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 /*
  82  * List definitions.
  83  */
  84 #define QLIST_HEAD(name, type)                                          \
  85 struct name {                                                           \
  86         struct type *lh_first;  /* first element */                     \
  87 }
  88
  89 #define QLIST_HEAD_INITIALIZER(head)                                    \
  90         { NULL }
  91
  92 #define QLIST_ENTRY(type)                                               \
  93 struct {                                                                \
  94         struct type *le_next;   /* next element */                      \
  95         struct type **le_prev;  /* address of previous next element */  \
  96 }
  97
  98 /*
  99  * List functions.
 100  */
 101 #define QLIST_INIT(head) do {                                           \
 102         (head)->lh_first = NULL;                                        \
 103 } while (/*CONSTCOND*/0)
 104
 105 #define QLIST_SWAP(dstlist, srclist, field) do {                        \
 106         void *tmplist;                                                  \
 107         tmplist = (srclist)->lh_first;                                  \
 108         (srclist)->lh_first = (dstlist)->lh_first;                      \
 109         if ((srclist)->lh_first != NULL) {                              \
 110             (srclist)->lh_first->field.le_prev = &(srclist)->lh_first;  \
 111         }                                                               \
 112         (dstlist)->lh_first = tmplist;                                  \
 113         if ((dstlist)->lh_first != NULL) {                              \
 114             (dstlist)->lh_first->field.le_prev = &(dstlist)->lh_first;  \
 115         }                                                               \
 116 } while (/*CONSTCOND*/0)
 117
 118 #define QLIST_INSERT_AFTER(listelm, elm, field) do {                    \
 119         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 120                 (listelm)->field.le_next->field.le_prev =               \
 121                     &(elm)->field.le_next;                              \
 122         (listelm)->field.le_next = (elm);                               \
 123         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 124 } while (/*CONSTCOND*/0)
 125
 126 #define QLIST_INSERT_BEFORE(listelm, elm, field) do {                   \
 127         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 128         (elm)->field.le_next = (listelm);                               \
 129         *(listelm)->field.le_prev = (elm);                              \
 130         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 131 } while (/*CONSTCOND*/0)
 132
 133 #define QLIST_INSERT_HEAD(head, elm, field) do {                        \
 134         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 135                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 136         (head)->lh_first = (elm);                                       \
 137         (elm)->field.le_prev = &(head)->lh_first;                       \
 138 } while (/*CONSTCOND*/0)
 139
 140 #define QLIST_REMOVE(elm, field) do {                                   \
 141         if ((elm)->field.le_next != NULL)                               \
 142                 (elm)->field.le_next->field.le_prev =                   \
 143                     (elm)->field.le_prev;                               \
 144         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 145 } while (/*CONSTCOND*/0)
 146
 147 /*
 148  * Like QLIST_REMOVE() but safe to call when elm is not in a list
 149  */
 150 #define QLIST_SAFE_REMOVE(elm, field) do {                              \
 151         if ((elm)->field.le_prev != NULL) {                             \
 152                 if ((elm)->field.le_next != NULL)                       \
 153                         (elm)->field.le_next->field.le_prev =           \
 154                             (elm)->field.le_prev;                       \
 155                 *(elm)->field.le_prev = (elm)->field.le_next;           \
 156                 (elm)->field.le_next = NULL;                            \
 157                 (elm)->field.le_prev = NULL;                            \
 158         }                                                               \
 159 } while (/*CONSTCOND*/0)
 160
 161 #define QLIST_FOREACH(var, head, field)                                 \
 162         for ((var) = ((head)->lh_first);                                \
 163                 (var);                                                  \
 164                 (var) = ((var)->field.le_next))
 165
 166 #define QLIST_FOREACH_SAFE(var, head, field, next_var)                  \
 167         for ((var) = ((head)->lh_first);                                \
 168                 (var) && ((next_var) = ((var)->field.le_next), 1);      \
 169                 (var) = (next_var))
 170
 171 /*
 172  * List access methods.
 173  */
 174 #define QLIST_EMPTY(head)                ((head)->lh_first == NULL)
 175 #define QLIST_FIRST(head)                ((head)->lh_first)
 176 #define QLIST_NEXT(elm, field)           ((elm)->field.le_next)
 177
 178
 179 /*
 180  * Singly-linked List definitions.
 181  */
 182 #define QSLIST_HEAD(name, type)                                          \
 183 struct name {                                                           \
 184         struct type *slh_first; /* first element */                     \
 185 }
 186
 187 #define QSLIST_HEAD_INITIALIZER(head)                                    \
 188         { NULL }
 189
 190 #define QSLIST_ENTRY(type)                                               \
 191 struct {                                                                \
 192         struct type *sle_next;  /* next element */                      \
 193 }
 194
 195 /*
 196  * Singly-linked List functions.
