Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/bsd/sys/queue.h
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1 /* 2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. 3 * 4 * @APPLE_LICENSE_HEADER_START@ 5 * 6 * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved. 7 * 8 * This file contains Original Code and/or Modifications of Original Code 9 * as defined in and that are subject to the Apple Public Source License 10 * Version 2.0 (the 'License'). You may not use this file except in 11 * compliance with the License. Please obtain a copy of the License at 12 * http://www.opensource.apple.com/apsl/ and read it before using this 13 * file. 14 * 15 * The Original Code and all software distributed under the License are 16 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 17 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 18 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 20 * Please see the License for the specific language governing rights and 21 * limitations under the License. 22 * 23 * @APPLE_LICENSE_HEADER_END@ 24 */ 25 /* 26 * Copyright (c) 1991, 1993 27 * The Regents of the University of California. All rights reserved. 28 * 29 * Redistribution and use in source and binary forms, with or without 30 * modification, are permitted provided that the following conditions 31 * are met: 32 * 1. Redistributions of source code must retain the above copyright 33 * notice, this list of conditions and the following disclaimer. 34 * 2. Redistributions in binary form must reproduce the above copyright 35 * notice, this list of conditions and the following disclaimer in the 36 * documentation and/or other materials provided with the distribution. 37 * 3. All advertising materials mentioning features or use of this software 38 * must display the following acknowledgement: 39 * This product includes software developed by the University of 40 * California, Berkeley and its contributors. 41 * 4. Neither the name of the University nor the names of its contributors 42 * may be used to endorse or promote products derived from this software 43 * without specific prior written permission. 44 * 45 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 48 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 55 * SUCH DAMAGE. 56 * 57 * @(#)queue.h 8.5 (Berkeley) 8/20/94 58 */ 59 60 #ifndef _SYS_QUEUE_H_ 61 #define _SYS_QUEUE_H_ 62 63 /* 64 * This file defines five types of data structures: singly-linked lists, 65 * slingly-linked tail queues, lists, tail queues, and circular queues. 66 * 67 * A singly-linked list is headed by a single forward pointer. The elements 68 * are singly linked for minimum space and pointer manipulation overhead at 69 * the expense of O(n) removal for arbitrary elements. New elements can be 70 * added to the list after an existing element or at the head of the list. 71 * Elements being removed from the head of the list should use the explicit 72 * macro for this purpose for optimum efficiency. A singly-linked list may 73 * only be traversed in the forward direction. Singly-linked lists are ideal 74 * for applications with large datasets and few or no removals or for 75 * implementing a LIFO queue. 76 * 77 * A singly-linked tail queue is headed by a pair of pointers, one to the 78 * head of the list and the other to the tail of the list. The elements are 79 * singly linked for minimum space and pointer manipulation overhead at the 80 * expense of O(n) removal for arbitrary elements. New elements can be added 81 * to the list after an existing element, at the head of the list, or at the 82 * end of the list. Elements being removed from the head of the tail queue 83 * should use the explicit macro for this purpose for optimum efficiency. 84 * A singly-linked tail queue may only be traversed in the forward direction. 85 * Singly-linked tail queues are ideal for applications with large datasets 86 * and few or no removals or for implementing a FIFO queue. 87 * 88 * A list is headed by a single forward pointer (or an array of forward 89 * pointers for a hash table header). The elements are doubly linked 90 * so that an arbitrary element can be removed without a need to 91 * traverse the list. New elements can be added to the list before 92 * or after an existing element or at the head of the list. A list 93 * may only be traversed in the forward direction. 