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/* Test of splitting a double into fraction and mantissa.
Copyright (C) 2007-2009 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 <http://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
#include <config.h>
#include <math.h>
#include "signature.h"
SIGNATURE_CHECK (frexp, double, (double, int *));
#include <float.h>
#include "isnand-nolibm.h"
#include "nan.h"
#include "macros.h"
/* Avoid some warnings from "gcc -Wshadow".
This file doesn't use the exp() function. */
#undef exp
#define exp exponent
/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
So we use -zero instead. */
double zero = 0.0;
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;
{ /* NaN. */
int exp = -9999;
double mantissa;
x = NaNd ();
mantissa = frexp (x, &exp);
ASSERT (isnand (mantissa));
}
{ /* Positive infinity. */
int exp = -9999;
double mantissa;
x = 1.0 / 0.0;
mantissa = frexp (x, &exp);
ASSERT (mantissa == x);
}
{ /* Negative infinity. */
int exp = -9999;
double mantissa;
x = -1.0 / 0.0;
mantissa = frexp (x, &exp);
ASSERT (mantissa == x);
}
{ /* Positive zero. */
int exp = -9999;
double mantissa;
x = 0.0;
mantissa = frexp (x, &exp);
ASSERT (exp == 0);
ASSERT (mantissa == x);
ASSERT (!signbit (mantissa));
}
{ /* Negative zero. */
int exp = -9999;
double mantissa;
x = -zero;
mantissa = frexp (x, &exp);
ASSERT (exp == 0);
ASSERT (mantissa == x);
ASSERT (signbit (mantissa));
}
for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.5);
}
for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.5);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.5);
}
for (i = 1, x = -1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == -0.5);
}
for (i = 1, x = -1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == -0.5);
}
for (; i >= DBL_MIN_EXP - 100 && x < 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == -0.5);
}
for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.505);
}
for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.505);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa >= 0.5);
ASSERT (mantissa < 1.0);
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 = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.866025);
}
for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i);
ASSERT (mantissa == 0.866025);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = frexp (x, &exp);
ASSERT (exp == i || exp == i + 1);
ASSERT (mantissa >= 0.5);
ASSERT (mantissa < 1.0);
ASSERT (mantissa == my_ldexp (x, - exp));
}
return 0;
}
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