 197  */
 198 #define QSLIST_INIT(head) do {                                           \
 199         (head)->slh_first = NULL;                                       \
 200 } while (/*CONSTCOND*/0)
 201
 202 #define QSLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 203         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 204         (slistelm)->field.sle_next = (elm);                             \
 205 } while (/*CONSTCOND*/0)
 206
 207 #define QSLIST_INSERT_HEAD(head, elm, field) do {                        \
 208         (elm)->field.sle_next = (head)->slh_first;                       \
 209         (head)->slh_first = (elm);                                       \
 210 } while (/*CONSTCOND*/0)
 211
 212 #define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do {                     \
 213         typeof(elm) save_sle_next;                                           \
 214         do {                                                                 \
 215             save_sle_next = (elm)->field.sle_next = (head)->slh_first;       \
 216         } while (atomic_cmpxchg(&(head)->slh_first, save_sle_next, (elm)) != \
 217                  save_sle_next);                                             \
 218 } while (/*CONSTCOND*/0)
 219
 220 #define QSLIST_MOVE_ATOMIC(dest, src) do {                               \
 221         (dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL);        \
 222 } while (/*CONSTCOND*/0)
 223
 224 #define QSLIST_REMOVE_HEAD(head, field) do {                             \
 225         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 226 } while (/*CONSTCOND*/0)
 227
 228 #define QSLIST_REMOVE_AFTER(slistelm, field) do {                       \
 229         (slistelm)->field.sle_next =                                    \
 230             QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field);         \
 231 } while (/*CONSTCOND*/0)
 232
 233 #define QSLIST_REMOVE(head, elm, type, field) do {                      \
 234     if ((head)->slh_first == (elm)) {                                   \
 235         QSLIST_REMOVE_HEAD((head), field);                              \
 236     } else {                                                            \
 237         struct type *curelm = (head)->slh_first;                        \
 238         while (curelm->field.sle_next != (elm))                         \
 239             curelm = curelm->field.sle_next;                            \
 240         curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \
 241     }                                                                   \
 242 } while (/*CONSTCOND*/0)
 243
 244 #define QSLIST_FOREACH(var, head, field)                                 \
 245         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 246
 247 #define QSLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 248         for ((var) = QSLIST_FIRST((head));                               \
 249             (var) && ((tvar) = QSLIST_NEXT((var), field), 1);            \
 250             (var) = (tvar))
 251
 252 /*
 253  * Singly-linked List access methods.
 254  */
 255 #define QSLIST_EMPTY(head)       ((head)->slh_first == NULL)
 256 #define QSLIST_FIRST(head)       ((head)->slh_first)
 257 #define QSLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 258
 259
 260 /*
 261  * Simple queue definitions.
 262  */
 263 #define QSIMPLEQ_HEAD(name, type)                                       \
 264 struct name {                                                           \
 265     struct type *sqh_first;    /* first element */                      \
 266     struct type **sqh_last;    /* addr of last next element */          \
 267 }
 268
 269 #define QSIMPLEQ_HEAD_INITIALIZER(head)                                 \
 270     { NULL, &(head).sqh_first }
 271
 272 #define QSIMPLEQ_ENTRY(type)                                            \
 273 struct {                                                                \
 274     struct type *sqe_next;    /* next element */                        \
 275 }
 276
 277 /*
 278  * Simple queue functions.
