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ea4df996 AM |
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 | #if defined(LIBC_SCCS) && !defined(lint) | |
30 | static char rcsid[] = "$Id: insque.c,v 1.2 1993/08/13 12:54:10 brezak Exp $"; | |
31 | #endif /* LIBC_SCCS and not lint */ | |
32 | ||
33 | struct qelem { | |
34 | struct qelem *q_forw; | |
35 | struct qelem *q_back; | |
36 | char *q_data; | |
37 | }; | |
38 | ||
39 | /* | |
40 | * Link p before s. | |
41 | */ | |
42 | #define reque(p, s) (p)->q_forw = (s), (s)->q_back = (p) | |
43 | ||
44 | /* | |
45 | * Insert entry in circular queue after pred. | |
46 | */ | |
47 | struct qelem * | |
48 | insque(entry, pred) | |
49 | struct qelem *entry, *pred; | |
50 | { | |
51 | reque(entry, pred->q_forw); | |
52 | reque(pred, entry); | |
53 | return (entry); | |
54 | } | |
55 | ||
56 | /* | |
57 | * Remove entry from circular queue. | |
58 | */ | |
59 | struct qelem * | |
60 | remque(entry) | |
61 | struct qelem *entry; | |
62 | { | |
63 | reque(entry->q_back, entry->q_forw); | |
64 | return (entry); | |
65 | } |