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queue.h
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1 /* $OpenBSD: queue.h,v 1.32 2007/04/30 18:42:34 pedro 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 #if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
86 #define _Q_INVALIDATE(a) (a) = ((void *)-1)
87 #else
88 #define _Q_INVALIDATE(a)
89 #endif
90 
91 /*
92  * Singly-linked List definitions.
93  */
94 #define SLIST_HEAD(name, type) \
95 struct name { \
96  struct type *slh_first; /* first element */ \
97 }
98 
99 #define SLIST_HEAD_INITIALIZER(head) \
100  { NULL }
101 
102 #define SLIST_ENTRY(type) \
103 struct { \
104  struct type *sle_next; /* next element */ \
105 }
106 
107 /*
108  * Singly-linked List access methods.
109  */
110 #define SLIST_FIRST(head) ((head)->slh_first)
111 #define SLIST_END(head) NULL
112 #define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
113 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
114 
115 #define SLIST_FOREACH(var, head, field) \
116  for((var) = SLIST_FIRST(head); \
117  (var) != SLIST_END(head); \
118  (var) = SLIST_NEXT(var, field))
119 
120 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
121  for ((varp) = &SLIST_FIRST((head)); \
122  ((var) = *(varp)) != SLIST_END(head); \
123  (varp) = &SLIST_NEXT((var), field))
124 
125 /*
126  * Singly-linked List functions.
127  */
128 #define SLIST_INIT(head) { \
129  SLIST_FIRST(head) = SLIST_END(head); \
130 }
131 
132 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
133  (elm)->field.sle_next = (slistelm)->field.sle_next; \
134  (slistelm)->field.sle_next = (elm); \
135 } while (0)
136 
137 #define SLIST_INSERT_HEAD(head, elm, field) do { \
138  (elm)->field.sle_next = (head)->slh_first; \
139  (head)->slh_first = (elm); \
140 } while (0)
141 
142 #define SLIST_REMOVE_NEXT(head, elm, field) do { \
143  (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
144 } while (0)
145 
146 #define SLIST_REMOVE_HEAD(head, field) do { \
147  (head)->slh_first = (head)->slh_first->field.sle_next; \
148 } while (0)
149 
150 #define SLIST_REMOVE(head, elm, type, field) do { \
151  if ((head)->slh_first == (elm)) { \
152  SLIST_REMOVE_HEAD((head), field); \
153  } else { \
154  struct type *curelm = (head)->slh_first; \
155  \
156  while (curelm->field.sle_next != (elm)) \
157  curelm = curelm->field.sle_next; \
158  curelm->field.sle_next = \
159  curelm->field.sle_next->field.sle_next; \
160  _Q_INVALIDATE((elm)->field.sle_next); \
161  } \
162 } while (0)
163 
164 /*
165  * List definitions.
166  */
167 #define LIST_HEAD(name, type) \
168 struct name { \
169  struct type *lh_first; /* first element */ \
170 }
171 
172 #define LIST_HEAD_INITIALIZER(head) \
173  { NULL }
174 
175 #define LIST_ENTRY(type) \
176 struct { \
177  struct type *le_next; /* next element */ \
178  struct type **le_prev; /* address of previous next element */ \
179 }
180 
181 /*
182  * List access methods
183  */
184 #define LIST_FIRST(head) ((head)->lh_first)
185 #define LIST_END(head) NULL
186 #define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
187 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
188 
189 #define LIST_FOREACH(var, head, field) \
190  for((var) = LIST_FIRST(head); \
191  (var)!= LIST_END(head); \
192  (var) = LIST_NEXT(var, field))
193 
194 /*
195  * List functions.
