sys/sys/queue.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  * $Id: queue.h,v 1.21 1998/05/12 03:55:25 gibbs Exp $
  35  */
  36
  37 #ifndef _SYS_QUEUE_H_
  38 #define _SYS_QUEUE_H_
  39
  40 /*
  41  * This file defines five types of data structures: singly-linked lists,
  42  * slingly-linked tail queues, lists, tail queues, and circular queues.
  43  *
  44  * A singly-linked list is headed by a single forward pointer. The elements
  45  * are singly linked for minimum space and pointer manipulation overhead at
  46  * the expense of O(n) removal for arbitrary elements. New elements can be
  47  * added to the list after an existing element or at the head of the list.
  48  * Elements being removed from the head of the list should use the explicit
  49  * macro for this purpose for optimum efficiency. A singly-linked list may
  50  * only be traversed in the forward direction.  Singly-linked lists are ideal
  51  * for applications with large datasets and few or no removals or for
  52  * implementing a LIFO queue.
  53  *
  54  * A singly-linked tail queue is headed by a pair of pointers, one to the
  55  * head of the list and the other to the tail of the list. The elements are
  56  * singly linked for minimum space and pointer manipulation overhead at the
  57  * expense of O(n) removal for arbitrary elements. New elements can be added
  58  * to the list after an existing element, at the head of the list, or at the
  59  * end of the list. Elements being removed from the head of the tail queue
  60  * should use the explicit macro for this purpose for optimum efficiency.
  61  * A singly-linked tail queue may only be traversed in the forward direction.
  62  * Singly-linked tail queues are ideal for applications with large datasets
  63  * and few or no removals or for implementing a FIFO queue.
  64  *
  65  * A list is headed by a single forward pointer (or an array of forward
  66  * pointers for a hash table header). The elements are doubly linked
  67  * 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
  69  * or after an existing element or at the head of the list. A list
  70  * 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 only be traversed in the forward 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  *                      SLIST   LIST    STAILQ  TAILQ   CIRCLEQ
  91  * _HEAD                +       +       +       +       +
  92  * _ENTRY               +       +       +       +       +
  93  * _INIT                +       +       +       +       +
  94  * _EMPTY               +       +       +       +       +
  95  * _FIRST               +       +       +       +       +
  96  * _NEXT                +       +       +       +       +
  97  * _PREV                -       -       -       +       +
  98  * _LAST                -       -       +       +       +
  99  * _FOREACH             +       +       -       +       +
 100  * _INSERT_HEAD         +       +       +       +       +
 101  * _INSERT_BEFORE       -       +       -       +       +
 102  * _INSERT_AFTER        +       +       +       +       +
 103  * _INSERT_TAIL         -       -       +       +       +
 104  * _REMOVE_HEAD         +       -       +       -       -
 105  * _REMOVE              +       +       +       +       +
 106  *
 107  */
 108
 109 /*
 110  * Singly-linked List definitions.
 111  */
 112 #define SLIST_HEAD(name, type)                                          \
 113 struct name {                                                           \
 114         struct type *slh_first; /* first element */                     \
 115 }
 116
 117 #define SLIST_ENTRY(type)                                               \
 118 struct {                                                                \
 119         struct type *sle_next;  /* next element */                      \
 120 }
 121
 122 /*
 123  * Singly-linked List functions.
