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 <search.h> 23 #include <stdlib.h> 24 25 /* find or insert datum into search tree */ 26 void * 27 tsearch(vkey, vrootp, compar) 28 const void *vkey; /* key to be located */ 29 void **vrootp; /* address of tree root */ 30 int (*compar) __P((const void *, const void *)); 31 { 32 node_t *q; 33 node_t **rootp = (node_t **)vrootp; 34 35 if (rootp == NULL) 36 return NULL; 37 38 while (*rootp != NULL) { /* Knuth's T1: */ 39 int r; 40 41 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 42 return *rootp; /* we found it! */ 43 44 rootp = (r < 0) ? 45 &(*rootp)->llink : /* T3: follow left branch */ 46 &(*rootp)->rlink; /* T4: follow right branch */ 47 } 48 49 q = malloc(sizeof(node_t)); /* T5: key not found */ 50 if (q != 0) { /* make new node */ 51 *rootp = q; /* link new node to old */ 52 /* LINTED const castaway ok */ 53 q->key = (void *)vkey; /* initialize new node */ 54 q->llink = q->rlink = NULL; 55 } 56 return q; 57 } 58