/* * 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. */#include <stddef.h>#include <stdlib.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 *)p); if (cmp > 0) { /* key > p: move right */ base = (char *)p + size; lim--; } /* else move left */ } return (NULL);}
/*
* 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.
*/
#include <stddef.h>
#include <stdlib.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 *)p);
if (cmp > 0) { /* key > p: move right */
base = (char *)p + size;
lim--;
} /* else move left */
}
return (NULL);
}