 124  */
 125 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 126
 127 #define SLIST_FIRST(head)       ((head)->slh_first)
 128
 129 #define SLIST_FOREACH(var, head, field)                                 \
 130         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 131
 132 #define SLIST_INIT(head) {                                              \
 133         (head)->slh_first = NULL;                                       \
 134 }
 135
 136 #define SLIST_INSERT_AFTER(slistelm, elm, field) do  {                  \
 137         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 138         (slistelm)->field.sle_next = (elm);                             \
 139 } while (0)
 140
 141 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 142         (elm)->field.sle_next = (head)->slh_first;                      \
 143         (head)->slh_first = (elm);                                      \
 144 } while (0)
 145
 146 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 147
 148 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 149         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 150 } while (0)
 151
 152 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 153         if ((head)->slh_first == (elm)) {                               \
 154                 SLIST_REMOVE_HEAD((head), field);                       \
 155         }                                                               \
 156         else {                                                          \
 157                 struct type *curelm = (head)->slh_first;                \
 158                 while( curelm->field.sle_next != (elm) )                \
 159                         curelm = curelm->field.sle_next;                \
 160                 curelm->field.sle_next =                                \
 161                     curelm->field.sle_next->field.sle_next;             \
 162         }                                                               \
 163 } while (0)
 164
 165 /*
 166  * Singly-linked Tail queue definitions.
 167  */
 168 #define STAILQ_HEAD(name, type)                                         \
 169 struct name {                                                           \
 170         struct type *stqh_first;/* first element */                     \
 171         struct type **stqh_last;/* addr of last next element */         \
 172 }
 173
 174 #define STAILQ_ENTRY(type)                                              \
 175 struct {                                                                \
 176         struct type *stqe_next; /* next element */                      \
 177 }
 178
 179 /*
 180  * Singly-linked Tail queue functions.
 181  */
 182 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
 183
 184 #define STAILQ_INIT(head) do {                                          \
 185         (head)->stqh_first = NULL;                                      \
 186         (head)->stqh_last = &(head)->stqh_first;                        \
 187 } while (0)
 188
 189 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 190 #define STAILQ_LAST(head)       (*(head)->stqh_last)
 191
 192 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 193         if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
 194                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 195         (head)->stqh_first = (elm);                                     \
 196 } while (0)
 197
 198 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 199         (elm)->field.stqe_next = NULL;                                  \
 200         *(head)->stqh_last = (elm);                                     \
 201         (head)->stqh_last = &(elm)->field.stqe_next;                    \
 202 } while (0)
 203
 204 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 205         if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
 206                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 207         (tqelm)->field.stqe_next = (elm);                               \
 208 } while (0)
 209
 210 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 211
 212 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 213         if (((head)->stqh_first =                                       \
 214              (head)->stqh_first->field.stqe_next) == NULL)              \
 215                 (head)->stqh_last = &(head)->stqh_first;                \
 216 } while (0)
 217
 218 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 219         if ((head)->stqh_first == (elm)) {                              \
 220                 STAILQ_REMOVE_HEAD(head, field);                        \
 221         }                                                               \
 222         else {                                                          \
 223                 struct type *curelm = (head)->stqh_first;               \
 224                 while( curelm->field.stqe_next != (elm) )               \
 225                         curelm = curelm->field.stqe_next;               \
 226                 if((curelm->field.stqe_next =                           \
 227                     curelm->field.stqe_next->field.stqe_next) == NULL)  \
 228                         (head)->stqh_last = &(curelm)->field.stqe_next; \
 229         }                                                               \
 230 } while (0)
 231
 232 /*
 233  * List definitions.
 234  */
 235 #define LIST_HEAD(name, type)                                           \
 236 struct name {                                                           \
 237         struct type *lh_first;  /* first element */                     \
 238 }
 239
 240 #define LIST_ENTRY(type)                                                \
 241 struct {                                                                \
 242         struct type *le_next;   /* next element */                      \
 243         struct type **le_prev;  /* address of previous next element */  \
 244 }
 245
 246 /*
 247  * List functions.
