GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libc/stdlib/bsearch.c Lines: 0 10 0.0 %
Date: 2017-11-13 Branches: 0 6 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: bsearch.c,v 1.8 2016/10/22 19:19:34 tb Exp $ */
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/*
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 * Copyright (c) 1990 Regents of the University of California.
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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#include <stdlib.h>
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/*
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 * Perform a binary search.
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 *
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 * The code below is a bit sneaky.  After a comparison fails, we
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 * divide the work in half by moving either left or right. If lim
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 * is odd, moving left simply involves halving lim: e.g., when lim
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 * is 5 we look at item 2, so we change lim to 2 so that we will
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 * look at items 0 & 1.  If lim is even, the same applies.  If lim
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 * is odd, moving right again involves halving lim, this time moving
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 * the base up one item past p: e.g., when lim is 5 we change base
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 * to item 3 and make lim 2 so that we will look at items 3 and 4.
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 * If lim is even, however, we have to shrink it by one before
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 * halving: e.g., when lim is 4, we still looked at item 2, so we
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 * have to make lim 3, then halve, obtaining 1, so that we will only
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 * look at item 3.
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 */
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void *
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bsearch(const void *key, const void *base0, size_t nmemb, size_t size,
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    int (*compar)(const void *, const void *))
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{
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	const char *base = base0;
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	int lim, cmp;
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	const void *p;
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	for (lim = nmemb; lim != 0; lim >>= 1) {
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		p = base + (lim >> 1) * size;
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		cmp = (*compar)(key, p);
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		if (cmp == 0)
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			return ((void *)p);
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		if (cmp > 0) {	/* key > p: move right */
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			base = (char *)p + size;
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			lim--;
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		} /* else move left */
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	}
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	return (NULL);
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}