196  */
197 #define LIST_INIT(head) do { \
198  LIST_FIRST(head) = LIST_END(head); \
199 } while (0)
200 
201 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
202  if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
203  (listelm)->field.le_next->field.le_prev = \
204  &(elm)->field.le_next; \
205  (listelm)->field.le_next = (elm); \
206  (elm)->field.le_prev = &(listelm)->field.le_next; \
207 } while (0)
208 
209 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
210  (elm)->field.le_prev = (listelm)->field.le_prev; \
211  (elm)->field.le_next = (listelm); \
212  *(listelm)->field.le_prev = (elm); \
213  (listelm)->field.le_prev = &(elm)->field.le_next; \
214 } while (0)
215 
216 #define LIST_INSERT_HEAD(head, elm, field) do { \
217  if (((elm)->field.le_next = (head)->lh_first) != NULL) \
218  (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
219  (head)->lh_first = (elm); \
220  (elm)->field.le_prev = &(head)->lh_first; \
221 } while (0)
222 
223 #define LIST_REMOVE(elm, field) do { \
224  if ((elm)->field.le_next != NULL) \
225  (elm)->field.le_next->field.le_prev = \
226  (elm)->field.le_prev; \
227  *(elm)->field.le_prev = (elm)->field.le_next; \
228  _Q_INVALIDATE((elm)->field.le_prev); \
229  _Q_INVALIDATE((elm)->field.le_next); \
230 } while (0)
231 
232 #define LIST_REPLACE(elm, elm2, field) do { \
233  if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
234  (elm2)->field.le_next->field.le_prev = \
235  &(elm2)->field.le_next; \
236  (elm2)->field.le_prev = (elm)->field.le_prev; \
237  *(elm2)->field.le_prev = (elm2); \
238  _Q_INVALIDATE((elm)->field.le_prev); \
239  _Q_INVALIDATE((elm)->field.le_next); \
240 } while (0)
241 
242 /*
243  * Simple queue definitions.
244  */
245 #define SIMPLEQ_HEAD(name, type) \
246 struct name { \
247  struct type *sqh_first; /* first element */ \
248  struct type **sqh_last; /* addr of last next element */ \
249 }
250 
251 #define SIMPLEQ_HEAD_INITIALIZER(head) \
252  { NULL, &(head).sqh_first }
253 
254 #define SIMPLEQ_ENTRY(type) \
255 struct { \
256  struct type *sqe_next; /* next element */ \
257 }
258 
259 /*
260  * Simple queue access methods.
261  */
262 #define SIMPLEQ_FIRST(head) ((head)->sqh_first)
263 #define SIMPLEQ_END(head) NULL
264 #define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
265 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
266 
267 #define SIMPLEQ_FOREACH(var, head, field) \
268  for((var) = SIMPLEQ_FIRST(head); \
269  (var) != SIMPLEQ_END(head); \
270  (var) = SIMPLEQ_NEXT(var, field))
271 
272 /*
273  * Simple queue functions.
274  */
275 #define SIMPLEQ_INIT(head) do { \
276  (head)->sqh_first = NULL; \
277  (head)->sqh_last = &(head)->sqh_first; \
278 } while (0)
279 
280 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
281  if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
282  (head)->sqh_last = &(elm)->field.sqe_next; \
283  (head)->sqh_first = (elm); \
284 } while (0)
285 
286 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
287  (elm)->field.sqe_next = NULL; \
288  *(head)->sqh_last = (elm); \
289  (head)->sqh_last = &(elm)->field.sqe_next; \
290 } while (0)
291 
292 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
293  if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
294  (head)->sqh_last = &(elm)->field.sqe_next; \
295  (listelm)->field.sqe_next = (elm); \
296 } while (0)
297 
298 #define SIMPLEQ_REMOVE_HEAD(head, field) do { \
299  if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
300  (head)->sqh_last = &(head)->sqh_first; \
301 } while (0)
302 
303 /*
304  * Tail queue definitions.
