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/* $NetBSD: strpct.c,v 1.3 2012/01/07 18:40:56 christos 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.
*
* 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 <stdint.h>
#include <locale.h>
#include <limits.h>
#include <stdio.h>
#include <errno.h>
#include "strpct.h"
char *
strspct(char *buf, size_t bufsiz, intmax_t numerator, intmax_t denominator,
size_t digits)
{
int sign;
switch (bufsiz) {
case 1:
*buf = '\0';
/*FALLTHROUGH*/
case 0:
return buf;
default:
break;
}
if (denominator < 0) {
denominator = -denominator;
sign = 1;
} else
sign = 0;
if (numerator < 0) {
numerator = -numerator;
sign++;
}
sign &= 1;
(void)strpct(buf + sign, bufsiz - sign, (uintmax_t)numerator,
(uintmax_t)denominator, digits);
if (sign)
*buf = '-';
return buf;
}
char *
strpct(char *buf, size_t bufsiz, uintmax_t numerator, uintmax_t denominator,
size_t digits)
{
uintmax_t factor, result;
size_t u;
factor = 100;
for (u = 0; u < digits; u++) {
/* watch out for overflow! */
if (factor < (UINTMAX_MAX / 10))
factor *= 10;
else
break;
}
/* watch out for overflow! */
if (numerator < (UINTMAX_MAX / factor))
numerator *= factor;
else {
/* toss some of the bits of lesser significance */
denominator /= factor;
}
if (denominator == 0)
denominator = 1;
result = numerator / denominator;
if (digits == 0)
(void)snprintf(buf, bufsiz, "%ju", result);
else {
factor /= 100; /* undo initialization */
(void)snprintf(buf, bufsiz, "%ju%s%0*ju",
result / factor, localeconv()->decimal_point, (int)u,
result % factor);
}
return buf;
}
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