package/ubsec_ssb/src/bsdqueue.h

   1 /*  $OpenBSD: queue.h,v 1.32 2007/04/30 18:42:34 pedro Exp $    */
   2 /*  $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $   */
   3
   4 /*
   5  * Copyright (c) 1991, 1993
   6  *  The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  *  @(#)queue.h 8.5 (Berkeley) 8/20/94
  33  */
  34
  35 #ifndef _BSD_SYS_QUEUE_H_
  36 #define _BSD_SYS_QUEUE_H_
  37
  38 /*
  39  * This file defines five types of data structures: singly-linked lists,
  40  * lists, simple queues, tail queues, and circular queues.
  41  *
  42  *
  43  * A singly-linked list is headed by a single forward pointer. The elements
  44  * are singly linked for minimum space and pointer manipulation overhead at
  45  * the expense of O(n) removal for arbitrary elements. New elements can be
  46  * added to the list after an existing element or at the head of the list.
  47  * Elements being removed from the head of the list should use the explicit
  48  * macro for this purpose for optimum efficiency. A singly-linked list may
  49  * only be traversed in the forward direction.  Singly-linked lists are ideal
  50  * for applications with large datasets and few or no removals or for
  51  * implementing a LIFO queue.
  52  *
  53  * A list is headed by a single forward pointer (or an array of forward
  54  * pointers for a hash table header). The elements are doubly linked
  55  * so that an arbitrary element can be removed without a need to
  56  * traverse the list. New elements can be added to the list before
  57  * or after an existing element or at the head of the list. A list
  58  * may only be traversed in the forward direction.
  59  *
  60  * A simple queue is headed by a pair of pointers, one the head of the
  61  * list and the other to the tail of the list. The elements are singly
  62  * linked to save space, so elements can only be removed from the
  63  * head of the list. New elements can be added to the list before or after
  64  * an existing element, at the head of the list, or at the end of the
  65  * list. A simple queue may only be traversed in the forward direction.
  66  *
  67  * A tail queue is headed by a pair of pointers, one to the head of the
  68  * list and the other to the tail of the list. The elements are doubly
  69  * linked so that an arbitrary element can be removed without a need to
  70  * traverse the list. New elements can be added to the list before or
  71  * after an existing element, at the head of the list, or at the end of
  72  * the list. A tail queue may be traversed in either direction.
  73  *
  74  * A circle queue is headed by a pair of pointers, one to the head of the
  75  * list and the other to the tail of the list. The elements are doubly
  76  * linked so that an arbitrary element can be removed without a need to
  77  * traverse the list. New elements can be added to the list before or after
  78  * an existing element, at the head of the list, or at the end of the list.
  79  * A circle queue may be traversed in either direction, but has a more
  80  * complex end of list detection.
  81  *
  82  * For details on the use of these macros, see the queue(3) manual page.
  83  */
  84
  85 #if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
  86 #define _Q_INVALIDATE(a) (a) = ((void *)-1)
  87 #else
  88 #define _Q_INVALIDATE(a)
  89 #endif
  90
  91 /*
  92  * Singly-linked List definitions.
  93  */
  94 #define BSD_SLIST_HEAD(name, type)                      \
  95 struct name {                               \
  96     struct type *slh_first; /* first element */         \
  97 }
  98
  99 #define BSD_SLIST_HEAD_INITIALIZER(head)                    \
 100     { NULL }
 101
 102 #define BSD_SLIST_ENTRY(type)                       \
 103 struct {                                \
 104     struct type *sle_next;  /* next element */          \
 105 }
 106
 107 /*
 108  * Singly-linked List access methods.
