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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)queue.h 8.5 (Berkeley) 8/20/94 30 * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.7 2002/04/17 14:21:02 des Exp $ 31 */ 32 33 #ifndef _QUEUE_H_ 34 #define _QUEUE_H_ 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 /* 41 * This file defines five types of data structures: singly-linked lists, 42 * singly-linked tail queues, lists, tail queues, and circular queues. 43 * 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. 53 * 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. 64 * 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. 71 * 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 be traversed in either direction. 78 * 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. 86 * 87 * For details on the use of these macros, see the queue(3) manual page. 88 * 89 * 90 * SLIST LIST STAILQ TAILQ CIRCLEQ 91 * _HEAD + + + + + 92 * _HEAD_INITIALIZER + + + + + 93 * _ENTRY + + + + + 94 * _INIT + + + + + 95 * _EMPTY + + + + + 96 * _FIRST + + + + + 97 * _NEXT + + + + + 98 * _PREV - - - + + 99 * _LAST - - + + + 100 * _FOREACH + + + + + 101 * _FOREACH_REVERSE - - - + + 102 * _INSERT_HEAD + + + + + 103 * _INSERT_BEFORE - + - + + 104 * _INSERT_AFTER + + + + + 105 * _INSERT_TAIL - - + + + 106 * _REMOVE_HEAD + - + - - 107 * _REMOVE + + + + + 108 * 109 */ 110 111 /* 112 * Singly-linked List declarations. 113 */ 114 #define SLIST_HEAD(name, type) \ 115 struct name { \ 116 struct type *slh_first; /* first element */ \ 117 } 118 119 #define SLIST_HEAD_INITIALIZER(head) \ 120 { NULL } 121 122 #define SLIST_ENTRY(type) \ 123 struct { \ 124 struct type *sle_next; /* next element */ \ 125 } 126 127 /* 128 * Singly-linked List functions. 129 */ 130 #define SLIST_EMPTY(head) ((head)->slh_first == NULL) 131 132 #define SLIST_FIRST(head) ((head)->slh_first) 133 134 #define SLIST_FOREACH(var, head, field) \ 135 for ((var) = SLIST_FIRST((head)); \ 136 (var); \ 137 (var) = SLIST_NEXT((var), field)) 138 139 #define SLIST_INIT(head) do { \ 140 SLIST_FIRST((head)) = NULL; \ 141 } while (0) 142 143 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 144 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \ 145 SLIST_NEXT((slistelm), field) = (elm); \ 146 } while (0) 147 148 #define SLIST_INSERT_HEAD(head, elm, field) do { \ 149 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \ 150 SLIST_FIRST((head)) = (elm); \ 151 } while (0) 152 153 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 154 155 #define SLIST_REMOVE(head, elm, type, field) do { \ 156 if (SLIST_FIRST((head)) == (elm)) { \ 157 SLIST_REMOVE_HEAD((head), field); \ 158 } \ 159 else { \ 160 struct type *curelm = SLIST_FIRST((head)); \ 161 while (SLIST_NEXT(curelm, field) != (elm)) \ 162 curelm = SLIST_NEXT(curelm, field); \ 163 SLIST_NEXT(curelm, field) = \ 164 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \ 165 } \ 166 } while (0) 167 168 #define SLIST_REMOVE_HEAD(head, field) do { \ 169 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \ 170 } while (0) 171 172 /* 173 * Singly-linked Tail queue declarations. 174 */ 175 #define STAILQ_HEAD(name, type) \ 176 struct name { \ 177 struct type *stqh_first; /* first element */ \ 178 struct type **stqh_last; /* addr of last next element */ \ 179 } 180 181 #define STAILQ_HEAD_INITIALIZER(head) \ 182 { NULL, &(head).stqh_first } 183 184 #define STAILQ_ENTRY(type) \ 185 struct { \ 186 struct type *stqe_next; /* next element */ \ 187 } 188 189 /* 190 * Singly-linked Tail queue functions. 191 */ 192 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 193 194 #define STAILQ_FIRST(head) ((head)->stqh_first) 195 196 #define STAILQ_FOREACH(var, head, field) \ 197 for ((var) = STAILQ_FIRST((head)); \ 198 (var); \ 199 (var) = STAILQ_NEXT((var), field)) 200 201 #define STAILQ_INIT(head) do { \ 202 STAILQ_FIRST((head)) = NULL; \ 203 (head)->stqh_last = &STAILQ_FIRST((head)); \ 204 } while (0) 205 206 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 207 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL) \ 208 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 209 STAILQ_NEXT((tqelm), field) = (elm); \ 210 } while (0) 211 212 #define STAILQ_INSERT_HEAD(head, elm, field) do { \ 213 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \ 214 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 215 STAILQ_FIRST((head)) = (elm); \ 216 } while (0) 217 218 #define STAILQ_INSERT_TAIL(head, elm, field) do { \ 219 STAILQ_NEXT((elm), field) = NULL; \ 220 *(head)->stqh_last = (elm); \ 221 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 222 } while (0) 223 224 #define STAILQ_LAST(head, type, field) \ 225 (STAILQ_EMPTY(head) ? \ 226 NULL : \ 227 ((struct type *) \ 228 ((char *)((head)->stqh_last) - offsetof(struct