include/qemu/queue.h

   1 /*      $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
   2
   3 /*
   4  * QEMU version: Copy from netbsd, removed debug code, removed some of
   5  * the implementations.  Left in singly-linked lists, lists, simple
   6  * queues, and tail queues.
   7  */
   8
   9 /*
  10  * Copyright (c) 1991, 1993
  11  *      The Regents of the University of California.  All rights reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  38  */
  39
  40 #ifndef QEMU_SYS_QUEUE_H_
  41 #define QEMU_SYS_QUEUE_H_
  42
  43 /*
  44  * This file defines four types of data structures: singly-linked lists,
  45  * lists, simple queues, and tail queues.
  46  *
  47  * A singly-linked list is headed by a single forward pointer. The
  48  * elements are singly linked for minimum space and pointer manipulation
  49  * overhead at the expense of O(n) removal for arbitrary elements. New
  50  * elements can be added to the list after an existing element or at the
  51  * head of the list.  Elements being removed from the head of the list
  52  * should use the explicit macro for this purpose for optimum
  53  * efficiency. A singly-linked list may only be traversed in the forward
  54  * direction.  Singly-linked lists are ideal for applications with large
  55  * datasets and few or no removals or for implementing a LIFO queue.
  56  *
  57  * A list is headed by a single forward pointer (or an array of forward
  58  * pointers for a hash table header). The elements are doubly linked
  59  * so that an arbitrary element can be removed without a need to
  60  * traverse the list. New elements can be added to the list before
  61  * or after an existing element or at the head of the list. A list
  62  * may only be traversed in the forward direction.
  63  *
  64  * A simple queue is headed by a pair of pointers, one the head of the
  65  * list and the other to the tail of the list. The elements are singly
  66  * linked to save space, so elements can only be removed from the
  67  * head of the list. New elements can be added to the list after
  68  * an existing element, at the head of the list, or at the end of the
  69  * list. A simple queue may only be traversed in the forward direction.
  70  *
  71  * A tail queue is headed by a pair of pointers, one to the head of the
  72  * list and the other to the tail of the list. The elements are doubly
  73  * linked so that an arbitrary element can be removed without a need to
  74  * traverse the list. New elements can be added to the list before or
  75  * after an existing element, at the head of the list, or at the end of
  76  * the list. A tail queue may be traversed in either direction.
  77  *
  78  * For details on the use of these macros, see the queue(3) manual page.
  79  */
  80
  81 #include "qemu/atomic.h" /* for smp_wmb() */
  82
  83 /*
  84  * List definitions.
  85  */
  86 #define QLIST_HEAD(name, type)                                          \
  87 struct name {                                                           \
  88         struct type *lh_first;  /* first element */                     \
  89 }
  90
  91 #define QLIST_HEAD_INITIALIZER(head)                                    \
  92         { NULL }
  93
  94 #define QLIST_ENTRY(type)                                               \
  95 struct {                                                                \
  96         struct type *le_next;   /* next element */                      \
  97         struct type **le_prev;  /* address of previous next element */  \
  98 }
  99
 100 /*
 101  * List functions.
 102  */
 103 #define QLIST_INIT(head) do {                                           \
 104         (head)->lh_first = NULL;                                        \
 105 } while (/*CONSTCOND*/0)
 106
 107 #define QLIST_SWAP(dstlist, srclist, field) do {                        \
 108         void *tmplist;                                                  \
 109         tmplist = (srclist)->lh_first;                                  \
 110         (srclist)->lh_first = (dstlist)->lh_first;                      \
 111         if ((srclist)->lh_first != NULL) {                              \
 112             (srclist)->lh_first->field.le_prev = &(srclist)->lh_first;  \
 113         }                                                               \
 114         (dstlist)->lh_first = tmplist;                                  \
 115         if ((dstlist)->lh_first != NULL) {                              \
 116             (dstlist)->lh_first->field.le_prev = &(dstlist)->lh_first;  \
 117         }                                                               \
 118 } while (/*CONSTCOND*/0)
 119
 120 #define QLIST_FIX_HEAD_PTR(head, field) do {                            \
 121         if ((head)->lh_first != NULL) {                                 \
 122             (head)->lh_first->field.le_prev = &(head)->lh_first;        \
 123         }                                                               \
 124 } while (/*CONSTCOND*/0)
 125
 126 #define QLIST_INSERT_AFTER(listelm, elm, field) do {                    \
 127         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 128                 (listelm)->field.le_next->field.le_prev =               \
 129                     &(elm)->field.le_next;                              \
 130         (listelm)->field.le_next = (elm);                               \
