164566a3eSAlfred Perlstein /* $NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $ */ 264566a3eSAlfred Perlstein /* $FreeBSD$ */ 364566a3eSAlfred Perlstein 464566a3eSAlfred Perlstein /* 564566a3eSAlfred Perlstein * Tree search generalized from Knuth (6.2.2) Algorithm T just like 664566a3eSAlfred Perlstein * the AT&T man page says. 764566a3eSAlfred Perlstein * 864566a3eSAlfred Perlstein * The node_t structure is for internal use only, lint doesn't grok it. 964566a3eSAlfred Perlstein * 1064566a3eSAlfred Perlstein * Written by reading the System V Interface Definition, not the code. 1164566a3eSAlfred Perlstein * 1264566a3eSAlfred Perlstein * Totally public domain. 1364566a3eSAlfred Perlstein */ 1464566a3eSAlfred Perlstein 1564566a3eSAlfred Perlstein #include <sys/cdefs.h> 1664566a3eSAlfred Perlstein #if defined(LIBC_SCCS) && !defined(lint) 1764566a3eSAlfred Perlstein __RCSID("$NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $"); 1864566a3eSAlfred Perlstein #endif /* LIBC_SCCS and not lint */ 1964566a3eSAlfred Perlstein 2064566a3eSAlfred Perlstein #include <assert.h> 2164566a3eSAlfred Perlstein #define _SEARCH_PRIVATE 2264566a3eSAlfred Perlstein #include <stdlib.h> 2364566a3eSAlfred Perlstein #include <search.h> 2464566a3eSAlfred Perlstein 2564566a3eSAlfred Perlstein /* find a node, or return 0 */ 2664566a3eSAlfred Perlstein void * 2764566a3eSAlfred Perlstein tfind(vkey, vrootp, compar) 2864566a3eSAlfred Perlstein const void *vkey; /* key to be found */ 2964566a3eSAlfred Perlstein void **vrootp; /* address of the tree root */ 3064566a3eSAlfred Perlstein int (*compar) __P((const void *, const void *)); 3164566a3eSAlfred Perlstein { 3264566a3eSAlfred Perlstein node_t **rootp = (node_t **)vrootp; 3364566a3eSAlfred Perlstein 3464566a3eSAlfred Perlstein if (rootp == NULL) 3564566a3eSAlfred Perlstein return NULL; 3664566a3eSAlfred Perlstein 3764566a3eSAlfred Perlstein while (*rootp != NULL) { /* T1: */ 3864566a3eSAlfred Perlstein int r; 3964566a3eSAlfred Perlstein 4064566a3eSAlfred Perlstein if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 4164566a3eSAlfred Perlstein return *rootp; /* key found */ 4264566a3eSAlfred Perlstein rootp = (r < 0) ? 4364566a3eSAlfred Perlstein &(*rootp)->llink : /* T3: follow left branch */ 4464566a3eSAlfred Perlstein &(*rootp)->rlink; /* T4: follow right branch */ 4564566a3eSAlfred Perlstein } 4664566a3eSAlfred Perlstein return NULL; 4764566a3eSAlfred Perlstein } 48