1 /*
2 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
3 * the AT&T man page says.
4 *
5 * The node_t structure is for internal use only, lint doesn't grok it.
6 *
7 * Written by reading the System V Interface Definition, not the code.
8 *
9 * Totally public domain.
10 *
11 * $NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $
12 * $FreeBSD: src/lib/libc/stdlib/tfind.c,v 1.5 2003/01/05 02:43:18 tjr Exp $
13 * $DragonFly: src/lib/libc/stdlib/tsearch.c,v 1.6 2005/11/24 17:18:30 swildner Exp $
14 */
15
16 #define _SEARCH_PRIVATE
17 #include <stdlib.h>
18 #include <search.h>
19
20 /*
21 * find a node, or return 0
22 *
23 * Parameters:
24 * vkey: key to be found
25 * vrootp: address of the tree root
26 */
27 void *
tfind(const void * vkey,void * const * vrootp,int (* compar)(const void *,const void *))28 tfind(const void *vkey, void * const *vrootp,
29 int (*compar)(const void *, const void *))
30 {
31 node_t **rootp = (node_t **)vrootp;
32
33 if (rootp == NULL)
34 return NULL;
35
36 while (*rootp != NULL) { /* T1: */
37 int r;
38
39 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
40 return *rootp; /* key found */
41 rootp = (r < 0) ?
42 &(*rootp)->llink : /* T3: follow left branch */
43 &(*rootp)->rlink; /* T4: follow right branch */
44 }
45 return NULL;
46 }
47