src/include/k5-queue.h

   1 /*
   2  * This is a copy of NetBSD's sys/queue.h, edited to use a different symbol for
   3  * multiple inclusion protection and to suppress the include of <sys/null.h>.
   4  */
   5
   6 /*      $NetBSD: queue.h,v 1.53 2011/11/19 22:51:31 tls Exp $   */
   7
   8 /*
   9  * Copyright (c) 1991, 1993
  10  *      The Regents of the University of California.  All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  37  */
  38
  39 #ifndef K5_QUEUE_H
  40 #define K5_QUEUE_H
  41
  42 /* #include <sys/null.h> */
  43
  44 /*
  45  * This file defines five types of data structures: singly-linked lists,
  46  * lists, simple queues, tail queues, and circular queues.
  47  *
  48  * A singly-linked list is headed by a single forward pointer. The
  49  * elements are singly linked for minimum space and pointer manipulation
  50  * overhead at the expense of O(n) removal for arbitrary elements. New
  51  * elements can be added to the list after an existing element or at the
  52  * head of the list.  Elements being removed from the head of the list
  53  * should use the explicit macro for this purpose for optimum
  54  * efficiency. A singly-linked list may only be traversed in the forward
  55  * direction.  Singly-linked lists are ideal for applications with large
  56  * datasets and few or no removals or for implementing a LIFO queue.
  57  *
  58  * A list is headed by a single forward pointer (or an array of forward
  59  * pointers for a hash table header). The elements are doubly linked
  60  * so that an arbitrary element can be removed without a need to
  61  * traverse the list. New elements can be added to the list before
  62  * or after an existing element or at the head of the list. A list
  63  * may only be traversed in the forward direction.
  64  *
  65  * A simple queue is headed by a pair of pointers, one the head of the
  66  * list and the other to the tail of the list. The elements are singly
  67  * linked to save space, so elements can only be removed from the
  68  * head of the list. New elements can be added to the list after
  69  * an existing element, at the head of the list, or at the end of the
  70  * list. A simple queue 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 be traversed in either 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 /*
  91  * List definitions.
  92  */
  93 #define K5_LIST_HEAD(name, type)                                        \
  94 struct name {                                                           \
  95         struct type *lh_first;  /* first element */                     \
  96 }
  97
  98 #define K5_LIST_HEAD_INITIALIZER(head)                                  \
  99         { NULL }
 100
 101 #define K5_LIST_ENTRY(type)                                             \
 102 struct {                                                                \
 103         struct type *le_next;   /* next element */                      \
 104         struct type **le_prev;  /* address of previous next element */  \
 105 }
 106
 107 /*
 108  * List functions.
 109  */
 110 #define K5_LIST_INIT(head) do {                                         \
 111         (head)->lh_first = NULL;                                        \
 112 } while (/*CONSTCOND*/0)
 113
 114 #define K5_LIST_INSERT_AFTER(listelm, elm, field) do {                  \
 115         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 116                 (listelm)->field.le_next->field.le_prev =               \
 117                     &(elm)->field.le_next;                              \
 118         (listelm)->field.le_next = (elm);                               \
 119         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 120 } while (/*CONSTCOND*/0)
 121
 122 #define K5_LIST_INSERT_BEFORE(listelm, elm, field) do {                 \
 123         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 124         (elm)->field.le_next = (listelm);                               \
 125         *(listelm)->field.le_prev = (elm);                              \
 126         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 127 } while (/*CONSTCOND*/0)
 128
 129 #define K5_LIST_INSERT_HEAD(head, elm, field) do {                      \
 130         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 131                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 132         (head)->lh_first = (elm);                                       \
 133         (elm)->field.le_prev = &(head)->lh_first;                       \
 134 } while (/*CONSTCOND*/0)
 135
 136 #define K5_LIST_REMOVE(elm, field) do {                                 \
 137         if ((elm)->field.le_next != NULL)                               \
 138                 (elm)->field.le_next->field.le_prev =                   \
 139                     (elm)->field.le_prev;                               \
 140         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 141 } while (/*CONSTCOND*/0)
 142
 143 #define K5_LIST_FOREACH(var, head, field)                               \
 144         for ((var) = ((head)->lh_first);                                \
 145                 (var);                                                  \
 146                 (var) = ((var)->field.le_next))
 147
 148 #define K5_LIST_FOREACH_SAFE(var, head, field, tvar)                    \
 149         for ((var) = K5_LIST_FIRST((head));                             \
 150                 (var) && ((tvar) = K5_LIST_NEXT((var), field), 1);      \
 151                 (var) = (tvar))
 152 /*
 153  * List access methods.
