2 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
3 * the AT&T man page says.
5 * The node_t structure is for internal use only, lint doesn't grok it.
7 * Written by reading the System V Interface Definition, not the code.
9 * Totally public domain.
11 * $NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $
12 * $FreeBSD: src/lib/libc/stdlib/tsearch.c,v 1.1.2.1 2000/08/17 07:38:39 jhb Exp $
13 * $DragonFly: src/lib/libc/stdlib/tsearch.c,v 1.3 2003/09/06 08:19:16 asmodai Exp $
16 #include <sys/cdefs.h>
19 #define _SEARCH_PRIVATE
23 /* find or insert datum into search tree */
25 tsearch(vkey, vrootp, compar)
26 const void *vkey; /* key to be located */
27 void **vrootp; /* address of tree root */
28 int (*compar) (const void *, const void *);
31 node_t **rootp = (node_t **)vrootp;
36 while (*rootp != NULL) { /* Knuth's T1: */
39 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
40 return *rootp; /* we found it! */
43 &(*rootp)->llink : /* T3: follow left branch */
44 &(*rootp)->rlink; /* T4: follow right branch */
47 q = malloc(sizeof(node_t)); /* T5: key not found */
48 if (q != 0) { /* make new node */
49 *rootp = q; /* link new node to old */
50 /* LINTED const castaway ok */
51 q->key = (void *)vkey; /* initialize new node */
52 q->llink = q->rlink = NULL;