 279  */
 280 #define QSIMPLEQ_INIT(head) do {                                        \
 281     (head)->sqh_first = NULL;                                           \
 282     (head)->sqh_last = &(head)->sqh_first;                              \
 283 } while (/*CONSTCOND*/0)
 284
 285 #define QSIMPLEQ_INSERT_HEAD(head, elm, field) do {                     \
 286     if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)            \
 287         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 288     (head)->sqh_first = (elm);                                          \
 289 } while (/*CONSTCOND*/0)
 290
 291 #define QSIMPLEQ_INSERT_TAIL(head, elm, field) do {                     \
 292     (elm)->field.sqe_next = NULL;                                       \
 293     *(head)->sqh_last = (elm);                                          \
 294     (head)->sqh_last = &(elm)->field.sqe_next;                          \
 295 } while (/*CONSTCOND*/0)
 296
 297 #define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 298     if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)    \
 299         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 300     (listelm)->field.sqe_next = (elm);                                  \
 301 } while (/*CONSTCOND*/0)
 302
 303 #define QSIMPLEQ_REMOVE_HEAD(head, field) do {                          \
 304     if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\
 305         (head)->sqh_last = &(head)->sqh_first;                          \
 306 } while (/*CONSTCOND*/0)
 307
 308 #define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do {            \
 309     QSIMPLEQ_INIT(removed);                                             \
 310     if (((removed)->sqh_first = (head)->sqh_first) != NULL) {           \
 311         if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) {      \
 312             (head)->sqh_last = &(head)->sqh_first;                      \
 313         }                                                               \
 314         (removed)->sqh_last = &(elm)->field.sqe_next;                   \
 315         (elm)->field.sqe_next = NULL;                                   \
 316     }                                                                   \
 317 } while (/*CONSTCOND*/0)
 318
 319 #define QSIMPLEQ_REMOVE(head, elm, type, field) do {                    \
 320     if ((head)->sqh_first == (elm)) {                                   \
 321         QSIMPLEQ_REMOVE_HEAD((head), field);                            \
 322     } else {                                                            \
 323         struct type *curelm = (head)->sqh_first;                        \
 324         while (curelm->field.sqe_next != (elm))                         \
 325             curelm = curelm->field.sqe_next;                            \
 326         if ((curelm->field.sqe_next =                                   \
 327             curelm->field.sqe_next->field.sqe_next) == NULL)            \
 328                 (head)->sqh_last = &(curelm)->field.sqe_next;           \
 329     }                                                                   \
 330 } while (/*CONSTCOND*/0)
 331
 332 #define QSIMPLEQ_FOREACH(var, head, field)                              \
 333     for ((var) = ((head)->sqh_first);                                   \
 334         (var);                                                          \
 335         (var) = ((var)->field.sqe_next))
 336
 337 #define QSIMPLEQ_FOREACH_SAFE(var, head, field, next)                   \
 338     for ((var) = ((head)->sqh_first);                                   \
 339         (var) && ((next = ((var)->field.sqe_next)), 1);                 \
 340         (var) = (next))
 341
 342 #define QSIMPLEQ_CONCAT(head1, head2) do {                              \
 343     if (!QSIMPLEQ_EMPTY((head2))) {                                     \
 344         *(head1)->sqh_last = (head2)->sqh_first;                        \
 345         (head1)->sqh_last = (head2)->sqh_last;                          \
 346         QSIMPLEQ_INIT((head2));                                         \
 347     }                                                                   \
 348 } while (/*CONSTCOND*/0)
 349
 350 #define QSIMPLEQ_PREPEND(head1, head2) do {                             \
 351     if (!QSIMPLEQ_EMPTY((head2))) {                                     \
 352         *(head2)->sqh_last = (head1)->sqh_first;                        \
 353         (head1)->sqh_first = (head2)->sqh_first;                          \
 354         QSIMPLEQ_INIT((head2));                                         \
 355     }                                                                   \
 356 } while (/*CONSTCOND*/0)
 357
 358 #define QSIMPLEQ_LAST(head, type, field)                                \
 359     (QSIMPLEQ_EMPTY((head)) ?                                           \
 360         NULL :                                                          \
 361             ((struct type *)(void *)                                    \
 362         ((char *)((head)->sqh_last) - offsetof(struct type, field))))
 363
 364 /*
 365  * Simple queue access methods.
 366  */
 367 #define QSIMPLEQ_EMPTY_ATOMIC(head) (atomic_read(&((head)->sqh_first)) == NULL)
 368 #define QSIMPLEQ_EMPTY(head)        ((head)->sqh_first == NULL)
 369 #define QSIMPLEQ_FIRST(head)        ((head)->sqh_first)
 370 #define QSIMPLEQ_NEXT(elm, field)   ((elm)->field.sqe_next)
 371
 372 typedef struct QTailQLink {
 373     void *tql_next;
 374     struct QTailQLink *tql_prev;
 375 } QTailQLink;
 376
 377 /*
 378  * Tail queue definitions.  The union acts as a poor man template, as if
 379  * it were QTailQLink<type>.
 380  */
 381 #define QTAILQ_HEAD(name, type)                                         \
 382 union name {                                                            \
 383         struct type *tqh_first;       /* first element */               \
 384         QTailQLink tqh_circ;          /* link for circular backwards list */ \
 385 }
 386
 387 #define QTAILQ_HEAD_INITIALIZER(head)                                   \
 388         { .tqh_circ = { NULL, &(head).tqh_circ } }
 389
 390 #define QTAILQ_ENTRY(type)                                              \
 391 union {                                                                 \
 392         struct type *tqe_next;        /* next element */                \
 393         QTailQLink tqe_circ;          /* link for circular backwards list */ \
 394 }
 395
 396 /*
 397  * Tail queue functions.