305  */
306 #define TAILQ_HEAD(name, type) \
307 struct name { \
308  struct type *tqh_first; /* first element */ \
309  struct type **tqh_last; /* addr of last next element */ \
310 }
311 
312 #define TAILQ_HEAD_INITIALIZER(head) \
313  { NULL, &(head).tqh_first }
314 
315 #define TAILQ_ENTRY(type) \
316 struct { \
317  struct type *tqe_next; /* next element */ \
318  struct type **tqe_prev; /* address of previous next element */ \
319 }
320 
321 /*
322  * tail queue access methods
323  */
324 #define TAILQ_FIRST(head) ((head)->tqh_first)
325 #define TAILQ_END(head) NULL
326 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
327 #define TAILQ_LAST(head, headname) \
328  (*(((struct headname *)((head)->tqh_last))->tqh_last))
329 /* XXX */
330 #define TAILQ_PREV(elm, headname, field) \
331  (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
332 #define TAILQ_EMPTY(head) \
333  (TAILQ_FIRST(head) == TAILQ_END(head))
334 
335 #define TAILQ_FOREACH(var, head, field) \
336  for((var) = TAILQ_FIRST(head); \
337  (var) != TAILQ_END(head); \
338  (var) = TAILQ_NEXT(var, field))
339 
340 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
341  for((var) = TAILQ_LAST(head, headname); \
342  (var) != TAILQ_END(head); \
343  (var) = TAILQ_PREV(var, headname, field))
344 
345 /*
346  * Tail queue functions.
347  */
348 #define TAILQ_INIT(head) do { \
349  (head)->tqh_first = NULL; \
350  (head)->tqh_last = &(head)->tqh_first; \
351 } while (0)
352 
353 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
354  if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
355  (head)->tqh_first->field.tqe_prev = \
356  &(elm)->field.tqe_next; \
357  else \
358  (head)->tqh_last = &(elm)->field.tqe_next; \
359  (head)->tqh_first = (elm); \
360  (elm)->field.tqe_prev = &(head)->tqh_first; \
361 } while (0)
362 
363 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
364  (elm)->field.tqe_next = NULL; \
365  (elm)->field.tqe_prev = (head)->tqh_last; \
366  *(head)->tqh_last = (elm); \
367  (head)->tqh_last = &(elm)->field.tqe_next; \
368 } while (0)
369 
370 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
371  if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
372  (elm)->field.tqe_next->field.tqe_prev = \
373  &(elm)->field.tqe_next; \
374  else \
375  (head)->tqh_last = &(elm)->field.tqe_next; \
376  (listelm)->field.tqe_next = (elm); \
377  (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
378 } while (0)
379 
380 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
381  (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
382  (elm)->field.tqe_next = (listelm); \
383  *(listelm)->field.tqe_prev = (elm); \
384  (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
385 } while (0)
386 
387 #define TAILQ_REMOVE(head, elm, field) do { \
388  if (((elm)->field.tqe_next) != NULL) \
389  (elm)->field.tqe_next->field.tqe_prev = \
390  (elm)->field.tqe_prev; \
391  else \
392  (head)->tqh_last = (elm)->field.tqe_prev; \
393  *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
394  _Q_INVALIDATE((elm)->field.tqe_prev); \
395  _Q_INVALIDATE((elm)->field.tqe_next); \
396 } while (0)
397 
398 #define TAILQ_REPLACE(head, elm, elm2, field) do { \
399  if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
400  (elm2)->field.tqe_next->field.tqe_prev = \
401  &(elm2)->field.tqe_next; \
402  else \
403  (head)->tqh_last = &(elm2)->field.tqe_next; \
404  (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
405  *(elm2)->field.tqe_prev = (elm2); \
406  _Q_INVALIDATE((elm)->field.tqe_prev); \
407  _Q_INVALIDATE((elm)->field.tqe_next); \
408 } while (0)
409 
410 /*
411  * Circular queue definitions.