 131         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 132 } while (/*CONSTCOND*/0)
 133
 134 #define QLIST_INSERT_BEFORE(listelm, elm, field) do {                   \
 135         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 136         (elm)->field.le_next = (listelm);                               \
 137         *(listelm)->field.le_prev = (elm);                              \
 138         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 139 } while (/*CONSTCOND*/0)
 140
 141 #define QLIST_INSERT_HEAD(head, elm, field) do {                        \
 142         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 143                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 144         (head)->lh_first = (elm);                                       \
 145         (elm)->field.le_prev = &(head)->lh_first;                       \
 146 } while (/*CONSTCOND*/0)
 147
 148 #define QLIST_REMOVE(elm, field) do {                                   \
 149         if ((elm)->field.le_next != NULL)                               \
 150                 (elm)->field.le_next->field.le_prev =                   \
 151                     (elm)->field.le_prev;                               \
 152         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 153 } while (/*CONSTCOND*/0)
 154
 155 #define QLIST_FOREACH(var, head, field)                                 \
 156         for ((var) = ((head)->lh_first);                                \
 157                 (var);                                                  \
 158                 (var) = ((var)->field.le_next))
 159
 160 #define QLIST_FOREACH_SAFE(var, head, field, next_var)                  \
 161         for ((var) = ((head)->lh_first);                                \
 162                 (var) && ((next_var) = ((var)->field.le_next), 1);      \
 163                 (var) = (next_var))
 164
 165 /*
 166  * List access methods.
 167  */
 168 #define QLIST_EMPTY(head)                ((head)->lh_first == NULL)
 169 #define QLIST_FIRST(head)                ((head)->lh_first)
 170 #define QLIST_NEXT(elm, field)           ((elm)->field.le_next)
 171
 172
 173 /*
 174  * Singly-linked List definitions.
 175  */
 176 #define QSLIST_HEAD(name, type)                                          \
 177 struct name {                                                           \
 178         struct type *slh_first; /* first element */                     \
 179 }
 180
 181 #define QSLIST_HEAD_INITIALIZER(head)                                    \
 182         { NULL }
 183
 184 #define QSLIST_ENTRY(type)                                               \
 185 struct {                                                                \
 186         struct type *sle_next;  /* next element */                      \
 187 }
 188
 189 /*
 190  * Singly-linked List functions.
 191  */
 192 #define QSLIST_INIT(head) do {                                           \
 193         (head)->slh_first = NULL;                                       \
 194 } while (/*CONSTCOND*/0)
 195
 196 #define QSLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 197         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 198         (slistelm)->field.sle_next = (elm);                             \
 199 } while (/*CONSTCOND*/0)
 200
 201 #define QSLIST_INSERT_HEAD(head, elm, field) do {                        \
 202         (elm)->field.sle_next = (head)->slh_first;                       \
 203         (head)->slh_first = (elm);                                       \
 204 } while (/*CONSTCOND*/0)
 205
 206 #define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do {                     \
 207         typeof(elm) save_sle_next;                                           \
 208         do {                                                                 \
 209             save_sle_next = (elm)->field.sle_next = (head)->slh_first;       \
 210         } while (atomic_cmpxchg(&(head)->slh_first, save_sle_next, (elm)) != \
 211                  save_sle_next);                                             \
 212 } while (/*CONSTCOND*/0)
 213
 214 #define QSLIST_MOVE_ATOMIC(dest, src) do {                               \
 215         (dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL);        \
 216 } while (/*CONSTCOND*/0)
 217
 218 #define QSLIST_REMOVE_HEAD(head, field) do {                             \
 219         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 220 } while (/*CONSTCOND*/0)
 221
 222 #define QSLIST_REMOVE_AFTER(slistelm, field) do {                        \
 223         (slistelm)->field.sle_next =                                    \
 224             QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field);           \
 225 } while (/*CONSTCOND*/0)
 226
 227 #define QSLIST_FOREACH(var, head, field)                                 \
 228         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 229
 230 #define QSLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 231         for ((var) = QSLIST_FIRST((head));                               \
 232             (var) && ((tvar) = QSLIST_NEXT((var), field), 1);            \
 233             (var) = (tvar))
 234
 235 /*
 236  * Singly-linked List access methods.
 237  */
 238 #define QSLIST_EMPTY(head)       ((head)->slh_first == NULL)
 239 #define QSLIST_FIRST(head)       ((head)->slh_first)
 240 #define QSLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 241
 242
 243 /*
 244  * Simple queue definitions.
