newlib/libc/include/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: src/sys/sys/queue.h,v 1.48 2002/04/17 14:00:37 tmm 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 four types of data structures: singly-linked lists,
  44  * singly-linked tail queues, lists and tail 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  * For details on the use of these macros, see the queue(3) manual page.
  82  *
  83  *
  84  *                      SLIST   LIST    STAILQ  TAILQ
  85  * _HEAD                +       +       +       +
  86  * _HEAD_INITIALIZER    +       +       +       +
  87  * _ENTRY               +       +       +       +
  88  * _INIT                +       +       +       +
  89  * _EMPTY               +       +       +       +
  90  * _FIRST               +       +       +       +
  91  * _NEXT                +       +       +       +
  92  * _PREV                -       -       -       +
  93  * _LAST                -       -       +       +
  94  * _FOREACH             +       +       +       +
  95  * _FOREACH_REVERSE     -       -       -       +
  96  * _INSERT_HEAD         +       +       +       +
  97  * _INSERT_BEFORE       -       +       -       +
  98  * _INSERT_AFTER        +       +       +       +
  99  * _INSERT_TAIL         -       -       +       +
 100  * _CONCAT              -       -       +       +
 101  * _REMOVE_HEAD         +       -       +       -
 102  * _REMOVE              +       +       +       +
 103  *
 104  */
 105
 106 /*
 107  * Singly-linked List declarations.
 108  */
 109 #define SLIST_HEAD(name, type)                                          \
 110 struct name {                                                           \
 111         struct type *slh_first; /* first element */                     \
 112 }
 113
 114 #define SLIST_HEAD_INITIALIZER(head)                                    \
 115         { NULL }
 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) = SLIST_FIRST((head));                               \
 131             (var);                                                      \
 132             (var) = SLIST_NEXT((var), field))
 133
 134 #define SLIST_INIT(head) do {                                           \
 135         SLIST_FIRST((head)) = NULL;                                     \
 136 } while (0)
 137
 138 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 139         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 140         SLIST_NEXT((slistelm), field) = (elm);                          \
 141 } while (0)
 142
 143 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 144         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 145         SLIST_FIRST((head)) = (elm);                                    \
 146 } while (0)
 147
 148 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 149
 150 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 151         if (SLIST_FIRST((head)) == (elm)) {                             \
 152                 SLIST_REMOVE_HEAD((head), field);                       \
 153         }                                                               \
 154         else {                                                          \
 155                 struct type *curelm = SLIST_FIRST((head));              \
 156                 while (SLIST_NEXT(curelm, field) != (elm))              \
 157                         curelm = SLIST_NEXT(curelm, field);             \
 158                 SLIST_NEXT(curelm, field) =                             \
 159                     SLIST_NEXT(SLIST_NEXT(curelm, field), field);       \
 160         }                                                               \
 161 } while (0)
 162
 163 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 164         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 165 } while (0)
 166
 167 /*
 168  * Singly-linked Tail queue declarations.
 169  */
 170 #define STAILQ_HEAD(name, type)                                         \
 171 struct name {                                                           \
 172         struct type *stqh_first;/* first element */                     \
 173         struct type **stqh_last;/* addr of last next element */         \
 174 }
 175
 176 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 177         { NULL, &(head).stqh_first }
 178
 179 #define STAILQ_ENTRY(type)                                              \
 180 struct {                                                                \
 181         struct type *stqe_next; /* next element */                      \
 182 }
 183
 184 /*
 185  * Singly-linked Tail queue functions.
