94 lines
2.9 KiB
C
94 lines
2.9 KiB
C
/* $NetBSD: strpct.c,v 1.8 2009/02/13 00:46:25 abs 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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*
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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/cdefs.h>
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__RCSID("$NetBSD: strpct.c,v 1.8 2009/02/13 00:46:25 abs Exp $");
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#include <sys/types.h>
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#include <limits.h>
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#include <stdio.h>
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char *strpct(u_long, u_long, u_int);
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char *
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strpct(u_long numerator, u_long denominator, u_int digits)
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{
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static char percent[32];
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u_long factor, result;
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u_int u;
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/* I should check for digit overflow here, too XXX */
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factor = 100L;
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for (u = 0; u < digits; u++) {
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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), fmt, result / factor,
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result % factor);
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}
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return (percent);
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}
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