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 1.32.2.7 2002/04/17 14:21:02 des Exp $ 35 * $DragonFly: src/sys/sys/queue.h,v 1.7 2005/03/04 02:21:49 hsu Exp $ 36 */ 37 38 #ifndef _SYS_QUEUE_H_ 39 #define _SYS_QUEUE_H_ 40 41 #ifndef _MACHINE_STDINT_H_ 42 #include <machine/stdint.h> /* for __offsetof */ 43 #endif 44 45 /* 46 * This file defines five types of data structures: singly-linked lists, 47 * singly-linked tail queues, lists, tail queues, and circular queues. 48 * 49 * A singly-linked list is headed by a single forward pointer. The elements 50 * are singly linked for minimum space and pointer manipulation overhead at 51 * the expense of O(n) removal for arbitrary elements. New elements can be 52 * added to the list after an existing element or at the head of the list. 53 * Elements being removed from the head of the list should use the explicit 54 * macro for this purpose for optimum efficiency. A singly-linked list may 55 * only be traversed in the forward direction. Singly-linked lists are ideal 56 * for applications with large datasets and few or no removals or for 57 * implementing a LIFO queue. 58 * 59 * A singly-linked tail queue is headed by a pair of pointers, one to the 60 * head of the list and the other to the tail of the list. The elements are 61 * singly linked for minimum space and pointer manipulation overhead at the 62 * expense of O(n) removal for arbitrary elements. New elements can be added 63 * to the list after an existing element, at the head of the list, or at the 64 * end of the list. Elements being removed from the head of the tail queue 65 * should use the explicit macro for this purpose for optimum efficiency. 66 * A singly-linked tail queue may only be traversed in the forward direction. 67 * Singly-linked tail queues are ideal for applications with large datasets 68 * and few or no removals or for implementing a FIFO queue. 69 * 70 * A list is headed by a single forward pointer (or an array of forward 71 * pointers for a hash table header). The elements are doubly linked 72 * so that an arbitrary element can be removed without a need to 73 * traverse the list. New elements can be added to the list before 74 * or after an existing element or at the head of the list. A list 75 * may only be traversed in the forward direction. 76 * 77 * A tail queue is headed by a pair of pointers, one to the head of the 78 * list and the other to the tail of the list. The elements are doubly 79 * linked so that an arbitrary element can be removed without a need to 80 * traverse the list. New elements can be added to the list before or 81 * after an existing element, at the head of the list, or at the end of 82 * the list. A tail queue may be traversed in either direction. 83 * 84 * A circle queue is headed by a pair of pointers, one to the head of the 85 * list and the other to the tail of the list. The elements are doubly 86 * linked so that an arbitrary element can be removed without a need to 87 * traverse the list. New elements can be added to the list before or after 88 * an existing element, at the head of the list, or at the end of the list. 89 * A circle queue may be traversed in either direction, but has a more 90 * complex end of list detection. 91 * 92 * For details on the use of these macros, see the queue(3) manual page. 93 * 94 * 95 * SLIST LIST STAILQ TAILQ CIRCLEQ 96 * _HEAD + + + + + 97 * _HEAD_INITIALIZER + + + + + 98 * _ENTRY + + + + + 99 * _INIT + + + + + 100 * _EMPTY + + + + + 101 * _FIRST + + + + + 102 * _NEXT + + + + + 103 * _PREV - - - + + 104 * _LAST - - + + + 105 * _FOREACH + + + + + 106 * _FOREACH_REVERSE - - - + + 107 * _INSERT_HEAD + + + + + 108 * _INSERT_BEFORE - + - + + 109 * _INSERT_AFTER + + + + + 110 * _INSERT_TAIL - - + + + 111 * _REMOVE_HEAD + - + - - 112 * _REMOVE + + + + + 113 * 114 */ 115 116 /* 117 * Singly-linked List declarations. 118 */ 119 #define SLIST_HEAD(name, type) \ 120 struct name { \ 121 struct type *slh_first; /* first element */ \ 122 } 123 124 #define SLIST_HEAD_INITIALIZER(head) \ 125 { NULL } 126 127 #define SLIST_ENTRY(type) \ 128 struct { \ 129 struct type *sle_next; /* next element */ \ 130 } 131 132 #define SLIST_ENTRY_INITIALIZER { NULL } 133 134 /* 135 * Singly-linked List functions. 