queue.h revision 60744
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 60744 2000-05-21 01:54:45Z jake $ 35 */ 36 37#ifndef _SYS_QUEUE_H_ 38#define _SYS_QUEUE_H_ 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) \ 115struct name { \ 116 struct type *slh_first; /* first element */ \ 117} 118 119#define SLIST_HEAD_INITIALIZER(head) \ 120 { NULL } 121 122#define SLIST_ENTRY(type) \ 123struct { \ 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) \ 176struct 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) \ 185struct { \ 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 STAILQ_LAST((head)) = (elm); \ 221 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 222} while (0) 223 224#define STAILQ_LAST(head) (*(head)->stqh_last) 225 226#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 227 228#define STAILQ_REMOVE(head, elm, type, field) do { \ 229 if (STAILQ_FIRST((head)) == (elm)) { \ 230 STAILQ_REMOVE_HEAD(head, field); \ 231 } \ 232 else { \ 233 struct type *curelm = STAILQ_FIRST((head)); \ 234 while (STAILQ_NEXT(curelm, field) != (elm)) \ 235 curelm = STAILQ_NEXT(curelm, field); \ 236 if ((STAILQ_NEXT(curelm, field) = \ 237 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\ 238 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\ 239 } \ 240} while (0) 241 242#define STAILQ_REMOVE_HEAD(head, field) do { \ 243 if ((STAILQ_FIRST((head)) = \ 244 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \ 245 (head)->stqh_last = &STAILQ_FIRST((head)); \ 246} while (0) 247 248#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 249 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \ 250 (head)->stqh_last = &STAILQ_FIRST((head)); \ 251} while (0) 252 253/* 254 * List declarations. 255 */ 256#define LIST_HEAD(name, type) \ 257struct name { \ 258 struct type *lh_first; /* first element */ \ 259} 260 261#define LIST_HEAD_INITIALIZER(head) \ 262 { NULL } 263 264#define LIST_ENTRY(type) \ 265struct { \ 266 struct type *le_next; /* next element */ \ 267 struct type **le_prev; /* address of previous next element */ \ 268} 269 270/* 271 * List functions. 272 */ 273 274#define LIST_EMPTY(head) ((head)->lh_first == NULL) 275 276#define LIST_FIRST(head) ((head)->lh_first) 277 278#define LIST_FOREACH(var, head, field) \ 279 for ((var) = LIST_FIRST((head)); \ 280 (var); \ 281 (var) = LIST_NEXT((var), field)) 282 283#define LIST_INIT(head) do { \ 284 LIST_FIRST((head)) = NULL; \ 285} while (0) 286 287#define LIST_INSERT_AFTER(listelm, elm, field) do { \ 288 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\ 289 LIST_NEXT((listelm), field)->field.le_prev = \ 290 &LIST_NEXT((elm), field); \ 291 LIST_NEXT((listelm), field) = (elm); \ 292 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \ 293} while (0) 294 295#define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 296 (elm)->field.le_prev = (listelm)->field.le_prev; \ 297 LIST_NEXT((elm), field) = (listelm); \ 298 *(listelm)->field.le_prev = (elm); \ 299 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \ 300} while (0) 301 302#define LIST_INSERT_HEAD(head, elm, field) do { \ 303 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \ 304 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\ 305 LIST_FIRST((head)) = (elm); \ 306 (elm)->field.le_prev = &LIST_FIRST((head)); \ 307} while (0) 308 309#define LIST_NEXT(elm, field) ((elm)->field.le_next) 310 311#define LIST_REMOVE(elm, field) do { \ 312 if (LIST_NEXT((elm), field) != NULL) \ 313 LIST_NEXT((elm), field)->field.le_prev = \ 314 (elm)->field.le_prev; \ 315 *(elm)->field.le_prev = LIST_NEXT((elm), field); \ 316} while (0) 317 318/* 319 * Tail queue declarations. 320 */ 321#define TAILQ_HEAD(name, type) \ 322struct name { \ 323 struct type *tqh_first; /* first element */ \ 324 struct type **tqh_last; /* addr of last next element */ \ 325} 326 327#define TAILQ_HEAD_INITIALIZER(head) \ 328 { NULL, &(head).tqh_first } 329 330#define TAILQ_ENTRY(type) \ 331struct { \ 332 struct type *tqe_next; /* next element */ \ 333 struct type **tqe_prev; /* address of previous next element */ \ 334} 335 336/* 337 * Tail queue functions. 338 */ 339#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 340 341#define TAILQ_FIRST(head) ((head)->tqh_first) 342 343#define TAILQ_FOREACH(var, head, field) \ 344 for ((var) = TAILQ_FIRST((head)); \ 345 (var); \ 346 (var) = TAILQ_NEXT((var), field)) 347 348#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 349 for ((var) = TAILQ_LAST((head), headname); \ 350 (var); \ 351 (var) = TAILQ_PREV((var), headname, field)) 352 353#define TAILQ_INIT(head) do { \ 354 TAILQ_FIRST((head)) = NULL; \ 355 (head)->tqh_last = &TAILQ_FIRST((head)); \ 356} while (0) 357 358#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 359 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\ 360 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 361 &TAILQ_NEXT((elm), field); \ 362 else \ 363 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 364 TAILQ_NEXT((listelm), field) = (elm); \ 365 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \ 366} while (0) 367 368#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 369 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 370 TAILQ_NEXT((elm), field) = (listelm); \ 371 *(listelm)->field.tqe_prev = (elm); \ 372 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \ 373} while (0) 374 375#define TAILQ_INSERT_HEAD(head, elm, field) do { \ 376 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \ 377 TAILQ_FIRST((head))->field.tqe_prev = \ 378 &TAILQ_NEXT((elm), field); \ 379 else \ 380 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 381 TAILQ_FIRST((head)) = (elm); \ 382 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \ 383} while (0) 384 385#define TAILQ_INSERT_TAIL(head, elm, field) do { \ 386 TAILQ_NEXT((elm), field) = NULL; \ 387 (elm)->field.tqe_prev = (head)->tqh_last; \ 388 *(head)->tqh_last = (elm); \ 389 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 390} while (0) 391 392#define TAILQ_LAST(head, headname) \ 393 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 394 395#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 396 397#define TAILQ_PREV(elm, headname, field) \ 398 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 399 400#define TAILQ_REMOVE(head, elm, field) do { \ 401 if ((TAILQ_NEXT((elm), field)) != NULL) \ 402 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 403 (elm)->field.tqe_prev; \ 404 else \ 405 (head)->tqh_last = (elm)->field.tqe_prev; \ 406 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \ 407} while (0) 408 409/* 410 * Circular queue declarations. 411 */ 412#define CIRCLEQ_HEAD(name, type) \ 413struct name { \ 414 struct type *cqh_first; /* first element */ \ 415 struct type *cqh_last; /* last element */ \ 416} 417 418#define CIRCLEQ_HEAD_INITIALIZER(head) \ 419 { (void *)&(head), (void *)&(head) } 420 421#define CIRCLEQ_ENTRY(type) \ 422struct { \ 423 struct type *cqe_next; /* next element */ \ 424 struct type *cqe_prev; /* previous element */ \ 425} 426 427/* 428 * Circular queue functions. 429 */ 430#define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 431 432#define CIRCLEQ_FIRST(head) ((head)->cqh_first) 433 434#define CIRCLEQ_FOREACH(var, head, field) \ 435 for ((var) = CIRCLEQ_FIRST((head)); \ 436 (var) != (void *)(head); \ 437 (var) = CIRCLEQ_NEXT((var), field)) 438 439#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ 440 for ((var) = CIRCLEQ_LAST((head)); \ 441 (var) != (void *)(head); \ 442 (var) = CIRCLEQ_PREV((var), field)) 443 444#define CIRCLEQ_INIT(head) do { \ 445 CIRCLEQ_FIRST((head)) = (void *)(head); \ 446 CIRCLEQ_LAST((head)) = (void *)(head); \ 447} while (0) 448 449#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 450 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \ 451 CIRCLEQ_PREV((elm), field) = (listelm); \ 452 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \ 453 CIRCLEQ_LAST((head)) = (elm); \ 454 else \ 455 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\ 456 CIRCLEQ_NEXT((listelm), field) = (elm); \ 457} while (0) 458 459#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 460 CIRCLEQ_NEXT((elm), field) = (listelm); \ 461 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \ 462 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \ 463 CIRCLEQ_FIRST((head)) = (elm); \ 464 else \ 465 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\ 466 CIRCLEQ_PREV((listelm), field) = (elm); \ 467} while (0) 468 469#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 470 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \ 471 CIRCLEQ_PREV((elm), field) = (void *)(head); \ 472 if (CIRCLEQ_LAST((head)) == (void *)(head)) \ 473 CIRCLEQ_LAST((head)) = (elm); \ 474 else \ 475 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \ 476 CIRCLEQ_FIRST((head)) = (elm); \ 477} while (0) 478 479#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 480 CIRCLEQ_NEXT((elm), field) = (void *)(head); \ 481 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \ 482 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \ 483 CIRCLEQ_FIRST((head)) = (elm); \ 484 else \ 485 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \ 486 CIRCLEQ_LAST((head)) = (elm); \ 487} while (0) 488 489#define CIRCLEQ_LAST(head) ((head)->cqh_last) 490 491#define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next) 492 493#define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev) 494 495#define CIRCLEQ_REMOVE(head, elm, field) do { \ 496 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \ 497 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \ 498 else \ 499 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \ 500 CIRCLEQ_PREV((elm), field); \ 501 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \ 502 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \ 503 else \ 504 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \ 505 CIRCLEQ_NEXT((elm), field); \ 506} while (0) 507 508#ifdef _KERNEL 509 510/* 511 * XXX insque() and remque() are an old way of handling certain queues. 512 * They bogusly assumes that all queue heads look alike. 513 */ 514 515struct quehead { 516 struct quehead *qh_link; 517 struct quehead *qh_rlink; 518}; 519 520#ifdef __GNUC__ 521 522static __inline void 523insque(void *a, void *b) 524{ 525 struct quehead *element = a, *head = b; 526 527 element->qh_link = head->qh_link; 528 element->qh_rlink = head; 529 head->qh_link = element; 530 element->qh_link->qh_rlink = element; 531} 532 533static __inline void 534remque(void *a) 535{ 536 struct quehead *element = a; 537 538 element->qh_link->qh_rlink = element->qh_rlink; 539 element->qh_rlink->qh_link = element->qh_link; 540 element->qh_rlink = 0; 541} 542 543#else /* !__GNUC__ */ 544 545void insque __P((void *a, void *b)); 546void remque __P((void *a)); 547 548#endif /* __GNUC__ */ 549 550#endif /* _KERNEL */ 551 552#endif /* !_SYS_QUEUE_H_ */ 553