 398  */
 399 #define QTAILQ_INIT(head) do {                                          \
 400         (head)->tqh_first = NULL;                                       \
 401         (head)->tqh_circ.tql_prev = &(head)->tqh_circ;                  \
 402 } while (/*CONSTCOND*/0)
 403
 404 #define QTAILQ_INSERT_HEAD(head, elm, field) do {                       \
 405         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 406             (head)->tqh_first->field.tqe_circ.tql_prev =                \
 407                 &(elm)->field.tqe_circ;                                 \
 408         else                                                            \
 409             (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
 410         (head)->tqh_first = (elm);                                      \
 411         (elm)->field.tqe_circ.tql_prev = &(head)->tqh_circ;             \
 412 } while (/*CONSTCOND*/0)
 413
 414 #define QTAILQ_INSERT_TAIL(head, elm, field) do {                       \
 415         (elm)->field.tqe_next = NULL;                                   \
 416         (elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev;     \
 417         (head)->tqh_circ.tql_prev->tql_next = (elm);                    \
 418         (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;             \
 419 } while (/*CONSTCOND*/0)
 420
 421 #define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
 422         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 423             (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
 424                 &(elm)->field.tqe_circ;                                 \
 425         else                                                            \
 426             (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
 427         (listelm)->field.tqe_next = (elm);                              \
 428         (elm)->field.tqe_circ.tql_prev = &(listelm)->field.tqe_circ;    \
 429 } while (/*CONSTCOND*/0)
 430
 431 #define QTAILQ_INSERT_BEFORE(listelm, elm, field) do {                       \
 432         (elm)->field.tqe_circ.tql_prev = (listelm)->field.tqe_circ.tql_prev; \
 433         (elm)->field.tqe_next = (listelm);                                   \
 434         (listelm)->field.tqe_circ.tql_prev->tql_next = (elm);                \
 435         (listelm)->field.tqe_circ.tql_prev = &(elm)->field.tqe_circ;         \
 436 } while (/*CONSTCOND*/0)
 437
 438 #define QTAILQ_REMOVE(head, elm, field) do {                            \
 439         if (((elm)->field.tqe_next) != NULL)                            \
 440             (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
 441                 (elm)->field.tqe_circ.tql_prev;                         \
 442         else                                                            \
 443             (head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \
 444         (elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \
 445         (elm)->field.tqe_circ.tql_prev = NULL;                          \
 446 } while (/*CONSTCOND*/0)
 447
 448 /* remove @left, @right and all elements in between from @head */
 449 #define QTAILQ_REMOVE_SEVERAL(head, left, right, field) do {            \
 450         if (((right)->field.tqe_next) != NULL)                          \
 451             (right)->field.tqe_next->field.tqe_circ.tql_prev =          \
 452                 (left)->field.tqe_circ.tql_prev;                        \
 453         else                                                            \
 454             (head)->tqh_circ.tql_prev = (left)->field.tqe_circ.tql_prev; \
 455         (left)->field.tqe_circ.tql_prev->tql_next = (right)->field.tqe_next; \
 456     } while (/*CONSTCOND*/0)
 457
 458 #define QTAILQ_FOREACH(var, head, field)                                \
 459         for ((var) = ((head)->tqh_first);                               \
 460                 (var);                                                  \
 461                 (var) = ((var)->field.tqe_next))
 462
 463 #define QTAILQ_FOREACH_SAFE(var, head, field, next_var)                 \
 464         for ((var) = ((head)->tqh_first);                               \
 465                 (var) && ((next_var) = ((var)->field.tqe_next), 1);     \
 466                 (var) = (next_var))
 467
 468 #define QTAILQ_FOREACH_REVERSE(var, head, field)                        \
 469         for ((var) = QTAILQ_LAST(head);                                 \
 470                 (var);                                                  \
 471                 (var) = QTAILQ_PREV(var, field))
 472
 473 #define QTAILQ_FOREACH_REVERSE_SAFE(var, head, field, prev_var)         \
 474         for ((var) = QTAILQ_LAST(head);                                 \
 475              (var) && ((prev_var) = QTAILQ_PREV(var, field), 1);        \
 476              (var) = (prev_var))
 477
 478 /*
 479  * Tail queue access methods.
