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1/*2 * Copyright (c) 1991, 19933 * The Regents of the University of California. All rights reserved.4 *5 * Redistribution and use in source and binary forms, with or without6 * modification, are permitted provided that the following conditions7 * are met:8 * 1. Redistributions of source code must retain the above copyright9 * notice, this list of conditions and the following disclaimer.10 * 2. Redistributions in binary form must reproduce the above copyright11 * notice, this list of conditions and the following disclaimer in the12 * documentation and/or other materials provided with the distribution.13 *14 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE17 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF24 * SUCH DAMAGE.25 *26 * @(#)queue.h 8.5 (Berkeley) 8/20/9427 * $FreeBSD: src/sys/sys/queue.h,v 1.38 2000/05/26 02:06:56 jake Exp $28 */29 30#ifndef _SYS_QUEUE_H_31#define _SYS_QUEUE_H_32 33/*34 * This file defines five types of data structures: singly-linked lists,35 * singly-linked tail queues, lists, tail queues, and circular queues.36 *37 * A singly-linked list is headed by a single forward pointer. The elements38 * are singly linked for minimum space and pointer manipulation overhead at39 * the expense of O(n) removal for arbitrary elements. New elements can be40 * added to the list after an existing element or at the head of the list.41 * Elements being removed from the head of the list should use the explicit42 * macro for this purpose for optimum efficiency. A singly-linked list may43 * only be traversed in the forward direction. Singly-linked lists are ideal44 * for applications with large datasets and few or no removals or for45 * implementing a LIFO queue.46 *47 * A singly-linked tail queue is headed by a pair of pointers, one to the48 * head of the list and the other to the tail of the list. The elements are49 * singly linked for minimum space and pointer manipulation overhead at the50 * expense of O(n) removal for arbitrary elements. New elements can be added51 * to the list after an existing element, at the head of the list, or at the52 * end of the list. Elements being removed from the head of the tail queue53 * should use the explicit macro for this purpose for optimum efficiency.54 * A singly-linked tail queue may only be traversed in the forward direction.55 * Singly-linked tail queues are ideal for applications with large datasets56 * and few or no removals or for implementing a FIFO queue.57 *58 * A list is headed by a single forward pointer (or an array of forward59 * pointers for a hash table header). The elements are doubly linked60 * so that an arbitrary element can be removed without a need to61 * traverse the list. New elements can be added to the list before62 * or after an existing element or at the head of the list. A list63 * may only be traversed in the forward direction.64 *65 * A tail queue is headed by a pair of pointers, one to the head of the66 * list and the other to the tail of the list. The elements are doubly67 * linked so that an arbitrary element can be removed without a need to68 * traverse the list. New elements can be added to the list before or69 * after an existing element, at the head of the list, or at the end of70 * the list. A tail queue may be traversed in either direction.71 *72 * A circle queue is headed by a pair of pointers, one to the head of the73 * list and the other to the tail of the list. The elements are doubly74 * linked so that an arbitrary element can be removed without a need to75 * traverse the list. New elements can be added to the list before or after76 * an existing element, at the head of the list, or at the end of the list.77 * A circle queue may be traversed in either direction, but has a more78 * complex end of list detection.79 *80 * For details on the use of these macros, see the queue(3) manual page.81 *82 *83 * SLIST LIST STAILQ TAILQ CIRCLEQ84 * _HEAD + + + + +85 * _HEAD_INITIALIZER + + + + +86 * _ENTRY + + + + +87 * _INIT + + + + +88 * _EMPTY + + + + +89 * _FIRST + + + + +90 * _NEXT + + + + +91 * _PREV - - - + +92 * _LAST - - + + +93 * _FOREACH + + + + +94 * _FOREACH_REVERSE - - - + +95 * _INSERT_HEAD + + + + +96 * _INSERT_BEFORE - + - + +97 * _INSERT_AFTER + + + + +98 * _INSERT_TAIL - - + + +99 * _REMOVE_HEAD + - + - -100 * _REMOVE + + + + +101 *102 */103 104/*105 * Singly-linked List declarations.106 */107#define SLIST_HEAD(name, type) \108struct name { \109 struct type *slh_first; /* first element */ \110}111 112#define SLIST_HEAD_INITIALIZER(head) \113 { NULL }114 115#define SLIST_ENTRY(type) \116struct { \117 struct type *sle_next; /* next element */ \118}119 120/*121 * Singly-linked List functions.122 */123#define SLIST_EMPTY(head) ((head)->slh_first == NULL)124 125#define SLIST_FIRST(head) ((head)->slh_first)126 127#define SLIST_FOREACH(var, head, field) \128 for ((var) = SLIST_FIRST((head)); \129 (var); \130 (var) = SLIST_NEXT((var), field))131 132#define SLIST_INIT(head) do { \133 SLIST_FIRST((head)) = NULL; \134} while (0)135 136#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \137 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \138 SLIST_NEXT((slistelm), field) = (elm); \139} while (0)140 141#define SLIST_INSERT_HEAD(head, elm, field) do { \142 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \143 SLIST_FIRST((head)) = (elm); \144} while (0)145 146#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)147 148#define SLIST_REMOVE(head, elm, type, field) do { \149 if (SLIST_FIRST((head)) == (elm)) { \150 SLIST_REMOVE_HEAD((head), field); \151 } \152 else { \153 struct type *curelm = SLIST_FIRST((head)); \154 while (SLIST_NEXT(curelm, field) != (elm)) \155 curelm = SLIST_NEXT(curelm, field); \156 SLIST_NEXT(curelm, field) = \157 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \158 } \159} while (0)160 161#define SLIST_REMOVE_HEAD(head, field) do { \162 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \163} while (0)164 165/*166 * Singly-linked Tail queue declarations.167 */168#define STAILQ_HEAD(name, type) \169struct name { \170 struct type *stqh_first;/* first element */ \171 struct type **stqh_last;/* addr of last next element */ \172}173 174#define STAILQ_HEAD_INITIALIZER(head) \175 { NULL, &(head).stqh_first }176 177#define STAILQ_ENTRY(type) \178struct { \179 struct type *stqe_next; /* next element */ \180}181 182/*183 * Singly-linked Tail queue functions.184 */185#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)186 187#define STAILQ_FIRST(head) ((head)->stqh_first)188 189#define STAILQ_FOREACH(var, head, field) \190 for((var) = STAILQ_FIRST((head)); \191 (var); \192 (var) = STAILQ_NEXT((var), field))193 194#define STAILQ_INIT(head) do { \195 STAILQ_FIRST((head)) = NULL; \196 (head)->stqh_last = &STAILQ_FIRST((head)); \197} while (0)198 199#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \200 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\201 (head)->stqh_last = &STAILQ_NEXT((elm), field); \202 STAILQ_NEXT((tqelm), field) = (elm); \203} while (0)204 205#define STAILQ_INSERT_HEAD(head, elm, field) do { \206 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \207 (head)->stqh_last = &STAILQ_NEXT((elm), field); \208 STAILQ_FIRST((head)) = (elm); \209} while (0)210 211#define STAILQ_INSERT_TAIL(head, elm, field) do { \212 STAILQ_NEXT((elm), field) = NULL; \213 STAILQ_LAST((head)) = (elm); \214 (head)->stqh_last = &STAILQ_NEXT((elm), field); \215} while (0)216 217#define STAILQ_LAST(head) (*(head)->stqh_last)218 219#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)220 221#define STAILQ_REMOVE(head, elm, type, field) do { \222 if (STAILQ_FIRST((head)) == (elm)) { \223 STAILQ_REMOVE_HEAD(head, field); \224 } \225 else { \226 struct type *curelm = STAILQ_FIRST((head)); \227 while (STAILQ_NEXT(curelm, field) != (elm)) \228 curelm = STAILQ_NEXT(curelm, field); \229 if ((STAILQ_NEXT(curelm, field) = \230 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\231 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\232 } \233} while (0)234 235#define STAILQ_REMOVE_HEAD(head, field) do { \236 if ((STAILQ_FIRST((head)) = \237 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \238 (head)->stqh_last = &STAILQ_FIRST((head)); \239} while (0)240 241#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \242 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \243 (head)->stqh_last = &STAILQ_FIRST((head)); \244} while (0)245 246/*247 * List declarations.248 */249#define BSD_LIST_HEAD(name, type) \250struct name { \251 struct type *lh_first; /* first element */ \252}253 254#define LIST_HEAD_INITIALIZER(head) \255 { NULL }256 257#define LIST_ENTRY(type) \258struct { \259 struct type *le_next; /* next element */ \260 struct type **le_prev; /* address of previous next element */ \261}262 263/*264 * List functions.265 */266 267#define LIST_EMPTY(head) ((head)->lh_first == NULL)268 269#define LIST_FIRST(head) ((head)->lh_first)270 271#define LIST_FOREACH(var, head, field) \272 for ((var) = LIST_FIRST((head)); \273 (var); \274 (var) = LIST_NEXT((var), field))275 276#define LIST_INIT(head) do { \277 LIST_FIRST((head)) = NULL; \278} while (0)279 280#define LIST_INSERT_AFTER(listelm, elm, field) do { \281 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\282 LIST_NEXT((listelm), field)->field.le_prev = \283 &LIST_NEXT((elm), field); \284 LIST_NEXT((listelm), field) = (elm); \285 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \286} while (0)287 288#define LIST_INSERT_BEFORE(listelm, elm, field) do { \289 (elm)->field.le_prev = (listelm)->field.le_prev; \290 LIST_NEXT((elm), field) = (listelm); \291 *(listelm)->field.le_prev = (elm); \292 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \293} while (0)294 295#define LIST_INSERT_HEAD(head, elm, field) do { \296 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \297 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\298 LIST_FIRST((head)) = (elm); \299 (elm)->field.le_prev = &LIST_FIRST((head)); \300} while (0)301 302#define LIST_NEXT(elm, field) ((elm)->field.le_next)303 304#define LIST_REMOVE(elm, field) do { \305 if (LIST_NEXT((elm), field) != NULL) \306 LIST_NEXT((elm), field)->field.le_prev = \307 (elm)->field.le_prev; \308 *(elm)->field.le_prev = LIST_NEXT((elm), field); \309} while (0)310 311/*312 * Tail queue declarations.313 */314#define TAILQ_HEAD(name, type) \315struct name { \316 struct type *tqh_first; /* first element */ \317 struct type **tqh_last; /* addr of last next element */ \318}319 320#define TAILQ_HEAD_INITIALIZER(head) \321 { NULL, &(head).tqh_first }322 323#define TAILQ_ENTRY(type) \324struct { \325 struct type *tqe_next; /* next element */ \326 struct type **tqe_prev; /* address of previous next element */ \327}328 329/*330 * Tail queue functions.331 */332#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)333 334#define TAILQ_FIRST(head) ((head)->tqh_first)335 336#define TAILQ_FOREACH(var, head, field) \337 for ((var) = TAILQ_FIRST((head)); \338 (var); \339 (var) = TAILQ_NEXT((var), field))340 341#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \342 for ((var) = TAILQ_LAST((head), headname); \343 (var); \344 (var) = TAILQ_PREV((var), headname, field))345 346#define TAILQ_INIT(head) do { \347 TAILQ_FIRST((head)) = NULL; \348 (head)->tqh_last = &TAILQ_FIRST((head)); \349} while (0)350 351#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \352 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\353 TAILQ_NEXT((elm), field)->field.tqe_prev = \354 &TAILQ_NEXT((elm), field); \355 else \356 (head)->tqh_last = &TAILQ_NEXT((elm), field); \357 TAILQ_NEXT((listelm), field) = (elm); \358 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \359} while (0)360 361#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \362 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \363 TAILQ_NEXT((elm), field) = (listelm); \364 *(listelm)->field.tqe_prev = (elm); \365 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \366} while (0)367 368#define TAILQ_INSERT_HEAD(head, elm, field) do { \369 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \370 TAILQ_FIRST((head))->field.tqe_prev = \371 &TAILQ_NEXT((elm), field); \372 else \373 (head)->tqh_last = &TAILQ_NEXT((elm), field); \374 TAILQ_FIRST((head)) = (elm); \375 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \376} while (0)377 378#define