queue.h revision 59719
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 59719 2000-04-27 22:50:12Z archie $ 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 only be traversed in the forward 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 * _ENTRY + + + + + 93 * _INIT + + + + + 94 * _EMPTY + + + + + 95 * _FIRST + + + + + 96 * _NEXT + + + + + 97 * _PREV - - - + + 98 * _LAST - - + + + 99 * _FOREACH + + + + + 100 * _INSERT_HEAD + + + + + 101 * _INSERT_BEFORE - + - + + 102 * _INSERT_AFTER + + + + + 103 * _INSERT_TAIL - - + + + 104 * _REMOVE_HEAD + - + - - 105 * _REMOVE + + + + + 106 * 107 */ 108 109/* 110 * Singly-linked List definitions. 111 */ 112#define SLIST_HEAD(name, type) \ 113struct name { \ 114 struct type *slh_first; /* first element */ \ 115} 116 117#define SLIST_HEAD_INITIALIZER(head) \ 118 { NULL } 119 120#define SLIST_ENTRY(type) \ 121struct { \ 122 struct type *sle_next; /* next element */ \ 123} 124 125/* 126 * Singly-linked List functions. 127 */ 128#define SLIST_EMPTY(head) ((head)->slh_first == NULL) 129 130#define SLIST_FIRST(head) ((head)->slh_first) 131 132#define SLIST_FOREACH(var, head, field) \ 133 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next) 134 135#define SLIST_INIT(head) { \ 136 (head)->slh_first = NULL; \ 137} 138 139#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 140 (elm)->field.sle_next = (slistelm)->field.sle_next; \ 141 (slistelm)->field.sle_next = (elm); \ 142} while (0) 143 144#define SLIST_INSERT_HEAD(head, elm, field) do { \ 145 (elm)->field.sle_next = (head)->slh_first; \ 146 (head)->slh_first = (elm); \ 147} while (0) 148 149#define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 150 151#define SLIST_REMOVE_HEAD(head, field) do { \ 152 (head)->slh_first = (head)->slh_first->field.sle_next; \ 153} while (0) 154 155#define SLIST_REMOVE(head, elm, type, field) do { \ 156 if ((head)->slh_first == (elm)) { \ 157 SLIST_REMOVE_HEAD((head), field); \ 158 } \ 159 else { \ 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; \ 165 } \ 166} while (0) 167 168/* 169 * Singly-linked Tail queue definitions. 170 */ 171#define STAILQ_HEAD(name, type) \ 172struct name { \ 173 struct type *stqh_first;/* first element */ \ 174 struct type **stqh_last;/* addr of last next element */ \ 175} 176 177#define STAILQ_HEAD_INITIALIZER(head) \ 178 { NULL, &(head).stqh_first } 179 180#define STAILQ_ENTRY(type) \ 181struct { \ 182 struct type *stqe_next; /* next element */ \ 183} 184 185/* 186 * Singly-linked Tail queue functions. 187 */ 188#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 189 190#define STAILQ_INIT(head) do { \ 191 (head)->stqh_first = NULL; \ 192 (head)->stqh_last = &(head)->stqh_first; \ 193} while (0) 194 195#define STAILQ_FIRST(head) ((head)->stqh_first) 196#define STAILQ_LAST(head) (*(head)->stqh_last) 197 198#define STAILQ_FOREACH(var, head, field) \ 199 for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next) 200 201#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); \ 205} while (0) 206 207#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; \ 211} while (0) 212 213#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); \ 217} while (0) 218 219#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 220 221#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; \ 225} while (0) 226 227#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; \ 230} while (0) 231 232#define STAILQ_REMOVE(head, elm, type, field) do { \ 233 if ((head)->stqh_first == (elm)) { \ 234 STAILQ_REMOVE_HEAD(head, field); \ 235 } \ 236 else { \ 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; \ 243 } \ 244} while (0) 245 246/* 247 * List definitions. 248 */ 249#define 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) = (head)->lh_first; (var); (var) = (var)->field.le_next) 273 274#define LIST_INIT(head) do { \ 275 (head)->lh_first = NULL; \ 276} while (0) 277 278#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; \ 284} while (0) 285 286#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; \ 291} while (0) 292 293#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; \ 298} while (0) 299 300#define LIST_NEXT(elm, field) ((elm)->field.le_next) 301 302#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; \ 307} while (0) 308 309/* 310 * Tail queue definitions. 311 */ 312#define TAILQ_HEAD(name, type) \ 313struct name { \ 314 struct type *tqh_first; /* first element */ \ 315 struct type **tqh_last; /* addr of last next element */ \ 316} 317 318#define TAILQ_HEAD_INITIALIZER(head) \ 319 { NULL, &(head).tqh_first } 320 321#define TAILQ_ENTRY(type) \ 322struct { \ 323 struct type *tqe_next; /* next element */ \ 324 struct type **tqe_prev; /* address of previous next element */ \ 325} 326 327/* 328 * Tail queue functions. 