST((head)) == (elm)) { \
228 STAILQ_REMOVE_HEAD(head, field); \
229 } \
230 else { \
231 struct type *curelm = STAILQ_FIRST((head)); \
232 while (STAILQ_NEXT(curelm, field) != (elm)) \
233 curelm = STAILQ_NEXT(curelm, field); \
234 if ((STAILQ_NEXT(curelm, field) = \
235 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
236 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
237 } \
238 } while (0)
239
240 #define STAILQ_REMOVE_HEAD(head, field) do { \
241 if ((STAILQ_FIRST((head)) = \
242 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
243 (head)->stqh_last = &STAILQ_FIRST((head)); \
244 } while (0)
245
246 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
247 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
248 (head)->stqh_last = &STAILQ_FIRST((head)); \
249 } while (0)
250
251 /*
252 * List declarations.
253 */
254 #define LIST_HEAD(name, type) \
255 struct name { \
256 struct type *lh_first; /* first element */ \
257 }
258
259 #define LIST_HEAD_INITIALIZER(head) \
260 { NULL }
261
262 #define LIST_ENTRY(type) \
263 struct { \
264 struct type *le_next; /* next element */ \
265 struct type **le_prev; /* address of previous next element */ \
266 }
267
268 /*
269 * List functions.
270 */
271
272 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
273
274 #define LIST_FIRST(head) ((head)->lh_first)
275
276 #define LIST_FOREACH(var, head, field) \
277 for ((var) = LIST_FIRST((head)); \
278 (var); \
279 (var) = LIST_NEXT((var), field))
280
281 #define LIST_INIT(head) do { \
282 LIST_FIRST((head)) = NULL; \
283 } while (0)
284
285 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
286 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
287 LIST_NEXT((listelm), field)->field.le_prev = \
288 &LIST_NEXT((elm), field); \
289 LIST_NEXT((listelm), field) = (elm); \
290 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
291 } while (0)
292
293 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
294 (elm)->field.le_prev = (listelm)->field.le_prev; \
295 LIST_NEXT((elm), field) = (listelm); \
296 *(listelm)->field.le_prev = (elm); \
297 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
298 } while (0)
299
300 #define LIST_INSERT_HEAD(head, elm, field) do { \
301 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
302 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
303 LIST_FIRST((head)) = (elm); \
304 (elm)->field.le_prev = &LIST_FIRST((head)); \
305 } while (0)
306
307 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
308
309 #define LIST_REMOVE(elm, field) do { \
310 if (LIST_NEXT((elm), field) != NULL) \
311 LIST_NEXT((elm), field)->field.le_prev = \
312 (elm)->field.le_prev; \
313 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
314 } while (0)
315
316 /*
317 * Tail queue declarations.
318 */
319 #define TAILQ_HEAD(name, type) \
320 struct name { \
321 struct type *tqh_first; /* first element */ \
322 struct type **tqh_last; /* addr of last next element */ \
323 }
324
325 #define TAILQ_HEAD_INITIALIZER(head) \
326 { NULL, &(head).tqh_first }
327
328 #define TAILQ_ENTRY(type) \
329 struct { \
330 struct type *tqe_next; /* next element */ \
331 struct type **tqe_prev; /* address of previous next element */ \
332 }
333
334 /*
335 * Tail queue functions.
336 */
337 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
338
339 #define TAILQ_FIRST(head) ((head)->tqh_first)
340
341 #define TAILQ_FOREACH(var, head, field) \
342 for ((var) = TAILQ_FIRST((head)); \
343 (var); \
344 (var) = TAILQ_NEXT((var), field))
345
346 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
347 for ((var) = TAILQ_LAST((head), headname); \
348 (var); \
349 (var) = TAILQ_PREV((var), headname, field))
350
351 #define TAILQ_INIT(head) do { \
352 TAILQ_FIRST((head)) = NULL; \
353 (head)->tqh_last = &TAILQ_FIRST((head)); \
354 } while (0)
355
356 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
357 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
358 TAILQ_NEXT((elm), field)->field.tqe_prev = \
359 &TAILQ_NEXT((elm), field); \
360 else \
361 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
362 TAILQ_NEXT((listelm), field) = (elm); \
363 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
364 } while (0)
365
366 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
367 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
368 TAILQ_NEXT((elm), field) = (listelm); \
369 *(listelm)->field.tqe_prev = (elm); \
370 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
371 } while (0)
372
373 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
374 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
375 TAILQ_FIRST((head))->field.tqe_prev = \
376 &TAILQ_NEXT((elm), field); \
377 else \
378 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
379 TAILQ_FIRST((head)) = (elm); \
380 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
381 } while (0)
382
383 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
384 TAILQ_NEXT((elm), field) = NULL; \
385 (elm)->field.tqe_prev = (head)->tqh_last; \
386 *(head)->tqh_last = (elm); \
387 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
388 } while (0)
389
390 #define TAILQ_LAST(head, headname) \
391 (*(((struct headname *)((head)->tqh_last))->tqh_last))
392
393 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
394
395 #define TAILQ_PREV(elm, headname, field) \
396 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
397
398 #define TAILQ_REMOVE(head, elm, field) do { \
399 if ((TAILQ_NEXT((elm), field)) != NULL) \
400 TAILQ_NEXT((elm), field)->field.tqe_prev = \
401 (elm)->field.tqe_prev; \
402 else \
403 (head)->tqh_last = (elm)->field.tqe_prev; \
404 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
405 } while (0)
406
407
408 #ifdef _KERNEL
409
410 /*
411 * XXX insque() and remque() are an old way of handling certain queues.
412 * They bogusly assumes that all queue heads look alike.
413 */
414
415 struct quehead {
416 struct quehead *qh_link;
417 struct quehead *qh_rlink;
418 };
419
420 #ifdef __GNUC__
421
422 static __inline void
insque(void * a,void * b)423 insque(void *a, void *b)
424 {
425 struct quehead *element = (struct quehead *)a,
426 *head = (struct quehead *)b;
427
428 element->qh_link = head->qh_link;
429 element->qh_rlink = head;
430 head->qh_link = element;
431 element->qh_link->qh_rlink = element;
432 }
433
434 static __inline void
remque(void * a)435 remque(void *a)
436 {
437 struct quehead *element = (struct quehead *)a;
438
439 element->qh_link->qh_rlink = element->qh_rlink;
440 element->qh_rlink->qh_link = element->qh_link;
441 element->qh_rlink = 0;
442 }
443
444 #else /* !__GNUC__ */
445
446 void insque __P((void *a, void *b));
447 void remque __P((void *a));
448
449 #endif /* __GNUC__ */
450
451 #endif /* _KERNEL */
452
453 #endif /* !_SYS_QUEUE_H_ */
454