TAILQ_INSERT_TAIL(head, elm, field) do { \379 TAILQ_NEXT((elm), field) = NULL; \380 (elm)->field.tqe_prev = (head)->tqh_last; \381 *(head)->tqh_last = (elm); \382 (head)->tqh_last = &TAILQ_NEXT((elm), field); \383} while (0)384 385#define TAILQ_LAST(head, headname) \386 (*(((struct headname *)((head)->tqh_last))->tqh_last))387 388#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)389 390#define TAILQ_PREV(elm, headname, field) \391 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))392 393#define TAILQ_REMOVE(head, elm, field) do { \394 if ((TAILQ_NEXT((elm), field)) != NULL) \395 TAILQ_NEXT((elm), field)->field.tqe_prev = \396 (elm)->field.tqe_prev; \397 else \398 (head)->tqh_last = (elm)->field.tqe_prev; \399 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \400} while (0)401 402/*403 * Circular queue declarations.404 */405#define CIRCLEQ_HEAD(name, type) \406struct name { \407 struct type *cqh_first; /* first element */ \408 struct type *cqh_last; /* last element */ \409}410 411#define CIRCLEQ_HEAD_INITIALIZER(head) \412 { (void *)&(head), (void *)&(head) }413 414#define CIRCLEQ_ENTRY(type) \415struct { \416 struct type *cqe_next; /* next element */ \417 struct type *cqe_prev; /* previous element */ \418}419 420/*421 * Circular queue functions.422 */423#define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))424 425#define CIRCLEQ_FIRST(head) ((head)->cqh_first)426 427#define CIRCLEQ_FOREACH(var, head, field) \428 for ((var) = CIRCLEQ_FIRST((head)); \429 (var) != (void *)(head); \430 (var) = CIRCLEQ_NEXT((var), field))431 432#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \433 for ((var) = CIRCLEQ_LAST((head)); \434 (var) != (void *)(head); \435 (var) = CIRCLEQ_PREV((var), field))436 437#define CIRCLEQ_INIT(head) do { \438 CIRCLEQ_FIRST((head)) = (void *)(head); \439 CIRCLEQ_LAST((head)) = (void *)(head); \440} while (0)441 442#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \443 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \444 CIRCLEQ_PREV((elm), field) = (listelm); \445 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \446 CIRCLEQ_LAST((head)) = (elm); \447 else \448 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\449 CIRCLEQ_NEXT((listelm), field) = (elm); \450} while (0)451 452#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \453 CIRCLEQ_NEXT((elm), field) = (listelm); \454 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \455 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \456 CIRCLEQ_FIRST((head)) = (elm); \457 else \458 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\459 CIRCLEQ_PREV((listelm), field) = (elm); \460} while (0)461 462#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \463 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \464 CIRCLEQ_PREV((elm), field) = (void *)(head); \465 if (CIRCLEQ_LAST((head)) == (void *)(head)) \466 CIRCLEQ_LAST((head)) = (elm); \467 else \468 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \469 CIRCLEQ_FIRST((head)) = (elm); \470} while (0)471 472#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \473 CIRCLEQ_NEXT((elm), field) = (void *)(head); \474 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \475 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \476 CIRCLEQ_FIRST((head)) = (elm); \477 else \478 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \479 CIRCLEQ_LAST((head)) = (elm); \480} while (0)481 482#define CIRCLEQ_LAST(head) ((head)->cqh_last)483 484#define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)485 486#define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)487 488#define CIRCLEQ_REMOVE(head, elm, field) do { \489 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \490 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \491 else \492 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \493 CIRCLEQ_PREV((elm), field); \494 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \495 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \496 else \497 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \498 CIRCLEQ_NEXT((elm), field); \499} while (0)500 501#endif /* !_SYS_QUEUE_H_ */502