1 /* $NetBSD: tsearch.c,v 1.5 2005/11/29 03:12:00 christos Exp $ */
4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
5 * the AT&T man page says.
7 * The node_t structure is for internal use only, lint doesn't grok it.
9 * Written by reading the System V Interface Definition, not the code.
11 * Totally public domain.
14 #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;
34 assert(compar != NULL);
39 while (*rootp != NULL) { /* Knuth's T1: */
42 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
43 return *rootp; /* we found it! */
46 &(*rootp)->llink : /* T3: follow left branch */
47 &(*rootp)->rlink; /* T4: follow right branch */
50 q = malloc(sizeof(node_t)); /* T5: key not found */
51 if (q != 0) { /* make new node */
52 *rootp = q; /* link new node to old */
53 q->key = (void*)vkey; /* initialize new node */
54 q->llink = q->rlink = NULL;