 480  */
 481 #define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
 482 #define QTAILQ_FIRST(head)               ((head)->tqh_first)
 483 #define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 484 #define QTAILQ_IN_USE(elm, field)        ((elm)->field.tqe_circ.tql_prev != NULL)
 485
 486 #define QTAILQ_LINK_PREV(link)                                          \
 487         ((link).tql_prev->tql_prev->tql_next)
 488 #define QTAILQ_LAST(head)                                               \
 489         ((typeof((head)->tqh_first)) QTAILQ_LINK_PREV((head)->tqh_circ))
 490 #define QTAILQ_PREV(elm, field)                                         \
 491         ((typeof((elm)->field.tqe_next)) QTAILQ_LINK_PREV((elm)->field.tqe_circ))
 492
 493 #define field_at_offset(base, offset, type)                                    \
 494         ((type *) (((char *) (base)) + (offset)))
 495
 496 /*
 497  * Raw access of elements of a tail queue head.  Offsets are all zero
 498  * because it's a union.
 499  */
 500 #define QTAILQ_RAW_FIRST(head)                                                 \
 501         field_at_offset(head, 0, void *)
 502 #define QTAILQ_RAW_TQH_CIRC(head)                                              \
 503         field_at_offset(head, 0, QTailQLink)
 504
 505 /*
 506  * Raw access of elements of a tail entry
 507  */
 508 #define QTAILQ_RAW_NEXT(elm, entry)                                            \
 509         field_at_offset(elm, entry, void *)
 510 #define QTAILQ_RAW_TQE_CIRC(elm, entry)                                        \
 511         field_at_offset(elm, entry, QTailQLink)
 512 /*
 513  * Tail queue traversal using pointer arithmetic.
 514  */
 515 #define QTAILQ_RAW_FOREACH(elm, head, entry)                                   \
 516         for ((elm) = *QTAILQ_RAW_FIRST(head);                                  \
 517              (elm);                                                            \
 518              (elm) = *QTAILQ_RAW_NEXT(elm, entry))
 519 /*
 520  * Tail queue insertion using pointer arithmetic.
 521  */
 522 #define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do {                           \
 523         *QTAILQ_RAW_NEXT(elm, entry) = NULL;                                    \
 524         QTAILQ_RAW_TQE_CIRC(elm, entry)->tql_prev = QTAILQ_RAW_TQH_CIRC(head)->tql_prev; \
 525         QTAILQ_RAW_TQH_CIRC(head)->tql_prev->tql_next = (elm);                  \
 526         QTAILQ_RAW_TQH_CIRC(head)->tql_prev = QTAILQ_RAW_TQE_CIRC(elm, entry);  \
 527 } while (/*CONSTCOND*/0)
 528
 529 #define QLIST_RAW_FIRST(head)                                                  \
 530         field_at_offset(head, 0, void *)
 531
 532 #define QLIST_RAW_NEXT(elm, entry)                                             \
 533         field_at_offset(elm, entry, void *)
 534
 535 #define QLIST_RAW_PREVIOUS(elm, entry)                                         \
 536         field_at_offset(elm, entry + sizeof(void *), void *)
 537
 538 #define QLIST_RAW_FOREACH(elm, head, entry)                                    \
 539         for ((elm) = *QLIST_RAW_FIRST(head);                                   \
 540              (elm);                                                            \
 541              (elm) = *QLIST_RAW_NEXT(elm, entry))
 542
 543 #define QLIST_RAW_INSERT_AFTER(head, prev, elem, entry) do {                   \
 544         *QLIST_RAW_NEXT(prev, entry) = elem;                                   \
 545         *QLIST_RAW_PREVIOUS(elem, entry) = QLIST_RAW_NEXT(prev, entry);        \
 546         *QLIST_RAW_NEXT(elem, entry) = NULL;                                   \
 547 } while (0)
 548
 549 #define QLIST_RAW_INSERT_HEAD(head, elm, entry) do {                           \
 550         void *first = *QLIST_RAW_FIRST(head);                                  \
 551         *QLIST_RAW_FIRST(head) = elm;                                          \
 552         *QLIST_RAW_PREVIOUS(elm, entry) = QLIST_RAW_FIRST(head);               \
 553         if (first) {                                                           \
 554             *QLIST_RAW_NEXT(elm, entry) = first;                               \
 555             *QLIST_RAW_PREVIOUS(first, entry) = QLIST_RAW_NEXT(elm, entry);    \
 556         } else {                                                               \
 557             *QLIST_RAW_NEXT(elm, entry) = NULL;                                \
 558         }                                                                      \
 559 } while (0)
 560
 561 #endif /* QEMU_SYS_QUEUE_H */