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queue.h
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, field, headname) \
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_ */