queue.h revision 84061
1/* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)queue.h 8.5 (Berkeley) 8/20/94 34 * $FreeBSD: head/sys/sys/queue.h 84061 2001-09-28 00:05:11Z luigi $ 35 */ 36 37#ifndef _SYS_QUEUE_H_ 38#define _SYS_QUEUE_H_ 39 40#include <machine/ansi.h> /* for __offsetof */ 41 42/* 43 * This file defines five types of data structures: singly-linked lists, 44 * singly-linked tail queues, lists, tail queues, and circular queues. 45 * 46 * A singly-linked list is headed by a single forward pointer. The elements 47 * are singly linked for minimum space and pointer manipulation overhead at 48 * the expense of O(n) removal for arbitrary elements. New elements can be 49 * added to the list after an existing element or at the head of the list. 50 * Elements being removed from the head of the list should use the explicit 51 * macro for this purpose for optimum efficiency. A singly-linked list may 52 * only be traversed in the forward direction. Singly-linked lists are ideal 53 * for applications with large datasets and few or no removals or for 54 * implementing a LIFO queue. 55 * 56 * A singly-linked tail queue is headed by a pair of pointers, one to the 57 * head of the list and the other to the tail of the list. The elements are 58 * singly linked for minimum space and pointer manipulation overhead at the 59 * expense of O(n) removal for arbitrary elements. New elements can be added 60 * to the list after an existing element, at the head of the list, or at the 61 * end of the list. Elements being removed from the head of the tail queue 62 * should use the explicit macro for this purpose for optimum efficiency. 63 * A singly-linked tail queue may only be traversed in the forward direction. 64 * Singly-linked tail queues are ideal for applications with large datasets 65 * and few or no removals or for implementing a FIFO queue. 66 * 67 * A list is headed by a single forward pointer (or an array of forward 68 * pointers for a hash table header). The elements are doubly linked 69 * 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 71 * or after an existing element or at the head of the list. A list 72 * may only be traversed in the forward direction. 73 * 74 * A tail 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 78 * after an existing element, at the head of the list, or at the end of 79 * the list. A tail queue may be traversed in either direction. 80 * 81 * For details on the use of these macros, see the queue(3) manual page. 82 * 83 * 84 * SLIST LIST STAILQ TAILQ 85 * _HEAD + + + + 86 * _HEAD_INITIALIZER + + + + 87 * _ENTRY + + + + 88 * _INIT + + + + 89 * _EMPTY + + + + 90 * _FIRST + + + + 91 * _NEXT + + + + 92 * _PREV - - - + 93 * _LAST - - + + 94 * _FOREACH + + + + 95 * _FOREACH_REVERSE - - - + 96 * _INSERT_HEAD + + + + 97 * _INSERT_BEFORE - + - + 98 * _INSERT_AFTER + + + + 99 * _INSERT_TAIL - - + + 100 * _REMOVE_HEAD + - + - 101 * _REMOVE + + + + 102 * 103 */ 104 105/* 106 * Singly-linked List declarations. 107 */ 108#define SLIST_HEAD(name, type) \ 109struct name { \ 110 struct type *slh_first; /* first element */ \ 111} 112 113#define SLIST_HEAD_INITIALIZER(head) \ 114 { NULL } 115 116#define SLIST_ENTRY(type) \ 117struct { \ 118 struct type *sle_next; /* next element */ \ 119} 120 121/* 122 * Singly-linked List functions. 123 */ 124#define SLIST_EMPTY(head) ((head)->slh_first == NULL) 125 126#define SLIST_FIRST(head) ((head)->slh_first) 127 128#define SLIST_FOREACH(var, head, field) \ 129 for ((var) = SLIST_FIRST((head)); \ 130 (var); \ 131 (var) = SLIST_NEXT((var), field)) 132 133#define SLIST_INIT(head) do { \ 134 SLIST_FIRST((head)) = NULL; \ 135} while (0) 136 137#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 138 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \ 139 SLIST_NEXT((slistelm), field) = (elm); \ 140} while (0) 141 142#define SLIST_INSERT_HEAD(head, elm, field) do { \ 143 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \ 144 SLIST_FIRST((head)) = (elm); \ 145} while (0) 146 147#define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 148 149#define SLIST_REMOVE(head, elm, type, field) do { \ 150 if (SLIST_FIRST((head)) == (elm)) { \ 151 SLIST_REMOVE_HEAD((head), field); \ 152 } \ 153 else { \ 154 struct type *curelm = SLIST_FIRST((head)); \ 155 while (SLIST_NEXT(curelm, field) != (elm)) \ 156 curelm = SLIST_NEXT(curelm, field); \ 157 SLIST_NEXT(curelm, field) = \ 158 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \ 159 } \ 160} while (0) 161 162#define SLIST_REMOVE_HEAD(head, field) do { \ 163 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \ 164} while (0) 165 166/* 167 * Singly-linked Tail queue declarations. 