1 /* $NetBSD: tfind.c,v 1.7 2012/06/25 22:32:45 abs Exp $ */
2
3 /*
4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
5 * the AT&T man page says.
6 *
7 * The node_t structure is for internal use only, lint doesn't grok it.
8 *
9 * Written by reading the System V Interface Definition, not the code.
10 *
11 * Totally public domain.
12 */
13
14 #include <sys/cdefs.h>
15 #if defined(LIBC_SCCS) && !defined(lint)
16 __RCSID("$NetBSD: tfind.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
17 #endif /* LIBC_SCCS and not lint */
18
19 #include <assert.h>
20 #define _SEARCH_PRIVATE
21 #include <stdlib.h>
22 #include <search.h>
23
24 /* find a node by key "vkey" in tree "vrootp", or return 0 */
25 void *
tfind(const void * vkey,void * const * vrootp,int (* compar)(const void *,const void *))26 tfind(const void *vkey, void * const *vrootp,
27 int (*compar)(const void *, const void *))
28 {
29 node_t * const *rootp = (node_t * const*)vrootp;
30
31 _DIAGASSERT(vkey != NULL);
32 _DIAGASSERT(compar != NULL);
33
34 if (rootp == NULL)
35 return NULL;
36
37 while (*rootp != NULL) { /* T1: */
38 int r;
39
40 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
41 return *rootp; /* key found */
42 rootp = (r < 0) ?
43 &(*rootp)->llink : /* T3: follow left branch */
44 &(*rootp)->rlink; /* T4: follow right branch */
45 }
46 return NULL;
47 }
48