mpir/tests/mpz/t-get_d_2exp.c

/* Test mpz_get_d_2exp.

Copyright 2002, 2003 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP 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 GNU MP 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 GNU MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */

#include <stdio.h>
#include <stdlib.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "tests.h"


static void
check_onebit (void)
{
  static const unsigned long data[] = {
    1, 32, 52, 53, 54, 63, 64, 65, 128, 256, 511, 512, 513
  };
  mpz_t   z;
  double  got, want;
  long    got_exp, want_exp;
  int     i;

  mpz_init (z);

  for (i = 0; i < numberof (data); i++)
    {
      mpz_set_ui (z, 1L);
      mpz_mul_2exp (z, z, data[i]);
      want = 0.5;
      want_exp = data[i] + 1;
      got = mpz_get_d_2exp (&got_exp, z);
      if (got != want || got_exp != want_exp)
        {
          printf    ("mpz_get_d_2exp wrong on 2**%ld\n", data[i]);
          mpz_trace ("   z    ", z);
          d_trace   ("   want ", want);
          d_trace   ("   got  ", got);
          printf    ("   want exp %ld\n", want_exp);
          printf    ("   got exp  %ld\n", got_exp);
          abort();
        }

      mpz_set_si (z, -1L);
      mpz_mul_2exp (z, z, data[i]);
      want = -0.5;
      want_exp = data[i] + 1;
      got = mpz_get_d_2exp (&got_exp, z);
      if (got != want || got_exp != want_exp)
        {
          printf    ("mpz_get_d_2exp wrong on -2**%ld\n", data[i]);
          mpz_trace ("   z    ", z);
          d_trace   ("   want ", want);
          d_trace   ("   got  ", got);
          printf    ("   want exp %ld\n", want_exp);
          printf    ("   got exp  %ld\n", got_exp);
          abort();
        }
    }
  mpz_clear (z);
}

/* Check that hardware rounding doesn't make mpz_get_d_2exp return a value
   outside its defined range. */
static void
check_round (void)
{
  static const unsigned long data[] = { 1, 32, 53, 54, 64, 128, 256, 512 };
  mpz_t   z;
  double  got;
  long    got_exp;
  int     i, rnd_mode, old_rnd_mode;

  mpz_init (z);
  old_rnd_mode = tests_hardware_getround ();

  for (rnd_mode = 0; rnd_mode < 4; rnd_mode++)
    {
      tests_hardware_setround (rnd_mode);

      for (i = 0; i < numberof (data); i++)
        {
          mpz_set_ui (z, 1L);
          mpz_mul_2exp (z, z, data[i]);
          mpz_sub_ui (z, z, 1L);

          got = mpz_get_d_2exp (&got_exp, z);
          if (got < 0.5 || got >= 1.0)
            {
              printf    ("mpz_get_d_2exp wrong on 2**%lu-1\n", data[i]);
              printf    ("result out of range, expect 0.5 <= got < 1.0\n");
              printf    ("   rnd_mode = %d\n", rnd_mode);
              printf    ("   data[i]  = %lu\n", data[i]);
              mpz_trace ("   z    ", z);
              d_trace   ("   got  ", got);
              printf    ("   got exp  %ld\n", got_exp);
              abort();
            }

          mpz_neg (z, z);
          got = mpz_get_d_2exp (&got_exp, z);
          if (got <= -1.0 || got > -0.5)
            {
              printf    ("mpz_get_d_2exp wrong on -2**%lu-1\n", data[i]);
              printf    ("result out of range, expect -1.0 < got <= -0.5\n");
              printf    ("   rnd_mode = %d\n", rnd_mode);
              printf    ("   data[i]  = %lu\n", data[i]);
              mpz_trace ("   z    ", z);
              d_trace   ("   got  ", got);
              printf    ("   got exp  %ld\n", got_exp);
              abort();
            }
        }
    }

  mpz_clear (z);
  tests_hardware_setround (old_rnd_mode);
}

static void
check_rand (void)
{
  gmp_randstate_ptr rands = RANDS;
  int     i;
  mpz_t   z;
  double  got;
  long    got_exp;
  unsigned long  bits;

  mpz_init (z);

  for (i = 0; i < 200; i++)
    {
      bits = gmp_urandomm_ui (rands, 512L);
      mpz_urandomb (z, rands, bits);

      got = mpz_get_d_2exp (&got_exp, z);
      if (mpz_sgn (z) == 0)
        continue;
      bits = mpz_sizeinbase (z, 2);

      if (got < 0.5 || got >= 1.0)
        {
          printf    ("mpz_get_d_2exp out of range, expect 0.5 <= got < 1.0\n");
          mpz_trace ("   z    ", z);
          d_trace   ("   got  ", got);
          printf    ("   got exp  %ld\n", got_exp);
          abort();
        }

      /* FIXME: If mpz_get_d_2exp rounds upwards we might have got_exp ==
         bits+1, so leave this test disabled until we decide if that's what
         should happen, or not.  */
#if 0
      if (got_exp != bits)
        {
          printf    ("mpz_get_d_2exp wrong exponent\n", i);
          mpz_trace ("   z    ", z);
          d_trace   ("   bits ", bits);
          d_trace   ("   got  ", got);
          printf    ("   got exp  %ld\n", got_exp);
          abort();
        }
#endif
    }
  mpz_clear (z);
}


int
main (void)
{
  tests_start ();
  mp_trace_base = -16;

  check_onebit ();
  check_round ();
  check_rand ();

  tests_end ();
  exit (0);
}