 186  */
 187 #define STAILQ_CONCAT(head1, head2) do {                                \
 188         if (!STAILQ_EMPTY((head2))) {                                   \
 189                 *(head1)->stqh_last = (head2)->stqh_first;              \
 190                 (head1)->stqh_last = (head2)->stqh_last;                \
 191                 STAILQ_INIT((head2));                                   \
 192         }                                                               \
 193 } while (0)
 194
 195 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 196
 197 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 198
 199 #define STAILQ_FOREACH(var, head, field)                                \
 200         for((var) = STAILQ_FIRST((head));                               \
 201            (var);                                                       \
 202            (var) = STAILQ_NEXT((var), field))
 203
 204 #define STAILQ_INIT(head) do {                                          \
 205         STAILQ_FIRST((head)) = NULL;                                    \
 206         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 207 } while (0)
 208
 209 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 210         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 211                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 212         STAILQ_NEXT((tqelm), field) = (elm);                            \
 213 } while (0)
 214
 215 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 216         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 217                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 218         STAILQ_FIRST((head)) = (elm);                                   \
 219 } while (0)
 220
 221 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 222         STAILQ_NEXT((elm), field) = NULL;                               \
 223         *(head)->stqh_last = (elm);                                     \
 224         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 225 } while (0)
 226
 227 #define STAILQ_LAST(head, type, field)                                  \
 228         (STAILQ_EMPTY((head)) ?                                         \
 229                 NULL :                                                  \
 230                 ((struct type *)                                        \
 231                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 232
 233 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 234
 235 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 236         if (STAILQ_FIRST((head)) == (elm)) {                            \
 237                 STAILQ_REMOVE_HEAD((head), field);                      \
 238         }                                                               \
 239         else {                                                          \
 240                 struct type *curelm = STAILQ_FIRST((head));             \
 241                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 242                         curelm = STAILQ_NEXT(curelm, field);            \
 243                 if ((STAILQ_NEXT(curelm, field) =                       \
 244                      STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
 245                         (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
 246         }                                                               \
 247 } while (0)
 248
 249 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 250         if ((STAILQ_FIRST((head)) =                                     \
 251              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 252                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 253 } while (0)
 254
 255 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
 256         if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
 257                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 258 } while (0)
 259
 260 /*
 261  * List declarations.
 262  */
 263 #define LIST_HEAD(name, type)                                           \
 264 struct name {                                                           \
 265         struct type *lh_first;  /* first element */                     \
 266 }
 267
 268 #define LIST_HEAD_INITIALIZER(head)                                     \
 269         { NULL }
 270
 271 #define LIST_ENTRY(type)                                                \
 272 struct {                                                                \
 273         struct type *le_next;   /* next element */                      \
 274         struct type **le_prev;  /* address of previous next element */  \
 275 }
 276
 277 /*
 278  * List functions.
 279  */
 280
 281 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 282
 283 #define LIST_FIRST(head)        ((head)->lh_first)
 284
 285 #define LIST_FOREACH(var, head, field)                                  \
 286         for ((var) = LIST_FIRST((head));                                \
 287             (var);                                                      \
 288             (var) = LIST_NEXT((var), field))
 289
 290 #define LIST_INIT(head) do {                                            \
 291         LIST_FIRST((head)) = NULL;                                      \
 292 } while (0)
 293
 294 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 295         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 296                 LIST_NEXT((listelm), field)->field.le_prev =            \
 297                     &LIST_NEXT((elm), field);                           \
 298         LIST_NEXT((listelm), field) = (elm);                            \
 299         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 300 } while (0)
 301
 302 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 303         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 304         LIST_NEXT((elm), field) = (listelm);                            \
 305         *(listelm)->field.le_prev = (elm);                              \
 306         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 307 } while (0)
 308
 309 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 310         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 311                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 312         LIST_FIRST((head)) = (elm);                                     \
 313         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 314 } while (0)
 315
 316 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 317
 318 #define LIST_REMOVE(elm, field) do {                                    \
 319         if (LIST_NEXT((elm), field) != NULL)                            \
 320                 LIST_NEXT((elm), field)->field.le_prev =                \
 321                     (elm)->field.le_prev;                               \
 322         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 323 } while (0)
 324
 325 /*
 326  * Tail queue declarations.