 154  */
 155 #define K5_LIST_EMPTY(head)             ((head)->lh_first == NULL)
 156 #define K5_LIST_FIRST(head)             ((head)->lh_first)
 157 #define K5_LIST_NEXT(elm, field)        ((elm)->field.le_next)
 158
 159
 160 /*
 161  * Singly-linked List definitions.
 162  */
 163 #define K5_SLIST_HEAD(name, type)                                       \
 164 struct name {                                                           \
 165         struct type *slh_first; /* first element */                     \
 166 }
 167
 168 #define K5_SLIST_HEAD_INITIALIZER(head)                                 \
 169         { NULL }
 170
 171 #define K5_SLIST_ENTRY(type)                                            \
 172 struct {                                                                \
 173         struct type *sle_next;  /* next element */                      \
 174 }
 175
 176 /*
 177  * Singly-linked List functions.
 178  */
 179 #define K5_SLIST_INIT(head) do {                                        \
 180         (head)->slh_first = NULL;                                       \
 181 } while (/*CONSTCOND*/0)
 182
 183 #define K5_SLIST_INSERT_AFTER(slistelm, elm, field) do {                \
 184         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 185         (slistelm)->field.sle_next = (elm);                             \
 186 } while (/*CONSTCOND*/0)
 187
 188 #define K5_SLIST_INSERT_HEAD(head, elm, field) do {                     \
 189         (elm)->field.sle_next = (head)->slh_first;                      \
 190         (head)->slh_first = (elm);                                      \
 191 } while (/*CONSTCOND*/0)
 192
 193 #define K5_SLIST_REMOVE_HEAD(head, field) do {                          \
 194         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 195 } while (/*CONSTCOND*/0)
 196
 197 #define K5_SLIST_REMOVE(head, elm, type, field) do {                    \
 198         if ((head)->slh_first == (elm)) {                               \
 199                 K5_SLIST_REMOVE_HEAD((head), field);                    \
 200         }                                                               \
 201         else {                                                          \
 202                 struct type *curelm = (head)->slh_first;                \
 203                 while(curelm->field.sle_next != (elm))                  \
 204                         curelm = curelm->field.sle_next;                \
 205                 curelm->field.sle_next =                                \
 206                     curelm->field.sle_next->field.sle_next;             \
 207         }                                                               \
 208 } while (/*CONSTCOND*/0)
 209
 210 #define K5_SLIST_REMOVE_AFTER(slistelm, field) do {                     \
 211         (slistelm)->field.sle_next =                                    \
 212             K5_SLIST_NEXT(K5_SLIST_NEXT((slistelm), field), field);     \
 213 } while (/*CONSTCOND*/0)
 214
 215 #define K5_SLIST_FOREACH(var, head, field)                              \
 216         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 217
 218 #define K5_SLIST_FOREACH_SAFE(var, head, field, tvar)                   \
 219         for ((var) = K5_SLIST_FIRST((head));                            \
 220             (var) && ((tvar) = K5_SLIST_NEXT((var), field), 1);         \
 221             (var) = (tvar))
 222
 223 /*
 224  * Singly-linked List access methods.