type, field)))) 229 230 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 231 232 #define STAILQ_REMOVE(head, elm, type, field) do { \ 233 if (STAILQ_FIRST((head)) == (elm)) { \ 234 STAILQ_REMOVE_HEAD(head, field); \ 235 } \ 236 else { \ 237 struct type *curelm = STAILQ_FIRST((head)); \ 238 while (STAILQ_NEXT(curelm, field) != (elm)) \ 239 curelm = STAILQ_NEXT(curelm, field); \ 240 if ((STAILQ_NEXT(curelm, field) = \ 241 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL) \ 242 (head)->stqh_last = &STAILQ_NEXT((curelm), field); \ 243 } \ 244 } while (0) 245 246 #define STAILQ_REMOVE_HEAD(head, field) do { \ 247 if ((STAILQ_FIRST((head)) = \ 248 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \ 249 (head)->stqh_last = &STAILQ_FIRST((head)); \ 250 } while (0) 251 252 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 253 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \ 254 (head)->stqh_last = &STAILQ_FIRST((head)); \ 255 } while (0) 256 257 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \ 258 if ((STAILQ_NEXT(elm, field) = \ 259 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \ 260 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 261 } while (0) 262 263 /* 264 * List declarations. 265 */ 266 #define LIST_HEAD(name, type) \ 267 struct name { \ 268 struct type *lh_first; /* first element */ \ 269 } 270 271 #define LIST_HEAD_INITIALIZER(head) \ 272 { NULL } 273 274 #define LIST_ENTRY(type) \ 275 struct { \ 276 struct type *le_next; /* next element */ \ 277 struct type **le_prev; /* address of previous next element */ \ 278 } 279 280 /* 281 * List functions. 282 */ 283 284 #define LIST_EMPTY(head) ((head)->lh_first == NULL) 285 286 #define LIST_FIRST(head) ((head)->lh_first) 287 288 #define LIST_FOREACH(var, head, field) \ 289 for ((var) = LIST_FIRST((head)); \ 290 (var); \ 291 (var) = LIST_NEXT((var), field)) 292 293 #define LIST_INIT(head) do { \ 294 LIST_FIRST((head)) = NULL; \ 295 } while (0) 296 297 #define LIST_INSERT_AFTER(listelm, elm, field) do { \ 298 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL) \ 299 LIST_NEXT((listelm), field)->field.le_prev = \ 300 &LIST_NEXT((elm), field); \ 301 LIST_NEXT((listelm), field) = (elm); \ 302 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \ 303 } while (0) 304 305 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 306 (elm)->field.le_prev = (listelm)->field.le_prev; \ 307 LIST_NEXT((elm), field) = (listelm); \ 308 *(listelm)->field.le_prev = (elm); \ 309 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \ 310 } while (0) 311 312 #define LIST_INSERT_HEAD(head, elm, field) do { \ 313 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \ 314 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field); \ 315 LIST_FIRST((head)) = (elm); \ 316 (elm)->field.le_prev = &LIST_FIRST((head)); \ 317 } while (0) 318 319 #define LIST_NEXT(elm, field) ((elm)->field.le_next) 320 321 #define LIST_REMOVE(elm, field) do { \ 322 if (LIST_NEXT((elm), field) != NULL) \ 323 LIST_NEXT((elm), field)->field.le_prev = \ 324 (elm)->field.le_prev; \ 325 *(elm)->field.le_prev = LIST_NEXT((elm), field); \ 326 } while (0) 327 328 /* 329 * Tail queue declarations. 330 */ 331 #define TAILQ_HEAD(name, type) \ 332 struct name { \ 333 struct type *tqh_first; /* first element */ \ 334 struct type **tqh_last; /* addr of last next element */ \ 335 } 336 337 #define TAILQ_HEAD_INITIALIZER(head) \ 338 { NULL, &(head).tqh_first } 339 340 #define TAILQ_ENTRY(type) \ 341 struct { \ 342 struct type *tqe_next; /* next element */ \ 343 struct type **tqe_prev; /* address of previous next element */ \ 344 } 345 346 /* 347 * Tail queue functions. 348 */ 349 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 350 351 #define TAILQ_FIRST(head) ((head)->tqh_first) 352 353 #define TAILQ_FOREACH(var, head, field) \ 354 for ((var) = TAILQ_FIRST((head)); \ 355 (var); \ 356 (var) = TAILQ_NEXT((var), field)) 357 358 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 359 for ((var) = TAILQ_LAST((head), headname); \ 360 (var); \ 361 (var) = TAILQ_PREV((var), headname, field)) 362 363 #define TAILQ_INIT(head) do { \ 364 TAILQ_FIRST((head)) = NULL; \ 365 (head)->tqh_last = &TAILQ_FIRST((head)); \ 366 } while (0) 367 368 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 369 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL) \ 370 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 371 &TAILQ_NEXT((elm), field); \ 372 else \ 373 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 374 TAILQ_NEXT((listelm), field) = (elm); \ 375 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \ 376 } while (0) 377 378 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 379 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 380 TAILQ_NEXT((elm), field) = (listelm); \ 381 *(listelm)->field.tqe_prev = (elm); \ 382 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \ 383 } while (0) 384 385 #define TAILQ_INSERT_HEAD(head, elm, field) do { \ 386 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \ 387 TAILQ_FIRST((head))->field.tqe_prev = \ 388 &TAILQ_NEXT((elm), field); \ 389 else \ 390 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 391 TAILQ_FIRST((head)) = (elm); \ 392 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \ 393 } while (0) 394 395 #define TAILQ_INSERT_TAIL(head, elm, field) do { \ 396 TAILQ_NEXT((elm), field) = NULL; \ 397 (elm)->field.tqe_prev = (head)->tqh_last; \ 398 *(head)->tqh_last = (elm); \ 399 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 400 } while (0) 401 402 #define TAILQ_LAST(head, headname) \ 403 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 404 405 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 406 407 #define TAILQ_PREV(elm, headname, field) \ 408 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 409 410 #define TAILQ_REMOVE(head, elm, field) do { \ 411 if ((TAILQ_NEXT((elm), field)) != NULL) \ 412 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 413 (elm)->field.tqe_prev; \ 414 else \ 415 (head)->tqh_last = (elm)->field.tqe_prev; \ 416 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \ 417 } while (0) 418 419 /* 420 * Circular queue declarations. 421 */ 422 #define CIRCLEQ_HEAD(name, type) \ 423 struct name { \ 424 struct type *cqh_first; /* first element */ \ 425 struct type *cqh_last; /* last element */ \ 426 } 427 428 #define CIRCLEQ_HEAD_INITIALIZER(head) \ 429 { (void *)&(head), (void *)&(head) } 430 431 #define CIRCLEQ_ENTRY(type) \ 432 struct { \ 433 struct type *cqe_next; /* next element */ \ 434 struct type *cqe_prev; /* previous element */ \ 435 } 436 437 /* 438 * Circular queue functions. 439 */ 440 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 441 442 #define CIRCLEQ_FIRST(head) ((head)->cqh_first) 443 444 #define CIRCLEQ_FOREACH(var, head, field) \ 445 for ((var) = CIRCLEQ_FIRST((head)); \ 446 (var) != (void *)(head) || ((var) = NULL); \ 447 (var) = CIRCLEQ_NEXT((var), field)) 448 449 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ 450 for ((var) = CIRCLEQ_LAST((head)); \ 451 (var) != (void *)(head) || ((var) = NULL); \ 452 (var) = CIRCLEQ_PREV((var), field)) 453 454 #define CIRCLEQ_INIT(head) do { \ 455 CIRCLEQ_FIRST((head)) = (void *)(head); \ 456 CIRCLEQ_LAST((head)) = (void *)(head); \ 457 } while (0) 458 459 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 460 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \ 461 CIRCLEQ_PREV((elm), field) = (listelm); \ 462 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \ 463 CIRCLEQ_LAST((head)) = (elm); \ 464 else \ 465 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm); \ 466 CIRCLEQ_NEXT((listelm), field) = (elm); \ 467 } while (0) 468 469 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 470 CIRCLEQ_NEXT((elm), field) = (listelm); \ 471 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \ 472 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \ 473 CIRCLEQ_FIRST((head)) = (elm); \ 474 else \ 475 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm); \ 476 CIRCLEQ_PREV((listelm), field) = (elm); \ 477 } while (0) 478 479 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 480 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \ 481 CIRCLEQ_PREV((elm), field) = (void *)(head); \ 482 if (CIRCLEQ_LAST((head)) == (void *)(head)) \ 483 CIRCLEQ_LAST((head)) = (elm); \ 484 else \ 485 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \ 486 CIRCLEQ_FIRST((head)) = (elm); \ 487 } while (0) 488 489 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 490 CIRCLEQ_NEXT((elm), field) = (void *)(head); \ 491 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \ 492 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \ 493 CIRCLEQ_FIRST((head)) = (elm); \ 494 else \ 495 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \ 496 CIRCLEQ_LAST((head)) = (elm); \ 497 } while (0) 498 499 #define CIRCLEQ_LAST(head) ((head)->cqh_last) 500 501 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next) 502 503 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev) 504 505 #define CIRCLEQ_REMOVE(head, elm, field) do { \ 506 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \ 507 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \ 508 else \ 509 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \ 510 CIRCLEQ_PREV((elm), field); \ 511 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \ 512 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \ 513 else \ 514 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \ 515 CIRCLEQ_NEXT((elm), field); \ 516 } while (0) 517 518 #ifdef __cplusplus 519 } 520 #endif 521 522 #endif /* !_QUEUE_H_ */