slirp/src/qtailq.h

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