slirp/qtailq.h

   1 /*      $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
   2
   3 /*
   4  * slirp version: Copy from QEMU, removed all but tail queues.
   5  */
   6
   7 /*
   8  * Copyright (c) 1991, 1993
   9  *      The Regents of the University of California.  All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  36  */
  37
  38 #ifndef QTAILQ_H
  39 #define QTAILQ_H
  40
  41 /*
  42  * A tail queue is headed by a pair of pointers, one to the head of the
  43  * list and the other to the tail of the list. The elements are doubly
  44  * linked so that an arbitrary element can be removed without a need to
  45  * traverse the list. New elements can be added to the list before or
  46  * after an existing element, at the head of the list, or at the end of
  47  * the list. A tail queue may be traversed in either direction.
  48  */
  49 typedef struct QTailQLink {
  50     void *tql_next;
  51     struct QTailQLink *tql_prev;
  52 } QTailQLink;
  53
  54 /*
  55  * Tail queue definitions.  The union acts as a poor man template, as if
  56  * it were QTailQLink<type>.
  57  */
  58 #define QTAILQ_HEAD(name, type)                                         \
  59     union name {                                                        \
  60         struct type *tqh_first;       /* first element */               \
  61         QTailQLink tqh_circ;          /* link for circular backwards list */ \
  62     }
  63
  64 #define QTAILQ_HEAD_INITIALIZER(head)           \
  65     { .tqh_circ = { NULL, &(head).tqh_circ } }
  66
  67 #define QTAILQ_ENTRY(type)                                              \
  68     union {                                                             \
  69         struct type *tqe_next;        /* next element */                \
  70         QTailQLink tqe_circ;          /* link for circular backwards list */ \
  71     }
  72
  73 #define QTAILQ_INIT(head) do {                                          \
  74         (head)->tqh_first = NULL;                                       \
  75         (head)->tqh_circ.tql_prev = &(head)->tqh_circ;                  \
  76 } while (/*CONSTCOND*/0)
  77
  78 #define QTAILQ_INSERT_HEAD(head, elm, field) do {                       \
  79         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
  80             (head)->tqh_first->field.tqe_circ.tql_prev =                \
  81                 &(elm)->field.tqe_circ;                                 \
  82         else                                                            \
  83             (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
  84         (head)->tqh_first = (elm);                                      \
  85         (elm)->field.tqe_circ.tql_prev = &(head)->tqh_circ;             \
  86 } while (/*CONSTCOND*/0)
  87
  88 #define QTAILQ_INSERT_TAIL(head, elm, field) do {                       \
  89         (elm)->field.tqe_next = NULL;                                   \
  90         (elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev;     \
  91         (head)->tqh_circ.tql_prev->tql_next = (elm);                    \
  92         (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;             \
  93 } while (/*CONSTCOND*/0)
  94
  95 #define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
  96         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
  97             (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
  98                 &(elm)->field.tqe_circ;                                 \
  99         else                                                            \
 100             (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
 101         (listelm)->field.tqe_next = (elm);                              \
 102         (elm)->field.tqe_circ.tql_prev = &(listelm)->field.tqe_circ;    \
 103 } while (/*CONSTCOND*/0)
 104
 105 #define QTAILQ_INSERT_BEFORE(listelm, elm, field) do {                       \
 106         (elm)->field.tqe_circ.tql_prev = (listelm)->field.tqe_circ.tql_prev; \
 107         (elm)->field.tqe_next = (listelm);                                   \
 108         (listelm)->field.tqe_circ.tql_prev->tql_next = (elm);                \
 109         (listelm)->field.tqe_circ.tql_prev = &(elm)->field.tqe_circ;         \
 110 } while (/*CONSTCOND*/0)
 111
 112 #define QTAILQ_REMOVE(head, elm, field) do {                            \
