17c478bdstevel@tonic-gate/*
27c478bdstevel@tonic-gate * CDDL HEADER START
37c478bdstevel@tonic-gate *
47c478bdstevel@tonic-gate * The contents of this file are subject to the terms of the
5ba5f51dat * Common Development and Distribution License (the "License").
6ba5f51dat * You may not use this file except in compliance with the License.
77c478bdstevel@tonic-gate *
87c478bdstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
97c478bdstevel@tonic-gate * or http://www.opensolaris.org/os/licensing.
107c478bdstevel@tonic-gate * See the License for the specific language governing permissions
117c478bdstevel@tonic-gate * and limitations under the License.
127c478bdstevel@tonic-gate *
137c478bdstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each
147c478bdstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
157c478bdstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the
167c478bdstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying
177c478bdstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner]
187c478bdstevel@tonic-gate *
197c478bdstevel@tonic-gate * CDDL HEADER END
207c478bdstevel@tonic-gate */
217c478bdstevel@tonic-gate
227c478bdstevel@tonic-gate/*
237257d1braf * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
247c478bdstevel@tonic-gate * Use is subject to license terms.
257c478bdstevel@tonic-gate */
267c478bdstevel@tonic-gate
277257d1braf/*	Copyright (c) 1988 AT&T	*/
287257d1braf/*	  All Rights Reserved  	*/
297257d1braf
307c478bdstevel@tonic-gate#pragma ident	"%Z%%M%	%I%	%E% SMI"
317c478bdstevel@tonic-gate
327c478bdstevel@tonic-gate/*
337c478bdstevel@tonic-gate * Binary search algorithm, generalized from Knuth (6.2.1) Algorithm B.
347c478bdstevel@tonic-gate */
357c478bdstevel@tonic-gate
367c478bdstevel@tonic-gate#if !defined(_BOOT) && !defined(_KMDB)
377257d1braf#include "lint.h"
387c478bdstevel@tonic-gate#endif /* !_BOOT && !_KMDB */
397c478bdstevel@tonic-gate#include <stddef.h>
407c478bdstevel@tonic-gate#include <stdlib.h>
417c478bdstevel@tonic-gate#include <sys/types.h>
427c478bdstevel@tonic-gate
437c478bdstevel@tonic-gatevoid *
447c478bdstevel@tonic-gatebsearch(const void *ky,		/* Key to be located */
457c478bdstevel@tonic-gate	const void *bs,		/* Beginning of table */
467c478bdstevel@tonic-gate	size_t nel,		/* Number of elements in the table */
477c478bdstevel@tonic-gate	size_t width,		/* Width of an element (bytes) */
487c478bdstevel@tonic-gate	int (*compar)(const void *, const void *)) /* Comparison function */
497c478bdstevel@tonic-gate{
507c478bdstevel@tonic-gate	char *base;
51ba5f51dat	size_t two_width;
527c478bdstevel@tonic-gate	char *last;		/* Last element in table */
537c478bdstevel@tonic-gate
547c478bdstevel@tonic-gate	if (nel == 0)
557c478bdstevel@tonic-gate		return (NULL);
567c478bdstevel@tonic-gate
577c478bdstevel@tonic-gate	base = (char *)bs;
587c478bdstevel@tonic-gate	two_width = width + width;
597c478bdstevel@tonic-gate	last = base + width * (nel - 1);
607c478bdstevel@tonic-gate
617c478bdstevel@tonic-gate	while (last >= base) {
627c478bdstevel@tonic-gate
637c478bdstevel@tonic-gate		char *p = base + width * ((last - base)/two_width);
647c478bdstevel@tonic-gate		int res = (*compar)(ky, (void *)p);
657c478bdstevel@tonic-gate
667c478bdstevel@tonic-gate		if (res == 0)
677c478bdstevel@tonic-gate			return (p);	/* Key found */
687c478bdstevel@tonic-gate		if (res < 0)
697c478bdstevel@tonic-gate			last = p - width;
707c478bdstevel@tonic-gate		else
717c478bdstevel@tonic-gate			base = p + width;
727c478bdstevel@tonic-gate	}
737c478bdstevel@tonic-gate	return (NULL);		/* Key not found */
747c478bdstevel@tonic-gate}
75