/* Test of splitting a double into fraction and mantissa.
   Copyright (C) 2007 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 2, 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, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */

#include <config.h>

#include <math.h>

#include <float.h>
#include <stdio.h>
#include <stdlib.h>

#include "isnan.h"

#define ASSERT(expr) \
  do									     \
    {									     \
      if (!(expr))							     \
        {								     \
          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
          abort ();							     \
        }								     \
    }									     \
  while (0)

/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
#ifdef __DECC
static double
NaN ()
{
  static double zero = 0.0;
  return zero / zero;
}
#else
# define NaN() (0.0 / 0.0)
#endif

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 = NaN ();
    mantissa = frexp (x, &exp);
    ASSERT (isnan (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 = -0.0;
    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;
}