1 /* 2 * Tree search generalized from Knuth (6.2.2) Algorithm T just like 3 * the AT&T man page says. 4 * 5 * The node_t structure is for internal use only, lint doesn't grok it. 6 * 7 * Written by reading the System V Interface Definition, not the code. 8 * 9 * Totally public domain. 10 * 11 * $NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $ 12 * $FreeBSD: src/lib/libc/stdlib/tfind.c,v 1.1.2.1 2000/08/17 07:38:39 jhb Exp $ 13 * $DragonFly: src/lib/libc/stdlib/tfind.c,v 1.4 2005/11/20 12:37:49 swildner Exp $ 14 */ 15 16 #include <sys/cdefs.h> 17 18 #include <assert.h> 19 #define _SEARCH_PRIVATE 20 #include <stdlib.h> 21 #include <search.h> 22 23 /* find a node, or return 0 */ 24 void * 25 tfind(const void *vkey, /* key to be found */ 26 void **vrootp, /* address of the tree root */ 27 int (*compar)(const void *, const void *)) 28 { 29 node_t **rootp = (node_t **)vrootp; 30 31 if (rootp == NULL) 32 return NULL; 33 34 while (*rootp != NULL) { /* T1: */ 35 int r; 36 37 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 38 return *rootp; /* key found */ 39 rootp = (r < 0) ? 40 &(*rootp)->llink : /* T3: follow left branch */ 41 &(*rootp)->rlink; /* T4: follow right branch */ 42 } 43 return NULL; 44 } 45