Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/sys/queue.h
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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: src/sys/sys/queue.h,v 1.10.2.5 1999/09/05 08:22:46 peter Exp $ 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 * slingly-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) \ 113 struct name { \ 114 struct type *slh_first; /* first element */ \ 115 } 116 117 #define SLIST_ENTRY(type) \ 118 struct { \ 119 struct type *sle_next; /* next element */ \ 120 } 121 122 /* 123 * Singly-linked List functions. 124 */ 125 #define SLIST_EMPTY(head) ((head)->slh_first == NULL) 126 127 #define SLIST_FIRST(head) ((head)->slh_first) 128 129 #define SLIST_FOREACH(var, head, field) \ 130 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next) 131 132 #define SLIST_INIT(head) { \ 133 (head)->slh_first = NULL; \ 134 } 135 136 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 137 (elm)->field.sle_next = (slistelm)->field.sle_next; \ 138 (slistelm)->field.sle_next = (elm); \ 139 } while (0) 140 141 #define SLIST_INSERT_HEAD(head, elm, field) do { \ 142 (elm)->field.sle_next = (head)->slh_first; \ 143 (head)->slh_first = (elm); \ 144 } while (0) 145 146 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 147 148 #define SLIST_REMOVE_HEAD(head, field) do { \ 149 (head)->slh_first = (head)->slh_first->field.sle_next; \ 150 } while (0) 151 152 #define SLIST_REMOVE(head, elm, type, field) do { \ 153 if ((head)->slh_first == (elm)) { \ 154 SLIST_REMOVE_HEAD((head), field); \ 155 } \ 156 else { \ 157 struct type *curelm = (head)->slh_first; \ 158 while( curelm->field.sle_next != (elm) ) \ 159 curelm = curelm->field.sle_next; \ 160 curelm->field.sle_next = \ 161 curelm->field.sle_next->field.sle_next; \ 162 } \ 163 } while (0) 164 165 /* 166 * Singly-linked Tail queue definitions. 167 */ 168 #define STAILQ_HEAD(name, type) \ 169 struct name { \ 170 struct type *stqh_first;/* first element */ \ 171 struct type **stqh_last;/* addr of last next element */ \ 172 } 173 174 #define STAILQ_ENTRY(type) \ 175 struct { \ 176 struct type *stqe_next; /* next element */ \ 177 } 178 179 /* 180 * Singly-linked Tail queue functions. 181 */ 182 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 183 184 #define STAILQ_INIT(head) do { \ 185 (head)->stqh_first = NULL; \ 186 (head)->stqh_last = &(head)->stqh_first; \ 187 } while (0) 188 189 #define STAILQ_FIRST(head) ((head)->stqh_first) 190 #define STAILQ_LAST(head) (*(head)->stqh_last) 191 192 #define STAILQ_INSERT_HEAD(head, elm, field) do { \ 193 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \ 194 (head)->stqh_last = &(elm)->field.stqe_next; \ 195 (head)->stqh_first = (elm); \ 196 } while (0) 197 198 #define STAILQ_INSERT_TAIL(head, elm, field) do { \ 199 (elm)->field.stqe_next = NULL; \ 200 *(head)->stqh_last = (elm); \ 201 (head)->stqh_last = &(elm)->field.stqe_next; \ 202 } while (0) 203 204 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 205 if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\ 206 (head)->stqh_last = &(elm)->field.stqe_next; \ 207 (tqelm)->field.stqe_next = (elm); \ 208 } while (0) 209 210 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 211 212 #define STAILQ_REMOVE_HEAD(head, field) do { \ 213 if (((head)->stqh_first = \ 214 (head)->stqh_first->field.stqe_next) == NULL) \ 215 (head)->stqh_last = &(head)->stqh_first; \ 216 } while (0) 217 218 #define STAILQ_REMOVE(head, elm, type, field) do { \ 219 if ((head)->stqh_first == (elm)) { \ 220 STAILQ_REMOVE_HEAD(head, field); \ 221 } \ 222 else { \ 223 struct type *curelm = (head)->stqh_first; \ 224 while( curelm->field.stqe_next != (elm) ) \ 225 curelm = curelm->field.stqe_next; \ 226 if((curelm->field.stqe_next = \ 227 curelm->field.stqe_next->field.stqe_next) == NULL) \ 228 (head)->stqh_last = &(curelm)->field.stqe_next; \ 229 } \ 230 } while (0) 231 232 /* 233 * List definitions. 234 */ 235 #define LIST_HEAD(name, type) \ 236 struct name { \ 237 struct type *lh_first; /* first element */ \ 238 } 239 240 #define LIST_ENTRY(type) \ 241 struct { \ 242 struct type *le_next; /* next element */ \ 243 struct type **le_prev; /* address of previous next element */ \ 244 } 245 246 /* 247 * List functions. 