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/* $NetBSD: strpct.c,v 1.2 1998/05/08 18:43:54 fair Exp $ */
/*-
* Copyright (c) 1998 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Erik E. Fair
*
* 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 NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* Calculate a percentage without resorting to floating point
* and return a pointer to a string
*
* "digits" is the number of digits past the decimal place you want
* (zero being the straight percentage with no decimals)
*
* Erik E. Fair <fair@clock.org>, May 8, 1997
*/
#include <sys/types.h>
#include <machine/limits.h>
#include <stdio.h>
char * strpct __P((u_long, u_long, u_int));
char *
strpct(numerator, denominator, digits)
u_long numerator, denominator;
u_int digits;
{
int i;
u_long result, factor;
static char percent[32];
/* I should check for digit overflow here, too XXX */
factor = 100L;
for(i = 0; i < digits; i++) {
factor *= 10;
}
/* watch out for overflow! */
if (numerator < (ULONG_MAX / factor)) {
numerator *= factor;
} else {
/* toss some of the bits of lesser significance */
denominator /= factor;
}
if (denominator == 0L)
denominator = 1L;
result = numerator / denominator;
if (digits == 0) {
(void) snprintf(percent, sizeof(percent), "%lu%%", result);
} else {
char fmt[32];
/* indirection to produce the right output format */
(void) snprintf(fmt, sizeof(fmt), "%%lu.%%0%ulu%%%%", digits);
factor /= 100L; /* undo initialization */
(void) snprintf(percent, sizeof(percent),
fmt, result / factor, result % factor);
}
return(percent);
}
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