412  */
413 #define CIRCLEQ_HEAD(name, type) \
414 struct name { \
415  struct type *cqh_first; /* first element */ \
416  struct type *cqh_last; /* last element */ \
417 }
418 
419 #define CIRCLEQ_HEAD_INITIALIZER(head) \
420  { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
421 
422 #define CIRCLEQ_ENTRY(type) \
423 struct { \
424  struct type *cqe_next; /* next element */ \
425  struct type *cqe_prev; /* previous element */ \
426 }
427 
428 /*
429  * Circular queue access methods
430  */
431 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
432 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
433 #define CIRCLEQ_END(head) ((void *)(head))
434 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
435 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
436 #define CIRCLEQ_EMPTY(head) \
437  (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
438 
439 #define CIRCLEQ_FOREACH(var, head, field) \
440  for((var) = CIRCLEQ_FIRST(head); \
441  (var) != CIRCLEQ_END(head); \
442  (var) = CIRCLEQ_NEXT(var, field))
443 
444 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
445  for((var) = CIRCLEQ_LAST(head); \
446  (var) != CIRCLEQ_END(head); \
447  (var) = CIRCLEQ_PREV(var, field))
448 
449 /*
450  * Circular queue functions.
451  */
452 #define CIRCLEQ_INIT(head) do { \
453  (head)->cqh_first = CIRCLEQ_END(head); \
454  (head)->cqh_last = CIRCLEQ_END(head); \
455 } while (0)
456 
457 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
458  (elm)->field.cqe_next = (listelm)->field.cqe_next; \
459  (elm)->field.cqe_prev = (listelm); \
460  if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
461  (head)->cqh_last = (elm); \
462  else \
463  (listelm)->field.cqe_next->field.cqe_prev = (elm); \
464  (listelm)->field.cqe_next = (elm); \
465 } while (0)
466 
467 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
468  (elm)->field.cqe_next = (listelm); \
469  (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
470  if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
471  (head)->cqh_first = (elm); \
472  else \
473  (listelm)->field.cqe_prev->field.cqe_next = (elm); \
474  (listelm)->field.cqe_prev = (elm); \
475 } while (0)
476 
477 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
478  (elm)->field.cqe_next = (head)->cqh_first; \
479  (elm)->field.cqe_prev = CIRCLEQ_END(head); \
480  if ((head)->cqh_last == CIRCLEQ_END(head)) \
481  (head)->cqh_last = (elm); \
482  else \
483  (head)->cqh_first->field.cqe_prev = (elm); \
484  (head)->cqh_first = (elm); \
485 } while (0)
486 
487 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
488  (elm)->field.cqe_next = CIRCLEQ_END(head); \
489  (elm)->field.cqe_prev = (head)->cqh_last; \
490  if ((head)->cqh_first == CIRCLEQ_END(head)) \
491  (head)->cqh_first = (elm); \
492  else \
493  (head)->cqh_last->field.cqe_next = (elm); \
494  (head)->cqh_last = (elm); \
495 } while (0)
496 
497 #define CIRCLEQ_REMOVE(head, elm, field) do { \
498  if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
499  (head)->cqh_last = (elm)->field.cqe_prev; \
500  else \
501  (elm)->field.cqe_next->field.cqe_prev = \
502  (elm)->field.cqe_prev; \
503  if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
504  (head)->cqh_first = (elm)->field.cqe_next; \
505  else \
506  (elm)->field.cqe_prev->field.cqe_next = \
507  (elm)->field.cqe_next; \
508  _Q_INVALIDATE((elm)->field.cqe_prev); \
509  _Q_INVALIDATE((elm)->field.cqe_next); \
510 } while (0)
511 
512 #define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
513  if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
514  CIRCLEQ_END(head)) \
515  (head).cqh_last = (elm2); \
516  else \
517  (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
518  if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
519  CIRCLEQ_END(head)) \
520  (head).cqh_first = (elm2); \
521  else \
522  (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
523  _Q_INVALIDATE((elm)->field.cqe_prev); \
524  _Q_INVALIDATE((elm)->field.cqe_next); \
525 } while (0)
526 
527 #endif /* !_SYS_QUEUE_H_ */
528 
529