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. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)queue.h 8.5 (Berkeley) 8/20/94 30 */ 31 32 #ifndef _SYS_QUEUE_H_ 33 #define _SYS_QUEUE_H_ 34 35 #include <sys/cdefs.h> 36 37 /* 38 * This file defines five types of data structures: singly-linked lists, 39 * lists, simple queues, tail queues, and circular queues. 40 * 41 * A singly-linked list is headed by a single forward pointer. The 42 * elements are singly linked for minimum space and pointer manipulation 43 * overhead at the expense of O(n) removal for arbitrary elements. New 44 * elements can be added to the list after an existing element or at the 45 * head of the list. Elements being removed from the head of the list 46 * should use the explicit macro for this purpose for optimum 47 * efficiency. A singly-linked list may only be traversed in the forward 48 * direction. Singly-linked lists are ideal for applications with large 49 * datasets and few or no removals or for implementing a LIFO queue. 50 * 51 * A list is headed by a single forward pointer (or an array of forward 52 * pointers for a hash table header). The elements are doubly linked 53 * so that an arbitrary element can be removed without a need to 54 * traverse the list. New elements can be added to the list before 55 * or after an existing element or at the head of the list. A list 56 * may only be traversed in the forward direction. 57 * 58 * A simple queue is headed by a pair of pointers, one the head of the 59 * list and the other to the tail of the list. The elements are singly 60 * linked to save space, so elements can only be removed from the 61 * head of the list. New elements can be added to the list after 62 * an existing element, at the head of the list, or at the end of the 63 * list. A simple queue may only be traversed in the forward direction. 64 * 65 * A tail queue is headed by a pair of pointers, one to the head of the 66 * list and the other to the tail of the list. The elements are doubly 67 * linked 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 or 69 * after an existing element, at the head of the list, or at the end of 70 * the list. A tail queue may be traversed in either direction. 71 * 72 * A circle 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 after 76 * an existing element, at the head of the list, or at the end of the list. 77 * A circle queue may be traversed in either direction, but has a more 78 * complex end of list detection. 79 * 80 * For details on the use of these macros, see the queue(3) manual page. 81 */ 82 83 /* 84 * List definitions. 85 */ 86 #define LIST_HEAD(name, type) \ 87 struct name { \ 88 struct type *lh_first; /* first element */ \ 89 } 90 91 #define LIST_HEAD_INITIALIZER(head) \ 92 { NULL } 93 94 #define LIST_ENTRY(type) \ 95 struct { \ 96 struct type *le_next; /* next element */ \ 97 struct type **le_prev; /* address of previous next element */ \ 98 } 99 100 /* 101 * List functions. 102 */ 103 #define LIST_INIT(head) do { \ 104 (head)->lh_first = NULL; \ 105 } while (/*CONSTCOND*/0) 106 107 #define LIST_INSERT_AFTER(listelm, elm, field) do { \ 108 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \ 109 (listelm)->field.le_next->field.le_prev = \ 110 &(elm)->field.le_next; \ 111 (listelm)->field.le_next = (elm); \ 112 (elm)->field.le_prev = &(listelm)->field.le_next; \ 113 } while (/*CONSTCOND*/0) 114 115 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 116 (elm)->field.le_prev = (listelm)->field.le_prev; \ 117 (elm)->field.le_next = (listelm); \ 118 *(listelm)->field.le_prev = (elm); \ 119 (listelm)->field.le_prev = &(elm)->field.le_next; \ 120 } while (/*CONSTCOND*/0) 121 122 #define LIST_INSERT_HEAD(head, elm, field) do { \ 123 if (((elm)->field.le_next = (head)->lh_first) != NULL) \ 124 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\ 125 (head)->lh_first = (elm); \ 126 (elm)->field.le_prev = &(head)->lh_first; \ 127 } while (/*CONSTCOND*/0) 128 129 #define LIST_REMOVE(elm, field) do { \ 130 if ((elm)->field.le_next != NULL) \ 131 (elm)->field.le_next->field.le_prev = \ 132 (elm)->field.le_prev; \ 133 *(elm)->field.le_prev = (elm)->field.le_next; \ 134 } while (/*CONSTCOND*/0) 135 136 #define LIST_FOREACH(var, head, field) \ 137 for ((var) = ((head)->lh_first); \ 138 (var); \ 139 (var) = ((var)->field.le_next)) 140 141 /* 142 * List access methods. 143 */ 144 #define LIST_EMPTY(head) ((head)->lh_first == NULL) 145 #define LIST_FIRST(head) ((head)->lh_first) 146 #define LIST_NEXT(elm, field) ((elm)->field.le_next) 147 148 149 /* 150 * Singly-linked List definitions. 151 */ 152 #define SLIST_HEAD(name, type) \ 153 struct name { \ 154 struct type *slh_first; /* first element */ \ 155 } 156 157 #define SLIST_HEAD_INITIALIZER(head) \ 158 { NULL } 159 160 #define SLIST_ENTRY(type) \ 161 struct { \ 162 struct type *sle_next; /* next element */ \ 163 } 164 165 /* 166 * Singly-linked List functions. 167 */ 168 #define SLIST_INIT(head) do { \ 169 (head)->slh_first = NULL; \ 170 } while (/*CONSTCOND*/0) 171 172 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 173 (elm)->field.sle_next = (slistelm)->field.sle_next; \ 174 (slistelm)->field.sle_next = (elm); \ 175 } while (/*CONSTCOND*/0) 176 177 #define SLIST_INSERT_HEAD(head, elm, field) do { \ 178 (elm)->field.sle_next = (head)->slh_first; \ 179 (head)->slh_first = (elm); \ 180 } while (/*CONSTCOND*/0) 181 182 #define SLIST_REMOVE_HEAD(head, field) do { \ 183 (head)->slh_first = (head)->slh_first->field.sle_next; \ 184 } while (/*CONSTCOND*/0) 185 186 #define SLIST_REMOVE(head, elm, type, field) do { \ 187 if ((head)->slh_first == (elm)) { \ 188 SLIST_REMOVE_HEAD((head), field); \ 189 } \ 190 else { \ 191 struct type *curelm = (head)->slh_first; \ 192 while(curelm->field.sle_next != (elm)) \ 193 curelm = curelm->field.sle_next; \ 194 curelm->field.sle_next = \ 195 curelm->field.sle_next->field.sle_next; \ 196 } \ 197 } while (/*CONSTCOND*/0) 198 199 #define SLIST_FOREACH(var, head, field) \ 200 for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next) 201 202 /* 203 * Singly-linked List access methods. 204 */ 205 #define SLIST_EMPTY(head) ((head)->slh_first == NULL) 206 #define SLIST_FIRST(head) ((head)->slh_first) 207 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 208 209 210 /* 211 * Singly-linked Tail queue declarations. 212 */ 213 #define STAILQ_HEAD(name, type) \ 214 struct name { \ 215 struct type *stqh_first; /* first element */ \ 216 struct type **stqh_last; /* addr of last next element */ \ 217 } 218 219 #define STAILQ_HEAD_INITIALIZER(head) \ 220 { NULL, &(head).stqh_first } 221 222 #define STAILQ_ENTRY(type) \ 223 struct { \ 224 struct type *stqe_next; /* next element */ \ 225 } 226 227 /* 228 * Singly-linked Tail queue functions. 