 248  */
 249
 250 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
 251
 252 #define LIST_FIRST(head)        ((head)->lh_first)
 253
 254 #define LIST_FOREACH(var, head, field)                                  \
 255         for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
 256
 257 #define LIST_INIT(head) do {                                            \
 258         (head)->lh_first = NULL;                                        \
 259 } while (0)
 260
 261 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 262         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 263                 (listelm)->field.le_next->field.le_prev =               \
 264                     &(elm)->field.le_next;                              \
 265         (listelm)->field.le_next = (elm);                               \
 266         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 267 } while (0)
 268
 269 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 270         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 271         (elm)->field.le_next = (listelm);                               \
 272         *(listelm)->field.le_prev = (elm);                              \
 273         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 274 } while (0)
 275
 276 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 277         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 278                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 279         (head)->lh_first = (elm);                                       \
 280         (elm)->field.le_prev = &(head)->lh_first;                       \
 281 } while (0)
 282
 283 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 284
 285 #define LIST_REMOVE(elm, field) do {                                    \
 286         if ((elm)->field.le_next != NULL)                               \
 287                 (elm)->field.le_next->field.le_prev =                   \
 288                     (elm)->field.le_prev;                               \
 289         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 290 } while (0)
 291
 292 /*
 293  * Tail queue definitions.
 294  */
 295 #define TAILQ_HEAD(name, type)                                          \
 296 struct name {                                                           \
 297         struct type *tqh_first; /* first element */                     \
 298         struct type **tqh_last; /* addr of last next element */         \
 299 }
 300
 301 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 302         { NULL, &(head).tqh_first }
 303
 304 #define TAILQ_ENTRY(type)                                               \
 305 struct {                                                                \
 306         struct type *tqe_next;  /* next element */                      \
 307         struct type **tqe_prev; /* address of previous next element */  \
 308 }
 309
 310 /*
 311  * Tail queue functions.
 312  */
 313 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
 314
 315 #define TAILQ_FOREACH(var, head, field)                                 \
 316         for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
 317
 318 #define TAILQ_FIRST(head) ((head)->tqh_first)
 319
 320 #define TAILQ_LAST(head, headname) \
 321         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 322
 323 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 324
 325 #define TAILQ_PREV(elm, headname, field) \
 326         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 327
 328 #define TAILQ_INIT(head) do {                                           \
 329         (head)->tqh_first = NULL;                                       \
 330         (head)->tqh_last = &(head)->tqh_first;                          \
 331 } while (0)
 332
 333 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 334         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 335                 (head)->tqh_first->field.tqe_prev =                     \
 336                     &(elm)->field.tqe_next;                             \
 337         else                                                            \
 338                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 339         (head)->tqh_first = (elm);                                      \
 340         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 341 } while (0)
 342
 343 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 344         (elm)->field.tqe_next = NULL;                                   \
 345         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 346         *(head)->tqh_last = (elm);                                      \
 347         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 348 } while (0)
 349
 350 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 351         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 352                 (elm)->field.tqe_next->field.tqe_prev =                 \
 353                     &(elm)->field.tqe_next;                             \
 354         else                                                            \
 355                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 356         (listelm)->field.tqe_next = (elm);                              \
 357         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 358 } while (0)
 359
 360 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 361         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 362         (elm)->field.tqe_next = (listelm);                              \
 363         *(listelm)->field.tqe_prev = (elm);                             \
 364         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 365 } while (0)
 366
 367 #define TAILQ_REMOVE(head, elm, field) do {                             \
 368         if (((elm)->field.tqe_next) != NULL)                            \
 369                 (elm)->field.tqe_next->field.tqe_prev =                 \
 370                     (elm)->field.tqe_prev;                              \
 371         else                                                            \
 372                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 373         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 374 } while (0)
 375
 376 /*
 377  * Circular queue definitions.
 378  */
 379 #define CIRCLEQ_HEAD(name, type)                                        \
 380 struct name {                                                           \
 381         struct type *cqh_first;         /* first element */             \
 382         struct type *cqh_last;          /* last element */              \
 383 }
 384
 385 #define CIRCLEQ_ENTRY(type)                                             \
 386 struct {                                                                \
 387         struct type *cqe_next;          /* next element */              \
 388         struct type *cqe_prev;          /* previous element */          \
 389 }
 390
 391 /*
 392  * Circular queue functions.