 327  */
 328 #define TAILQ_HEAD(name, type)                                          \
 329 struct name {                                                           \
 330         struct type *tqh_first; /* first element */                     \
 331         struct type **tqh_last; /* addr of last next element */         \
 332 }
 333
 334 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 335         { NULL, &(head).tqh_first }
 336
 337 #define TAILQ_ENTRY(type)                                               \
 338 struct {                                                                \
 339         struct type *tqe_next;  /* next element */                      \
 340         struct type **tqe_prev; /* address of previous next element */  \
 341 }
 342
 343 /*
 344  * Tail queue functions.
 345  */
 346 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 347         if (!TAILQ_EMPTY(head2)) {                                      \
 348                 *(head1)->tqh_last = (head2)->tqh_first;                \
 349                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 350                 (head1)->tqh_last = (head2)->tqh_last;                  \
 351                 TAILQ_INIT((head2));                                    \
 352         }                                                               \
 353 } while (0)
 354
 355 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 356
 357 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 358
 359 #define TAILQ_FOREACH(var, head, field)                                 \
 360         for ((var) = TAILQ_FIRST((head));                               \
 361             (var);                                                      \
 362             (var) = TAILQ_NEXT((var), field))
 363
 364 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 365         for ((var) = TAILQ_LAST((head), headname);                      \
 366             (var);                                                      \
 367             (var) = TAILQ_PREV((var), headname, field))
 368
 369 #define TAILQ_INIT(head) do {                                           \
 370         TAILQ_FIRST((head)) = NULL;                                     \
 371         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 372 } while (0)
 373
 374 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 375         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 376                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 377                     &TAILQ_NEXT((elm), field);                          \
 378         else                                                            \
 379                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 380         TAILQ_NEXT((listelm), field) = (elm);                           \
 381         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 382 } while (0)
 383
 384 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 385         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 386         TAILQ_NEXT((elm), field) = (listelm);                           \
 387         *(listelm)->field.tqe_prev = (elm);                             \
 388         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 389 } while (0)
 390
 391 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 392         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 393                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 394                     &TAILQ_NEXT((elm), field);                          \
 395         else                                                            \
 396                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 397         TAILQ_FIRST((head)) = (elm);                                    \
 398         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 399 } while (0)
 400
 401 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 402         TAILQ_NEXT((elm), field) = NULL;                                \
 403         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 404         *(head)->tqh_last = (elm);                                      \
 405         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 406 } while (0)
 407
 408 #define TAILQ_LAST(head, headname)                                      \
 409         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 410
 411 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 412
 413 #define TAILQ_PREV(elm, headname, field)                                \
 414         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 415
 416 #define TAILQ_REMOVE(head, elm, field) do {                             \
 417         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 418                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 419                     (elm)->field.tqe_prev;                              \
 420         else                                                            \
 421                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 422         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 423 } while (0)
 424
 425
 426 #ifdef _KERNEL
 427
 428 /*
 429  * XXX insque() and remque() are an old way of handling certain queues.
 430  * They bogusly assumes that all queue heads look alike.
 431  */
 432
 433 struct quehead {
 434         struct quehead *qh_link;
 435         struct quehead *qh_rlink;
 436 };
 437
 438 #ifdef  __GNUC__
 439
 440 static __inline void
 441 insque(void *a, void *b)
 442 {
 443         struct quehead *element = (struct quehead *)a,
 444                  *head = (struct quehead *)b;
 445
 446         element->qh_link = head->qh_link;
 447         element->qh_rlink = head;
 448         head->qh_link = element;
 449         element->qh_link->qh_rlink = element;
 450 }
 451
 452 static __inline void
 453 remque(void *a)
 454 {
 455         struct quehead *element = (struct quehead *)a;
 456
 457         element->qh_link->qh_rlink = element->qh_rlink;
 458         element->qh_rlink->qh_link = element->qh_link;
 459         element->qh_rlink = 0;
 460 }
 461
 462 #else /* !__GNUC__ */
 463
 464 void    insque(void *a, void *b);
 465 void    remque(void *a);
 466
 467 #endif /* __GNUC__ */
 468
 469 #endif /* _KERNEL */
 470
 471 #endif /* !_SYS_QUEUE_H_ */