 113         if (((elm)->field.tqe_next) != NULL)                            \
 114             (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
 115                 (elm)->field.tqe_circ.tql_prev;                         \
 116         else                                                            \
 117             (head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \
 118         (elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \
 119         (elm)->field.tqe_circ.tql_prev = NULL;                          \
 120 } while (/*CONSTCOND*/0)
 121
 122 #define QTAILQ_FOREACH(var, head, field)                                \
 123         for ((var) = ((head)->tqh_first);                               \
 124                 (var);                                                  \
 125                 (var) = ((var)->field.tqe_next))
 126
 127 #define QTAILQ_FOREACH_SAFE(var, head, field, next_var)                 \
 128         for ((var) = ((head)->tqh_first);                               \
 129                 (var) && ((next_var) = ((var)->field.tqe_next), 1);     \
 130                 (var) = (next_var))
 131
 132 #define QTAILQ_FOREACH_REVERSE(var, head, field)                        \
 133         for ((var) = QTAILQ_LAST(head);                                 \
 134                 (var);                                                  \
 135                 (var) = QTAILQ_PREV(var, field))
 136
 137 #define QTAILQ_FOREACH_REVERSE_SAFE(var, head, field, prev_var)         \
 138         for ((var) = QTAILQ_LAST(head);                                 \
 139              (var) && ((prev_var) = QTAILQ_PREV(var, field));           \
 140              (var) = (prev_var))
 141
 142 /*
 143  * Tail queue access methods.
 144  */
 145 #define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
 146 #define QTAILQ_FIRST(head)               ((head)->tqh_first)
 147 #define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 148 #define QTAILQ_IN_USE(elm, field)        ((elm)->field.tqe_circ.tql_prev != NULL)
 149
 150 #define QTAILQ_LINK_PREV(link)                                          \
 151         ((link).tql_prev->tql_prev->tql_next)
 152 #define QTAILQ_LAST(head)                                               \
 153         ((typeof((head)->tqh_first)) QTAILQ_LINK_PREV((head)->tqh_circ))
 154 #define QTAILQ_PREV(elm, field)                                         \
 155         ((typeof((elm)->field.tqe_next)) QTAILQ_LINK_PREV((elm)->field.tqe_circ))
 156
 157 #define field_at_offset(base, offset, type)                                    \
 158         ((type *) (((char *) (base)) + (offset)))
 159
 160 /*
 161  * Raw access of elements of a tail queue head.  Offsets are all zero
 162  * because it's a union.
 163  */
 164 #define QTAILQ_RAW_FIRST(head)                                                 \
 165         field_at_offset(head, 0, void *)
 166 #define QTAILQ_RAW_TQH_CIRC(head)                                              \
 167         field_at_offset(head, 0, QTailQLink)
 168
 169 /*
 170  * Raw access of elements of a tail entry
 171  */
 172 #define QTAILQ_RAW_NEXT(elm, entry)                                            \
 173         field_at_offset(elm, entry, void *)
 174 #define QTAILQ_RAW_TQE_CIRC(elm, entry)                                        \
 175         field_at_offset(elm, entry, QTailQLink)
 176 /*
 177  * Tail queue traversal using pointer arithmetic.
 178  */
 179 #define QTAILQ_RAW_FOREACH(elm, head, entry)                                   \
 180         for ((elm) = *QTAILQ_RAW_FIRST(head);                                  \
 181              (elm);                                                            \
 182              (elm) = *QTAILQ_RAW_NEXT(elm, entry))
 183 /*
 184  * Tail queue insertion using pointer arithmetic.
 185  */
 186 #define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do {                           \
 187         *QTAILQ_RAW_NEXT(elm, entry) = NULL;                                    \
 188         QTAILQ_RAW_TQE_CIRC(elm, entry)->tql_prev = QTAILQ_RAW_TQH_CIRC(head)->tql_prev; \
 189         QTAILQ_RAW_TQH_CIRC(head)->tql_prev->tql_next = (elm);                  \
 190         QTAILQ_RAW_TQH_CIRC(head)->tql_prev = QTAILQ_RAW_TQE_CIRC(elm, entry);  \
 191 } while (/*CONSTCOND*/0)
 192
 193 #endif /* QTAILQ_H */