1 /* Copyright (C) 1992-2022 Free Software Foundation, Inc.
2    This file is part of the GNU C Library.
3 
4    The GNU C Library is free software; you can redistribute it and/or
5    modify it under the terms of the GNU Lesser General Public
6    License as published by the Free Software Foundation; either
7    version 2.1 of the License, or (at your option) any later version.
8 
9    The GNU C Library is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12    Lesser General Public License for more details.
13 
14    You should have received a copy of the GNU Lesser General Public
15    License along with the GNU C Library; if not, see
16    <https://www.gnu.org/licenses/>.  */
17 
18 #include <stddef.h>
19 #include <search.h>
20 
21 /* Insert ELEM into a doubly-linked list, after PREV.  */
22 
23 void
insque(void * elem,void * prev)24 insque (void *elem, void *prev)
25 {
26   if (prev == NULL)
27     {
28       ((struct qelem *) elem)->q_forw = NULL;
29       ((struct qelem *) elem)->q_back = NULL;
30     }
31   else
32     {
33       struct qelem *next = ((struct qelem *) prev)->q_forw;
34       ((struct qelem *) prev)->q_forw = (struct qelem *) elem;
35       if (next != NULL)
36 	next->q_back = (struct qelem *) elem;
37       ((struct qelem *) elem)->q_forw = next;
38       ((struct qelem *) elem)->q_back = (struct qelem *) prev;
39     }
40 }
41 
42 /* Unlink ELEM from the doubly-linked list that it is in.  */
43 
44 void
remque(void * elem)45 remque (void *elem)
46 {
47   struct qelem *next = ((struct qelem *) elem)->q_forw;
48   struct qelem *prev = ((struct qelem *) elem)->q_back;
49   if (next != NULL)
50     next->q_back = prev;
51   if (prev != NULL)
52     prev->q_forw = (struct qelem *) next;
53 }
54