1 /* $NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $ */
2 /* $FreeBSD: src/lib/libc/stdlib/tsearch.c,v 1.1.2.1 2000/08/17 07:38:39 jhb Exp $ */
3
4 /*
5 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
6 * the AT&T man page says.
7 *
8 * The node_t structure is for internal use only, lint doesn't grok it.
9 *
10 * Written by reading the System V Interface Definition, not the code.
11 *
12 * Totally public domain.
13 */
14
15 #include <sys/cdefs.h>
16 #if defined(LIBC_SCCS) && !defined(lint)
17 __RCSID("$NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $");
18 #endif /* LIBC_SCCS and not lint */
19
20 #include <assert.h>
21 #define _SEARCH_PRIVATE
22 #include "config.h"
23 #ifdef HAVE_SEARCH_H
24 # include <search.h>
25 #else
26 # include "search-freebsd.h"
27 #endif
28 #include <stdlib.h>
29
30 /* find or insert datum into search tree */
31 void *
tsearch(vkey,vrootp,compar)32 tsearch(vkey, vrootp, compar)
33 const void *vkey; /* key to be located */
34 void **vrootp; /* address of tree root */
35 int (*compar) __P((const void *, const void *));
36 {
37 node_t *q;
38 node_t **rootp = (node_t **)vrootp;
39
40 if (rootp == NULL)
41 return NULL;
42
43 while (*rootp != NULL) { /* Knuth's T1: */
44 int r;
45
46 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
47 return *rootp; /* we found it! */
48
49 rootp = (r < 0) ?
50 &(*rootp)->llink : /* T3: follow left branch */
51 &(*rootp)->rlink; /* T4: follow right branch */
52 }
53
54 q = malloc(sizeof(node_t)); /* T5: key not found */
55 if (q != 0) { /* make new node */
56 *rootp = q; /* link new node to old */
57 /* LINTED const castaway ok */
58 q->key = (void *)vkey; /* initialize new node */
59 q->llink = q->rlink = NULL;
60 }
61 return q;
62 }
63