1 /* $NetBSD: tfind.c,v 1.5 2005/03/23 08:16:53 kleink 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 1.5 2005/03/23 08:16:53 kleink 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, or return 0 */ 25 void * 26 tfind(vkey, vrootp, compar) 27 const void *vkey; /* key to be found */ 28 void * const *vrootp; /* address of the tree root */ 29 int (*compar) __P((const void *, const void *)); 30 { 31 node_t * const *rootp = (node_t * const*)vrootp; 32 33 _DIAGASSERT(vkey != NULL); 34 _DIAGASSERT(compar != NULL); 35 36 if (rootp == NULL) 37 return NULL; 38 39 while (*rootp != NULL) { /* T1: */ 40 int r; 41 42 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 43 return *rootp; /* key found */ 44 rootp = (r < 0) ? 45 &(*rootp)->llink : /* T3: follow left branch */ 46 &(*rootp)->rlink; /* T4: follow right branch */ 47 } 48 return NULL; 49 } 50