132 lines
3.9 KiB
C
132 lines
3.9 KiB
C
/* Test of splitting a double into fraction and mantissa.
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Copyright (C) 2007-2008 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program 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. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
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#include <config.h>
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#include "printf-frexp.h"
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#include <float.h>
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#include <stdio.h>
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#include <stdlib.h>
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#define ASSERT(expr) \
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do \
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{ \
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if (!(expr)) \
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{ \
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fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
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fflush (stderr); \
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abort (); \
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} \
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} \
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while (0)
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static double
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my_ldexp (double x, int d)
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{
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for (; d > 0; d--)
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x *= 2.0;
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for (; d < 0; d++)
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x *= 0.5;
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return x;
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}
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int
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main ()
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{
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int i;
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/* The use of 'volatile' guarantees that excess precision bits are dropped
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when dealing with denormalized numbers. It is necessary on x86 systems
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where double-floats are not IEEE compliant by default, to avoid that the
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results become platform and compiler option dependent. 'volatile' is a
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portable alternative to gcc's -ffloat-store option. */
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volatile double x;
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for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == i - 1);
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ASSERT (mantissa == 1.0);
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}
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for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == i - 1);
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ASSERT (mantissa == 1.0);
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}
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for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == DBL_MIN_EXP - 1);
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ASSERT (mantissa == my_ldexp (1.0, i - DBL_MIN_EXP));
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}
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for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == i - 1);
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ASSERT (mantissa == 1.01);
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}
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for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == i - 1);
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ASSERT (mantissa == 1.01);
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}
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for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == DBL_MIN_EXP - 1);
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ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
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ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
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ASSERT (mantissa == my_ldexp (x, - exp));
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}
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for (i = 1, x = 1.73205; i <= DBL_MAX_EXP; i++, x *= 2.0)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == i - 1);
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ASSERT (mantissa == 1.73205);
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}
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for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == i - 1);
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ASSERT (mantissa == 1.73205);
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}
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for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
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{
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int exp = -9999;
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double mantissa = printf_frexp (x, &exp);
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ASSERT (exp == DBL_MIN_EXP - 1);
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ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
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ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
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ASSERT (mantissa == my_ldexp (x, - exp));
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}
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return 0;
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}
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