 225  */
 226 #define K5_SLIST_EMPTY(head)    ((head)->slh_first == NULL)
 227 #define K5_SLIST_FIRST(head)    ((head)->slh_first)
 228 #define K5_SLIST_NEXT(elm, field)       ((elm)->field.sle_next)
 229
 230
 231 /*
 232  * Singly-linked Tail queue declarations.
 233  */
 234 #define K5_STAILQ_HEAD(name, type)                                      \
 235 struct name {                                                           \
 236         struct type *stqh_first;        /* first element */                     \
 237         struct type **stqh_last;        /* addr of last next element */         \
 238 }
 239
 240 #define K5_STAILQ_HEAD_INITIALIZER(head)                                \
 241         { NULL, &(head).stqh_first }
 242
 243 #define K5_STAILQ_ENTRY(type)                                           \
 244 struct {                                                                \
 245         struct type *stqe_next; /* next element */                      \
 246 }
 247
 248 /*
 249  * Singly-linked Tail queue functions.
 250  */
 251 #define K5_STAILQ_INIT(head) do {                                       \
 252         (head)->stqh_first = NULL;                                      \
 253         (head)->stqh_last = &(head)->stqh_first;                                \
 254 } while (/*CONSTCOND*/0)
 255
 256 #define K5_STAILQ_INSERT_HEAD(head, elm, field) do {                    \
 257         if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
 258                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 259         (head)->stqh_first = (elm);                                     \
 260 } while (/*CONSTCOND*/0)
 261
 262 #define K5_STAILQ_INSERT_TAIL(head, elm, field) do {                    \
 263         (elm)->field.stqe_next = NULL;                                  \
 264         *(head)->stqh_last = (elm);                                     \
 265         (head)->stqh_last = &(elm)->field.stqe_next;                    \
 266 } while (/*CONSTCOND*/0)
 267
 268 #define K5_STAILQ_INSERT_AFTER(head, listelm, elm, field) do {          \
 269         if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\
 270                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 271         (listelm)->field.stqe_next = (elm);                             \
 272 } while (/*CONSTCOND*/0)
 273
 274 #define K5_STAILQ_REMOVE_HEAD(head, field) do {                         \
 275         if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \
 276                 (head)->stqh_last = &(head)->stqh_first;                        \
 277 } while (/*CONSTCOND*/0)
 278
 279 #define K5_STAILQ_REMOVE(head, elm, type, field) do {                   \
 280         if ((head)->stqh_first == (elm)) {                              \
 281                 K5_STAILQ_REMOVE_HEAD((head), field);                   \
 282         } else {                                                        \
 283                 struct type *curelm = (head)->stqh_first;               \
 284                 while (curelm->field.stqe_next != (elm))                \
 285                         curelm = curelm->field.stqe_next;               \
 286                 if ((curelm->field.stqe_next =                          \
 287                         curelm->field.stqe_next->field.stqe_next) == NULL) \
 288                             (head)->stqh_last = &(curelm)->field.stqe_next; \
 289         }                                                               \
 290 } while (/*CONSTCOND*/0)
 291
 292 #define K5_STAILQ_FOREACH(var, head, field)                             \
 293         for ((var) = ((head)->stqh_first);                              \
 294                 (var);                                                  \
 295                 (var) = ((var)->field.stqe_next))
 296
 297 #define K5_STAILQ_FOREACH_SAFE(var, head, field, tvar)                  \
 298         for ((var) = K5_STAILQ_FIRST((head));                           \
 299             (var) && ((tvar) = K5_STAILQ_NEXT((var), field), 1);        \
 300             (var) = (tvar))
 301
 302 #define K5_STAILQ_CONCAT(head1, head2) do {                             \
 303         if (!K5_STAILQ_EMPTY((head2))) {                                \
 304                 *(head1)->stqh_last = (head2)->stqh_first;              \
 305                 (head1)->stqh_last = (head2)->stqh_last;                \
 306                 K5_STAILQ_INIT((head2));                                \
 307         }                                                               \
 308 } while (/*CONSTCOND*/0)
 309
 310 #define K5_STAILQ_LAST(head, type, field)                               \
 311         (K5_STAILQ_EMPTY((head)) ?                                      \
 312                 NULL :                                                  \
 313                 ((struct type *)(void *)                                \
 314                 ((char *)((head)->stqh_last) - offsetof(struct type, field))))
 315
 316 /*
 317  * Singly-linked Tail queue access methods.