168 */ 169#define STAILQ_HEAD(name, type) \ 170struct name { \ 171 struct type *stqh_first;/* first element */ \ 172 struct type **stqh_last;/* addr of last next element */ \ 173} 174 175#define STAILQ_HEAD_INITIALIZER(head) \ 176 { NULL, &(head).stqh_first } 177 178#define STAILQ_ENTRY(type) \ 179struct { \ 180 struct type *stqe_next; /* next element */ \ 181} 182 183/* 184 * Singly-linked Tail queue functions. 185 */ 186#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 187 188#define STAILQ_FIRST(head) ((head)->stqh_first) 189 190#define STAILQ_FOREACH(var, head, field) \ 191 for((var) = STAILQ_FIRST((head)); \ 192 (var); \ 193 (var) = STAILQ_NEXT((var), field)) 194 195#define STAILQ_INIT(head) do { \ 196 STAILQ_FIRST((head)) = NULL; \ 197 (head)->stqh_last = &STAILQ_FIRST((head)); \ 198} while (0) 199 200#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 201 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\ 202 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 203 STAILQ_NEXT((tqelm), field) = (elm); \ 204} while (0) 205 206#define STAILQ_INSERT_HEAD(head, elm, field) do { \ 207 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \ 208 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 209 STAILQ_FIRST((head)) = (elm); \ 210} while (0) 211 212#define STAILQ_INSERT_TAIL(head, elm, field) do { \ 213 STAILQ_NEXT((elm), field) = NULL; \ 214 *(head)->stqh_last = (elm); \ 215 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 216} while (0) 217 218#define STAILQ_LAST(head, type, field) \ 219 (STAILQ_EMPTY(head) ? \ 220 NULL : \ 221 ((struct type *) \ 222 ((char *)((head)->stqh_last) - __offsetof(struct type, field)))) 223 224#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 225 226#define STAILQ_REMOVE(head, elm, type, field) do { \ 227 if (STAILQ_FIRST((head)) == (elm)) { \ 228 STAILQ_REMOVE_HEAD(head, field); \ 229 } \ 230 else { \ 231 struct type *curelm = STAILQ_FIRST((head)); \ 232 while (STAILQ_NEXT(curelm, field) != (elm)) \ 233 curelm = STAILQ_NEXT(curelm, field); \ 234 if ((STAILQ_NEXT(curelm, field) = \ 235 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\ 236 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\ 237 } \ 238} while (0) 239 240#define STAILQ_REMOVE_HEAD(head, field) do { \ 241 if ((STAILQ_FIRST((head)) = \ 242 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \ 243 (head)->stqh_last = &STAILQ_FIRST((head)); \ 244} while (0) 245 246#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 247 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \ 248 (head)->stqh_last = &STAILQ_FIRST((head)); \ 249} while (0) 250 251/* 252 * List declarations. 253 */ 254#define LIST_HEAD(name, type) \ 255struct name { \ 256 struct type *lh_first; /* first element */ \ 257} 258 259#define LIST_HEAD_INITIALIZER(head) \ 260 { NULL } 261 262#define LIST_ENTRY(type) \ 263struct { \ 264 struct type *le_next; /* next element */ \ 265 struct type **le_prev; /* address of previous next element */ \ 266} 267 268/* 269 * List functions. 270 */ 271 272#define LIST_EMPTY(head) ((head)->lh_first == NULL) 273 274#define LIST_FIRST(head) ((head)->lh_first) 275 276#define LIST_FOREACH(var, head, field) \ 277 for ((var) = LIST_FIRST((head)); \ 278 (var); \ 279 (var) = LIST_NEXT((var), field)) 280 281#define LIST_INIT(head) do { \ 282 LIST_FIRST((head)) = NULL; \ 283} while (0) 284 285#define LIST_INSERT_AFTER(listelm, elm, field) do { \ 286 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\ 287 LIST_NEXT((listelm), field)->field.le_prev = \ 288 &LIST_NEXT((elm), field); \ 289 LIST_NEXT((listelm), field) = (elm); \ 290 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \ 291} while (0) 292 293#define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 294 (elm)->field.le_prev = (listelm)->field.le_prev; \ 295 LIST_NEXT((elm), field) = (listelm); \ 296 *(listelm)->field.le_prev = (elm); \ 297 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \ 298} while (0) 299 300#define LIST_INSERT_HEAD(head, elm, field) do { \ 301 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \ 302 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\ 303 LIST_FIRST((head)) = (elm); \ 304 (elm)->field.le_prev = &LIST_FIRST((head)); \ 305} while (0) 306 307#define LIST_NEXT(elm, field) ((elm)->field.le_next) 308 309#define LIST_REMOVE(elm, field) do { \ 310 if (LIST_NEXT((elm), field) != NULL) \ 311 LIST_NEXT((elm), field)->field.le_prev = \ 312 (elm)->field.le_prev; \ 313 *(elm)->field.le_prev = LIST_NEXT((elm), field); \ 314} while (0) 315 316/* 317 * Tail queue declarations. 