2 * Copyright (c) 1991, 1993
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30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * @(#)queue.h 8.5 (Berkeley) 8/20/94
41 * This file defines five types of data structures: singly-linked lists,
42 * slingly-linked tail queues, lists, tail queues, and circular queues.
44 * A singly-linked list is headed by a single forward pointer. The elements
45 * are singly linked for minimum space and pointer manipulation overhead at
46 * the expense of O(n) removal for arbitrary elements. New elements can be
47 * added to the list after an existing element or at the head of the list.
48 * Elements being removed from the head of the list should use the explicit
49 * macro for this purpose for optimum efficiency. A singly-linked list may
50 * only be traversed in the forward direction. Singly-linked lists are ideal
51 * for applications with large datasets and few or no removals or for
52 * implementing a LIFO queue.
54 * A singly-linked tail queue is headed by a pair of pointers, one to the
55 * head of the list and the other to the tail of the list. The elements are
56 * singly linked for minimum space and pointer manipulation overhead at the
57 * expense of O(n) removal for arbitrary elements. New elements can be added
58 * to the list after an existing element, at the head of the list, or at the
59 * end of the list. Elements being removed from the head of the tail queue
60 * should use the explicit macro for this purpose for optimum efficiency.
61 * A singly-linked tail queue may only be traversed in the forward direction.
62 * Singly-linked tail queues are ideal for applications with large datasets
63 * and few or no removals or for implementing a FIFO queue.
65 * A list is headed by a single forward pointer (or an array of forward
66 * pointers for a hash table header). The elements are doubly linked
67 * so that an arbitrary element can be removed without a need to
68 * traverse the list. New elements can be added to the list before
69 * or after an existing element or at the head of the list. A list
70 * may only be traversed in the forward direction.
72 * A tail queue is headed by a pair of pointers, one to the head of the
73 * list and the other to the tail of the list. The elements are doubly
74 * linked so that an arbitrary element can be removed without a need to
75 * traverse the list. New elements can be added to the list before or
76 * after an existing element, at the head of the list, or at the end of
77 * the list. A tail queue may only be traversed in the forward direction.
79 * A circle queue is headed by a pair of pointers, one to the head of the
80 * list and the other to the tail of the list. The elements are doubly
81 * linked so that an arbitrary element can be removed without a need to
82 * traverse the list. New elements can be added to the list before or after
83 * an existing element, at the head of the list, or at the end of the list.
84 * A circle queue may be traversed in either direction, but has a more
85 * complex end of list detection.
87 * For details on the use of these macros, see the queue(3) manual page.
90 * SLIST LIST STAILQ TAILQ CIRCLEQ
100 * _INSERT_HEAD + + + + +
101 * _INSERT_BEFORE - + - + +
102 * _INSERT_AFTER + + + + +
103 * _INSERT_TAIL - - + + +
104 * _REMOVE_HEAD + - + - -
110 * Singly-linked List definitions.
112 #define SLIST_HEAD(name, type) \
114 struct type *slh_first; /* first element */ \
117 #define SLIST_HEAD_INITIALIZER(head) \
120 #define SLIST_ENTRY(type) \
122 struct type *sle_next; /* next element */ \
126 * Singly-linked List functions.
128 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
130 #define SLIST_FIRST(head) ((head)->slh_first)
132 #define SLIST_FOREACH(var, head, field) \
133 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
135 #define SLIST_INIT(head) { \
136 (head)->slh_first = NULL; \
139 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
140 (elm)->field.sle_next = (slistelm)->field.sle_next; \
141 (slistelm)->field.sle_next = (elm); \
144 #define SLIST_INSERT_HEAD(head, elm, field) do { \
145 (elm)->field.sle_next = (head)->slh_first; \
146 (head)->slh_first = (elm); \
149 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
151 #define SLIST_REMOVE_HEAD(head, field) do { \
152 (head)->slh_first = (head)->slh_first->field.sle_next; \
155 #define SLIST_REMOVE(head, elm, type, field) do { \
156 if ((head)->slh_first == (elm)) { \
157 SLIST_REMOVE_HEAD((head), field); \
160 struct type *curelm = (head)->slh_first; \
161 while( curelm->field.sle_next != (elm) ) \
162 curelm = curelm->field.sle_next; \
163 curelm->field.sle_next = \
164 curelm->field.sle_next->field.sle_next; \
169 * Singly-linked Tail queue definitions.
171 #define STAILQ_HEAD(name, type) \
173 struct type *stqh_first;/* first element */ \
174 struct type **stqh_last;/* addr of last next element */ \
177 #define STAILQ_HEAD_INITIALIZER(head) \
178 { NULL, &(head).stqh_first }
180 #define STAILQ_ENTRY(type) \
182 struct type *stqe_next; /* next element */ \
186 * Singly-linked Tail queue functions.