229 */ 230 #define STAILQ_INIT(head) do { \ 231 (head)->stqh_first = NULL; \ 232 (head)->stqh_last = &(head)->stqh_first; \ 233 } while (/*CONSTCOND*/0) 234 235 #define STAILQ_INSERT_HEAD(head, elm, field) do { \ 236 if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \ 237 (head)->stqh_last = &(elm)->field.stqe_next; \ 238 (head)->stqh_first = (elm); \ 239 } while (/*CONSTCOND*/0) 240 241 #define STAILQ_INSERT_TAIL(head, elm, field) do { \ 242 (elm)->field.stqe_next = NULL; \ 243 *(head)->stqh_last = (elm); \ 244 (head)->stqh_last = &(elm)->field.stqe_next; \ 245 } while (/*CONSTCOND*/0) 246 247 #define STAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 248 if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\ 249 (head)->stqh_last = &(elm)->field.stqe_next; \ 250 (listelm)->field.stqe_next = (elm); \ 251 } while (/*CONSTCOND*/0) 252 253 #define STAILQ_REMOVE_HEAD(head, field) do { \ 254 if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \ 255 (head)->stqh_last = &(head)->stqh_first; \ 256 } while (/*CONSTCOND*/0) 257 258 #define STAILQ_REMOVE(head, elm, type, field) do { \ 259 if ((head)->stqh_first == (elm)) { \ 260 STAILQ_REMOVE_HEAD((head), field); \ 261 } else { \ 262 struct type *curelm = (head)->stqh_first; \ 263 while (curelm->field.stqe_next != (elm)) \ 264 curelm = curelm->field.stqe_next; \ 265 if ((curelm->field.stqe_next = \ 266 curelm->field.stqe_next->field.stqe_next) == NULL) \ 267 (head)->stqh_last = &(curelm)->field.stqe_next; \ 268 } \ 269 } while (/*CONSTCOND*/0) 270 271 #define STAILQ_FOREACH(var, head, field) \ 272 for ((var) = ((head)->stqh_first); \ 273 (var); \ 274 (var) = ((var)->field.stqe_next)) 275 276 /* 277 * Singly-linked Tail queue access methods. 278 */ 279 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 280 #define STAILQ_FIRST(head) ((head)->stqh_first) 281 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 282 283 284 /* 285 * Simple queue definitions. 286 */ 287 #define SIMPLEQ_HEAD(name, type) \ 288 struct name { \ 289 struct type *sqh_first; /* first element */ \ 290 struct type **sqh_last; /* addr of last next element */ \ 291 } 292 293 #define SIMPLEQ_HEAD_INITIALIZER(head) \ 294 { NULL, &(head).sqh_first } 295 296 #define SIMPLEQ_ENTRY(type) \ 297 struct { \ 298 struct type *sqe_next; /* next element */ \ 299 } 300 301 /* 302 * Simple queue functions. 303 */ 304 #define SIMPLEQ_INIT(head) do { \ 305 (head)->sqh_first = NULL; \ 306 (head)->sqh_last = &(head)->sqh_first; \ 307 } while (/*CONSTCOND*/0) 308 309 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \ 310 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \ 311 (head)->sqh_last = &(elm)->field.sqe_next; \ 312 (head)->sqh_first = (elm); \ 313 } while (/*CONSTCOND*/0) 314 315 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \ 316 (elm)->field.sqe_next = NULL; \ 317 *(head)->sqh_last = (elm); \ 318 (head)->sqh_last = &(elm)->field.sqe_next; \ 319 } while (/*CONSTCOND*/0) 320 321 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 322 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\ 323 (head)->sqh_last = &(elm)->field.sqe_next; \ 324 (listelm)->field.sqe_next = (elm); \ 325 } while (/*CONSTCOND*/0) 326 327 #define SIMPLEQ_REMOVE_HEAD(head, field) do { \ 328 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \ 329 (head)->sqh_last = &(head)->sqh_first; \ 330 } while (/*CONSTCOND*/0) 331 332 #define SIMPLEQ_REMOVE(head, elm, type, field) do { \ 333 if ((head)->sqh_first == (elm)) { \ 334 SIMPLEQ_REMOVE_HEAD((head), field); \ 335 } else { \ 336 struct type *curelm = (head)->sqh_first; \ 337 while (curelm->field.sqe_next != (elm)) \ 338 curelm = curelm->field.sqe_next; \ 339 if ((curelm->field.sqe_next = \ 340 curelm->field.sqe_next->field.sqe_next) == NULL) \ 341 (head)->sqh_last = &(curelm)->field.sqe_next; \ 342 } \ 343 } while (/*CONSTCOND*/0) 344 345 #define SIMPLEQ_FOREACH(var, head, field) \ 346 for ((var) = ((head)->sqh_first); \ 347 (var); \ 348 (var) = ((var)->field.sqe_next)) 349 350 /* 351 * Simple queue access methods. 