/*
* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* The contents of this file constitute Original Code as defined in and
* are subject to the Apple Public Source License Version 1.1 (the
* "License"). You may not use this file except in compliance with the
* License. Please obtain a copy of the License at
* http://www.apple.com/publicsource and read it before using this file.
*
* This Original Code and all software distributed under the License are
* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
* License for the specific language governing rights and limitations
* under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
/*
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bsearch.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include
/*
* Perform a binary search.
*
* The code below is a bit sneaky. After a comparison fails, we
* divide the work in half by moving either left or right. If lim
* is odd, moving left simply involves halving lim: e.g., when lim
* is 5 we look at item 2, so we change lim to 2 so that we will
* look at items 0 & 1. If lim is even, the same applies. If lim
* is odd, moving right again involes halving lim, this time moving
* the base up one item past p: e.g., when lim is 5 we change base
* to item 3 and make lim 2 so that we will look at items 3 and 4.
* If lim is even, however, we have to shrink it by one before
* halving: e.g., when lim is 4, we still looked at item 2, so we
* have to make lim 3, then halve, obtaining 1, so that we will only
* look at item 3.
*/
__private_extern__
void * bsearch(
register const void *key,
const void *base0,
size_t nmemb,
register size_t size,
register int (*compar)(const void *, const void *)) {
register const char *base = base0;
register size_t lim;
register int cmp;
register const void *p;
for (lim = nmemb; lim != 0; lim >>= 1) {
p = base + (lim >> 1) * size;
cmp = (*compar)(key, p);
if (cmp == 0)
return ((void *)p);
if (cmp > 0) { /* key > p: move right */
base = (char *)p + size;
lim--;
} /* else move left */
}
return (NULL);
}