freebsd-skq/lib/libc/stdlib/tfind.c

/*	$NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $	*/

/*
 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
 * the AT&T man page says.
 *
 * Written by reading the System V Interface Definition, not the code.
 *
 * Totally public domain.
 */

#include <sys/cdefs.h>
#if 0
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
#endif /* LIBC_SCCS and not lint */
#endif
__FBSDID("$FreeBSD$");

#define _SEARCH_PRIVATE
#include <stdlib.h>
#include <search.h>

/* 
 * find a node, or return 0
 *
 * vkey   - key to be found 
 * vrootp - address of the tree root 
 */
posix_tnode *
tfind(const void *vkey, posix_tnode * const *rootp,
    int (*compar)(const void *, const void *))
{

	if (rootp == NULL)
		return NULL;

	while (*rootp != NULL) {		/* T1: */
		int r;

		if ((r = (*compar)(vkey, (*rootp)->key)) == 0)	/* T2: */
			return *rootp;		/* key found */
		rootp = (r < 0) ?
		    &(*rootp)->llink :		/* T3: follow left branch */
		    &(*rootp)->rlink;		/* T4: follow right branch */
	}
	return NULL;
}