136 */ 137 #define SLIST_EMPTY(head) ((head)->slh_first == NULL) 138 139 #define SLIST_FIRST(head) ((head)->slh_first) 140 141 #define SLIST_FOREACH(var, head, field) \ 142 for ((var) = SLIST_FIRST((head)); \ 143 (var); \ 144 (var) = SLIST_NEXT((var), field)) 145 146 #define SLIST_INIT(head) do { \ 147 SLIST_FIRST((head)) = NULL; \ 148 } while (0) 149 150 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 151 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \ 152 SLIST_NEXT((slistelm), field) = (elm); \ 153 } while (0) 154 155 #define SLIST_INSERT_HEAD(head, elm, field) do { \ 156 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \ 157 SLIST_FIRST((head)) = (elm); \ 158 } while (0) 159 160 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 161 162 #define SLIST_REMOVE(head, elm, type, field) do { \ 163 if (SLIST_FIRST((head)) == (elm)) { \ 164 SLIST_REMOVE_HEAD((head), field); \ 165 } \ 166 else { \ 167 struct type *curelm = SLIST_FIRST((head)); \ 168 while (SLIST_NEXT(curelm, field) != (elm)) \ 169 curelm = SLIST_NEXT(curelm, field); \ 170 SLIST_NEXT(curelm, field) = \ 171 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \ 172 } \ 173 } while (0) 174 175 #define SLIST_REMOVE_HEAD(head, field) do { \ 176 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \ 177 } while (0) 178 179 /* 180 * Singly-linked Tail queue declarations. 181 */ 182 #define STAILQ_HEAD(name, type) \ 183 struct name { \ 184 struct type *stqh_first;/* first element */ \ 185 struct type **stqh_last;/* addr of last next element */ \ 186 } 187 188 #define STAILQ_HEAD_INITIALIZER(head) \ 189 { NULL, &(head).stqh_first } 190 191 #define STAILQ_ENTRY(type) \ 192 struct { \ 193 struct type *stqe_next; /* next element */ \ 194 } 195 196 /* 197 * Singly-linked Tail queue functions. 198 */ 199 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 200 201 #define STAILQ_FIRST(head) ((head)->stqh_first) 202 203 #define STAILQ_FOREACH(var, head, field) \ 204 for((var) = STAILQ_FIRST((head)); \ 205 (var); \ 206 (var) = STAILQ_NEXT((var), field)) 207 208 #define STAILQ_INIT(head) do { \ 209 STAILQ_FIRST((head)) = NULL; \ 210 (head)->stqh_last = &STAILQ_FIRST((head)); \ 211 } while (0) 212 213 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 214 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\ 215 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 216 STAILQ_NEXT((tqelm), field) = (elm); \ 217 } while (0) 218 219 #define STAILQ_INSERT_HEAD(head, elm, field) do { \ 220 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \ 221 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 222 STAILQ_FIRST((head)) = (elm); \ 223 } while (0) 224 225 #define STAILQ_INSERT_TAIL(head, elm, field) do { \ 226 STAILQ_NEXT((elm), field) = NULL; \ 227 *(head)->stqh_last = (elm); \ 228 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 229 } while (0) 230 231 #define STAILQ_LAST(head, type, field) \ 232 (STAILQ_EMPTY(head) ? \ 233 NULL : \ 234 ((struct type *) \ 235 ((char *)((head)->stqh_last) - __offsetof(struct type, field)))) 236 237 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 238 239 #define STAILQ_REMOVE(head, elm, type, field) do { \ 240 if (STAILQ_FIRST((head)) == (elm)) { \ 241 STAILQ_REMOVE_HEAD(head, field); \ 242 } \ 243 else { \ 244 struct type *curelm = STAILQ_FIRST((head)); \ 245 while (STAILQ_NEXT(curelm, field) != (elm)) \ 246 curelm = STAILQ_NEXT(curelm, field); \ 247 if ((STAILQ_NEXT(curelm, field) = \ 248 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\ 249 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\ 250 } \ 251 } while (0) 252 253 #define STAILQ_REMOVE_HEAD(head, field) do { \ 254 if ((STAILQ_FIRST((head)) = \ 255 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \ 256 (head)->stqh_last = &STAILQ_FIRST((head)); \ 257 } while (0) 258 259 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 260 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \ 261 (head)->stqh_last = &STAILQ_FIRST((head)); \ 262 } while (0) 263 264 /* 265 * List declarations. 