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 1.5 2003/01/05 02:43:18 tjr Exp $ 13 * $DragonFly: src/lib/libc/stdlib/tsearch.c,v 1.6 2005/11/24 17:18:30 swildner Exp $ 14 */ 15 16 #define _SEARCH_PRIVATE 17 #include <stdlib.h> 18 #include <search.h> 19 20 /* 21 * find a node, or return 0 22 * 23 * Parameters: 24 * vkey: key to be found 25 * vrootp: address of the tree root 26 */ 27 void * 28 tfind(const void *vkey, void * const *vrootp, 29 int (*compar)(const void *, const void *)) 30 { 31 node_t **rootp = (node_t **)vrootp; 32 33 if (rootp == NULL) 34 return NULL; 35 36 while (*rootp != NULL) { /* T1: */ 37 int r; 38 39 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 40 return *rootp; /* key found */ 41 rootp = (r < 0) ? 42 &(*rootp)->llink : /* T3: follow left branch */ 43 &(*rootp)->rlink; /* T4: follow right branch */ 44 } 45 return NULL; 46 } 47