 109  */
 110 #define BSD_SLIST_FIRST(head)   ((head)->slh_first)
 111 #define BSD_SLIST_END(head)     NULL
 112 #define BSD_SLIST_EMPTY(head)   (BSD_SLIST_FIRST(head) == BSD_SLIST_END(head))
 113 #define BSD_SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 114
 115 #define BSD_SLIST_FOREACH(var, head, field)                 \
 116     for((var) = BSD_SLIST_FIRST(head);                  \
 117         (var) != BSD_SLIST_END(head);                   \
 118         (var) = BSD_SLIST_NEXT(var, field))
 119
 120 #define BSD_SLIST_FOREACH_PREVPTR(var, varp, head, field)           \
 121     for ((varp) = &BSD_SLIST_FIRST((head));             \
 122         ((var) = *(varp)) != BSD_SLIST_END(head);           \
 123         (varp) = &BSD_SLIST_NEXT((var), field))
 124
 125 /*
 126  * Singly-linked List functions.
 127  */
 128 #define BSD_SLIST_INIT(head) {                      \
 129     BSD_SLIST_FIRST(head) = BSD_SLIST_END(head);                \
 130 }
 131
 132 #define BSD_SLIST_INSERT_AFTER(slistelm, elm, field) do {           \
 133     (elm)->field.sle_next = (slistelm)->field.sle_next;     \
 134     (slistelm)->field.sle_next = (elm);             \
 135 } while (0)
 136
 137 #define BSD_SLIST_INSERT_HEAD(head, elm, field) do {            \
 138     (elm)->field.sle_next = (head)->slh_first;          \
 139     (head)->slh_first = (elm);                  \
 140 } while (0)
 141
 142 #define BSD_SLIST_REMOVE_NEXT(head, elm, field) do {            \
 143     (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;  \
 144 } while (0)
 145
 146 #define BSD_SLIST_REMOVE_HEAD(head, field) do {             \
 147     (head)->slh_first = (head)->slh_first->field.sle_next;      \
 148 } while (0)
 149
 150 #define BSD_SLIST_REMOVE(head, elm, type, field) do {           \
 151     if ((head)->slh_first == (elm)) {               \
 152         BSD_SLIST_REMOVE_HEAD((head), field);           \
 153     } else {                            \
 154         struct type *curelm = (head)->slh_first;        \
 155                                     \
 156         while (curelm->field.sle_next != (elm))         \
 157             curelm = curelm->field.sle_next;        \
 158         curelm->field.sle_next =                \
 159             curelm->field.sle_next->field.sle_next;     \
 160         _Q_INVALIDATE((elm)->field.sle_next);           \
 161     }                               \
 162 } while (0)
 163
 164 /*
 165  * List definitions.
 166  */
 167 #define BSD_LIST_HEAD(name, type)                       \
 168 struct name {                               \
 169     struct type *lh_first;  /* first element */         \
 170 }
 171
 172 #define BSD_LIST_HEAD_INITIALIZER(head)                 \
 173     { NULL }
 174
 175 #define BSD_LIST_ENTRY(type)                        \
 176 struct {                                \
 177     struct type *le_next;   /* next element */          \
 178     struct type **le_prev;  /* address of previous next element */  \
 179 }
 180
 181 /*
 182  * List access methods
 183  */
 184 #define BSD_LIST_FIRST(head)        ((head)->lh_first)
 185 #define BSD_LIST_END(head)          NULL
 186 #define BSD_LIST_EMPTY(head)        (BSD_LIST_FIRST(head) == BSD_LIST_END(head))
 187 #define BSD_LIST_NEXT(elm, field)       ((elm)->field.le_next)
 188
 189 #define BSD_LIST_FOREACH(var, head, field)                  \
 190     for((var) = BSD_LIST_FIRST(head);                   \
 191         (var)!= BSD_LIST_END(head);                 \
 192         (var) = BSD_LIST_NEXT(var, field))
 193
 194 /*
 195  * List functions.