 393  */
 394 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 395
 396 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
 397
 398 #define CIRCLEQ_FOREACH(var, head, field)                               \
 399         for((var) = (head)->cqh_first;                                  \
 400             (var) != (void *)(head);                                    \
 401             (var) = (var)->field.cqe_next)
 402
 403 #define CIRCLEQ_INIT(head) do {                                         \
 404         (head)->cqh_first = (void *)(head);                             \
 405         (head)->cqh_last = (void *)(head);                              \
 406 } while (0)
 407
 408 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 409         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 410         (elm)->field.cqe_prev = (listelm);                              \
 411         if ((listelm)->field.cqe_next == (void *)(head))                \
 412                 (head)->cqh_last = (elm);                               \
 413         else                                                            \
 414                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 415         (listelm)->field.cqe_next = (elm);                              \
 416 } while (0)
 417
 418 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 419         (elm)->field.cqe_next = (listelm);                              \
 420         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 421         if ((listelm)->field.cqe_prev == (void *)(head))                \
 422                 (head)->cqh_first = (elm);                              \
 423         else                                                            \
 424                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 425         (listelm)->field.cqe_prev = (elm);                              \
 426 } while (0)
 427
 428 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 429         (elm)->field.cqe_next = (head)->cqh_first;                      \
 430         (elm)->field.cqe_prev = (void *)(head);                         \
 431         if ((head)->cqh_last == (void *)(head))                         \
 432                 (head)->cqh_last = (elm);                               \
 433         else                                                            \
 434                 (head)->cqh_first->field.cqe_prev = (elm);              \
 435         (head)->cqh_first = (elm);                                      \
 436 } while (0)
 437
 438 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 439         (elm)->field.cqe_next = (void *)(head);                         \
 440         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 441         if ((head)->cqh_first == (void *)(head))                        \
 442                 (head)->cqh_first = (elm);                              \
 443         else                                                            \
 444                 (head)->cqh_last->field.cqe_next = (elm);               \
 445         (head)->cqh_last = (elm);                                       \
 446 } while (0)
 447
 448 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
 449
 450 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 451
 452 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 453
 454 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 455         if ((elm)->field.cqe_next == (void *)(head))                    \
 456                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 457         else                                                            \
 458                 (elm)->field.cqe_next->field.cqe_prev =                 \
 459                     (elm)->field.cqe_prev;                              \
 460         if ((elm)->field.cqe_prev == (void *)(head))                    \
 461                 (head)->cqh_first = (elm)->field.cqe_next;              \
 462         else                                                            \
 463                 (elm)->field.cqe_prev->field.cqe_next =                 \
 464                     (elm)->field.cqe_next;                              \
 465 } while (0)
 466
 467 #ifdef KERNEL
 468
 469 /*
 470  * XXX insque() and remque() are an old way of handling certain queues.
 471  * They bogusly assumes that all queue heads look alike.
 472  */
 473
 474 struct quehead {
 475         struct quehead *qh_link;
 476         struct quehead *qh_rlink;
 477 };
 478
 479 #ifdef  __GNUC__
 480
 481 static __inline void
 482 insque(void *a, void *b)
 483 {
 484         struct quehead *element = a, *head = b;
 485
 486         element->qh_link = head->qh_link;
 487         element->qh_rlink = head;
 488         head->qh_link = element;
 489         element->qh_link->qh_rlink = element;
 490 }
 491
 492 static __inline void
 493 remque(void *a)
 494 {
 495         struct quehead *element = a;
 496
 497         element->qh_link->qh_rlink = element->qh_rlink;
 498         element->qh_rlink->qh_link = element->qh_link;
 499         element->qh_rlink = 0;
 500 }
 501
 502 #else /* !__GNUC__ */
 503
 504 void    insque __P((void *a, void *b));
 505 void    remque __P((void *a));
 506
 507 #endif /* __GNUC__ */
 508
 509 #endif /* KERNEL */
 510
 511 #endif /* !_SYS_QUEUE_H_ */