1/*	$OpenBSD: insque.c,v 1.3 2014/08/15 04:14:36 guenther Exp $	*/
2
3/*
4 *  Copyright (c) 1993 John Brezak
5 *  All rights reserved.
6 *
7 *  Redistribution and use in source and binary forms, with or without
8 *  modification, are permitted provided that the following conditions
9 *  are met:
10 *  1. Redistributions of source code must retain the above copyright
11 *     notice, this list of conditions and the following disclaimer.
12 *  2. Redistributions in binary form must reproduce the above copyright
13 *     notice, this list of conditions and the following disclaimer in the
14 *     documentation and/or other materials provided with the distribution.
15 *  3. The name of the author may be used to endorse or promote products
16 *     derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
22 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
27 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include <stdlib.h>
32#include <search.h>
33
34struct qelem {
35        struct qelem *q_forw;
36        struct qelem *q_back;
37};
38
39void
40insque(void *entry, void *pred)
41{
42	struct qelem *e = entry;
43	struct qelem *p = pred;
44
45	if (p == NULL)
46		e->q_forw = e->q_back = NULL;
47	else {
48		e->q_forw = p->q_forw;
49		e->q_back = p;
50		if (p->q_forw != NULL)
51			p->q_forw->q_back = e;
52		p->q_forw = e;
53	}
54}
55