318 */ 319#define TAILQ_HEAD(name, type) \ 320struct name { \ 321 struct type *tqh_first; /* first element */ \ 322 struct type **tqh_last; /* addr of last next element */ \ 323} 324 325#define TAILQ_HEAD_INITIALIZER(head) \ 326 { NULL, &(head).tqh_first } 327 328#define TAILQ_ENTRY(type) \ 329struct { \ 330 struct type *tqe_next; /* next element */ \ 331 struct type **tqe_prev; /* address of previous next element */ \ 332} 333 334/* 335 * Tail queue functions. 336 */ 337#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 338 339#define TAILQ_FIRST(head) ((head)->tqh_first) 340 341#define TAILQ_FOREACH(var, head, field) \ 342 for ((var) = TAILQ_FIRST((head)); \ 343 (var); \ 344 (var) = TAILQ_NEXT((var), field)) 345 346#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 347 for ((var) = TAILQ_LAST((head), headname); \ 348 (var); \ 349 (var) = TAILQ_PREV((var), headname, field)) 350 351#define TAILQ_INIT(head) do { \ 352 TAILQ_FIRST((head)) = NULL; \ 353 (head)->tqh_last = &TAILQ_FIRST((head)); \ 354} while (0) 355 356#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 357 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\ 358 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 359 &TAILQ_NEXT((elm), field); \ 360 else \ 361 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 362 TAILQ_NEXT((listelm), field) = (elm); \ 363 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \ 364} while (0) 365 366#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 367 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 368 TAILQ_NEXT((elm), field) = (listelm); \ 369 *(listelm)->field.tqe_prev = (elm); \ 370 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \ 371} while (0) 372 373#define TAILQ_INSERT_HEAD(head, elm, field) do { \ 374 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \ 375 TAILQ_FIRST((head))->field.tqe_prev = \ 376 &TAILQ_NEXT((elm), field); \ 377 else \ 378 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 379 TAILQ_FIRST((head)) = (elm); \ 380 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \ 381} while (0) 382 383#define TAILQ_INSERT_TAIL(head, elm, field) do { \ 384 TAILQ_NEXT((elm), field) = NULL; \ 385 (elm)->field.tqe_prev = (head)->tqh_last; \ 386 *(head)->tqh_last = (elm); \ 387 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 388} while (0) 389 390#define TAILQ_LAST(head, headname) \ 391 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 392 393#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 394 395#define TAILQ_PREV(elm, headname, field) \ 396 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 397 398#define TAILQ_REMOVE(head, elm, field) do { \ 399 if ((TAILQ_NEXT((elm), field)) != NULL) \ 400 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 401 (elm)->field.tqe_prev; \ 402 else \ 403 (head)->tqh_last = (elm)->field.tqe_prev; \ 404 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \ 405} while (0) 406 407 408#ifdef _KERNEL 409 410/* 411 * XXX insque() and remque() are an old way of handling certain queues. 412 * They bogusly assumes that all queue heads look alike. 413 */ 414 415struct quehead { 416 struct quehead *qh_link; 417 struct quehead *qh_rlink; 418}; 419 420#ifdef __GNUC__ 421 422static __inline void 423insque(void *a, void *b) 424{ 425 struct quehead *element = (struct quehead *)a, 426 *head = (struct quehead *)b; 427 428 element->qh_link = head->qh_link; 429 element->qh_rlink = head; 430 head->qh_link = element; 431 element->qh_link->qh_rlink = element; 432} 433 434static __inline void 435remque(void *a) 436{ 437 struct quehead *element = (struct quehead *)a; 438 439 element->qh_link->qh_rlink = element->qh_rlink; 440 element->qh_rlink->qh_link = element->qh_link; 441 element->qh_rlink = 0; 442} 443 444#else /* !__GNUC__ */ 445 446void insque __P((void *a, void *b)); 447void remque __P((void *a)); 448 449#endif /* __GNUC__ */ 450 451#endif /* _KERNEL */ 452 453#endif /* !_SYS_QUEUE_H_ */ 454