1/* $NetBSD: tfind.c,v 1.6 2011/05/18 19:36:36 dsl Exp $ */ 2 3/* 4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like 5 * the AT&T man page says. 6 * 7 * The node_t structure is for internal use only, lint doesn't grok it. 8 * 9 * Written by reading the System V Interface Definition, not the code. 10 * 11 * Totally public domain. 12 */ 13 14#include <sys/cdefs.h> 15#if defined(LIBC_SCCS) && !defined(lint) 16__RCSID("$NetBSD: tfind.c,v 1.6 2011/05/18 19:36:36 dsl Exp $"); 17#endif /* LIBC_SCCS and not lint */ 18 19#include <assert.h> 20#define _SEARCH_PRIVATE 21#include <stdlib.h> 22#include <search.h> 23 24/* find a node by key "vkey" in tree "vrootp", or return 0 */ 25void * 26tfind(const void *vkey, void * const *vrootp, 27 int (*compar)(const void *, const void *)) 28{ 29 node_t * const *rootp = (node_t * const*)vrootp; 30 31 _DIAGASSERT(vkey != NULL); 32 _DIAGASSERT(compar != NULL); 33 34 if (rootp == NULL) 35 return NULL; 36 37 while (*rootp != NULL) { /* T1: */ 38 int r; 39 40 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 41 return *rootp; /* key found */ 42 rootp = (r < 0) ? 43 &(*rootp)->llink : /* T3: follow left branch */ 44 &(*rootp)->rlink; /* T4: follow right branch */ 45 } 46 return NULL; 47} 48