 196  */
 197 #define BSD_LIST_INIT(head) do {                        \
 198     BSD_LIST_FIRST(head) = BSD_LIST_END(head);              \
 199 } while (0)
 200
 201 #define BSD_LIST_INSERT_AFTER(listelm, elm, field) do {         \
 202     if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 203         (listelm)->field.le_next->field.le_prev =       \
 204             &(elm)->field.le_next;              \
 205     (listelm)->field.le_next = (elm);               \
 206     (elm)->field.le_prev = &(listelm)->field.le_next;       \
 207 } while (0)
 208
 209 #define BSD_LIST_INSERT_BEFORE(listelm, elm, field) do {            \
 210     (elm)->field.le_prev = (listelm)->field.le_prev;        \
 211     (elm)->field.le_next = (listelm);               \
 212     *(listelm)->field.le_prev = (elm);              \
 213     (listelm)->field.le_prev = &(elm)->field.le_next;       \
 214 } while (0)
 215
 216 #define BSD_LIST_INSERT_HEAD(head, elm, field) do {             \
 217     if (((elm)->field.le_next = (head)->lh_first) != NULL)      \
 218         (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 219     (head)->lh_first = (elm);                   \
 220     (elm)->field.le_prev = &(head)->lh_first;           \
 221 } while (0)
 222
 223 #define BSD_LIST_REMOVE(elm, field) do {                    \
 224     if ((elm)->field.le_next != NULL)               \
 225         (elm)->field.le_next->field.le_prev =           \
 226             (elm)->field.le_prev;               \
 227     *(elm)->field.le_prev = (elm)->field.le_next;           \
 228     _Q_INVALIDATE((elm)->field.le_prev);                \
 229     _Q_INVALIDATE((elm)->field.le_next);                \
 230 } while (0)
 231
 232 #define BSD_LIST_REPLACE(elm, elm2, field) do {             \
 233     if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
 234         (elm2)->field.le_next->field.le_prev =          \
 235             &(elm2)->field.le_next;             \
 236     (elm2)->field.le_prev = (elm)->field.le_prev;           \
 237     *(elm2)->field.le_prev = (elm2);                \
 238     _Q_INVALIDATE((elm)->field.le_prev);                \
 239     _Q_INVALIDATE((elm)->field.le_next);                \
 240 } while (0)
 241
 242 /*
 243  * Simple queue definitions.
 244  */
 245 #define BSD_SIMPLEQ_HEAD(name, type)                    \
 246 struct name {                               \
 247     struct type *sqh_first; /* first element */         \
 248     struct type **sqh_last; /* addr of last next element */     \
 249 }
 250
 251 #define BSD_SIMPLEQ_HEAD_INITIALIZER(head)                  \
 252     { NULL, &(head).sqh_first }
 253
 254 #define BSD_SIMPLEQ_ENTRY(type)                     \
 255 struct {                                \
 256     struct type *sqe_next;  /* next element */          \
 257 }
 258
 259 /*
 260  * Simple queue access methods.
 261  */
 262 #define BSD_SIMPLEQ_FIRST(head)     ((head)->sqh_first)
 263 #define BSD_SIMPLEQ_END(head)       NULL
 264 #define BSD_SIMPLEQ_EMPTY(head)     (BSD_SIMPLEQ_FIRST(head) == BSD_SIMPLEQ_END(head))
 265 #define BSD_SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
 266
 267 #define BSD_SIMPLEQ_FOREACH(var, head, field)               \
 268     for((var) = BSD_SIMPLEQ_FIRST(head);                \
 269         (var) != BSD_SIMPLEQ_END(head);                 \
 270         (var) = BSD_SIMPLEQ_NEXT(var, field))
 271
 272 /*
 273  * Simple queue functions.
 274  */
 275 #define BSD_SIMPLEQ_INIT(head) do {                     \
 276     (head)->sqh_first = NULL;                   \
 277     (head)->sqh_last = &(head)->sqh_first;              \
 278 } while (0)
 279
 280 #define BSD_SIMPLEQ_INSERT_HEAD(head, elm, field) do {          \
 281     if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)    \
 282         (head)->sqh_last = &(elm)->field.sqe_next;      \
 283     (head)->sqh_first = (elm);                  \
 284 } while (0)
 285
 286 #define BSD_SIMPLEQ_INSERT_TAIL(head, elm, field) do {          \
 287     (elm)->field.sqe_next = NULL;                   \
 288     *(head)->sqh_last = (elm);                  \
 289     (head)->sqh_last = &(elm)->field.sqe_next;          \
 290 } while (0)
 291
 292 #define BSD_SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {        \
 293     if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
 294         (head)->sqh_last = &(elm)->field.sqe_next;      \
 295     (listelm)->field.sqe_next = (elm);              \
 296 } while (0)
 297
 298 #define BSD_SIMPLEQ_REMOVE_HEAD(head, field) do {           \
 299     if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
 300         (head)->sqh_last = &(head)->sqh_first;          \
 301 } while (0)
 302
 303 /*
 304  * Tail queue definitions.
