99 lines
2.3 KiB
C
99 lines
2.3 KiB
C
/* ****************************************************************************
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* bcd/double.c -- make a libcasio BCD out of a double.
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* Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
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*
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* This file is part of libcasio.
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* libcasio is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3.0 of the License,
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* or (at your option) any later version.
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*
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* libcasio is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with libcasio; if not, see <http://www.gnu.org/licenses/>.
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* ************************************************************************* */
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#include "../internals.h"
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#include <math.h>
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/**
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* casio_bcd_fromdouble:
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* Make a libcasio BCD number out of a C-double.
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*
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* @arg bcd the BCD to make.
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* @arg dbl the source double.
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*/
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void CASIO_EXPORT casio_bcd_fromdouble(casio_bcd_t *bcd, double dbl)
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{
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int neg = 0, exp = 1, i;
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/* Check if is negative. */
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if (dbl < 0) {
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neg = 1;
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dbl = -dbl;
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}
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/* Check the exponent, normalize the number. */
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while (dbl >= 10) {
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exp++;
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dbl /= 10;
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}
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if (dbl > 0) while (dbl < 1) {
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exp--;
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dbl *= 10;
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}
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/* Get the mantissa. */
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for (i = 0; i < 15; i++) {
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double work = floor(dbl);
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bcd->casio_bcd_mant[i] = (int)work;
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dbl = (dbl - work) * 10;
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}
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/* Set the flags */
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bcd->casio_bcd_flags = casio_make_bcdflags(0, neg, 15);
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bcd->casio_bcd_exp = exp;
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}
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/**
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* casio_bcd_todouble:
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* Make a C-double out of a libcasio BCD number.
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*
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* @arg bcd the BCD to convert.
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* @return the double.
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*/
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double CASIO_EXPORT casio_bcd_todouble(casio_bcd_t const *bcd)
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{
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double val = 0.0;
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double power = 1.0;
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int i;
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/* Use the mantissa. */
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for (i = 0; i < casio_bcd_precision(bcd); i++) {
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val += bcd->casio_bcd_mant[i] * power;
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power /= 10.0;
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}
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/* Use the exponent. */
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power = pow(10, (double)bcd->casio_bcd_exp);
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val *= power;
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/* Use the flags. */
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if (casio_bcd_is_negative(bcd))
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val = -val;
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return (val);
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}
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