 318  */
 319 #define K5_STAILQ_EMPTY(head)   ((head)->stqh_first == NULL)
 320 #define K5_STAILQ_FIRST(head)   ((head)->stqh_first)
 321 #define K5_STAILQ_NEXT(elm, field)      ((elm)->field.stqe_next)
 322
 323
 324 /*
 325  * Simple queue definitions.
 326  */
 327 #define K5_SIMPLEQ_HEAD(name, type)                                     \
 328 struct name {                                                           \
 329         struct type *sqh_first; /* first element */                     \
 330         struct type **sqh_last; /* addr of last next element */         \
 331 }
 332
 333 #define K5_SIMPLEQ_HEAD_INITIALIZER(head)                               \
 334         { NULL, &(head).sqh_first }
 335
 336 #define K5_SIMPLEQ_ENTRY(type)                                          \
 337 struct {                                                                \
 338         struct type *sqe_next;  /* next element */                      \
 339 }
 340
 341 /*
 342  * Simple queue functions.
 343  */
 344 #define K5_SIMPLEQ_INIT(head) do {                                      \
 345         (head)->sqh_first = NULL;                                       \
 346         (head)->sqh_last = &(head)->sqh_first;                          \
 347 } while (/*CONSTCOND*/0)
 348
 349 #define K5_SIMPLEQ_INSERT_HEAD(head, elm, field) do {                   \
 350         if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)        \
 351                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 352         (head)->sqh_first = (elm);                                      \
 353 } while (/*CONSTCOND*/0)
 354
 355 #define K5_SIMPLEQ_INSERT_TAIL(head, elm, field) do {                   \
 356         (elm)->field.sqe_next = NULL;                                   \
 357         *(head)->sqh_last = (elm);                                      \
 358         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 359 } while (/*CONSTCOND*/0)
 360
 361 #define K5_SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {         \
 362         if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
 363                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 364         (listelm)->field.sqe_next = (elm);                              \
 365 } while (/*CONSTCOND*/0)
 366
 367 #define K5_SIMPLEQ_REMOVE_HEAD(head, field) do {                        \
 368         if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
 369                 (head)->sqh_last = &(head)->sqh_first;                  \
 370 } while (/*CONSTCOND*/0)
 371
 372 #define K5_SIMPLEQ_REMOVE(head, elm, type, field) do {                  \
 373         if ((head)->sqh_first == (elm)) {                               \
 374                 K5_SIMPLEQ_REMOVE_HEAD((head), field);                  \
 375         } else {                                                        \
 376                 struct type *curelm = (head)->sqh_first;                \
 377                 while (curelm->field.sqe_next != (elm))                 \
 378                         curelm = curelm->field.sqe_next;                \
 379                 if ((curelm->field.sqe_next =                           \
 380                         curelm->field.sqe_next->field.sqe_next) == NULL) \
 381                             (head)->sqh_last = &(curelm)->field.sqe_next; \
 382         }                                                               \
 383 } while (/*CONSTCOND*/0)
 384
 385 #define K5_SIMPLEQ_FOREACH(var, head, field)                            \
 386         for ((var) = ((head)->sqh_first);                               \
 387                 (var);                                                  \
 388                 (var) = ((var)->field.sqe_next))
 389
 390 #define K5_SIMPLEQ_FOREACH_SAFE(var, head, field, next)                 \
 391         for ((var) = ((head)->sqh_first);                               \
 392                 (var) && ((next = ((var)->field.sqe_next)), 1);         \
 393                 (var) = (next))
 394
 395 #define K5_SIMPLEQ_CONCAT(head1, head2) do {                            \
 396         if (!K5_SIMPLEQ_EMPTY((head2))) {                               \
 397                 *(head1)->sqh_last = (head2)->sqh_first;                \
 398                 (head1)->sqh_last = (head2)->sqh_last;          \
 399                 K5_SIMPLEQ_INIT((head2));                               \
 400         }                                                               \
 401 } while (/*CONSTCOND*/0)
 402
 403 #define K5_SIMPLEQ_LAST(head, type, field)                              \
 404         (K5_SIMPLEQ_EMPTY((head)) ?                                     \
 405                 NULL :                                                  \
 406                 ((struct type *)(void *)                                \
 407                 ((char *)((head)->sqh_last) - offsetof(struct type, field))))
 408
 409 /*
 410  * Simple queue access methods.