329 */ 330#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 331 332#define TAILQ_FOREACH(var, head, field) \ 333 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field)) 334 335#define TAILQ_FIRST(head) ((head)->tqh_first) 336 337#define TAILQ_LAST(head, headname) \ 338 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 339 340#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 341 342#define TAILQ_PREV(elm, headname, field) \ 343 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 344 345#define TAILQ_INIT(head) do { \ 346 (head)->tqh_first = NULL; \ 347 (head)->tqh_last = &(head)->tqh_first; \ 348} while (0) 349 350#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; \ 354 else \ 355 (head)->tqh_last = &(elm)->field.tqe_next; \ 356 (head)->tqh_first = (elm); \ 357 (elm)->field.tqe_prev = &(head)->tqh_first; \ 358} while (0) 359 360#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; \ 365} while (0) 366 367#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; \ 371 else \ 372 (head)->tqh_last = &(elm)->field.tqe_next; \ 373 (listelm)->field.tqe_next = (elm); \ 374 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ 375} while (0) 376 377#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; \ 382} while (0) 383 384#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; \ 388 else \ 389 (head)->tqh_last = (elm)->field.tqe_prev; \ 390 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ 391} while (0) 392 393/* 394 * Circular queue definitions. 395 */ 396#define CIRCLEQ_HEAD(name, type) \ 397struct name { \ 398 struct type *cqh_first; /* first element */ \ 399 struct type *cqh_last; /* last element */ \ 400} 401 402#define CIRCLEQ_ENTRY(type) \ 403struct { \ 404 struct type *cqe_next; /* next element */ \ 405 struct type *cqe_prev; /* previous element */ \ 406} 407 408/* 409 * Circular queue functions. 410 */ 411#define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 412 413#define CIRCLEQ_FIRST(head) ((head)->cqh_first) 414 415#define CIRCLEQ_FOREACH(var, head, field) \ 416 for((var) = (head)->cqh_first; \ 417 (var) != (void *)(head); \ 418 (var) = (var)->field.cqe_next) 419 420#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ 421 for((var) = (head)->cqh_last; \ 422 (var) != (void *)(head); \ 423 (var) = (var)->field.cqe_prev) 424 425#define CIRCLEQ_INIT(head) do { \ 426 (head)->cqh_first = (void *)(head); \ 427 (head)->cqh_last = (void *)(head); \ 428} while (0) 429 430#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 431 (elm)->field.cqe_next = (listelm)->field.cqe_next; \ 432 (elm)->field.cqe_prev = (listelm); \ 433 if ((listelm)->field.cqe_next == (void *)(head)) \ 434 (head)->cqh_last = (elm); \ 435 else \ 436 (listelm)->field.cqe_next->field.cqe_prev = (elm); \ 437 (listelm)->field.cqe_next = (elm); \ 438} while (0) 439 440#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 441 (elm)->field.cqe_next = (listelm); \ 442 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \ 443 if ((listelm)->field.cqe_prev == (void *)(head)) \ 444 (head)->cqh_first = (elm); \ 445 else \ 446 (listelm)->field.cqe_prev->field.cqe_next = (elm); \ 447 (listelm)->field.cqe_prev = (elm); \ 448} while (0) 449 450#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 451 (elm)->field.cqe_next = (head)->cqh_first; \ 452 (elm)->field.cqe_prev = (void *)(head); \ 453 if ((head)->cqh_last == (void *)(head)) \ 454 (head)->cqh_last = (elm); \ 455 else \ 456 (head)->cqh_first->field.cqe_prev = (elm); \ 457 (head)->cqh_first = (elm); \ 458} while (0) 459 460#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 461 (elm)->field.cqe_next = (void *)(head); \ 462 (elm)->field.cqe_prev = (head)->cqh_last; \ 463 if ((head)->cqh_first == (void *)(head)) \ 464 (head)->cqh_first = (elm); \ 465 else \ 466 (head)->cqh_last->field.cqe_next = (elm); \ 467 (head)->cqh_last = (elm); \ 468} while (0) 469 470#define CIRCLEQ_LAST(head) ((head)->cqh_last) 471 472#define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next) 473 474#define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev) 475 476#define CIRCLEQ_REMOVE(head, elm, field) do { \ 477 if ((elm)->field.cqe_next == (void *)(head)) \ 478 (head)->cqh_last = (elm)->field.cqe_prev; \ 479 else \ 480 (elm)->field.cqe_next->field.cqe_prev = \ 481 (elm)->field.cqe_prev; \ 482 if ((elm)->field.cqe_prev == (void *)(head)) \ 483 (head)->cqh_first = (elm)->field.cqe_next; \ 484 else \ 485 (elm)->field.cqe_prev->field.cqe_next = \ 486 (elm)->field.cqe_next; \ 487} while (0) 488 489#ifdef _KERNEL 490 491/* 492 * XXX insque() and remque() are an old way of handling certain queues. 493 * They bogusly assumes that all queue heads look alike. 494 */ 495 496struct quehead { 497 struct quehead *qh_link; 498 struct quehead *qh_rlink; 499}; 500 501#ifdef __GNUC__ 502 503static __inline void 504insque(void *a, void *b) 505{ 506 struct quehead *element = a, *head = b; 507 508 element->qh_link = head->qh_link; 509 element->qh_rlink = head; 510 head->qh_link = element; 511 element->qh_link->qh_rlink = element; 512} 513 514static __inline void 515remque(void *a) 516{ 517 struct quehead *element = a; 518 519 element->qh_link->qh_rlink = element->qh_rlink; 520 element->qh_rlink->qh_link = element->qh_link; 521 element->qh_rlink = 0; 522} 523 524#else /* !__GNUC__ */ 525 526void insque __P((void *a, void *b)); 527void remque __P((void *a)); 528 529#endif /* __GNUC__ */ 530 531#endif /* _KERNEL */ 532 533#endif /* !_SYS_QUEUE_H_ */ 534