188 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
190 #define STAILQ_INIT(head) do { \
191 (head)->stqh_first = NULL; \
192 (head)->stqh_last = &(head)->stqh_first; \
195 #define STAILQ_FIRST(head) ((head)->stqh_first)
196 #define STAILQ_LAST(head) (*(head)->stqh_last)
198 #define STAILQ_FOREACH(var, head, field) \
199 for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)
201 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
202 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \
203 (head)->stqh_last = &(elm)->field.stqe_next; \
204 (head)->stqh_first = (elm); \
207 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
208 (elm)->field.stqe_next = NULL; \
209 *(head)->stqh_last = (elm); \
210 (head)->stqh_last = &(elm)->field.stqe_next; \
213 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
214 if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
215 (head)->stqh_last = &(elm)->field.stqe_next; \
216 (tqelm)->field.stqe_next = (elm); \
219 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
221 #define STAILQ_REMOVE_HEAD(head, field) do { \
222 if (((head)->stqh_first = \
223 (head)->stqh_first->field.stqe_next) == NULL) \
224 (head)->stqh_last = &(head)->stqh_first; \
227 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
228 if (((head)->stqh_first = (elm)->field.stqe_next) == NULL) \
229 (head)->stqh_last = &(head)->stqh_first; \
232 #define STAILQ_REMOVE(head, elm, type, field) do { \
233 if ((head)->stqh_first == (elm)) { \
234 STAILQ_REMOVE_HEAD(head, field); \
237 struct type *curelm = (head)->stqh_first; \
238 while( curelm->field.stqe_next != (elm) ) \
239 curelm = curelm->field.stqe_next; \
240 if((curelm->field.stqe_next = \
241 curelm->field.stqe_next->field.stqe_next) == NULL) \
242 (head)->stqh_last = &(curelm)->field.stqe_next; \
249 #define LIST_HEAD(name, type) \
251 struct type *lh_first; /* first element */ \
254 #define LIST_HEAD_INITIALIZER(head) \
257 #define LIST_ENTRY(type) \
259 struct type *le_next; /* next element */ \
260 struct type **le_prev; /* address of previous next element */ \
267 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
269 #define LIST_FIRST(head) ((head)->lh_first)
271 #define LIST_FOREACH(var, head, field) \
272 for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
274 #define LIST_INIT(head) do { \
275 (head)->lh_first = NULL; \
278 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
279 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
280 (listelm)->field.le_next->field.le_prev = \
281 &(elm)->field.le_next; \
282 (listelm)->field.le_next = (elm); \
283 (elm)->field.le_prev = &(listelm)->field.le_next; \
286 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
287 (elm)->field.le_prev = (listelm)->field.le_prev; \
288 (elm)->field.le_next = (listelm); \
289 *(listelm)->field.le_prev = (elm); \
290 (listelm)->field.le_prev = &(elm)->field.le_next; \
293 #define LIST_INSERT_HEAD(head, elm, field) do { \
294 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
295 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
296 (head)->lh_first = (elm); \
297 (elm)->field.le_prev = &(head)->lh_first; \
300 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
302 #define LIST_REMOVE(elm, field) do { \
303 if ((elm)->field.le_next != NULL) \
304 (elm)->field.le_next->field.le_prev = \
305 (elm)->field.le_prev; \
306 *(elm)->field.le_prev = (elm)->field.le_next; \
310 * Tail queue definitions.
312 #define TAILQ_HEAD(name, type) \
314 struct type *tqh_first; /* first element */ \
315 struct type **tqh_last; /* addr of last next element */ \
318 #define TAILQ_HEAD_INITIALIZER(head) \
319 { NULL, &(head).tqh_first }
321 #define TAILQ_ENTRY(type) \
323 struct type *tqe_next; /* next element */ \
324 struct type **tqe_prev; /* address of previous next element */ \
328 * Tail queue functions.
