2018-01-18 Richard Biener <rguenther@suse.de>
[official-gcc.git] / libiberty / insque.c
blobfd02357bb23970dcda529f1f4a939074c07c54ad
1 /* insque(3C) routines
2 This file is in the public domain. */
4 /*
6 @deftypefn Supplemental void insque (struct qelem *@var{elem}, @
7 struct qelem *@var{pred})
8 @deftypefnx Supplemental void remque (struct qelem *@var{elem})
10 Routines to manipulate queues built from doubly linked lists. The
11 @code{insque} routine inserts @var{elem} in the queue immediately
12 after @var{pred}. The @code{remque} routine removes @var{elem} from
13 its containing queue. These routines expect to be passed pointers to
14 structures which have as their first members a forward pointer and a
15 back pointer, like this prototype (although no prototype is provided):
17 @example
18 struct qelem @{
19 struct qelem *q_forw;
20 struct qelem *q_back;
21 char q_data[];
22 @};
23 @end example
25 @end deftypefn
30 struct qelem {
31 struct qelem *q_forw;
32 struct qelem *q_back;
36 void
37 insque (struct qelem *elem, struct qelem *pred)
39 elem -> q_forw = pred -> q_forw;
40 pred -> q_forw -> q_back = elem;
41 elem -> q_back = pred;
42 pred -> q_forw = elem;
46 void
47 remque (struct qelem *elem)
49 elem -> q_forw -> q_back = elem -> q_back;
50 elem -> q_back -> q_forw = elem -> q_forw;