git.sur5r.net Git - openldap/blob - include/queue-compat.h

   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 1.32.2.5 2001/09/30 21:12:54 luigi Exp $
  35  */
  36
  37 #ifndef _SYS_QUEUE_H_
  38 #define _SYS_QUEUE_H_
  39
  40 #include <machine/ansi.h>       /* for __offsetof */
  41
  42 /*
  43  * This file defines five types of data structures: singly-linked lists,
  44  * singly-linked tail queues, lists, tail queues, and circular queues.
  45  *
  46  * A singly-linked list is headed by a single forward pointer. The elements
  47  * are singly linked for minimum space and pointer manipulation overhead at
  48  * the expense of O(n) removal for arbitrary elements. New elements can be
  49  * added to the list after an existing element or at the head of the list.
  50  * Elements being removed from the head of the list should use the explicit
  51  * macro for this purpose for optimum efficiency. A singly-linked list may
  52  * only be traversed in the forward direction.  Singly-linked lists are ideal
  53  * for applications with large datasets and few or no removals or for
  54  * implementing a LIFO queue.
  55  *
  56  * A singly-linked tail queue is headed by a pair of pointers, one to the
  57  * head of the list and the other to the tail of the list. The elements are
  58  * singly linked for minimum space and pointer manipulation overhead at the
  59  * expense of O(n) removal for arbitrary elements. New elements can be added
  60  * to the list after an existing element, at the head of the list, or at the
  61  * end of the list. Elements being removed from the head of the tail queue
  62  * should use the explicit macro for this purpose for optimum efficiency.
  63  * A singly-linked tail queue may only be traversed in the forward direction.
  64  * Singly-linked tail queues are ideal for applications with large datasets
  65  * and few or no removals or for implementing a FIFO queue.
  66  *
  67  * A list is headed by a single forward pointer (or an array of forward
  68  * pointers for a hash table header). The elements are doubly linked
  69  * 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
  71  * or after an existing element or at the head of the list. A list
  72  * may only be traversed in the forward direction.
  73  *
  74  * A tail 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
  78  * after an existing element, at the head of the list, or at the end of
  79  * the list. A tail queue may be traversed in either direction.
  80  *
  81  * A circle queue is headed by a pair of pointers, one to the head of the
  82  * list and the other to the tail of the list. The elements are doubly
  83  * linked so that an arbitrary element can be removed without a need to
  84  * traverse the list. New elements can be added to the list before or after
  85  * an existing element, at the head of the list, or at the end of the list.
  86  * A circle queue may be traversed in either direction, but has a more
  87  * complex end of list detection.
  88  *
  89  * For details on the use of these macros, see the queue(3) manual page.
  90  *
  91  *
  92  *                      SLIST   LIST    STAILQ  TAILQ   CIRCLEQ
  93  * _HEAD                +       +       +       +       +
  94  * _ENTRY               +       +       +       +       +
  95  * _INIT                +       +       +       +       +
  96  * _EMPTY               +       +       +       +       +
  97  * _FIRST               +       +       +       +       +
  98  * _NEXT                +       +       +       +       +
  99  * _PREV                -       -       -       +       +
 100  * _LAST                -       -       +       +       +
 101  * _FOREACH             +       +       +       +       +
 102  * _FOREACH_REVERSE     -       -       -       +       +
 103  * _INSERT_HEAD         +       +       +       +       +
 104  * _INSERT_BEFORE       -       +       -       +       +
 105  * _INSERT_AFTER        +       +       +       +       +
 106  * _INSERT_TAIL         -       -       +       +       +
 107  * _REMOVE_HEAD         +       -       +       -       -
 108  * _REMOVE              +       +       +       +       +
 109  *
 110  */
 111
 112 /*
 113  * Singly-linked List definitions.
 114  */
 115 #define SLIST_HEAD(name, type)                                          \
 116 struct name {                                                           \
 117         struct type *slh_first; /* first element */                     \
 118 }
 119
 120 #define SLIST_HEAD_INITIALIZER(head)                                    \
 121         { NULL }
 122
 123 #define SLIST_ENTRY(type)                                               \
 124 struct {                                                                \
 125         struct type *sle_next;  /* next element */                      \
 126 }
 127
 128 /*
 129  * Singly-linked List functions.
