1 /* $OpenBSD: queue.h,v 1.30 2005/10/25 06:37:47 otto Exp $ */ 2 /* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */ 3 4 /* 5 * Copyright (c) 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)queue.h 8.5 (Berkeley) 8/20/94 33 */ 34 35 #ifndef SM_TAILQ_H_ 36 #define SM_TAILQ_H_ 37 38 /* 39 * $Id: tailq.h,v 1.3 2012/01/21 00:12:14 ashish Exp $ 40 * 41 * This file is a modified copy of queue.h from a BSD system: 42 * we only need tail queues here. 43 * We do not use queue.h directly because there is a conflict with 44 * some versions of that file on some OSs. 45 * 46 * A tail queue is headed by a pair of pointers, one to the head of the 47 * list and the other to the tail of the list. The elements are doubly 48 * linked so that an arbitrary element can be removed without a need to 49 * traverse the list. New elements can be added to the list before or 50 * after an existing element, at the head of the list, or at the end of 51 * the list. A tail queue may be traversed in either direction. 52 */ 53 54 /* 55 * Tail queue definitions. 56 */ 57 #define SM_TAILQ_HEAD(name, type) \ 58 struct name { \ 59 struct type *tqh_first; /* first element */ \ 60 struct type **tqh_last; /* addr of last next element */ \ 61 } 62 63 #define SM_TAILQ_HEAD_INITIALIZER(head) \ 64 { NULL, &(head).tqh_first } 65 66 #define SM_TAILQ_ENTRY(type) \ 67 struct { \ 68 struct type *tqe_next; /* next element */ \ 69 struct type **tqe_prev; /* address of previous next element */ \ 70 } 71 72 /* 73 * tail queue access methods 74 */ 75 #define SM_TAILQ_FIRST(head) ((head)->tqh_first) 76 #define SM_TAILQ_END(head) NULL 77 #define SM_TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 78 #define SM_TAILQ_LAST(head, headname) \ 79 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 80 /* XXX */ 81 #define SM_TAILQ_PREV(elm, headname, field) \ 82 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 83 #define SM_TAILQ_EMPTY(head) \ 84 (SM_TAILQ_FIRST(head) == SM_TAILQ_END(head)) 85 86 #define SM_TAILQ_FOREACH(var, head, field) \ 87 for((var) = SM_TAILQ_FIRST(head); \ 88 (var) != SM_TAILQ_END(head); \ 89 (var) = SM_TAILQ_NEXT(var, field)) 90 91 #define SM_TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 92 for((var) = SM_TAILQ_LAST(head, headname); \ 93 (var) != SM_TAILQ_END(head); \ 94 (var) = SM_TAILQ_PREV(var, headname, field)) 95 96 /* 97 * Tail queue functions. 98 */ 99 #define SM_TAILQ_INIT(head) do { \ 100 (head)->tqh_first = NULL; \ 101 (head)->tqh_last = &(head)->tqh_first; \ 102 } while (0) 103 104 #define SM_TAILQ_INSERT_HEAD(head, elm, field) do { \ 105 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ 106 (head)->tqh_first->field.tqe_prev = \ 107 &(elm)->field.tqe_next; \ 108 else \ 109 (head)->tqh_last = &(elm)->field.tqe_next; \ 110 (head)->tqh_first = (elm); \ 111 (elm)->field.tqe_prev = &(head)->tqh_first; \ 112 } while (0) 113 114 #define SM_TAILQ_INSERT_TAIL(head, elm, field) do { \ 115 (elm)->field.tqe_next = NULL; \ 116 (elm)->field.tqe_prev = (head)->tqh_last; \ 117 *(head)->tqh_last = (elm); \ 118 (head)->tqh_last = &(elm)->field.tqe_next; \ 119 } while (0) 120 121 #define SM_TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 122 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\ 123 (elm)->field.tqe_next->field.tqe_prev = \ 124 &(elm)->field.tqe_next; \ 125 else \ 126 (head)->tqh_last = &(elm)->field.tqe_next; \ 127 (listelm)->field.tqe_next = (elm); \ 128 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ 129 } while (0) 130 131 #define SM_TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 132 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 133 (elm)->field.tqe_next = (listelm); \ 134 *(listelm)->field.tqe_prev = (elm); \ 135 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \ 136 } while (0) 137 138 #define SM_TAILQ_REMOVE(head, elm, field) do { \ 139 if (((elm)->field.tqe_next) != NULL) \ 140 (elm)->field.tqe_next->field.tqe_prev = \ 141 (elm)->field.tqe_prev; \ 142 else \ 143 (head)->tqh_last = (elm)->field.tqe_prev; \ 144 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ 145 } while (0) 146 147 #define SM_TAILQ_REPLACE(head, elm, elm2, field) do { \ 148 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \ 149 (elm2)->field.tqe_next->field.tqe_prev = \ 150 &(elm2)->field.tqe_next; \ 151 else \ 152 (head)->tqh_last = &(elm2)->field.tqe_next; \ 153 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \ 154 *(elm2)->field.tqe_prev = (elm2); \ 155 } while (0) 156 157 #endif /* !SM_TAILQ_H_ */ 158