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