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/* Test of splitting a double into fraction and mantissa.
Copyright (C) 2007-2022 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
#include <config.h>
#include "printf-frexp.h"
#include <float.h>
#include "macros.h"
static double
my_ldexp (double x, int d)
{
for (; d > 0; d--)
x *= 2.0;
for (; d < 0; d++)
x *= 0.5;
return x;
}
int
main ()
{
int i;
/* The use of 'volatile' guarantees that excess precision bits are dropped
when dealing with denormalized numbers. It is necessary on x86 systems
where double-floats are not IEEE compliant by default, to avoid that the
results become platform and compiler option dependent. 'volatile' is a
portable alternative to gcc's -ffloat-store option. */
volatile double x;
for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.0);
}
for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.0);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == DBL_MIN_EXP - 1);
ASSERT (mantissa == my_ldexp (1.0, i - DBL_MIN_EXP));
}
for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.01);
}
for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.01);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == DBL_MIN_EXP - 1);
ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
ASSERT (mantissa == my_ldexp (x, - exp));
}
for (i = 1, x = 1.73205; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.73205);
}
for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.73205);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == DBL_MIN_EXP - 1);
ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
ASSERT (mantissa == my_ldexp (x, - exp));
}
return 0;
}
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