330 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
332 #define TAILQ_FOREACH(var, head, field) \
333 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
335 #define TAILQ_FIRST(head) ((head)->tqh_first)
337 #define TAILQ_LAST(head, headname) \
338 (*(((struct headname *)((head)->tqh_last))->tqh_last))
340 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
342 #define TAILQ_PREV(elm, headname, field) \
343 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
345 #define TAILQ_INIT(head) do { \
346 (head)->tqh_first = NULL; \
347 (head)->tqh_last = &(head)->tqh_first; \
350 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
351 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
352 (head)->tqh_first->field.tqe_prev = \
353 &(elm)->field.tqe_next; \
355 (head)->tqh_last = &(elm)->field.tqe_next; \
356 (head)->tqh_first = (elm); \
357 (elm)->field.tqe_prev = &(head)->tqh_first; \
360 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
361 (elm)->field.tqe_next = NULL; \
362 (elm)->field.tqe_prev = (head)->tqh_last; \
363 *(head)->tqh_last = (elm); \
364 (head)->tqh_last = &(elm)->field.tqe_next; \
367 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
368 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
369 (elm)->field.tqe_next->field.tqe_prev = \
370 &(elm)->field.tqe_next; \
372 (head)->tqh_last = &(elm)->field.tqe_next; \
373 (listelm)->field.tqe_next = (elm); \
374 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
377 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
378 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
379 (elm)->field.tqe_next = (listelm); \
380 *(listelm)->field.tqe_prev = (elm); \
381 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
384 #define TAILQ_REMOVE(head, elm, field) do { \
385 if (((elm)->field.tqe_next) != NULL) \
386 (elm)->field.tqe_next->field.tqe_prev = \
387 (elm)->field.tqe_prev; \
389 (head)->tqh_last = (elm)->field.tqe_prev; \
390 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
394 * Circular queue definitions.
396 #define CIRCLEQ_HEAD(name, type) \
398 struct type *cqh_first; /* first element */ \
399 struct type *cqh_last; /* last element */ \
402 #define CIRCLEQ_ENTRY(type) \
404 struct type *cqe_next; /* next element */ \
405 struct type *cqe_prev; /* previous element */ \
409 * Circular queue functions.
411 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
413 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
415 #define CIRCLEQ_FOREACH(var, head, field) \
416 for((var) = (head)->cqh_first; \
417 (var) != (void *)(head); \
418 (var) = (var)->field.cqe_next)
420 #define CIRCLEQ_INIT(head) do { \
421 (head)->cqh_first = (void *)(head); \
422 (head)->cqh_last = (void *)(head); \
425 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
426 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
427 (elm)->field.cqe_prev = (listelm); \
428 if ((listelm)->field.cqe_next == (void *)(head)) \
429 (head)->cqh_last = (elm); \
431 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
432 (listelm)->field.cqe_next = (elm); \
435 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
436 (elm)->field.cqe_next = (listelm); \
437 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
438 if ((listelm)->field.cqe_prev == (void *)(head)) \
439 (head)->cqh_first = (elm); \
441 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
442 (listelm)->field.cqe_prev = (elm); \
445 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
446 (elm)->field.cqe_next = (head)->cqh_first; \
447 (elm)->field.cqe_prev = (void *)(head); \
448 if ((head)->cqh_last == (void *)(head)) \
449 (head)->cqh_last = (elm); \
451 (head)->cqh_first->field.cqe_prev = (elm); \
452 (head)->cqh_first = (elm); \
455 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
456 (elm)->field.cqe_next = (void *)(head); \
457 (elm)->field.cqe_prev = (head)->cqh_last; \
458 if ((head)->cqh_first == (void *)(head)) \
459 (head)->cqh_first = (elm); \
461 (head)->cqh_last->field.cqe_next = (elm); \
462 (head)->cqh_last = (elm); \
465 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
467 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
469 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
471 #define CIRCLEQ_REMOVE(head, elm, field) do { \
472 if ((elm)->field.cqe_next == (void *)(head)) \
473 (head)->cqh_last = (elm)->field.cqe_prev; \
475 (elm)->field.cqe_next->field.cqe_prev = \
476 (elm)->field.cqe_prev; \
477 if ((elm)->field.cqe_prev == (void *)(head)) \
478 (head)->cqh_first = (elm)->field.cqe_next; \
480 (elm)->field.cqe_prev->field.cqe_next = \
481 (elm)->field.cqe_next; \
487 * XXX insque() and remque() are an old way of handling certain queues.
488 * They bogusly assumes that all queue heads look alike.
492 struct quehead *qh_link;
493 struct quehead *qh_rlink;
499 insque(void *a, void *b)
501 struct quehead *element = a, *head = b;
503 element->qh_link = head->qh_link;
504 element->qh_rlink = head;
505 head->qh_link = element;
506 element->qh_link->qh_rlink = element;
512 struct quehead *element = a;
514 element->qh_link->qh_rlink = element->qh_rlink;
515 element->qh_rlink->qh_link = element->qh_link;
516 element->qh_rlink = 0;
519 #else /* !__GNUC__ */
521 void insque __P((void *a, void *b));
522 void remque __P((void *a));
524 #endif /* __GNUC__ */
528 #endif /* !_SYS_QUEUE_H_ */