/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

/*
 * Binary search algorithm, generalized from Knuth (6.2.1) Algorithm B.
 */

#if !defined(_BOOT) && !defined(_KMDB)
#include "lint.h"
#endif /* !_BOOT && !_KMDB */
#include <stddef.h>
#include <stdlib.h>
#include <sys/types.h>

void *
bsearch(const void *ky,         /* Key to be located */
        const void *bs,         /* Beginning of table */
        size_t nel,             /* Number of elements in the table */
        size_t width,           /* Width of an element (bytes) */
        int (*compar)(const void *, const void *)) /* Comparison function */
{
        char *base;
        size_t two_width;
        char *last;             /* Last element in table */

        if (nel == 0)
                return (NULL);

        base = (char *)bs;
        two_width = width + width;
        last = base + width * (nel - 1);

        while (last >= base) {

                char *p = base + width * ((last - base)/two_width);
                int res = (*compar)(ky, (void *)p);

                if (res == 0)
                        return (p);     /* Key found */
                if (res < 0)
                        last = p - width;
                else
                        base = p + width;
        }
        return (NULL);          /* Key not found */
}