352 */ 353 #define SIMPLEQ_EMPTY(head) ((head)->sqh_first == NULL) 354 #define SIMPLEQ_FIRST(head) ((head)->sqh_first) 355 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next) 356 357 358 /* 359 * Tail queue definitions. 360 */ 361 #define _TAILQ_HEAD(name, type, qual) \ 362 struct name { \ 363 qual type *tqh_first; /* first element */ \ 364 qual type *qual *tqh_last; /* addr of last next element */ \ 365 } 366 #define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type,) 367 368 #define TAILQ_HEAD_INITIALIZER(head) \ 369 { NULL, &(head).tqh_first } 370 371 #define _TAILQ_ENTRY(type, qual) \ 372 struct { \ 373 qual type *tqe_next; /* next element */ \ 374 qual type *qual *tqe_prev; /* address of previous next element */\ 375 } 376 #define TAILQ_ENTRY(type) _TAILQ_ENTRY(struct type,) 377 378 /* 379 * Tail queue functions. 380 */ 381 #define TAILQ_INIT(head) do { \ 382 (head)->tqh_first = NULL; \ 383 (head)->tqh_last = &(head)->tqh_first; \ 384 } while (/*CONSTCOND*/0) 385 386 #define TAILQ_INSERT_HEAD(head, elm, field) do { \ 387 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ 388 (head)->tqh_first->field.tqe_prev = \ 389 &(elm)->field.tqe_next; \ 390 else \ 391 (head)->tqh_last = &(elm)->field.tqe_next; \ 392 (head)->tqh_first = (elm); \ 393 (elm)->field.tqe_prev = &(head)->tqh_first; \ 394 } while (/*CONSTCOND*/0) 395 396 #define TAILQ_INSERT_TAIL(head, elm, field) do { \ 397 (elm)->field.tqe_next = NULL; \ 398 (elm)->field.tqe_prev = (head)->tqh_last; \ 399 *(head)->tqh_last = (elm); \ 400 (head)->tqh_last = &(elm)->field.tqe_next; \ 401 } while (/*CONSTCOND*/0) 402 403 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 404 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\ 405 (elm)->field.tqe_next->field.tqe_prev = \ 406 &(elm)->field.tqe_next; \ 407 else \ 408 (head)->tqh_last = &(elm)->field.tqe_next; \ 409 (listelm)->field.tqe_next = (elm); \ 410 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ 411 } while (/*CONSTCOND*/0) 412 413 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 414 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 415 (elm)->field.tqe_next = (listelm); \ 416 *(listelm)->field.tqe_prev = (elm); \ 417 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \ 418 } while (/*CONSTCOND*/0) 419 420 #define TAILQ_REMOVE(head, elm, field) do { \ 421 if (((elm)->field.tqe_next) != NULL) \ 422 (elm)->field.tqe_next->field.tqe_prev = \ 423 (elm)->field.tqe_prev; \ 424 else \ 425 (head)->tqh_last = (elm)->field.tqe_prev; \ 426 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ 427 } while (/*CONSTCOND*/0) 428 429 #define TAILQ_FOREACH(var, head, field) \ 430 for ((var) = ((head)->tqh_first); \ 431 (var); \ 432 (var) = ((var)->field.tqe_next)) 433 434 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 435 for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last)); \ 436 (var); \ 437 (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last))) 438 439 /* 440 * Tail queue access methods. 441 */ 442 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 443 #define TAILQ_FIRST(head) ((head)->tqh_first) 444 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 445 446 #define TAILQ_LAST(head, headname) \ 447 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 448 #define TAILQ_PREV(elm, headname, field) \ 449 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 450 451 452 /* 453 * Circular queue definitions. 