tget_d.c

a very popular packet of cryptography tools,it encloses the most common used algorithm and protocols

/* Test file for mpfr_get_d

Copyright 1999, 2000, 2001, 2002 Free Software Foundation.

This file is part of the MPFR Library.

The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.

The MPFR Library 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the MPFR Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

#include <stdio.h>
#include <stdlib.h>
#include <float.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "mpfr.h"
#include "mpfr-impl.h"
#include "mpfr-test.h"

int check_denorms _PROTO ((void));

int
check_denorms ()
{
  mp_rnd_t rnd_mode;
  mpfr_t x;
  double d, d2, dd, f;
  int fail = 0, k, n;

  mpfr_init2 (x, BITS_PER_MP_LIMB);

  for (rnd_mode = 0; rnd_mode <= 3; rnd_mode++)
    {
#ifdef MPFR_HAVE_FESETROUND
      mpfr_set_machine_rnd_mode (rnd_mode);
#else
      if (rnd_mode)
        break; /* second iteration */
      rnd_mode = GMP_RNDN;
#endif
      for (k = -17; k <= 17; k += 2)
        {
          d = k * DBL_MIN; /* k * 2^(-1022) */
          f = 1.0;
          mpfr_set_si (x, k, GMP_RNDN);
          mpfr_div_2exp (x, x, 1022, GMP_RNDN); /* k * 2^(-1022) */
          for (n = 0; n <= 58; n++)
            {
              d2 = d * f;
              dd = mpfr_get_d (x, rnd_mode);
              if (d2 != dd) /* should be k * 2^(-1022-n) for n < 53 */
                {
                  fprintf (stderr,
                           "Wrong result for %d * 2^(%d), rnd_mode %d\n",
                           k, -1022-n, rnd_mode);
                  fprintf (stderr, "got %.20e instead of %.20e\n", dd, d2);
                  fail = 1;
                }
              f *= 0.5;
              mpfr_div_2exp (x, x, 1, GMP_RNDN);
            }
        }
    }

  mpfr_clear (x);
  return fail;
}

int
main (void)
{

#ifdef MPFR_HAVE_FESETROUND

  mpfr_t half, x, y;
  mp_rnd_t rnd_mode;

#endif

  mpfr_test_init ();

#ifdef MPFR_HAVE_FESETROUND

  mpfr_init2(half, 2);
  mpfr_set_ui(half, 1, GMP_RNDZ);
  mpfr_div_2ui(half, half, 1, GMP_RNDZ); /* has exponent 0 */

  mpfr_init2(x, 128);
  mpfr_init2(y, 128);

  for (rnd_mode = 0; rnd_mode <= 3; rnd_mode++)
    {
      int i, j, si, sj;
      double di, dj;

      mpfr_set_machine_rnd_mode (rnd_mode);
      for (i = 1, di = 0.25; i < 127; i++, di *= 0.5)
        for (si = 0; si <= 1; si++)
          {
            mpfr_div_2ui (x, half, i, GMP_RNDZ);
            (si ? mpfr_sub : mpfr_add)(x, half, x, GMP_RNDZ);
            /* x = 1/2 +/- 1/2^(1+i) */
            for (j = i+1, dj = di * 0.5; j < 128 && j < i+53; j++, dj *= 0.5)
              for (sj = 0; sj <= 1; sj++)
                {
                  double c, d, dd;
                  int exp;
                  char *f;

                  mpfr_div_2ui (y, half, j, GMP_RNDZ);
                  (sj ? mpfr_sub : mpfr_add)(y, x, y, GMP_RNDZ);
                  /* y = 1/2 +/- 1/2^(1+i) +/- 1/2^(1+j) */
                  exp = (LONG_RAND() % 47) - 23;
                  mpfr_mul_2si (y, y, exp, GMP_RNDZ);
                  if (mpfr_inexflag_p())
                    {
                      fprintf(stderr, "Error in tget_d: inexact flag for "
                              "(i,si,j,sj,rnd,exp) = (%d,%d,%d,%d,%d,%d)\n",
                              i, si, j, sj, rnd_mode, exp);
                      exit(1);
                    }
                  dd = si != sj ? di - dj : di + dj;
                  d = si ? 0.5 - dd : 0.5 + dd;
                  if ((LONG_RAND() / 1024) & 1)
                    {
                      c = mpfr_get_d (y, rnd_mode);
                      f = "mpfr_get_d";
                    }
                  else
                    {
                      exp = (LONG_RAND() % 47) - 23;
                      c = mpfr_get_d3 (y, exp, rnd_mode);
                      f = "mpfr_get_d3";
                      if (si) /* then real d < 0.5 */
                        d *= sj && i == 1 ? 4 : 2; /* normalize real d */
                    }
                  if (exp > 0)
                    d *= 1 << exp;
                  if (exp < 0)
                    d /= 1 << -exp;
                  if (c != d)
                    {
                      fprintf (stderr, "Error in tget_d (%s) for "
                               "(i,si,j,sj,rnd,exp) = (%d,%d,%d,%d,%d,%d)\n"
                               "got %.25Le instead of %.25Le\n"
                               "Difference: %.19e\n",
                               f, i, si, j, sj, rnd_mode, exp,
                               (long double) c, (long double) d, d - c);
                      exit (1);
                    }
                }
          }
    }

  mpfr_clear(half);
  mpfr_clear(x);
  mpfr_clear(y);

#endif

  if (check_denorms ())
    exit (1);

  return 0;
}