 245  */
 246 #define QSIMPLEQ_HEAD(name, type)                                       \
 247 struct name {                                                           \
 248     struct type *sqh_first;    /* first element */                      \
 249     struct type **sqh_last;    /* addr of last next element */          \
 250 }
 251
 252 #define QSIMPLEQ_HEAD_INITIALIZER(head)                                 \
 253     { NULL, &(head).sqh_first }
 254
 255 #define QSIMPLEQ_ENTRY(type)                                            \
 256 struct {                                                                \
 257     struct type *sqe_next;    /* next element */                        \
 258 }
 259
 260 /*
 261  * Simple queue functions.
 262  */
 263 #define QSIMPLEQ_INIT(head) do {                                        \
 264     (head)->sqh_first = NULL;                                           \
 265     (head)->sqh_last = &(head)->sqh_first;                              \
 266 } while (/*CONSTCOND*/0)
 267
 268 #define QSIMPLEQ_INSERT_HEAD(head, elm, field) do {                     \
 269     if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)            \
 270         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 271     (head)->sqh_first = (elm);                                          \
 272 } while (/*CONSTCOND*/0)
 273
 274 #define QSIMPLEQ_INSERT_TAIL(head, elm, field) do {                     \
 275     (elm)->field.sqe_next = NULL;                                       \
 276     *(head)->sqh_last = (elm);                                          \
 277     (head)->sqh_last = &(elm)->field.sqe_next;                          \
 278 } while (/*CONSTCOND*/0)
 279
 280 #define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 281     if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)    \
 282         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 283     (listelm)->field.sqe_next = (elm);                                  \
 284 } while (/*CONSTCOND*/0)
 285
 286 #define QSIMPLEQ_REMOVE_HEAD(head, field) do {                          \
 287     if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\
 288         (head)->sqh_last = &(head)->sqh_first;                          \
 289 } while (/*CONSTCOND*/0)
 290
 291 #define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do {            \
 292     QSIMPLEQ_INIT(removed);                                             \
 293     if (((removed)->sqh_first = (head)->sqh_first) != NULL) {           \
 294         if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) {      \
 295             (head)->sqh_last = &(head)->sqh_first;                      \
 296         }                                                               \
 297         (removed)->sqh_last = &(elm)->field.sqe_next;                   \
 298         (elm)->field.sqe_next = NULL;                                   \
 299     }                                                                   \
 300 } while (/*CONSTCOND*/0)
 301
 302 #define QSIMPLEQ_REMOVE(head, elm, type, field) do {                    \
 303     if ((head)->sqh_first == (elm)) {                                   \
 304         QSIMPLEQ_REMOVE_HEAD((head), field);                            \
 305     } else {                                                            \
 306         struct type *curelm = (head)->sqh_first;                        \
 307         while (curelm->field.sqe_next != (elm))                         \
 308             curelm = curelm->field.sqe_next;                            \
 309         if ((curelm->field.sqe_next =                                   \
 310             curelm->field.sqe_next->field.sqe_next) == NULL)            \
 311                 (head)->sqh_last = &(curelm)->field.sqe_next;           \
 312     }                                                                   \
 313 } while (/*CONSTCOND*/0)
 314
 315 #define QSIMPLEQ_FOREACH(var, head, field)                              \
 316     for ((var) = ((head)->sqh_first);                                   \
 317         (var);                                                          \
 318         (var) = ((var)->field.sqe_next))
 319
 320 #define QSIMPLEQ_FOREACH_SAFE(var, head, field, next)                   \
 321     for ((var) = ((head)->sqh_first);                                   \
 322         (var) && ((next = ((var)->field.sqe_next)), 1);                 \
 323         (var) = (next))
 324
 325 #define QSIMPLEQ_CONCAT(head1, head2) do {                              \
 326     if (!QSIMPLEQ_EMPTY((head2))) {                                     \
 327         *(head1)->sqh_last = (head2)->sqh_first;                        \
 328         (head1)->sqh_last = (head2)->sqh_last;                          \
 329         QSIMPLEQ_INIT((head2));                                         \
 330     }                                                                   \
 331 } while (/*CONSTCOND*/0)
 332
 333 #define QSIMPLEQ_LAST(head, type, field)                                \
 334     (QSIMPLEQ_EMPTY((head)) ?                                           \
 335         NULL :                                                          \
 336             ((struct type *)(void *)                                    \
 337         ((char *)((head)->sqh_last) - offsetof(struct type, field))))
 338
 339 /*
 340  * Simple queue access methods.