454 */ 455 #define CIRCLEQ_HEAD(name, type) \ 456 struct name { \ 457 struct type *cqh_first; /* first element */ \ 458 struct type *cqh_last; /* last element */ \ 459 } 460 461 #define CIRCLEQ_HEAD_INITIALIZER(head) \ 462 { (void *)&head, (void *)&head } 463 464 #define CIRCLEQ_ENTRY(type) \ 465 struct { \ 466 struct type *cqe_next; /* next element */ \ 467 struct type *cqe_prev; /* previous element */ \ 468 } 469 470 /* 471 * Circular queue functions. 472 */ 473 #define CIRCLEQ_INIT(head) do { \ 474 (head)->cqh_first = (void *)(head); \ 475 (head)->cqh_last = (void *)(head); \ 476 } while (/*CONSTCOND*/0) 477 478 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 479 (elm)->field.cqe_next = (listelm)->field.cqe_next; \ 480 (elm)->field.cqe_prev = (listelm); \ 481 if ((listelm)->field.cqe_next == (void *)(head)) \ 482 (head)->cqh_last = (elm); \ 483 else \ 484 (listelm)->field.cqe_next->field.cqe_prev = (elm); \ 485 (listelm)->field.cqe_next = (elm); \ 486 } while (/*CONSTCOND*/0) 487 488 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 489 (elm)->field.cqe_next = (listelm); \ 490 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \ 491 if ((listelm)->field.cqe_prev == (void *)(head)) \ 492 (head)->cqh_first = (elm); \ 493 else \ 494 (listelm)->field.cqe_prev->field.cqe_next = (elm); \ 495 (listelm)->field.cqe_prev = (elm); \ 496 } while (/*CONSTCOND*/0) 497 498 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 499 (elm)->field.cqe_next = (head)->cqh_first; \ 500 (elm)->field.cqe_prev = (void *)(head); \ 501 if ((head)->cqh_last == (void *)(head)) \ 502 (head)->cqh_last = (elm); \ 503 else \ 504 (head)->cqh_first->field.cqe_prev = (elm); \ 505 (head)->cqh_first = (elm); \ 506 } while (/*CONSTCOND*/0) 507 508 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 509 (elm)->field.cqe_next = (void *)(head); \ 510 (elm)->field.cqe_prev = (head)->cqh_last; \ 511 if ((head)->cqh_first == (void *)(head)) \ 512 (head)->cqh_first = (elm); \ 513 else \ 514 (head)->cqh_last->field.cqe_next = (elm); \ 515 (head)->cqh_last = (elm); \ 516 } while (/*CONSTCOND*/0) 517 518 #define CIRCLEQ_REMOVE(head, elm, field) do { \ 519 if ((elm)->field.cqe_next == (void *)(head)) \ 520 (head)->cqh_last = (elm)->field.cqe_prev; \ 521 else \ 522 (elm)->field.cqe_next->field.cqe_prev = \ 523 (elm)->field.cqe_prev; \ 524 if ((elm)->field.cqe_prev == (void *)(head)) \ 525 (head)->cqh_first = (elm)->field.cqe_next; \ 526 else \ 527 (elm)->field.cqe_prev->field.cqe_next = \ 528 (elm)->field.cqe_next; \ 529 } while (/*CONSTCOND*/0) 530 531 #define CIRCLEQ_FOREACH(var, head, field) \ 532 for ((var) = ((head)->cqh_first); \ 533 (var) != (const void *)(head); \ 534 (var) = ((var)->field.cqe_next)) 535 536 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ 537 for ((var) = ((head)->cqh_last); \ 538 (var) != (const void *)(head); \ 539 (var) = ((var)->field.cqe_prev)) 540 541 /* 542 * Circular queue access methods. 543 */ 544 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 545 #define CIRCLEQ_FIRST(head) ((head)->cqh_first) 546 #define CIRCLEQ_LAST(head) ((head)->cqh_last) 547 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next) 548 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev) 549 550 #define CIRCLEQ_LOOP_NEXT(head, elm, field) \ 551 (((elm)->field.cqe_next == (void *)(head)) \ 552 ? ((head)->cqh_first) \ 553 : (elm->field.cqe_next)) 554 #define CIRCLEQ_LOOP_PREV(head, elm, field) \ 555 (((elm)->field.cqe_prev == (void *)(head)) \ 556 ? ((head)->cqh_last) \ 557 : (elm->field.cqe_prev)) 558 559 #endif /* sys/queue.h */ 560