 411  */
 412 #define K5_SIMPLEQ_EMPTY(head)          ((head)->sqh_first == NULL)
 413 #define K5_SIMPLEQ_FIRST(head)          ((head)->sqh_first)
 414 #define K5_SIMPLEQ_NEXT(elm, field)     ((elm)->field.sqe_next)
 415
 416
 417 /*
 418  * Tail queue definitions.
 419  */
 420 #define _K5_TAILQ_HEAD(name, type, qual)                                \
 421 struct name {                                                           \
 422         qual type *tqh_first;           /* first element */             \
 423         qual type *qual *tqh_last;      /* addr of last next element */ \
 424 }
 425 #define K5_TAILQ_HEAD(name, type)       _K5_TAILQ_HEAD(name, struct type,)
 426
 427 #define K5_TAILQ_HEAD_INITIALIZER(head)                                 \
 428         { NULL, &(head).tqh_first }
 429
 430 #define _K5_TAILQ_ENTRY(type, qual)                                     \
 431 struct {                                                                \
 432         qual type *tqe_next;            /* next element */              \
 433         qual type *qual *tqe_prev;      /* address of previous next element */\
 434 }
 435 #define K5_TAILQ_ENTRY(type)    _K5_TAILQ_ENTRY(struct type,)
 436
 437 /*
 438  * Tail queue functions.
 439  */
 440 #define K5_TAILQ_INIT(head) do {                                        \
 441         (head)->tqh_first = NULL;                                       \
 442         (head)->tqh_last = &(head)->tqh_first;                          \
 443 } while (/*CONSTCOND*/0)
 444
 445 #define K5_TAILQ_INSERT_HEAD(head, elm, field) do {                     \
 446         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 447                 (head)->tqh_first->field.tqe_prev =                     \
 448                     &(elm)->field.tqe_next;                             \
 449         else                                                            \
 450                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 451         (head)->tqh_first = (elm);                                      \
 452         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 453 } while (/*CONSTCOND*/0)
 454
 455 #define K5_TAILQ_INSERT_TAIL(head, elm, field) do {                     \
 456         (elm)->field.tqe_next = NULL;                                   \
 457         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 458         *(head)->tqh_last = (elm);                                      \
 459         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 460 } while (/*CONSTCOND*/0)
 461
 462 #define K5_TAILQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 463         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 464                 (elm)->field.tqe_next->field.tqe_prev =                 \
 465                     &(elm)->field.tqe_next;                             \
 466         else                                                            \
 467                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 468         (listelm)->field.tqe_next = (elm);                              \
 469         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 470 } while (/*CONSTCOND*/0)
 471
 472 #define K5_TAILQ_INSERT_BEFORE(listelm, elm, field) do {                \
 473         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 474         (elm)->field.tqe_next = (listelm);                              \
 475         *(listelm)->field.tqe_prev = (elm);                             \
 476         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 477 } while (/*CONSTCOND*/0)
 478
 479 #define K5_TAILQ_REMOVE(head, elm, field) do {                          \
