texceptions.c

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

/* Test file for exceptions.

Copyright 2001 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 "gmp.h"
#include "mpfr.h"

void mpfr_set_double_range _PROTO((void));

void
mpfr_set_double_range (void)
{
  mpfr_set_default_prec (53);
  
  /* in double precision format, the unbiased exponent is between 0 and
     2047, where 0 is used for subnormal numbers, and 2047 for special
     numbers (infinities, NaN), and the bias is 1023, thus "normal" numbers
     have an exponent between -1022 and 1023, corresponding to numbers
     between 2^(-1022) and previous(2^(1024)).
     (The smallest subnormal number is 0.(0^51)1*2^(-1022)= 2^(-1074).)

     The smallest normal power of two is 1.0*2^(-1022).
     The largest normal power of two is 2^1023.
     (We have to add one for mpfr since mantissa are between 1/2 and 1.)
  */

  mpfr_set_emin (-1021);
  mpfr_set_emax (1024);
}

int
main (int argc, char *argv[])
{
  mpfr_t x, y;
  mp_exp_t emin, emax;

  mpfr_init (x);
  mpfr_init (y);

  emin = mpfr_get_emin ();
  emax = mpfr_get_emax ();
  if (emin >= emax)
    {
      fprintf (stderr, "Error: emin >= emax\n");
      exit (1);
    }

  mpfr_set_ui (x, 1, GMP_RNDN);
  mpfr_mul_2exp (x, x, 1024, GMP_RNDN);
  mpfr_set_double_range ();
  mpfr_check_range (x, GMP_RNDN);
  if (!mpfr_inf_p (x) || (mpfr_sgn(x) <= 0))
    {
      fprintf (stderr, "Error: 2^1024 rounded to nearest should give +Inf\n");
      exit (1);
    }

  mpfr_set_emax (1025);
  mpfr_set_ui (x, 1, GMP_RNDN);
  mpfr_mul_2exp (x, x, 1024, GMP_RNDN);
  mpfr_set_double_range ();
  mpfr_check_range (x, GMP_RNDD);
  if (!mpfr_number_p (x))
    {
      fprintf (stderr, "Error: 2^1024 rounded down should give a normal number\n");
      exit (1);
    }

  mpfr_set_ui (x, 1, GMP_RNDN);
  mpfr_mul_2exp (x, x, 1023, GMP_RNDN);
  mpfr_add (x, x, x, GMP_RNDN);
  if (!mpfr_inf_p (x) || (mpfr_sgn(x) <= 0))
    {
      fprintf (stderr, "Error: x+x rounded to nearest for x=2^1023 should give +Inf\n");
      printf ("emax = %ld\n", mpfr_get_emax ());
      printf ("got "); mpfr_print_binary (x); putchar ('\n');
      exit (1);
    }

  mpfr_set_ui (x, 1, GMP_RNDN);
  mpfr_mul_2exp (x, x, 1023, GMP_RNDN);
  mpfr_add (x, x, x, GMP_RNDD);
  if (!mpfr_number_p (x))
    {
      fprintf (stderr, "Error: x+x rounded down for x=2^1023 should give a normal number\n");
      exit (1);
    }

  mpfr_set_ui (x, 1, GMP_RNDN);
  mpfr_div_2exp (x, x, 1022, GMP_RNDN);
  mpfr_set_str_raw (y, "1.1e-1022"); /* y = 3/2*x */
  mpfr_sub (y, y, x, GMP_RNDZ);
  if (mpfr_cmp_ui (y, 0))
    {
      fprintf (stderr, "Error: y-x rounded to zero should give 0 for y=3/2*2^(-1022), x=2^(-1022)\n");
      printf ("y="); mpfr_print_binary (y); putchar ('\n');
      exit (1);
    }

  mpfr_clear (x);
  mpfr_clear (y);
    
  return 0;
}