bsearch.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (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 (c) 1988 AT&T */
/* All Rights Reserved */
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Binary search algorithm, generalized from Knuth (6.2.1) Algorithm B.
*/
#if !defined(_BOOT) && !defined(_KMDB)
#include "synonyms.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;
ssize_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 */
}