 480         if (((elm)->field.tqe_next) != NULL)                            \
 481                 (elm)->field.tqe_next->field.tqe_prev =                 \
 482                     (elm)->field.tqe_prev;                              \
 483         else                                                            \
 484                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 485         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 486 } while (/*CONSTCOND*/0)
 487
 488 #define K5_TAILQ_FOREACH(var, head, field)                              \
 489         for ((var) = ((head)->tqh_first);                               \
 490                 (var);                                                  \
 491                 (var) = ((var)->field.tqe_next))
 492
 493 #define K5_TAILQ_FOREACH_SAFE(var, head, field, next)                   \
 494         for ((var) = ((head)->tqh_first);                               \
 495                 (var) != NULL && ((next) = K5_TAILQ_NEXT(var, field), 1);       \
 496                 (var) = (next))
 497
 498 #define K5_TAILQ_FOREACH_REVERSE(var, head, headname, field)            \
 499         for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));    \
 500                 (var);                                                  \
 501                 (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
 502
 503 #define K5_TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, prev) \
 504         for ((var) = K5_TAILQ_LAST((head), headname);                   \
 505                 (var) && ((prev) = K5_TAILQ_PREV((var), headname, field), 1);\
 506                 (var) = (prev))
 507
 508 #define K5_TAILQ_CONCAT(head1, head2, field) do {                       \
 509         if (!K5_TAILQ_EMPTY(head2)) {                                   \
 510                 *(head1)->tqh_last = (head2)->tqh_first;                \
 511                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 512                 (head1)->tqh_last = (head2)->tqh_last;                  \
 513                 K5_TAILQ_INIT((head2));                                 \
 514         }                                                               \
 515 } while (/*CONSTCOND*/0)
 516
 517 /*
 518  * Tail queue access methods.
 519  */
 520 #define K5_TAILQ_EMPTY(head)            ((head)->tqh_first == NULL)
 521 #define K5_TAILQ_FIRST(head)            ((head)->tqh_first)
 522 #define K5_TAILQ_NEXT(elm, field)       ((elm)->field.tqe_next)
 523
 524 #define K5_TAILQ_LAST(head, headname) \
 525         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 526 #define K5_TAILQ_PREV(elm, headname, field) \
 527         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 528
 529
 530 /*
 531  * Circular queue definitions.
 532  */
 533 #define K5_CIRCLEQ_HEAD(name, type)                                     \
 534 struct name {                                                           \
 535         struct type *cqh_first;         /* first element */             \
 536         struct type *cqh_last;          /* last element */              \
 537 }
 538
 539 #define K5_CIRCLEQ_HEAD_INITIALIZER(head)                               \
 540         { (void *)&head, (void *)&head }
 541
 542 #define K5_CIRCLEQ_ENTRY(type)                                          \
 543 struct {                                                                \
 544         struct type *cqe_next;          /* next element */              \
 545         struct type *cqe_prev;          /* previous element */          \
 546 }
 547
 548 /*
 549  * Circular queue functions.