 130  */
 131 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 132
 133 #define SLIST_FIRST(head)       ((head)->slh_first)
 134
 135 #define SLIST_FOREACH(var, head, field)                                 \
 136         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 137
 138 #define SLIST_INIT(head) {                                              \
 139         (head)->slh_first = NULL;                                       \
 140 }
 141
 142 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 143         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 144         (slistelm)->field.sle_next = (elm);                             \
 145 } while (0)
 146
 147 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 148         (elm)->field.sle_next = (head)->slh_first;                      \
 149         (head)->slh_first = (elm);                                      \
 150 } while (0)
 151
 152 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 153
 154 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 155         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 156 } while (0)
 157
 158 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 159         if ((head)->slh_first == (elm)) {                               \
 160                 SLIST_REMOVE_HEAD((head), field);                       \
 161         }                                                               \
 162         else {                                                          \
 163                 struct type *curelm = (head)->slh_first;                \
 164                 while( curelm->field.sle_next != (elm) )                \
 165                         curelm = curelm->field.sle_next;                \
 166                 curelm->field.sle_next =                                \
 167                     curelm->field.sle_next->field.sle_next;             \
 168         }                                                               \
 169 } while (0)
 170
 171 /*
 172  * Singly-linked Tail queue definitions.
 173  */
 174 #define STAILQ_HEAD(name, type)                                         \
 175 struct name {                                                           \
 176         struct type *stqh_first;/* first element */                     \
 177         struct type **stqh_last;/* addr of last next element */         \
 178 }
 179
 180 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 181         { NULL, &(head).stqh_first }
 182
 183 #define STAILQ_ENTRY(type)                                              \
 184 struct {                                                                \
 185         struct type *stqe_next; /* next element */                      \
 186 }
 187
 188 /*
 189  * Singly-linked Tail queue functions.
 190  */
 191 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
 192
 193 #define STAILQ_INIT(head) do {                                          \
 194         (head)->stqh_first = NULL;                                      \
 195         (head)->stqh_last = &(head)->stqh_first;                        \
 196 } while (0)
 197
 198 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 199
 200 #define STAILQ_LAST(head, type, field)                                  \
 201         (STAILQ_EMPTY(head) ?                                           \
 202                 NULL :                                                  \
 203                 ((struct type *)                                        \
 204                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 205
 206 #define STAILQ_FOREACH(var, head, field)                                \
 207         for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)
 208
 209 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 210         if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
 211                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 212         (head)->stqh_first = (elm);                                     \
 213 } while (0)
 214
 215 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 216         (elm)->field.stqe_next = NULL;                                  \
 217         *(head)->stqh_last = (elm);                                     \
 218         (head)->stqh_last = &(elm)->field.stqe_next;                    \
 219 } while (0)
 220
 221 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 222         if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
 223                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 224         (tqelm)->field.stqe_next = (elm);                               \
 225 } while (0)
 226
 227 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 228
 229 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 230         if (((head)->stqh_first =                                       \
 231              (head)->stqh_first->field.stqe_next) == NULL)              \
 232                 (head)->stqh_last = &(head)->stqh_first;                \
 233 } while (0)
 234
 235 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
 236         if (((head)->stqh_first = (elm)->field.stqe_next) == NULL)      \
 237                 (head)->stqh_last = &(head)->stqh_first;                \
 238 } while (0)
 239
 240 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 241         if ((head)->stqh_first == (elm)) {                              \
 242                 STAILQ_REMOVE_HEAD(head, field);                        \
 243         }                                                               \
 244         else {                                                          \
 245                 struct type *curelm = (head)->stqh_first;               \
 246                 while( curelm->field.stqe_next != (elm) )               \
 247                         curelm = curelm->field.stqe_next;               \
 248                 if((curelm->field.stqe_next =                           \
 249                     curelm->field.stqe_next->field.stqe_next) == NULL)  \
 250                         (head)->stqh_last = &(curelm)->field.stqe_next; \
 251         }                                                               \
 252 } while (0)
 253
 254 /*
 255  * List definitions.
 256  */
 257 #define LIST_HEAD(name, type)                                           \
 258 struct name {                                                           \
 259         struct type *lh_first;  /* first element */                     \
 260 }
 261
 262 #define LIST_HEAD_INITIALIZER(head)                                     \
 263         { NULL }
 264
 265 #define LIST_ENTRY(type)                                                \
 266 struct {                                                                \
 267         struct type *le_next;   /* next element */                      \
 268         struct type **le_prev;  /* address of previous next element */  \
 269 }
 270
 271 /*
 272  * List functions.
