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comparison libiberty/insque.c @ 0:a06113de4d67

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first commit
author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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children f6334be47118
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-1:000000000000 0:a06113de4d67
1 /* insque(3C) routines
2 This file is in the public domain. */
3
4 /*
5
6 @deftypefn Supplemental void insque (struct qelem *@var{elem}, struct qelem *@var{pred})
7 @deftypefnx Supplemental void remque (struct qelem *@var{elem})
8
9 Routines to manipulate queues built from doubly linked lists. The
10 @code{insque} routine inserts @var{elem} in the queue immediately
11 after @var{pred}. The @code{remque} routine removes @var{elem} from
12 its containing queue. These routines expect to be passed pointers to
13 structures which have as their first members a forward pointer and a
14 back pointer, like this prototype (although no prototype is provided):
15
16 @example
17 struct qelem @{
18 struct qelem *q_forw;
19 struct qelem *q_back;
20 char q_data[];
21 @};
22 @end example
23
24 @end deftypefn
25
26 */
27
28
29 struct qelem {
30 struct qelem *q_forw;
31 struct qelem *q_back;
32 };
33
34
35 void
36 insque (struct qelem *elem, struct qelem *pred)
37 {
38 elem -> q_forw = pred -> q_forw;
39 pred -> q_forw -> q_back = elem;
40 elem -> q_back = pred;
41 pred -> q_forw = elem;
42 }
43
44
45 void
46 remque (struct qelem *elem)
47 {
48 elem -> q_forw -> q_back = elem -> q_back;
49 elem -> q_back -> q_forw = elem -> q_forw;
50 }