1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1988 AT&T	*/
28/*	  All Rights Reserved  	*/
29
30#pragma ident	"%Z%%M%	%I%	%E% SMI"
31
32/*
33 * Binary search algorithm, generalized from Knuth (6.2.1) Algorithm B.
34 */
35
36#if !defined(_BOOT) && !defined(_KMDB)
37#include "lint.h"
38#endif /* !_BOOT && !_KMDB */
39#include <stddef.h>
40#include <stdlib.h>
41#include <sys/types.h>
42
43void *
44bsearch(const void *ky,		/* Key to be located */
45	const void *bs,		/* Beginning of table */
46	size_t nel,		/* Number of elements in the table */
47	size_t width,		/* Width of an element (bytes) */
48	int (*compar)(const void *, const void *)) /* Comparison function */
49{
50	char *base;
51	size_t two_width;
52	char *last;		/* Last element in table */
53
54	if (nel == 0)
55		return (NULL);
56
57	base = (char *)bs;
58	two_width = width + width;
59	last = base + width * (nel - 1);
60
61	while (last >= base) {
62
63		char *p = base + width * ((last - base)/two_width);
64		int res = (*compar)(ky, (void *)p);
65
66		if (res == 0)
67			return (p);	/* Key found */
68		if (res < 0)
69			last = p - width;
70		else
71			base = p + width;
72	}
73	return (NULL);		/* Key not found */
74}
75