insque.c revision b902641d7303d2ea24c10f6d6e7ff49e7ee75611 
1/*
2 *  Copyright (c) 1993 John Brezak
3 *  All rights reserved.
4 *
5 *  Redistribution and use in source and binary forms, with or without
6 *  modification, are permitted provided that the following conditions
7 *  are met:
8 *  1. Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 *  3. The name of the author may be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
24 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
25 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30#if defined(LIBC_SCCS) && !defined(lint)
31__RCSID("$NetBSD: insque.c,v 1.3 2012/06/25 22:32:45 abs Exp $");
32#endif /* LIBC_SCCS and not lint */
33
34#include <assert.h>
35#include <search.h>
36
37struct qelem {
38        struct qelem *q_forw;
39        struct qelem *q_back;
40};
41
42void
43insque(void *entry, void *pred)
44{
45	struct qelem *e = (struct qelem *) entry;
46	struct qelem *p = (struct qelem *) pred;
47
48	_DIAGASSERT(e != 0);
49
50	e->q_back = p;
51	if (p) {
52		e->q_forw = p->q_forw;
53		if (p->q_forw)
54			p->q_forw->q_back = e;
55		p->q_forw = e;
56	} else
57		e->q_forw = 0;
58}
59