 305  */
 306 #define BSD_TAILQ_HEAD(name, type)                      \
 307 struct name {                               \
 308     struct type *tqh_first; /* first element */         \
 309     struct type **tqh_last; /* addr of last next element */     \
 310 }
 311
 312 #define BSD_TAILQ_HEAD_INITIALIZER(head)                    \
 313     { NULL, &(head).tqh_first }
 314
 315 #define BSD_TAILQ_ENTRY(type)                       \
 316 struct {                                \
 317     struct type *tqe_next;  /* next element */          \
 318     struct type **tqe_prev; /* address of previous next element */  \
 319 }
 320
 321 /*
 322  * tail queue access methods
 323  */
 324 #define BSD_TAILQ_FIRST(head)       ((head)->tqh_first)
 325 #define BSD_TAILQ_END(head)         NULL
 326 #define BSD_TAILQ_NEXT(elm, field)      ((elm)->field.tqe_next)
 327 #define BSD_TAILQ_LAST(head, headname)                  \
 328     (*(((struct headname *)((head)->tqh_last))->tqh_last))
 329 /* XXX */
 330 #define BSD_TAILQ_PREV(elm, headname, field)                \
 331     (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 332 #define BSD_TAILQ_EMPTY(head)                       \
 333     (BSD_TAILQ_FIRST(head) == BSD_TAILQ_END(head))
 334
 335 #define BSD_TAILQ_FOREACH(var, head, field)                 \
 336     for((var) = BSD_TAILQ_FIRST(head);                  \
 337         (var) != BSD_TAILQ_END(head);                   \
 338         (var) = BSD_TAILQ_NEXT(var, field))
 339
 340 #define BSD_TAILQ_FOREACH_REVERSE(var, head, headname, field)       \
 341     for((var) = BSD_TAILQ_LAST(head, headname);             \
 342         (var) != BSD_TAILQ_END(head);                   \
 343         (var) = BSD_TAILQ_PREV(var, headname, field))
 344
 345 /*
 346  * Tail queue functions.
 347  */
 348 #define BSD_TAILQ_INIT(head) do {                       \
 349     (head)->tqh_first = NULL;                   \
 350     (head)->tqh_last = &(head)->tqh_first;              \
 351 } while (0)
 352
 353 #define BSD_TAILQ_INSERT_HEAD(head, elm, field) do {            \
 354     if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)    \
 355         (head)->tqh_first->field.tqe_prev =         \
 356             &(elm)->field.tqe_next;             \
 357     else                                \
 358         (head)->tqh_last = &(elm)->field.tqe_next;      \
 359     (head)->tqh_first = (elm);                  \
 360     (elm)->field.tqe_prev = &(head)->tqh_first;         \
 361 } while (0)
 362
 363 #define BSD_TAILQ_INSERT_TAIL(head, elm, field) do {            \
 364     (elm)->field.tqe_next = NULL;                   \
 365     (elm)->field.tqe_prev = (head)->tqh_last;           \
 366     *(head)->tqh_last = (elm);                  \
 367     (head)->tqh_last = &(elm)->field.tqe_next;          \
 368 } while (0)
 369
 370 #define BSD_TAILQ_INSERT_AFTER(head, listelm, elm, field) do {      \
 371     if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 372         (elm)->field.tqe_next->field.tqe_prev =         \
 373             &(elm)->field.tqe_next;             \
 374     else                                \
 375         (head)->tqh_last = &(elm)->field.tqe_next;      \
 376     (listelm)->field.tqe_next = (elm);              \
 377     (elm)->field.tqe_prev = &(listelm)->field.tqe_next;     \