 273  */
 274
 275 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
 276
 277 #define LIST_FIRST(head)        ((head)->lh_first)
 278
 279 #define LIST_FOREACH(var, head, field)                                  \
 280         for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
 281
 282 #define LIST_INIT(head) do {                                            \
 283         (head)->lh_first = NULL;                                        \
 284 } while (0)
 285
 286 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 287         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 288                 (listelm)->field.le_next->field.le_prev =               \
 289                     &(elm)->field.le_next;                              \
 290         (listelm)->field.le_next = (elm);                               \
 291         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 292 } while (0)
 293
 294 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 295         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 296         (elm)->field.le_next = (listelm);                               \
 297         *(listelm)->field.le_prev = (elm);                              \
 298         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 299 } while (0)
 300
 301 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 302         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 303                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 304         (head)->lh_first = (elm);                                       \
 305         (elm)->field.le_prev = &(head)->lh_first;                       \
 306 } while (0)
 307
 308 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 309
 310 #define LIST_REMOVE(elm, field) do {                                    \
 311         if ((elm)->field.le_next != NULL)                               \
 312                 (elm)->field.le_next->field.le_prev =                   \
 313                     (elm)->field.le_prev;                               \
 314         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 315 } while (0)
 316
 317 /*
 318  * Tail queue definitions.
 319  */
 320 #define TAILQ_HEAD(name, type)                                          \
 321 struct name {                                                           \
 322         struct type *tqh_first; /* first element */                     \
 323         struct type **tqh_last; /* addr of last next element */         \
 324 }
 325
 326 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 327         { NULL, &(head).tqh_first }
 328
 329 #define TAILQ_ENTRY(type)                                               \
 330 struct {                                                                \
 331         struct type *tqe_next;  /* next element */                      \
 332         struct type **tqe_prev; /* address of previous next element */  \
 333 }
 334
 335 /*
 336  * Tail queue functions.
 337  */
 338 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
 339
 340 #define TAILQ_FOREACH(var, head, field)                                 \
 341         for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
 342
 343 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 344         for ((var) = TAILQ_LAST((head), headname);                      \
 345              (var);                                                     \
 346              (var) = TAILQ_PREV((var), headname, field))
 347
 348 #define TAILQ_FIRST(head) ((head)->tqh_first)
 349
 350 #define TAILQ_LAST(head, headname) \
 351         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 352
 353 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 354
 355 #define TAILQ_PREV(elm, headname, field) \
 356         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 357
 358 #define TAILQ_INIT(head) do {                                           \
 359         (head)->tqh_first = NULL;                                       \
 360         (head)->tqh_last = &(head)->tqh_first;                          \
 361 } while (0)
 362
 363 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 364         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 365                 (head)->tqh_first->field.tqe_prev =                     \
 366                     &(elm)->field.tqe_next;                             \
 367         else                                                            \
 368                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 369         (head)->tqh_first = (elm);                                      \
 370         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 371 } while (0)
 372
 373 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 374         (elm)->field.tqe_next = NULL;                                   \
 375         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 376         *(head)->tqh_last = (elm);                                      \
 377         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 378 } while (0)
 379
 380 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 381         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 382                 (elm)->field.tqe_next->field.tqe_prev =                 \
 383                     &(elm)->field.tqe_next;                             \
 384         else                                                            \
 385                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 386         (listelm)->field.tqe_next = (elm);                              \
 387         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 388 } while (0)
 389
 390 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 391         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 392         (elm)->field.tqe_next = (listelm);                              \
 393         *(listelm)->field.tqe_prev = (elm);                             \
 394         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 395 } while (0)
 396
 397 #define TAILQ_REMOVE(head, elm, field) do {                             \
 398         if (((elm)->field.tqe_next) != NULL)                            \
 399                 (elm)->field.tqe_next->field.tqe_prev =                 \
 400                     (elm)->field.tqe_prev;                              \
 401         else                                                            \
 402                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 403         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 404 } while (0)
 405
 406 /*
 407  * Circular queue definitions.
 408  */
 409 #define CIRCLEQ_HEAD(name, type)                                        \
 410 struct name {                                                           \
 411         struct type *cqh_first;         /* first element */             \
 412         struct type *cqh_last;          /* last element */              \
 413 }
 414
 415 #define CIRCLEQ_ENTRY(type)                                             \
 416 struct {                                                                \
 417         struct type *cqe_next;          /* next element */              \
 418         struct type *cqe_prev;          /* previous element */          \
 419 }
 420
 421 /*
 422  * Circular queue functions.
