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: src/lib/libc/stdlib/insque.c,v 1.3 2003/01/04 07:34:41 tjr Exp $");
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
21  insque(void *element, void *pred)
22  {
23  	struct que_elem *prev, *next, *elem;
24  
25  	elem = (struct que_elem *)element;
26  	prev = (struct que_elem *)pred;
27  
28  	if (prev == NULL) {
29  		elem->prev = elem->next = NULL;
30  		return;
31  	}
32  
33  	next = prev->next;
34  	if (next != NULL) {
35  #ifdef DEBUG
36  		if (next->prev != prev) {
37  			fprintf(stderr, "insque: Inconsistency detected:"
38  			    " next(%p)->prev(%p) != prev(%p)\n",
39  			    next, next->prev, prev);
40  		}
41  #endif
42  		next->prev = elem;
43  	}
44  	prev->next = elem;
45  	elem->prev = prev;
46  	elem->next = next;
47  }