248 */ 249 250 #define LIST_EMPTY(head) ((head)->lh_first == NULL) 251 252 #define LIST_FIRST(head) ((head)->lh_first) 253 254 #define LIST_FOREACH(var, head, field) \ 255 for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next) 256 257 #define LIST_INIT(head) do { \ 258 (head)->lh_first = NULL; \ 259 } while (0) 260 261 #define LIST_INSERT_AFTER(listelm, elm, field) do { \ 262 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \ 263 (listelm)->field.le_next->field.le_prev = \ 264 &(elm)->field.le_next; \ 265 (listelm)->field.le_next = (elm); \ 266 (elm)->field.le_prev = &(listelm)->field.le_next; \ 267 } while (0) 268 269 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 270 (elm)->field.le_prev = (listelm)->field.le_prev; \ 271 (elm)->field.le_next = (listelm); \ 272 *(listelm)->field.le_prev = (elm); \ 273 (listelm)->field.le_prev = &(elm)->field.le_next; \ 274 } while (0) 275 276 #define LIST_INSERT_HEAD(head, elm, field) do { \ 277 if (((elm)->field.le_next = (head)->lh_first) != NULL) \ 278 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\ 279 (head)->lh_first = (elm); \ 280 (elm)->field.le_prev = &(head)->lh_first; \ 281 } while (0) 282 283 #define LIST_NEXT(elm, field) ((elm)->field.le_next) 284 285 #define LIST_REMOVE(elm, field) do { \ 286 if ((elm)->field.le_next != NULL) \ 287 (elm)->field.le_next->field.le_prev = \ 288 (elm)->field.le_prev; \ 289 *(elm)->field.le_prev = (elm)->field.le_next; \ 290 } while (0) 291 292 /* 293 * Tail queue definitions. 294 */ 295 #define TAILQ_HEAD(name, type) \ 296 struct name { \ 297 struct type *tqh_first; /* first element */ \ 298 struct type **tqh_last; /* addr of last next element */ \ 299 } 300 301 #define TAILQ_HEAD_INITIALIZER(head) \ 302 { NULL, &(head).tqh_first } 303 304 #define TAILQ_ENTRY(type) \ 305 struct { \ 306 struct type *tqe_next; /* next element */ \ 307 struct type **tqe_prev; /* address of previous next element */ \ 308 } 309 310 /* 311 * Tail queue functions. 312 */ 313 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 314 315 #define TAILQ_FOREACH(var, head, field) \ 316 for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field)) 317 318 #define TAILQ_FIRST(head) ((head)->tqh_first) 319 320 #define TAILQ_LAST(head, headname) \ 321 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 322 323 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 324 325 #define TAILQ_PREV(elm, headname, field) \ 326 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 327 328 #define TAILQ_INIT(head) do { \ 329 (head)->tqh_first = NULL; \ 330 (head)->tqh_last = &(head)->tqh_first; \ 331 } while (0) 332 333 #define TAILQ_INSERT_HEAD(head, elm, field) do { \ 334 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ 335 (head)->tqh_first->field.tqe_prev = \ 336 &(elm)->field.tqe_next; \ 337 else \ 338 (head)->tqh_last = &(elm)->field.tqe_next; \ 339 (head)->tqh_first = (elm); \ 340 (elm)->field.tqe_prev = &(head)->tqh_first; \ 341 } while (0) 342 343 #define TAILQ_INSERT_TAIL(head, elm, field) do { \ 344 (elm)->field.tqe_next = NULL; \ 345 (elm)->field.tqe_prev = (head)->tqh_last; \ 346 *(head)->tqh_last = (elm); \ 347 (head)->tqh_last = &(elm)->field.tqe_next; \ 348 } while (0) 349 350 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 351 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\ 352 (elm)->field.tqe_next->field.tqe_prev = \ 353 &(elm)->field.tqe_next; \ 354 else \ 355 (head)->tqh_last = &(elm)->field.tqe_next; \ 356 (listelm)->field.tqe_next = (elm); \ 357 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ 358 } while (0) 359 360 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 361 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 362 (elm)->field.tqe_next = (listelm); \ 363 *(listelm)->field.tqe_prev = (elm); \ 364 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \ 365 } while (0) 366 367 #define TAILQ_REMOVE(head, elm, field) do { \ 368 if (((elm)->field.tqe_next) != NULL) \ 369 (elm)->field.tqe_next->field.tqe_prev = \ 370 (elm)->field.tqe_prev; \ 371 else \ 372 (head)->tqh_last = (elm)->field.tqe_prev; \ 373 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ 374 } while (0) 375 376 /* 377 * Circular queue definitions. 