 423  */
 424 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 425
 426 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
 427
 428 #define CIRCLEQ_FOREACH(var, head, field)                               \
 429         for((var) = (head)->cqh_first;                                  \
 430             (var) != (void *)(head);                                    \
 431             (var) = (var)->field.cqe_next)
 432
 433 #define CIRCLEQ_FOREACH_REVERSE(var, head, field)                       \
 434         for((var) = (head)->cqh_last;                                   \
 435             (var) != (void *)(head);                                    \
 436             (var) = (var)->field.cqe_prev)
 437
 438 #define CIRCLEQ_INIT(head) do {                                         \
 439         (head)->cqh_first = (void *)(head);                             \
 440         (head)->cqh_last = (void *)(head);                              \
 441 } while (0)
 442
 443 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 444         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 445         (elm)->field.cqe_prev = (listelm);                              \
 446         if ((listelm)->field.cqe_next == (void *)(head))                \
 447                 (head)->cqh_last = (elm);                               \
 448         else                                                            \
 449                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 450         (listelm)->field.cqe_next = (elm);                              \
 451 } while (0)
 452
 453 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 454         (elm)->field.cqe_next = (listelm);                              \
 455         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 456         if ((listelm)->field.cqe_prev == (void *)(head))                \
 457                 (head)->cqh_first = (elm);                              \
 458         else                                                            \
 459                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 460         (listelm)->field.cqe_prev = (elm);                              \
 461 } while (0)
 462
 463 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 464         (elm)->field.cqe_next = (head)->cqh_first;                      \
 465         (elm)->field.cqe_prev = (void *)(head);                         \
 466         if ((head)->cqh_last == (void *)(head))                         \
 467                 (head)->cqh_last = (elm);                               \
 468         else                                                            \
 469                 (head)->cqh_first->field.cqe_prev = (elm);              \
 470         (head)->cqh_first = (elm);                                      \
 471 } while (0)
 472
 473 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 474         (elm)->field.cqe_next = (void *)(head);                         \
 475         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 476         if ((head)->cqh_first == (void *)(head))                        \
 477                 (head)->cqh_first = (elm);                              \
 478         else                                                            \
 479                 (head)->cqh_last->field.cqe_next = (elm);               \
 480         (head)->cqh_last = (elm);                                       \
 481 } while (0)
 482
 483 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
 484
 485 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 486
 487 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 488
 489 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 490         if ((elm)->field.cqe_next == (void *)(head))                    \
 491                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 492         else                                                            \
 493                 (elm)->field.cqe_next->field.cqe_prev =                 \
 494                     (elm)->field.cqe_prev;                              \
 495         if ((elm)->field.cqe_prev == (void *)(head))                    \
 496                 (head)->cqh_first = (elm)->field.cqe_next;              \
 497         else                                                            \
 498                 (elm)->field.cqe_prev->field.cqe_next =                 \
 499                     (elm)->field.cqe_next;                              \
 500 } while (0)
 501
 502 #ifdef _KERNEL
 503
 504 /*
 505  * XXX insque() and remque() are an old way of handling certain queues.
 506  * They bogusly assumes that all queue heads look alike.
 507  */
 508
 509 struct quehead {
 510         struct quehead *qh_link;
 511         struct quehead *qh_rlink;
 512 };
 513
 514 #ifdef  __GNUC__
 515
 516 static __inline void
 517 insque(void *a, void *b)
 518 {
 519         struct quehead *element = (struct quehead *)a,
 520                 *head = (struct quehead *)b;
 521
 522         element->qh_link = head->qh_link;
 523         element->qh_rlink = head;
 524         head->qh_link = element;
 525         element->qh_link->qh_rlink = element;
 526 }
 527
 528 static __inline void
 529 remque(void *a)
 530 {
 531         struct quehead *element = (struct quehead *)a;
 532
 533         element->qh_link->qh_rlink = element->qh_rlink;
 534         element->qh_rlink->qh_link = element->qh_link;
 535         element->qh_rlink = 0;
 536 }
 537
 538 #else /* !__GNUC__ */
 539
 540 void    insque __P((void *a, void *b));
 541 void    remque __P((void *a));
 542
 543 #endif /* __GNUC__ */
 544
 545 #endif /* _KERNEL */
 546
 547 #endif /* !_SYS_QUEUE_H_ */