 378 } while (0)
 379
 380 #define BSD_TAILQ_INSERT_BEFORE(listelm, elm, field) do {           \
 381     (elm)->field.tqe_prev = (listelm)->field.tqe_prev;      \
 382     (elm)->field.tqe_next = (listelm);              \
 383     *(listelm)->field.tqe_prev = (elm);             \
 384     (listelm)->field.tqe_prev = &(elm)->field.tqe_next;     \
 385 } while (0)
 386
 387 #define BSD_TAILQ_REMOVE(head, elm, field) do {             \
 388     if (((elm)->field.tqe_next) != NULL)                \
 389         (elm)->field.tqe_next->field.tqe_prev =         \
 390             (elm)->field.tqe_prev;              \
 391     else                                \
 392         (head)->tqh_last = (elm)->field.tqe_prev;       \
 393     *(elm)->field.tqe_prev = (elm)->field.tqe_next;         \
 394     _Q_INVALIDATE((elm)->field.tqe_prev);               \
 395     _Q_INVALIDATE((elm)->field.tqe_next);               \
 396 } while (0)
 397
 398 #define BSD_TAILQ_REPLACE(head, elm, elm2, field) do {          \
 399     if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)   \
 400         (elm2)->field.tqe_next->field.tqe_prev =        \
 401             &(elm2)->field.tqe_next;                \
 402     else                                \
 403         (head)->tqh_last = &(elm2)->field.tqe_next;     \
 404     (elm2)->field.tqe_prev = (elm)->field.tqe_prev;         \
 405     *(elm2)->field.tqe_prev = (elm2);               \
 406     _Q_INVALIDATE((elm)->field.tqe_prev);               \
 407     _Q_INVALIDATE((elm)->field.tqe_next);               \
 408 } while (0)
 409
 410 /*
 411  * Circular queue definitions.
 412  */
 413 #define BSD_CIRCLEQ_HEAD(name, type)                    \
 414 struct name {                               \
 415     struct type *cqh_first;     /* first element */     \
 416     struct type *cqh_last;      /* last element */      \
 417 }
 418
 419 #define BSD_CIRCLEQ_HEAD_INITIALIZER(head)                  \
 420     { BSD_CIRCLEQ_END(&head), BSD_CIRCLEQ_END(&head) }
 421
 422 #define BSD_CIRCLEQ_ENTRY(type)                     \
 423 struct {                                \
 424     struct type *cqe_next;      /* next element */      \
 425     struct type *cqe_prev;      /* previous element */      \
 426 }
 427
 428 /*
 429  * Circular queue access methods
 430  */
 431 #define BSD_CIRCLEQ_FIRST(head)     ((head)->cqh_first)
 432 #define BSD_CIRCLEQ_LAST(head)      ((head)->cqh_last)
 433 #define BSD_CIRCLEQ_END(head)       ((void *)(head))
 434 #define BSD_CIRCLEQ_NEXT(elm, field)    ((elm)->field.cqe_next)
 435 #define BSD_CIRCLEQ_PREV(elm, field)    ((elm)->field.cqe_prev)
 436 #define BSD_CIRCLEQ_EMPTY(head)                     \
 437     (BSD_CIRCLEQ_FIRST(head) == BSD_CIRCLEQ_END(head))
 438
 439 #define BSD_CIRCLEQ_FOREACH(var, head, field)               \
 440     for((var) = BSD_CIRCLEQ_FIRST(head);                \
 441         (var) != BSD_CIRCLEQ_END(head);                 \
 442         (var) = BSD_CIRCLEQ_NEXT(var, field))
 443
 444 #define BSD_CIRCLEQ_FOREACH_REVERSE(var, head, field)           \
 445     for((var) = BSD_CIRCLEQ_LAST(head);                 \
 446         (var) != BSD_CIRCLEQ_END(head);                 \
 447         (var) = BSD_CIRCLEQ_PREV(var, field))
 448
 449 /*
 450  * Circular queue functions.
