1 /* $OpenBSD: queue.h,v 1.31 2005/11/25 08:06:25 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 _SIMPLE_QUEUE_H_ 36 #define _SIMPLE_QUEUE_H_ 37 38 /* 39 * A simple queue is headed by a pair of pointers, one the head of the 40 * list and the other to the tail of the list. The elements are singly 41 * linked to save space, so elements can only be removed from the 42 * head of the list. New elements can be added to the list before or after 43 * an existing element, at the head of the list, or at the end of the 44 * list. A simple queue may only be traversed in the forward direction. 45 * 46 * For details on the use of these macros, see the queue(3) manual page. 47 */ 48 49 /* 50 * Simple queue definitions. 51 */ 52 #define SIMPLEQ_HEAD(name, type) \ 53 struct name { \ 54 struct type *sqh_first; /* first element */ \ 55 struct type **sqh_last; /* addr of last next element */ \ 56 } 57 58 #define SIMPLEQ_HEAD_INITIALIZER(head) \ 59 { NULL, &(head).sqh_first } 60 61 #define SIMPLEQ_ENTRY(type) \ 62 struct { \ 63 struct type *sqe_next; /* next element */ \ 64 } 65 66 /* 67 * Simple queue access methods. 68 */ 69 #define SIMPLEQ_FIRST(head) ((head)->sqh_first) 70 #define SIMPLEQ_END(head) NULL 71 #define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head)) 72 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next) 73 74 #define SIMPLEQ_FOREACH(var, head, field) \ 75 for((var) = SIMPLEQ_FIRST(head); \ 76 (var) != SIMPLEQ_END(head); \ 77 (var) = SIMPLEQ_NEXT(var, field)) 78 79 /* 80 * Simple queue functions. 81 */ 82 #define SIMPLEQ_INIT(head) do { \ 83 (head)->sqh_first = NULL; \ 84 (head)->sqh_last = &(head)->sqh_first; \ 85 } while (0) 86 87 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \ 88 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \ 89 (head)->sqh_last = &(elm)->field.sqe_next; \ 90 (head)->sqh_first = (elm); \ 91 } while (0) 92 93 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \ 94 (elm)->field.sqe_next = NULL; \ 95 *(head)->sqh_last = (elm); \ 96 (head)->sqh_last = &(elm)->field.sqe_next; \ 97 } while (0) 98 99 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 100 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\ 101 (head)->sqh_last = &(elm)->field.sqe_next; \ 102 (listelm)->field.sqe_next = (elm); \ 103 } while (0) 104 105 #define SIMPLEQ_REMOVE_HEAD(head, field) do { \ 106 if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \ 107 (head)->sqh_last = &(head)->sqh_first; \ 108 } while (0) 109 110 #endif /* !_SIMPLE_QUEUE_H_ */ 111