| 1 | /*
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| 2 | * Copyright (c) 1991, 1993
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| 3 | * The Regents of the University of California. All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | * 1. Redistributions of source code must retain the above copyright
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| 9 | * notice, this list of conditions and the following disclaimer.
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| 10 | * 2. Redistributions in binary form must reproduce the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer in the
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| 12 | * documentation and/or other materials provided with the distribution.
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| 13 | * 4. Neither the name of the University nor the names of its contributors
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| 14 | * may be used to endorse or promote products derived from this software
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| 15 | * without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 27 | * SUCH DAMAGE.
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| 28 | *
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| 29 | * @(#)queue.h 8.3 (Berkeley) 12/13/93
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| 30 | */
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| 31 |
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| 32 | #ifndef _SYS_QUEUE_H
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| 33 | #define _SYS_QUEUE_H 1
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| 34 |
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| 35 | /*
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| 36 | * This file defines three types of data structures: lists, tail queues,
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| 37 | * and circular queues.
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| 38 | *
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| 39 | * A list is headed by a single forward pointer (or an array of forward
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| 40 | * pointers for a hash table header). The elements are doubly linked
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| 41 | * so that an arbitrary element can be removed without a need to
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| 42 | * traverse the list. New elements can be added to the list after
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| 43 | * an existing element or at the head of the list. A list may only be
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| 44 | * traversed in the forward direction.
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| 45 | *
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| 46 | * A tail queue is headed by a pair of pointers, one to the head of the
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| 47 | * list and the other to the tail of the list. The elements are doubly
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| 48 | * linked so that an arbitrary element can be removed without a need to
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| 49 | * traverse the list. New elements can be added to the list after
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| 50 | * an existing element, at the head of the list, or at the end of the
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| 51 | * list. A tail queue may only be traversed in the forward direction.
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| 52 | *
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| 53 | * A circle queue is headed by a pair of pointers, one to the head of the
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| 54 | * list and the other to the tail of the list. The elements are doubly
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| 55 | * linked so that an arbitrary element can be removed without a need to
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| 56 | * traverse the list. New elements can be added to the list before or after
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| 57 | * an existing element, at the head of the list, or at the end of the list.
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| 58 | * A circle queue may be traversed in either direction, but has a more
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| 59 | * complex end of list detection.
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| 60 | *
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| 61 | * For details on the use of these macros, see the queue(3) manual page.
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| 62 | */
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| 63 |
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| 64 | /*
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| 65 | * List definitions.
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| 66 | */
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| 67 | #define LIST_HEAD(name, type) \
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| 68 | struct name { \
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| 69 | struct type *lh_first; /* first element */ \
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| 70 | }
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| 71 |
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| 72 | #define LIST_ENTRY(type) \
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| 73 | struct { \
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| 74 | struct type *le_next; /* next element */ \
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| 75 | struct type **le_prev; /* address of previous next element */ \
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| 76 | }
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| 77 |
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| 78 | /*
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| 79 | * List functions.
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| 80 | */
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| 81 | #define LIST_INIT(head) { \
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| 82 | (head)->lh_first = NULL; \
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| 83 | }
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| 84 |
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| 85 | #define LIST_INSERT_AFTER(listelm, elm, field) { \
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| 86 | if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
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| 87 | (listelm)->field.le_next->field.le_prev = \
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| 88 | &(elm)->field.le_next; \
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| 89 | (listelm)->field.le_next = (elm); \
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| 90 | (elm)->field.le_prev = &(listelm)->field.le_next; \
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| 91 | }
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| 92 |
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| 93 | #define LIST_INSERT_HEAD(head, elm, field) { \
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| 94 | if (((elm)->field.le_next = (head)->lh_first) != NULL) \
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| 95 | (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
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| 96 | (head)->lh_first = (elm); \
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| 97 | (elm)->field.le_prev = &(head)->lh_first; \
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| 98 | }
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| 99 |
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| 100 | #define LIST_REMOVE(elm, field) { \
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| 101 | if ((elm)->field.le_next != NULL) \
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| 102 | (elm)->field.le_next->field.le_prev = \
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| 103 | (elm)->field.le_prev; \
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| 104 | *(elm)->field.le_prev = (elm)->field.le_next; \
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| 105 | }
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| 106 |
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| 107 | /*
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| 108 | * Tail queue definitions.
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| 109 | */
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| 110 | #define TAILQ_HEAD(name, type) \
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| 111 | struct name { \
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| 112 | struct type *tqh_first; /* first element */ \
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| 113 | struct type **tqh_last; /* addr of last next element */ \
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| 114 | }
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| 115 |
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| 116 | #define TAILQ_ENTRY(type) \
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| 117 | struct { \
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| 118 | struct type *tqe_next; /* next element */ \
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| 119 | struct type **tqe_prev; /* address of previous next element */ \
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| 120 | }
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| 121 |
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| 122 | /*
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| 123 | * Tail queue functions.