94 * 95 * A tail queue is headed by a pair of pointers, one to the head of the 96 * list and the other to the tail of the list. The elements are doubly 97 * linked so that an arbitrary element can be removed without a need to 98 * traverse the list. New elements can be added to the list before or 99 * after an existing element, at the head of the list, or at the end of 100 * the list. A tail queue may only be traversed in the forward direction. 101 * 102 * A circle queue is headed by a pair of pointers, one to the head of the 103 * list and the other to the tail of the list. The elements are doubly 104 * linked so that an arbitrary element can be removed without a need to 105 * traverse the list. New elements can be added to the list before or after 106 * an existing element, at the head of the list, or at the end of the list. 107 * A circle queue may be traversed in either direction, but has a more 108 * complex end of list detection. 109 * 110 * For details on the use of these macros, see the queue(3) manual page. 111 * 112 * 113 * SLIST LIST STAILQ TAILQ CIRCLEQ 114 * _HEAD + + + + + 115 * _ENTRY + + + + + 116 * _INIT + + + + + 117 * _EMPTY + + + + + 118 * _FIRST + + + + + 119 * _NEXT + + + + + 120 * _PREV - - - + + 121 * _LAST - - + + + 122 * _FOREACH + + - + + 123 * _INSERT_HEAD + + + + + 124 * _INSERT_BEFORE - + - + + 125 * _INSERT_AFTER + + + + + 126 * _INSERT_TAIL - - + + + 127 * _REMOVE_HEAD + - + - - 128 * _REMOVE + + + + + 129 * 130 */ 131 132 /* 133 * Singly-linked List definitions. 134 */ 135 #define SLIST_HEAD(name, type) \ 136 struct name { \ 137 struct type *slh_first; /* first element */ \ 138 } 139 140 #define SLIST_ENTRY(type) \ 141 struct { \ 142 struct type *sle_next; /* next element */ \ 143 } 144 145 /* 146 * Singly-linked List functions. 147 */ 148 #define SLIST_EMPTY(head) ((head)->slh_first == NULL) 149 150 #define SLIST_FIRST(head) ((head)->slh_first) 151 152 #define SLIST_FOREACH(var, head, field) \ 153 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next) 154 155 #define SLIST_INIT(head) { \ 156 (head)->slh_first = NULL; \ 157 } 158 159 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 160 (elm)->field.sle_next = (slistelm)->field.sle_next; \ 161 (slistelm)->field.sle_next = (elm); \ 162 } while (0) 163 164 #define SLIST_INSERT_HEAD(head, elm, field) do { \ 165 (elm)->field.sle_next = (head)->slh_first; \ 166 (head)->slh_first = (elm); \ 167 } while (0) 168 169 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 170 171 #define SLIST_REMOVE_HEAD(head, field) do { \ 172 (head)->slh_first = (head)->slh_first->field.sle_next; \ 173 } while (0) 174 175 #define SLIST_REMOVE(head, elm, type, field) do { \ 176 if ((head)->slh_first == (elm)) { \ 177 SLIST_REMOVE_HEAD((head), field); \ 178 } \ 179 else { \ 180 struct type *curelm = (head)->slh_first; \ 181 while( curelm->field.sle_next != (elm) ) \ 182 curelm = curelm->field.sle_next; \ 183 curelm->field.sle_next = \ 184 curelm->field.sle_next->field.sle_next; \ 185 } \ 186 } while (0) 187 188 /* 189 * Singly-linked Tail queue definitions. 190 */ 191 #define STAILQ_HEAD(name, type) \ 192 struct name { \ 193 struct type *stqh_first;/* first element */ \ 194 struct type **stqh_last;/* addr of last next element */ \ 195 } 196 197 #define STAILQ_HEAD_INITIALIZER(head) \ 198 { NULL, &(head).stqh_first } 199 200 #define STAILQ_ENTRY(type) \ 201 struct { \ 202 struct type *stqe_next; /* next element */ \ 203 } 204 205 /* 206 * Singly-linked Tail queue functions. 207 */ 208 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 209 210 #define STAILQ_INIT(head) do { \ 211 (head)->stqh_first = NULL; \ 212 (head)->stqh_last = &(head)->stqh_first; \ 213 } while (0) 214 215 #define STAILQ_FIRST(head) ((head)->stqh_first) 216 #define STAILQ_LAST(head) (*(head)->stqh_last) 217 218 #define STAILQ_INSERT_HEAD(head, elm, field) do { \ 219 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \ 220 (head)->stqh_last = &(elm)->field.stqe_next; \ 221 (head)->stqh_first = (elm); \ 222 } while (0) 223 224 #define STAILQ_INSERT_TAIL(head, elm, field) do { \ 225 (elm)->field.stqe_next = NULL; \ 226 *(head)->stqh_last = (elm); \ 227 (head)->stqh_last = &(elm)->field.stqe_next; \ 228 } while (0) 229 230 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 231 if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\ 232 (head)->stqh_last = &(elm)->field.stqe_next; \ 233 (tqelm)->field.stqe_next = (elm); \ 234 } while (0) 235 236 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 237 238 #define STAILQ_REMOVE_HEAD(head, field) do { \ 239 if (((head)->stqh_first = \ 240 (head)->stqh_first->field.stqe_next) == NULL) \ 