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_ */


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