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  * $FreeBSD$
  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_HEAD_INITIALIZER(head)                                    \
 118         { NULL }
 119
 120 #define SLIST_ENTRY(type)                                               \
 121 struct {                                                                \
 122         struct type *sle_next;  /* next element */                      \
 123 }
 124
 125 /*
 126  * Singly-linked List functions.
 127  */
 128 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 129
 130 #define SLIST_FIRST(head)       ((head)->slh_first)
 131
 132 #define SLIST_FOREACH(var, head, field)                                 \
 133         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 134
 135 #define SLIST_INIT(head) {                                              \
 136         (head)->slh_first = NULL;                                       \
 137 }
 138
 139 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 140         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 141         (slistelm)->field.sle_next = (elm);                             \
 142 } while (0)
 143
 144 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 145         (elm)->field.sle_next = (head)->slh_first;                      \
 146         (head)->slh_first = (elm);                                      \
 147 } while (0)
 148
 149 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 150
 151 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 152         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 153 } while (0)
 154
 155 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 156         if ((head)->slh_first == (elm)) {                               \
 157                 SLIST_REMOVE_HEAD((head), field);                       \
 158         }                                                               \
 159         else {                                                          \
 160                 struct type *curelm = (head)->slh_first;                \
 161                 while( curelm->field.sle_next != (elm) )                \
 162                         curelm = curelm->field.sle_next;                \
 163                 curelm->field.sle_next =                                \
 164                     curelm->field.sle_next->field.sle_next;             \
 165         }                                                               \
 166 } while (0)
 167
 168 /*
 169  * Singly-linked Tail queue definitions.
 170  */
 171 #define STAILQ_HEAD(name, type)                                         \
 172 struct name {                                                           \
 173         struct type *stqh_first;/* first element */                     \
 174         struct type **stqh_last;/* addr of last next element */         \
 175 }
 176
 177 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 178         { NULL, &(head).stqh_first }
 179
 180 #define STAILQ_ENTRY(type)                                              \
 181 struct {                                                                \
 182         struct type *stqe_next; /* next element */                      \
 183 }
 184
 185 /*
 186  * Singly-linked Tail queue functions.
 187  */
 188 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
 189
 190 #define STAILQ_INIT(head) do {                                          \
 191         (head)->stqh_first = NULL;                                      \
 192         (head)->stqh_last = &(head)->stqh_first;                        \
 193 } while (0)
 194
 195 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 196 #define STAILQ_LAST(head)       (*(head)->stqh_last)
 197
 198 #define STAILQ_FOREACH(var, head, field)                                \
 199         for((var) = (head)->stqh_first; (var); (var) = (var)->field.stqe_next)
 200
 201 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 202         if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
 203                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 204         (head)->stqh_first = (elm);                                     \
 205 } while (0)
 206
 207 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 208         (elm)->field.stqe_next = NULL;                                  \
 209         *(head)->stqh_last = (elm);                                     \
 210         (head)->stqh_last = &(elm)->field.stqe_next;                    \
 211 } while (0)
 212
 213 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 214         if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
 215                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 216         (tqelm)->field.stqe_next = (elm);                               \
 217 } while (0)
 218
 219 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 220
 221 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 222         if (((head)->stqh_first =                                       \
 223              (head)->stqh_first->field.stqe_next) == NULL)              \
 224                 (head)->stqh_last = &(head)->stqh_first;                \
 225 } while (0)
 226
 227 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
 228         if (((head)->stqh_first = (elm)->field.stqe_next) == NULL)      \
 229                 (head)->stqh_last = &(head)->stqh_first;                \
 230 } while (0)
 231
 232 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 233         if ((head)->stqh_first == (elm)) {                              \
 234                 STAILQ_REMOVE_HEAD(head, field);                        \
 235         }                                                               \
 236         else {                                                          \
 237                 struct type *curelm = (head)->stqh_first;               \
 238                 while( curelm->field.stqe_next != (elm) )               \
 239                         curelm = curelm->field.stqe_next;               \
 240                 if((curelm->field.stqe_next =                           \
 241                     curelm->field.stqe_next->field.stqe_next) == NULL)  \
 242                         (head)->stqh_last = &(curelm)->field.stqe_next; \
 243         }                                                               \
 244 } while (0)
 245
 246 /*
 247  * List definitions.