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| 124 | */
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| 125 | #define TAILQ_INIT(head) { \
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| 126 | (head)->tqh_first = NULL; \
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| 127 | (head)->tqh_last = &(head)->tqh_first; \
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| 128 | }
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| 129 |
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| 130 | #define TAILQ_INSERT_HEAD(head, elm, field) { \
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| 131 | if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
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| 132 | (elm)->field.tqe_next->field.tqe_prev = \
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| 133 | &(elm)->field.tqe_next; \
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| 134 | else \
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| 135 | (head)->tqh_last = &(elm)->field.tqe_next; \
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| 136 | (head)->tqh_first = (elm); \
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| 137 | (elm)->field.tqe_prev = &(head)->tqh_first; \
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| 138 | }
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| 139 |
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| 140 | #define TAILQ_INSERT_TAIL(head, elm, field) { \
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| 141 | (elm)->field.tqe_next = NULL; \
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| 142 | (elm)->field.tqe_prev = (head)->tqh_last; \
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| 143 | *(head)->tqh_last = (elm); \
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| 144 | (head)->tqh_last = &(elm)->field.tqe_next; \
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| 145 | }
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| 146 |
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| 147 | #define TAILQ_INSERT_AFTER(head, listelm, elm, field) { \
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| 148 | if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
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| 149 | (elm)->field.tqe_next->field.tqe_prev = \
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| 150 | &(elm)->field.tqe_next; \
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| 151 | else \
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| 152 | (head)->tqh_last = &(elm)->field.tqe_next; \
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| 153 | (listelm)->field.tqe_next = (elm); \
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| 154 | (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
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| 155 | }
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| 156 |
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| 157 | #define TAILQ_REMOVE(head, elm, field) { \
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| 158 | if (((elm)->field.tqe_next) != NULL) \
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| 159 | (elm)->field.tqe_next->field.tqe_prev = \
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| 160 | (elm)->field.tqe_prev; \
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| 161 | else \
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| 162 | (head)->tqh_last = (elm)->field.tqe_prev; \
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| 163 | *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
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| 164 | }
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| 165 |
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| 166 | /*
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| 167 | * Circular queue definitions.
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| 168 | */
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| 169 | #define CIRCLEQ_HEAD(name, type) \
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| 170 | struct name { \
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| 171 | struct type *cqh_first; /* first element */ \
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| 172 | struct type *cqh_last; /* last element */ \
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| 173 | }
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| 174 |
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| 175 | #define CIRCLEQ_ENTRY(type) \
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| 176 | struct { \
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| 177 | struct type *cqe_next; /* next element */ \
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| 178 | struct type *cqe_prev; /* previous element */ \
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| 179 | }
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| 180 |
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| 181 | /*
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| 182 | * Circular queue functions.
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| 183 | */
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| 184 | #define CIRCLEQ_INIT(head) { \
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| 185 | (head)->cqh_first = (void *)(head); \
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| 186 | (head)->cqh_last = (void *)(head); \
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| 187 | }
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| 188 |
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| 189 | #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) { \
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| 190 | (elm)->field.cqe_next = (listelm)->field.cqe_next; \
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| 191 | (elm)->field.cqe_prev = (listelm); \
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| 192 | if ((listelm)->field.cqe_next == (void *)(head)) \
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| 193 | (head)->cqh_last = (elm); \
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| 194 | else \
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| 195 | (listelm)->field.cqe_next->field.cqe_prev = (elm); \
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| 196 | (listelm)->field.cqe_next = (elm); \
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| 197 | }
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| 198 |
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| 199 | #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) { \
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| 200 | (elm)->field.cqe_next = (listelm); \
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| 201 | (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
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| 202 | if ((listelm)->field.cqe_prev == (void *)(head)) \
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| 203 | (head)->cqh_first = (elm); \
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| 204 | else \
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| 205 | (listelm)->field.cqe_prev->field.cqe_next = (elm); \
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| 206 | (listelm)->field.cqe_prev = (elm); \
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| 207 | }
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| 208 |
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| 209 | #define CIRCLEQ_INSERT_HEAD(head, elm, field) { \
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| 210 | (elm)->field.cqe_next = (head)->cqh_first; \
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| 211 | (elm)->field.cqe_prev = (void *)(head); \
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| 212 | if ((head)->cqh_last == (void *)(head)) \
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| 213 | (head)->cqh_last = (elm); \
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| 214 | else \
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| 215 | (head)->cqh_first->field.cqe_prev = (elm); \
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| 216 | (head)->cqh_first = (elm); \
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| 217 | }
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| 218 |
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| 219 | #define CIRCLEQ_INSERT_TAIL(head, elm, field) { \
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| 220 | (elm)->field.cqe_next = (void *)(head); \
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| 221 | (elm)->field.cqe_prev = (head)->cqh_last; \
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| 222 | if ((head)->cqh_first == (void *)(head)) \
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| 223 | (head)->cqh_first = (elm); \
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| 224 | else \
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| 225 | (head)->cqh_last->field.cqe_next = (elm); \
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| 226 | (head)->cqh_last = (elm); \
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| 227 | }
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| 228 |
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| 229 | #define CIRCLEQ_REMOVE(head, elm, field) { \
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| 230 | if ((elm)->field.cqe_next == (void *)(head)) \
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| 231 | (head)->cqh_last = (elm)->field.cqe_prev; \
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| 232 | else \
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| 233 | (elm)->field.cqe_next->field.cqe_prev = \
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| 234 | (elm)->field.cqe_prev; \
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| 235 | if ((elm)->field.cqe_prev == (void *)(head)) \
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| 236 | (head)->cqh_first = (elm)->field.cqe_next; \
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| 237 | else \
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| 238 | (elm)->field.cqe_prev->field.cqe_next = \
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| 239 | (elm)->field.cqe_next; \
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| 240 | }
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| 241 | #endif /* sys/queue.h */
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