241 (head)->stqh_last = &(head)->stqh_first; \ 242 } while (0) 243 244 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 245 if (((head)->stqh_first = (elm)->field.stqe_next) == NULL) \ 246 (head)->stqh_last = &(head)->stqh_first; \ 247 } while (0) 248 249 250 #define STAILQ_REMOVE(head, elm, type, field) do { \ 251 if ((head)->stqh_first == (elm)) { \ 252 STAILQ_REMOVE_HEAD(head, field); \ 253 } \ 254 else { \ 255 struct type *curelm = (head)->stqh_first; \ 256 while( curelm->field.stqe_next != (elm) ) \ 257 curelm = curelm->field.stqe_next; \ 258 if((curelm->field.stqe_next = \ 259 curelm->field.stqe_next->field.stqe_next) == NULL) \ 260 (head)->stqh_last = &(curelm)->field.stqe_next; \ 261 } \ 262 } while (0) 263 264 /* 265 * List definitions. 266 */ 267 #define LIST_HEAD(name, type) \ 268 struct name { \ 269 struct type *lh_first; /* first element */ \ 270 } 271 272 #define LIST_HEAD_INITIALIZER(head) \ 273 { NULL } 274 275 #define LIST_ENTRY(type) \ 276 struct { \ 277 struct type *le_next; /* next element */ \ 278 struct type **le_prev; /* address of previous next element */ \ 279 } 280 281 /* 282 * List functions. 283 */ 284 285 #define LIST_EMPTY(head) ((head)->lh_first == NULL) 286 287 #define LIST_FIRST(head) ((head)->lh_first) 288 289 #define LIST_FOREACH(var, head, field) \ 290 for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next) 291 292 #define LIST_INIT(head) do { \ 293 (head)->lh_first = NULL; \ 294 } while (0) 295 296 #define LIST_INSERT_AFTER(listelm, elm, field) do { \ 297 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \ 298 (listelm)->field.le_next->field.le_prev = \ 299 &(elm)->field.le_next; \ 300 (listelm)->field.le_next = (elm); \ 301 (elm)->field.le_prev = &(listelm)->field.le_next; \ 302 } while (0) 303 304 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 305 (elm)->field.le_prev = (listelm)->field.le_prev; \ 306 (elm)->field.le_next = (listelm); \ 307 *(listelm)->field.le_prev = (elm); \ 308 (listelm)->field.le_prev = &(elm)->field.le_next; \ 309 } while (0) 310 311 #define LIST_INSERT_HEAD(head, elm, field) do { \ 312 if (((elm)->field.le_next = (head)->lh_first) != NULL) \ 313 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\ 314 (head)->lh_first = (elm); \ 315 (elm)->field.le_prev = &(head)->lh_first; \ 316 } while (0) 317 318 #define LIST_NEXT(elm, field) ((elm)->field.le_next) 319 320 #define LIST_REMOVE(elm, field) do { \ 321 if ((elm)->field.le_next != NULL) \ 322 (elm)->field.le_next->field.le_prev = \ 323 (elm)->field.le_prev; \ 324 *(elm)->field.le_prev = (elm)->field.le_next; \ 325 } while (0) 326 327 /* 328 * Tail queue definitions. 329 */ 330 #define TAILQ_HEAD(name, type) \ 331 struct name { \ 332 struct type *tqh_first; /* first element */ \ 333 struct type **tqh_last; /* addr of last next element */ \ 334 } 335 336 #define TAILQ_HEAD_INITIALIZER(head) \ 337 { NULL, &(head).tqh_first } 338 339 #define TAILQ_ENTRY(type) \ 340 struct { \ 341 struct type *tqe_next; /* next element */ \ 342 struct type **tqe_prev; /* address of previous next element */ \ 343 } 344 345 /* 346 * Tail queue functions. 347 */ 348 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 349 350 #define TAILQ_FOREACH(var, head, field) \ 351 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field)) 352 353 #define TAILQ_FOREACH_REVERSE(var, head, field, headname) \ 354 for (var = TAILQ_LAST(head, headname); \ 355 var; var = TAILQ_PREV(var, headname, field)) 356 357 #define TAILQ_FIRST(head) ((head)->tqh_first) 358 359 #define TAILQ_LAST(head, headname) \ 360 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 361 362 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 363 364 #define TAILQ_PREV(elm, headname, field) \ 365 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 366 367 #define TAILQ_INIT(head) do { \ 368 (head)->tqh_first = NULL; \ 369 (head)->tqh_last = &(head)->tqh_first; \ 370 } while (0) 371 372 #define TAILQ_INSERT_HEAD(head, elm, field) do { \ 373 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ 374 (head)->tqh_first->field.tqe_prev = \ 375 &(elm)->field.tqe_next; \ 376 else \ 377 (head)->tqh_last = &(elm)->field.tqe_next; \ 378 (head)->tqh_first = (elm); \ 379 (elm)->field.tqe_prev = &(head)->tqh_first; \ 380 } while (0) 381 382 #define TAILQ_INSERT_TAIL(head, elm, field) do { \ 383 (elm)->field.tqe_next = NULL; \ 384 (elm)->field.tqe_prev = (head)->tqh_last; \ 385 *(head)->tqh_last = (elm); \ 386 (head)->tqh_last = &(elm)->field.tqe_next; \ 387 } while (0) 388 389 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 390 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\ 391 (elm)->field.tqe_next->field.tqe_prev = \ 392 &(elm)->field.tqe_next; \ 393 else \ 394 (head)->tqh_last = &(elm)->field.tqe_next; \ 395 (listelm)->field.tqe_next = (elm); \ 396 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ 397 } while (0) 398 399 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 400 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 401 (elm)->field.tqe_next = (listelm); \ 402 *(listelm)->field.tqe_prev = (elm); \ 403 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \ 404 } while (0) 405 406 #define TAILQ_REMOVE(head, elm, field) do { \ 407 if (((elm)->field.tqe_next) != NULL) \ 408 (elm)->field.tqe_next->field.tqe_prev = \ 409 (elm)->field.tqe_prev; \ 410 else \ 411 (head)->tqh_last = (elm)->field.tqe_prev; \ 412 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ 413 } while (0) 414 415 /* 416 * Circular queue definitions. 417 */ 418 #define CIRCLEQ_HEAD(name, type) \ 419 struct name { \ 420 struct type *cqh_first; /* first element */ \ 421 struct type *cqh_last; /* last element */ \ 422 } 423 424 #define CIRCLEQ_ENTRY(type) \ 425 struct { \ 426 struct type *cqe_next; /* next element */ \ 427 struct type *cqe_prev; /* previous element */ \ 428 } 429 430 /* 431 * Circular queue functions. 432 */ 433 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 434 435 #define CIRCLEQ_FIRST(head) ((head)->cqh_first) 436 437 #define CIRCLEQ_FOREACH(var, head, field) \ 438 for((var) = (head)->cqh_first; \ 439 (var) != (void *)(head); \ 440 (var) = (var)->field.cqe_next) 441 442 #define CIRCLEQ_INIT(head) do { \ 443 (head)->cqh_first = (void *)(head); \ 444 (head)->cqh_last = (void *)(head); \ 445 } while (0) 446 447 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 448 (elm)->field.cqe_next = (listelm)->field.cqe_next; \ 449 (elm)->field.cqe_prev = (listelm); \ 450 if ((listelm)->field.cqe_next == (void *)(head)) \ 451 (head)->cqh_last = (elm); \ 452 else \ 453 (listelm)->field.cqe_next->field.cqe_prev = (elm); \ 454 (listelm)->field.cqe_next = (elm); \ 455 } while (0) 456 457 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 458 (elm)->field.cqe_next = (listelm); \ 459 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \ 460 if ((listelm)->field.cqe_prev == (void *)(head)) \ 461 (head)->cqh_first = (elm); \ 462 else \ 463 (listelm)->field.cqe_prev->field.cqe_next = (elm); \ 464 (listelm)->field.cqe_prev = (elm); \ 465 } while (0) 466 467 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 468 (elm)->field.cqe_next = (head)->cqh_first; \ 469 (elm)->field.cqe_prev = (void *)(head); \ 470 if ((head)->cqh_last == (void *)(head)) \ 471 (head)->cqh_last = (elm); \ 472 else \ 473 (head)->cqh_first->field.cqe_prev = (elm); \ 474 (head)->cqh_first = (elm); \ 475 } while (0) 476 477 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 478 (elm)->field.cqe_next = (void *)(head); \ 479 (elm)->field.cqe_prev = (head)->cqh_last; \ 480 if ((head)->cqh_first == (void *)(head)) \ 481 (head)->cqh_first = (elm); \ 482 else \ 483 (head)->cqh_last->field.cqe_next = (elm); \ 484 (head)->cqh_last = (elm); \ 485 } while (0) 486 487 #define CIRCLEQ_LAST(head) ((head)->cqh_last) 488 489 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next) 490 491 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev) 492 493 #define CIRCLEQ_REMOVE(head, elm, field) do { \ 494 if ((elm)->field.cqe_next == (void *)(head)) \ 495 (head)->cqh_last = (elm)->field.cqe_prev; \ 496 else \ 497 (elm)->field.cqe_next->field.cqe_prev = \ 498 (elm)->field.cqe_prev; \ 499 if ((elm)->field.cqe_prev == (void *)(head)) \ 500 (head)->cqh_first = (elm)->field.cqe_next; \ 501 else \ 502 (elm)->field.cqe_prev->field.cqe_next = \ 503 (elm)->field.cqe_next; \ 504 } while (0) 505 506 #ifdef KERNEL 507 508 #if NOTFB31 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 */ 514 515 struct quehead { 516 struct quehead *qh_link; 517 struct quehead *qh_rlink; 518 }; 519 520 #ifdef __GNUC__ 521 522 static __inline void 523 insque(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 } 532 533 static __inline void 534 remque(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__ */ 544 545 void insque __P((void *a, void *b)); 546 void remque __P((void *a)); 547 548 #endif /* __GNUC__ */ 549 550 #endif 551 #endif /* KERNEL */ 552 553 #endif /* !_SYS_QUEUE_H_ */
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