 451  */
 452 #define BSD_CIRCLEQ_INIT(head) do {                     \
 453     (head)->cqh_first = BSD_CIRCLEQ_END(head);              \
 454     (head)->cqh_last = BSD_CIRCLEQ_END(head);               \
 455 } while (0)
 456
 457 #define BSD_CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {        \
 458     (elm)->field.cqe_next = (listelm)->field.cqe_next;      \
 459     (elm)->field.cqe_prev = (listelm);              \
 460     if ((listelm)->field.cqe_next == BSD_CIRCLEQ_END(head))     \
 461         (head)->cqh_last = (elm);               \
 462     else                                \
 463         (listelm)->field.cqe_next->field.cqe_prev = (elm);  \
 464     (listelm)->field.cqe_next = (elm);              \
 465 } while (0)
 466
 467 #define BSD_CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {       \
 468     (elm)->field.cqe_next = (listelm);              \
 469     (elm)->field.cqe_prev = (listelm)->field.cqe_prev;      \
 470     if ((listelm)->field.cqe_prev == BSD_CIRCLEQ_END(head))     \
 471         (head)->cqh_first = (elm);              \
 472     else                                \
 473         (listelm)->field.cqe_prev->field.cqe_next = (elm);  \
 474     (listelm)->field.cqe_prev = (elm);              \
 475 } while (0)
 476
 477 #define BSD_CIRCLEQ_INSERT_HEAD(head, elm, field) do {          \
 478     (elm)->field.cqe_next = (head)->cqh_first;          \
 479     (elm)->field.cqe_prev = BSD_CIRCLEQ_END(head);          \
 480     if ((head)->cqh_last == BSD_CIRCLEQ_END(head))          \
 481         (head)->cqh_last = (elm);               \
 482     else                                \
 483         (head)->cqh_first->field.cqe_prev = (elm);      \
 484     (head)->cqh_first = (elm);                  \
 485 } while (0)
 486
 487 #define BSD_CIRCLEQ_INSERT_TAIL(head, elm, field) do {          \
 488     (elm)->field.cqe_next = BSD_CIRCLEQ_END(head);          \
 489     (elm)->field.cqe_prev = (head)->cqh_last;           \
 490     if ((head)->cqh_first == BSD_CIRCLEQ_END(head))         \
 491         (head)->cqh_first = (elm);              \
 492     else                                \
 493         (head)->cqh_last->field.cqe_next = (elm);       \
 494     (head)->cqh_last = (elm);                   \
 495 } while (0)
 496
 497 #define BSD_CIRCLEQ_REMOVE(head, elm, field) do {               \
 498     if ((elm)->field.cqe_next == BSD_CIRCLEQ_END(head))         \
 499         (head)->cqh_last = (elm)->field.cqe_prev;       \
 500     else                                \
 501         (elm)->field.cqe_next->field.cqe_prev =         \
 502             (elm)->field.cqe_prev;              \
 503     if ((elm)->field.cqe_prev == BSD_CIRCLEQ_END(head))         \
 504         (head)->cqh_first = (elm)->field.cqe_next;      \
 505     else                                \
 506         (elm)->field.cqe_prev->field.cqe_next =         \
 507             (elm)->field.cqe_next;              \
 508     _Q_INVALIDATE((elm)->field.cqe_prev);               \
 509     _Q_INVALIDATE((elm)->field.cqe_next);               \
 510 } while (0)
 511
 512 #define BSD_CIRCLEQ_REPLACE(head, elm, elm2, field) do {            \
 513     if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==     \
 514         BSD_CIRCLEQ_END(head))                      \
 515         (head).cqh_last = (elm2);               \
 516     else                                \
 517         (elm2)->field.cqe_next->field.cqe_prev = (elm2);    \
 518     if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==     \
 519         BSD_CIRCLEQ_END(head))                      \
 520         (head).cqh_first = (elm2);              \
 521     else                                \
 522         (elm2)->field.cqe_prev->field.cqe_next = (elm2);    \
 523     _Q_INVALIDATE((elm)->field.cqe_prev);               \
 524     _Q_INVALIDATE((elm)->field.cqe_next);               \
 525 } while (0)
 526
 527 #endif  /* !_BSD_SYS_QUEUE_H_ */