 248  */
 249 #define LIST_HEAD(name, type)                                           \
 250 struct name {                                                           \
 251         struct type *lh_first;  /* first element */                     \
 252 }
 253
 254 #define LIST_HEAD_INITIALIZER(head)                                     \
 255         { NULL }
 256
 257 #define LIST_ENTRY(type)                                                \
 258 struct {                                                                \
 259         struct type *le_next;   /* next element */                      \
 260         struct type **le_prev;  /* address of previous next element */  \
 261 }
 262
 263 /*
 264  * List functions.
 265  */
 266
 267 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
 268
 269 #define LIST_FIRST(head)        ((head)->lh_first)
 270
 271 #define LIST_FOREACH(var, head, field)                                  \
 272         for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
 273
 274 #define LIST_INIT(head) do {                                            \
 275         (head)->lh_first = NULL;                                        \
 276 } while (0)
 277
 278 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 279         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 280                 (listelm)->field.le_next->field.le_prev =               \
 281                     &(elm)->field.le_next;                              \
 282         (listelm)->field.le_next = (elm);                               \
 283         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 284 } while (0)
 285
 286 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 287         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 288         (elm)->field.le_next = (listelm);                               \
 289         *(listelm)->field.le_prev = (elm);                              \
 290         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 291 } while (0)
 292
 293 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 294         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 295                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 296         (head)->lh_first = (elm);                                       \
 297         (elm)->field.le_prev = &(head)->lh_first;                       \
 298 } while (0)
 299
 300 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 301
 302 #define LIST_REMOVE(elm, field) do {                                    \
 303         if ((elm)->field.le_next != NULL)                               \
 304                 (elm)->field.le_next->field.le_prev =                   \
 305                     (elm)->field.le_prev;                               \
 306         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 307 } while (0)
 308
 309 /*
 310  * Tail queue definitions.
 311  */
 312 #define TAILQ_HEAD(name, type)                                          \
 313 struct name {                                                           \
 314         struct type *tqh_first; /* first element */                     \
 315         struct type **tqh_last; /* addr of last next element */         \
 316 }
 317
 318 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 319         { NULL, &(head).tqh_first }
 320
 321 #define TAILQ_ENTRY(type)                                               \
 322 struct {                                                                \
 323         struct type *tqe_next;  /* next element */                      \
 324         struct type **tqe_prev; /* address of previous next element */  \
 325 }
 326
 327 /*
 328  * Tail queue functions.
 329  */
 330 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
 331
 332 #define TAILQ_FOREACH(var, head, field)                                 \
 333         for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
 334
 335 #define TAILQ_FIRST(head) ((head)->tqh_first)
 336
 337 #define TAILQ_LAST(head, headname) \
 338         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 339
 340 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 341
 342 #define TAILQ_PREV(elm, headname, field) \
 343         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 344
 345 #define TAILQ_INIT(head) do {                                           \
 346         (head)->tqh_first = NULL;                                       \
 347         (head)->tqh_last = &(head)->tqh_first;                          \
 348 } while (0)
 349
 350 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 351         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 352                 (head)->tqh_first->field.tqe_prev =                     \
 353                     &(elm)->field.tqe_next;                             \
 354         else                                                            \
 355                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 356         (head)->tqh_first = (elm);                                      \
 357         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 358 } while (0)
 359
 360 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 361         (elm)->field.tqe_next = NULL;                                   \
 362         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 363         *(head)->tqh_last = (elm);                                      \
 364         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 365 } while (0)
 366
 367 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 368         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 369                 (elm)->field.tqe_next->field.tqe_prev =                 \
 370                     &(elm)->field.tqe_next;                             \
 371         else                                                            \
 372                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 373         (listelm)->field.tqe_next = (elm);                              \
 374         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 375 } while (0)
 376
 377 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 378         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 379         (elm)->field.tqe_next = (listelm);                              \
 380         *(listelm)->field.tqe_prev = (elm);                             \
 381         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 382 } while (0)
 383
 384 #define TAILQ_REMOVE(head, elm, field) do {                             \
 385         if (((elm)->field.tqe_next) != NULL)                            \
 386                 (elm)->field.tqe_next->field.tqe_prev =                 \
 387                     (elm)->field.tqe_prev;                              \
 388         else                                                            \
 389                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 390         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 391 } while (0)
 392
 393 /*
 394  * Circular queue definitions.
