100 lines
3.6 KiB
C
100 lines
3.6 KiB
C
/* $NetBSD: strpct.c,v 1.2 1998/05/08 18:43:54 fair Exp $ */
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/*-
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* Copyright (c) 1998 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Erik E. Fair
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Calculate a percentage without resorting to floating point
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* and return a pointer to a string
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*
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* "digits" is the number of digits past the decimal place you want
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* (zero being the straight percentage with no decimals)
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*
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* Erik E. Fair <fair@clock.org>, May 8, 1997
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*/
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#include <sys/types.h>
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#include <machine/limits.h>
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#include <stdio.h>
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char * strpct __P((u_long, u_long, u_int));
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char *
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strpct(numerator, denominator, digits)
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u_long numerator, denominator;
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u_int digits;
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{
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int i;
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u_long result, factor;
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static char percent[32];
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/* I should check for digit overflow here, too XXX */
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factor = 100L;
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for(i = 0; i < digits; i++) {
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factor *= 10;
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}
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/* watch out for overflow! */
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if (numerator < (ULONG_MAX / factor)) {
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numerator *= factor;
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} else {
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/* toss some of the bits of lesser significance */
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denominator /= factor;
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}
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if (denominator == 0L)
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denominator = 1L;
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result = numerator / denominator;
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if (digits == 0) {
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(void) snprintf(percent, sizeof(percent), "%lu%%", result);
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} else {
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char fmt[32];
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/* indirection to produce the right output format */
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(void) snprintf(fmt, sizeof(fmt), "%%lu.%%0%ulu%%%%", digits);
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factor /= 100L; /* undo initialization */
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(void) snprintf(percent, sizeof(percent),
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fmt, result / factor, result % factor);
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}
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return(percent);
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}
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