378 */ 379 #define CIRCLEQ_HEAD(name, type) \ 380 struct name { \ 381 struct type *cqh_first; /* first element */ \ 382 struct type *cqh_last; /* last element */ \ 383 } 384 385 #define CIRCLEQ_ENTRY(type) \ 386 struct { \ 387 struct type *cqe_next; /* next element */ \ 388 struct type *cqe_prev; /* previous element */ \ 389 } 390 391 /* 392 * Circular queue functions. 393 */ 394 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 395 396 #define CIRCLEQ_FIRST(head) ((head)->cqh_first) 397 398 #define CIRCLEQ_FOREACH(var, head, field) \ 399 for((var) = (head)->cqh_first; \ 400 (var) != (void *)(head); \ 401 (var) = (var)->field.cqe_next) 402 403 #define CIRCLEQ_INIT(head) do { \ 404 (head)->cqh_first = (void *)(head); \ 405 (head)->cqh_last = (void *)(head); \ 406 } while (0) 407 408 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 409 (elm)->field.cqe_next = (listelm)->field.cqe_next; \ 410 (elm)->field.cqe_prev = (listelm); \ 411 if ((listelm)->field.cqe_next == (void *)(head)) \ 412 (head)->cqh_last = (elm); \ 413 else \ 414 (listelm)->field.cqe_next->field.cqe_prev = (elm); \ 415 (listelm)->field.cqe_next = (elm); \ 416 } while (0) 417 418 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 419 (elm)->field.cqe_next = (listelm); \ 420 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \ 421 if ((listelm)->field.cqe_prev == (void *)(head)) \ 422 (head)->cqh_first = (elm); \ 423 else \ 424 (listelm)->field.cqe_prev->field.cqe_next = (elm); \ 425 (listelm)->field.cqe_prev = (elm); \ 426 } while (0) 427 428 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 429 (elm)->field.cqe_next = (head)->cqh_first; \ 430 (elm)->field.cqe_prev = (void *)(head); \ 431 if ((head)->cqh_last == (void *)(head)) \ 432 (head)->cqh_last = (elm); \ 433 else \ 434 (head)->cqh_first->field.cqe_prev = (elm); \ 435 (head)->cqh_first = (elm); \ 436 } while (0) 437 438 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 439 (elm)->field.cqe_next = (void *)(head); \ 440 (elm)->field.cqe_prev = (head)->cqh_last; \ 441 if ((head)->cqh_first == (void *)(head)) \ 442 (head)->cqh_first = (elm); \ 443 else \ 444 (head)->cqh_last->field.cqe_next = (elm); \ 445 (head)->cqh_last = (elm); \ 446 } while (0) 447 448 #define CIRCLEQ_LAST(head) ((head)->cqh_last) 449 450 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next) 451 452 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev) 453 454 #define CIRCLEQ_REMOVE(head, elm, field) do { \ 455 if ((elm)->field.cqe_next == (void *)(head)) \ 456 (head)->cqh_last = (elm)->field.cqe_prev; \ 457 else \ 458 (elm)->field.cqe_next->field.cqe_prev = \ 459 (elm)->field.cqe_prev; \ 460 if ((elm)->field.cqe_prev == (void *)(head)) \ 461 (head)->cqh_first = (elm)->field.cqe_next; \ 462 else \ 463 (elm)->field.cqe_prev->field.cqe_next = \ 464 (elm)->field.cqe_next; \ 465 } while (0) 466 467 #ifdef KERNEL 468 469 /* 470 * XXX insque() and remque() are an old way of handling certain queues. 471 * They bogusly assumes that all queue heads look alike. 472 */ 473 474 struct quehead { 475 struct quehead *qh_link; 476 struct quehead *qh_rlink; 477 }; 478 479 #ifdef __GNUC__ 480 481 static __inline void 482 insque(void *a, void *b) 483 { 484 struct quehead *element = a, *head = b; 485 486 element->qh_link = head->qh_link; 487 element->qh_rlink = head; 488 head->qh_link = element; 489 element->qh_link->qh_rlink = element; 490 } 491 492 static __inline void 493 remque(void *a) 494 { 495 struct quehead *element = a; 496 497 element->qh_link->qh_rlink = element->qh_rlink; 498 element->qh_rlink->qh_link = element->qh_link; 499 element->qh_rlink = 0; 500 } 501 502 #else /* !__GNUC__ */ 503 504 void insque __P((void *a, void *b)); 505 void remque __P((void *a)); 506 507 #endif /* __GNUC__ */ 508 509 #endif /* KERNEL */ 510 511 #endif /* !_SYS_QUEUE_H_ */
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