xref: /freebsd/lib/libc/stdlib/insque.c (revision a3e8fd0b7f663db7eafff527d5c3ca3bcfa8a537)
1 /*
2  * Initial implementation:
3  * Copyright (c) 2002 Robert Drehmel
4  * All rights reserved.
5  *
6  * As long as the above copyright statement and this notice remain
7  * unchanged, you can do what ever you want with this file.
8  */
9 #include <sys/cdefs.h>
10 __FBSDID("$FreeBSD$");
11 
12 #define	_SEARCH_PRIVATE
13 #include <search.h>
14 #ifdef DEBUG
15 #include <stdio.h>
16 #else
17 #include <stdlib.h>	/* for NULL */
18 #endif
19 
20 void insque(void *element, void *pred)
21 {
22 	struct que_elem *prev, *next, *elem;
23 
24 	elem = (struct que_elem *)element;
25 	prev = (struct que_elem *)pred;
26 
27 	if (prev == NULL) {
28 		elem->prev = elem->next = NULL;
29 		return;
30 	}
31 
32 	next = prev->next;
33 	if (next != NULL) {
34 #ifdef DEBUG
35 		if (next->prev != prev) {
36 			fprintf(stderr, "insque: Inconsistency detected:"
37 			    " next(%p)->prev(%p) != prev(%p)\n",
38 			    next, next->prev, prev);
39 		}
40 #endif
41 		next->prev = elem;
42 	}
43 	prev->next = elem;
44 	elem->prev = prev;
45 	elem->next = next;
46 }
47