1/* $NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem 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 0
16#if defined(LIBC_SCCS) && !defined(lint)
17__RCSID("$NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $");
18#endif /* LIBC_SCCS and not lint */
19#endif
20__FBSDID("$FreeBSD: head/lib/libc/stdlib/tsearch.c 92986 2002-03-22 21:53:29Z obrien $");
21
22#include <assert.h>
23#define _SEARCH_PRIVATE
24#include <search.h>
25#include <stdlib.h>
26
27/* find or insert datum into search tree */
28void *
29tsearch(vkey, vrootp, compar)
30 const void *vkey; /* key to be located */
31 void **vrootp; /* address of tree root */
32 int (*compar)(const void *, const void *);
33{
34 node_t *q;
35 node_t **rootp = (node_t **)vrootp;
36
37 if (rootp == NULL)
38 return NULL;
39
40 while (*rootp != NULL) { /* Knuth's T1: */
41 int r;
42
43 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
44 return *rootp; /* we found it! */
45
46 rootp = (r < 0) ?
47 &(*rootp)->llink : /* T3: follow left branch */
48 &(*rootp)->rlink; /* T4: follow right branch */
49 }
50
51 q = malloc(sizeof(node_t)); /* T5: key not found */
52 if (q != 0) { /* make new node */
53 *rootp = q; /* link new node to old */
54 /* LINTED const castaway ok */
55 q->key = (void *)vkey; /* initialize new node */
56 q->llink = q->rlink = NULL;
57 }
58 return q;
59}