fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
80 lines
3.1 KiB
C
80 lines
3.1 KiB
C
/*-
|
|
* 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. 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 <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/libkern.h>
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
void *
|
|
bsearch(key, base0, nmemb, size, compar)
|
|
const void *key;
|
|
const void *base0;
|
|
size_t nmemb;
|
|
size_t size;
|
|
int (*compar)(const void *, const void *);
|
|
{
|
|
const char *base = base0;
|
|
size_t lim;
|
|
int cmp;
|
|
const void *p;
|
|
|
|
for (lim = nmemb; lim != 0; lim >>= 1) {
|
|
p = base + (lim >> 1) * size;
|
|
cmp = (*compar)(key, p);
|
|
if (cmp == 0)
|
|
return ((void *)(uintptr_t)p);
|
|
if (cmp > 0) { /* key > p: move right */
|
|
base = (const char *)p + size;
|
|
lim--;
|
|
} /* else move left */
|
|
}
|
|
return (NULL);
|
|
}
|