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) = LIST_FIRST((head)); \ 291 (var); \ 292 (var) = LIST_NEXT((var), field)) 293 294 #define LIST_FOREACH_MUTABLE(var, head, field, nvar) \ 295 for ((var) = LIST_FIRST((head)); \ 296 (var) && ((nvar) = LIST_NEXT((var), field), (var)); \ 297 (var) = (nvar)) 298 299 #define LIST_INIT(head) do { \ 300 LIST_FIRST((head)) = NULL; \ 301 } while (0) 302 303 #define LIST_INSERT_AFTER(listelm, elm, field) do { \ 304 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\ 305 LIST_NEXT((listelm), field)->field.le_prev = \ 306 &LIST_NEXT((elm), field); \ 307 LIST_NEXT((listelm), field) = (elm); \ 308 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \ 309 } while (0) 310 311 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 312 (elm)->field.le_prev = (listelm)->field.le_prev; \ 313 LIST_NEXT((elm), field) = (listelm); \ 314 *(listelm)->field.le_prev = (elm); \ 315 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \ 316 } while (0) 317 318 #define LIST_INSERT_HEAD(head, elm, field) do { \ 319 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \ 320 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\ 321 LIST_FIRST((head)) = (elm); \ 322 (elm)->field.le_prev = &LIST_FIRST((head)); \ 323 } while (0) 324 325 #define LIST_NEXT(elm, field) ((elm)->field.le_next) 326 327 #define LIST_REMOVE(elm, field) do { \ 328 if (LIST_NEXT((elm), field) != NULL) \ 329 LIST_NEXT((elm), field)->field.le_prev = \ 330 (elm)->field.le_prev; \ 331 *(elm)->field.le_prev = LIST_NEXT((elm), field); \ 332 } while (0) 333 334 /* 335 * Tail queue declarations. 336 */ 337 #define TAILQ_HEAD(name, type) \ 338 struct name { \ 339 struct type *tqh_first; /* first element */ \ 340 struct type **tqh_last; /* addr of last next element */ \ 341 } 342 343 #define TAILQ_HEAD_INITIALIZER(head) \ 344 { NULL, &(head).tqh_first } 345 346 #define TAILQ_ENTRY(type) \ 347 struct { \ 348 struct type *tqe_next; /* next element */ \ 349 struct type **tqe_prev; /* address of previous next element */ \ 350 } 351 352 /* 353 * Tail queue functions. 354 */ 355 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 356 357 #define TAILQ_FIRST(head) ((head)->tqh_first) 358 359 #define TAILQ_FOREACH(var, head, field) \ 360 for ((var) = TAILQ_FIRST((head)); \ 361 (var); \ 362 (var) = TAILQ_NEXT((var), field)) 363 364 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 365 for ((var) = TAILQ_LAST((head), headname); \ 366 (var); \ 367 (var) = TAILQ_PREV((var), headname, field)) 368 369 #define TAILQ_FOREACH_MUTABLE(var, head, field, nvar) \ 370 for ((var) = TAILQ_FIRST((head)); \ 371 (var) && ((nvar) = TAILQ_NEXT((var), field), (var)); \ 372 (var) = (nvar)) 373 374 #define TAILQ_INIT(head) do { \ 375 TAILQ_FIRST((head)) = NULL; \ 376 (head)->tqh_last = &TAILQ_FIRST((head)); \ 377 } while (0) 378 379 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 380 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\ 381 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 382 &TAILQ_NEXT((elm), field); \ 383 else \ 384 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 385 TAILQ_NEXT((listelm), field) = (elm); \ 386 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \ 387 } while (0) 388 389 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 390 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 391 TAILQ_NEXT((elm), field) = (listelm); \ 392 *(listelm)->field.tqe_prev = (elm); \ 393 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \ 394 } while (0) 395 396 #define TAILQ_INSERT_HEAD(head, elm, field) do { \ 397 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \ 398 TAILQ_FIRST((head))->field.tqe_prev = \ 399 &TAILQ_NEXT((elm), field); \ 400 else \ 401 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 402 TAILQ_FIRST((head)) = (elm); \ 403 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \ 404 } while (0) 405 406 #define TAILQ_INSERT_TAIL(head, elm, field) do { \ 407 TAILQ_NEXT((elm), field) = NULL; \ 408 (elm)->field.tqe_prev = (head)->tqh_last; \ 409 *(head)->tqh_last = (elm); \ 410 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 411 } while (0) 412 413 #define TAILQ_LAST(head, headname) \ 414 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 415 416 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 417 418 #define TAILQ_PREV(elm, headname, field) \ 419 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 420 421 #define TAILQ_REMOVE(head, elm, field) do { \ 422 if ((TAILQ_NEXT((elm), field)) != NULL) \ 423 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 424 (elm)->field.tqe_prev; \ 425 else \ 426 (head)->tqh_last = (elm)->field.tqe_prev; \ 427 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \ 428 } while (0) 429 430 /* 431 * Circular queue declarations. 