 395  */
 396 #define CIRCLEQ_HEAD(name, type)                                        \
 397 struct name {                                                           \
 398         struct type *cqh_first;         /* first element */             \
 399         struct type *cqh_last;          /* last element */              \
 400 }
 401
 402 #define CIRCLEQ_ENTRY(type)                                             \
 403 struct {                                                                \
 404         struct type *cqe_next;          /* next element */              \
 405         struct type *cqe_prev;          /* previous element */          \
 406 }
 407
 408 /*
 409  * Circular queue functions.
 410  */
 411 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 412
 413 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
 414
 415 #define CIRCLEQ_FOREACH(var, head, field)                               \
 416         for((var) = (head)->cqh_first;                                  \
 417             (var) != (void *)(head);                                    \
 418             (var) = (var)->field.cqe_next)
 419
 420 #define CIRCLEQ_INIT(head) do {                                         \
 421         (head)->cqh_first = (void *)(head);                             \
 422         (head)->cqh_last = (void *)(head);                              \
 423 } while (0)
 424
 425 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 426         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 427         (elm)->field.cqe_prev = (listelm);                              \
 428         if ((listelm)->field.cqe_next == (void *)(head))                \
 429                 (head)->cqh_last = (elm);                               \
 430         else                                                            \
 431                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 432         (listelm)->field.cqe_next = (elm);                              \
 433 } while (0)
 434
 435 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 436         (elm)->field.cqe_next = (listelm);                              \
 437         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 438         if ((listelm)->field.cqe_prev == (void *)(head))                \
 439                 (head)->cqh_first = (elm);                              \
 440         else                                                            \
 441                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 442         (listelm)->field.cqe_prev = (elm);                              \
 443 } while (0)
 444
 445 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 446         (elm)->field.cqe_next = (head)->cqh_first;                      \
 447         (elm)->field.cqe_prev = (void *)(head);                         \
 448         if ((head)->cqh_last == (void *)(head))                         \
 449                 (head)->cqh_last = (elm);                               \
 450         else                                                            \
 451                 (head)->cqh_first->field.cqe_prev = (elm);              \
 452         (head)->cqh_first = (elm);                                      \
 453 } while (0)
 454
 455 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 456         (elm)->field.cqe_next = (void *)(head);                         \
 457         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 458         if ((head)->cqh_first == (void *)(head))                        \
 459                 (head)->cqh_first = (elm);                              \
 460         else                                                            \
 461                 (head)->cqh_last->field.cqe_next = (elm);               \
 462         (head)->cqh_last = (elm);                                       \
 463 } while (0)
 464
 465 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
 466
 467 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 468
 469 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 470
 471 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 472         if ((elm)->field.cqe_next == (void *)(head))                    \
 473                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 474         else                                                            \
 475                 (elm)->field.cqe_next->field.cqe_prev =                 \
 476                     (elm)->field.cqe_prev;                              \
 477         if ((elm)->field.cqe_prev == (void *)(head))                    \
 478                 (head)->cqh_first = (elm)->field.cqe_next;              \
 479         else                                                            \
 480                 (elm)->field.cqe_prev->field.cqe_next =                 \
 481                     (elm)->field.cqe_next;                              \
 482 } while (0)
 483
 484 #ifdef _KERNEL
 485
 486 /*
 487  * XXX insque() and remque() are an old way of handling certain queues.
 488  * They bogusly assumes that all queue heads look alike.
 489  */
 490
 491 struct quehead {
 492         struct quehead *qh_link;
 493         struct quehead *qh_rlink;
 494 };
 495
 496 #ifdef  __GNUC__
 497
 498 static __inline void
 499 insque(void *a, void *b)
 500 {
 501         struct quehead *element = a, *head = b;
 502
 503         element->qh_link = head->qh_link;
 504         element->qh_rlink = head;
 505         head->qh_link = element;
 506         element->qh_link->qh_rlink = element;
 507 }
 508
 509 static __inline void
 510 remque(void *a)
 511 {
 512         struct quehead *element = a;
 513
 514         element->qh_link->qh_rlink = element->qh_rlink;
 515         element->qh_rlink->qh_link = element->qh_link;
 516         element->qh_rlink = 0;
 517 }
 518
 519 #else /* !__GNUC__ */
 520
 521 void    insque __P((void *a, void *b));
 522 void    remque __P((void *a));
 523
 524 #endif /* __GNUC__ */
 525
 526 #endif /* _KERNEL */
 527
 528 #endif /* !_SYS_QUEUE_H_ */