 550  */
 551 #define K5_CIRCLEQ_INIT(head) do {                                      \
 552         (head)->cqh_first = (void *)(head);                             \
 553         (head)->cqh_last = (void *)(head);                              \
 554 } while (/*CONSTCOND*/0)
 555
 556 #define K5_CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {         \
 557         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 558         (elm)->field.cqe_prev = (listelm);                              \
 559         if ((listelm)->field.cqe_next == (void *)(head))                \
 560                 (head)->cqh_last = (elm);                               \
 561         else                                                            \
 562                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 563         (listelm)->field.cqe_next = (elm);                              \
 564 } while (/*CONSTCOND*/0)
 565
 566 #define K5_CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {        \
 567         (elm)->field.cqe_next = (listelm);                              \
 568         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 569         if ((listelm)->field.cqe_prev == (void *)(head))                \
 570                 (head)->cqh_first = (elm);                              \
 571         else                                                            \
 572                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 573         (listelm)->field.cqe_prev = (elm);                              \
 574 } while (/*CONSTCOND*/0)
 575
 576 #define K5_CIRCLEQ_INSERT_HEAD(head, elm, field) do {                   \
 577         (elm)->field.cqe_next = (head)->cqh_first;                      \
 578         (elm)->field.cqe_prev = (void *)(head);                         \
 579         if ((head)->cqh_last == (void *)(head))                         \
 580                 (head)->cqh_last = (elm);                               \
 581         else                                                            \
 582                 (head)->cqh_first->field.cqe_prev = (elm);              \
 583         (head)->cqh_first = (elm);                                      \
 584 } while (/*CONSTCOND*/0)
 585
 586 #define K5_CIRCLEQ_INSERT_TAIL(head, elm, field) do {                   \
 587         (elm)->field.cqe_next = (void *)(head);                         \
 588         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 589         if ((head)->cqh_first == (void *)(head))                        \
 590                 (head)->cqh_first = (elm);                              \
 591         else                                                            \
 592                 (head)->cqh_last->field.cqe_next = (elm);               \
 593         (head)->cqh_last = (elm);                                       \
 594 } while (/*CONSTCOND*/0)
 595
 596 #define K5_CIRCLEQ_REMOVE(head, elm, field) do {                        \
 597         if ((elm)->field.cqe_next == (void *)(head))                    \
 598                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 599         else                                                            \
 600                 (elm)->field.cqe_next->field.cqe_prev =                 \
 601                     (elm)->field.cqe_prev;                              \
 602         if ((elm)->field.cqe_prev == (void *)(head))                    \
 603                 (head)->cqh_first = (elm)->field.cqe_next;              \
 604         else                                                            \
 605                 (elm)->field.cqe_prev->field.cqe_next =                 \
 606                     (elm)->field.cqe_next;                              \
 607 } while (/*CONSTCOND*/0)
 608
 609 #define K5_CIRCLEQ_FOREACH(var, head, field)                            \
 610         for ((var) = ((head)->cqh_first);                               \
 611                 (var) != (const void *)(head);                          \
 612                 (var) = ((var)->field.cqe_next))
 613
 614 #define K5_CIRCLEQ_FOREACH_REVERSE(var, head, field)                    \
 615         for ((var) = ((head)->cqh_last);                                \
 616                 (var) != (const void *)(head);                          \
 617                 (var) = ((var)->field.cqe_prev))
 618
 619 /*
 620  * Circular queue access methods.
 621  */
 622 #define K5_CIRCLEQ_EMPTY(head)          ((head)->cqh_first == (void *)(head))
 623 #define K5_CIRCLEQ_FIRST(head)          ((head)->cqh_first)
 624 #define K5_CIRCLEQ_LAST(head)           ((head)->cqh_last)
 625 #define K5_CIRCLEQ_NEXT(elm, field)     ((elm)->field.cqe_next)
 626 #define K5_CIRCLEQ_PREV(elm, field)     ((elm)->field.cqe_prev)
 627
 628 #define K5_CIRCLEQ_LOOP_NEXT(head, elm, field)                          \
 629         (((elm)->field.cqe_next == (void *)(head))                      \
 630             ? ((head)->cqh_first)                                       \
 631             : (elm->field.cqe_next))
 632 #define K5_CIRCLEQ_LOOP_PREV(head, elm, field)                          \
 633         (((elm)->field.cqe_prev == (void *)(head))                      \
 634             ? ((head)->cqh_last)                                        \
 635             : (elm->field.cqe_prev))
 636
 637 #endif  /* !K5_QUEUE_H */