432 */ 433 #define CIRCLEQ_HEAD(name, type) \ 434 struct name { \ 435 struct type *cqh_first; /* first element */ \ 436 struct type *cqh_last; /* last element */ \ 437 } 438 439 #define CIRCLEQ_HEAD_INITIALIZER(head) \ 440 { (void *)&(head), (void *)&(head) } 441 442 #define CIRCLEQ_ENTRY(type) \ 443 struct { \ 444 struct type *cqe_next; /* next element */ \ 445 struct type *cqe_prev; /* previous element */ \ 446 } 447 448 /* 449 * Circular queue functions. 450 */ 451 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 452 453 #define CIRCLEQ_FIRST(head) ((head)->cqh_first) 454 455 #define CIRCLEQ_FOREACH(var, head, field) \ 456 for ((var) = CIRCLEQ_FIRST((head)); \ 457 (var) != (void *)(head) || ((var) = NULL); \ 458 (var) = CIRCLEQ_NEXT((var), field)) 459 460 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ 461 for ((var) = CIRCLEQ_LAST((head)); \ 462 (var) != (void *)(head) || ((var) = NULL); \ 463 (var) = CIRCLEQ_PREV((var), field)) 464 465 #define CIRCLEQ_INIT(head) do { \ 466 CIRCLEQ_FIRST((head)) = (void *)(head); \ 467 CIRCLEQ_LAST((head)) = (void *)(head); \ 468 } while (0) 469 470 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 471 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \ 472 CIRCLEQ_PREV((elm), field) = (listelm); \ 473 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \ 474 CIRCLEQ_LAST((head)) = (elm); \ 475 else \ 476 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\ 477 CIRCLEQ_NEXT((listelm), field) = (elm); \ 478 } while (0) 479 480 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 481 CIRCLEQ_NEXT((elm), field) = (listelm); \ 482 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \ 483 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \ 484 CIRCLEQ_FIRST((head)) = (elm); \ 485 else \ 486 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\ 487 CIRCLEQ_PREV((listelm), field) = (elm); \ 488 } while (0) 489 490 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 491 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \ 492 CIRCLEQ_PREV((elm), field) = (void *)(head); \ 493 if (CIRCLEQ_LAST((head)) == (void *)(head)) \ 494 CIRCLEQ_LAST((head)) = (elm); \ 495 else \ 496 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \ 497 CIRCLEQ_FIRST((head)) = (elm); \ 498 } while (0) 499 500 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 501 CIRCLEQ_NEXT((elm), field) = (void *)(head); \ 502 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \ 503 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \ 504 CIRCLEQ_FIRST((head)) = (elm); \ 505 else \ 506 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \ 507 CIRCLEQ_LAST((head)) = (elm); \ 508 } while (0) 509 510 #define CIRCLEQ_LAST(head) ((head)->cqh_last) 511 512 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next) 513 514 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev) 515 516 #define CIRCLEQ_REMOVE(head, elm, field) do { \ 517 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \ 518 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \ 519 else \ 520 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \ 521 CIRCLEQ_PREV((elm), field); \ 522 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \ 523 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \ 524 else \ 525 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \ 526 CIRCLEQ_NEXT((elm), field); \ 527 } while (0) 528 529 #ifdef _KERNEL 530 531 /* 532 * XXX insque() and remque() are an old way of handling certain queues. 533 * They bogusly assumes that all queue heads look alike. 534 */ 535 536 struct quehead { 537 struct quehead *qh_link; 538 struct quehead *qh_rlink; 539 }; 540 541 #ifdef __GNUC__ 542 543 static __inline void 544 insque(void *a, void *b) 545 { 546 struct quehead *element = (struct quehead *)a, 547 *head = (struct quehead *)b; 548 549 element->qh_link = head->qh_link; 550 element->qh_rlink = head; 551 head->qh_link = element; 552 element->qh_link->qh_rlink = element; 553 } 554 555 static __inline void 556 remque(void *a) 557 { 558 struct quehead *element = (struct quehead *)a; 559 560 element->qh_link->qh_rlink = element->qh_rlink; 561 element->qh_rlink->qh_link = element->qh_link; 562 element->qh_rlink = 0; 563 } 564 565 #else /* !__GNUC__ */ 566 567 void insque (void *a, void *b); 568 void remque (void *a); 569 570 #endif /* __GNUC__ */ 571 572 #endif /* _KERNEL */ 573 574 #endif /* !_SYS_QUEUE_H_ */ 575