 341  */
 342 #define QSIMPLEQ_EMPTY(head)        ((head)->sqh_first == NULL)
 343 #define QSIMPLEQ_FIRST(head)        ((head)->sqh_first)
 344 #define QSIMPLEQ_NEXT(elm, field)   ((elm)->field.sqe_next)
 345
 346
 347 /*
 348  * Tail queue definitions.
 349  */
 350 #define Q_TAILQ_HEAD(name, type, qual)                                  \
 351 struct name {                                                           \
 352         qual type *tqh_first;           /* first element */             \
 353         qual type *qual *tqh_last;      /* addr of last next element */ \
 354 }
 355 #define QTAILQ_HEAD(name, type)  Q_TAILQ_HEAD(name, struct type,)
 356
 357 #define QTAILQ_HEAD_INITIALIZER(head)                                   \
 358         { NULL, &(head).tqh_first }
 359
 360 #define Q_TAILQ_ENTRY(type, qual)                                       \
 361 struct {                                                                \
 362         qual type *tqe_next;            /* next element */              \
 363         qual type *qual *tqe_prev;      /* address of previous next element */\
 364 }
 365 #define QTAILQ_ENTRY(type)       Q_TAILQ_ENTRY(struct type,)
 366
 367 /*
 368  * Tail queue functions.
 369  */
 370 #define QTAILQ_INIT(head) do {                                          \
 371         (head)->tqh_first = NULL;                                       \
 372         (head)->tqh_last = &(head)->tqh_first;                          \
 373 } while (/*CONSTCOND*/0)
 374
 375 #define QTAILQ_INSERT_HEAD(head, elm, field) do {                       \
 376         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 377                 (head)->tqh_first->field.tqe_prev =                     \
 378                     &(elm)->field.tqe_next;                             \
 379         else                                                            \
 380                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 381         (head)->tqh_first = (elm);                                      \
 382         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 383 } while (/*CONSTCOND*/0)
 384
 385 #define QTAILQ_INSERT_TAIL(head, elm, field) do {                       \
 386         (elm)->field.tqe_next = NULL;                                   \
 387         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 388         *(head)->tqh_last = (elm);                                      \
 389         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 390 } while (/*CONSTCOND*/0)
 391
 392 #define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
 393         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 394                 (elm)->field.tqe_next->field.tqe_prev =                 \
 395                     &(elm)->field.tqe_next;                             \
 396         else                                                            \
 397                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 398         (listelm)->field.tqe_next = (elm);                              \
 399         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 400 } while (/*CONSTCOND*/0)
 401
 402 #define QTAILQ_INSERT_BEFORE(listelm, elm, field) do {                  \
 403         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 404         (elm)->field.tqe_next = (listelm);                              \
 405         *(listelm)->field.tqe_prev = (elm);                             \
 406         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 407 } while (/*CONSTCOND*/0)
 408
 409 #define QTAILQ_REMOVE(head, elm, field) do {                            \
 410         if (((elm)->field.tqe_next) != NULL)                            \
 411                 (elm)->field.tqe_next->field.tqe_prev =                 \
 412                     (elm)->field.tqe_prev;                              \
 413         else                                                            \
 414                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 415         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 416 } while (/*CONSTCOND*/0)
 417
 418 #define QTAILQ_FOREACH(var, head, field)                                \
 419         for ((var) = ((head)->tqh_first);                               \
 420                 (var);                                                  \
 421                 (var) = ((var)->field.tqe_next))
 422
 423 #define QTAILQ_FOREACH_SAFE(var, head, field, next_var)                 \
 424         for ((var) = ((head)->tqh_first);                               \
 425                 (var) && ((next_var) = ((var)->field.tqe_next), 1);     \
 426                 (var) = (next_var))
 427
 428 #define QTAILQ_FOREACH_REVERSE(var, head, headname, field)              \
 429         for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));    \
 430                 (var);                                                  \
 431                 (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
 432
 433 /*
 434  * Tail queue access methods.
 435  */
 436 #define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
 437 #define QTAILQ_FIRST(head)               ((head)->tqh_first)
 438 #define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 439
 440 #define QTAILQ_LAST(head, headname) \
 441         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 442 #define QTAILQ_PREV(elm, headname, field) \
 443         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 444
 445 #endif  /* !QEMU_SYS_QUEUE_H_ */