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      1 /* Test mpz_set_d and mpz_init_set_d.
      2 
      3 Copyright 2000-2003, 2006 Free Software Foundation, Inc.
      4 
      5 This file is part of the GNU MP Library test suite.
      6 
      7 The GNU MP Library test suite is free software; you can redistribute it
      8 and/or modify it under the terms of the GNU General Public License as
      9 published by the Free Software Foundation; either version 3 of the License,
     10 or (at your option) any later version.
     11 
     12 The GNU MP Library test suite is distributed in the hope that it will be
     13 useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
     14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
     15 Public License for more details.
     16 
     17 You should have received a copy of the GNU General Public License along with
     18 the GNU MP Library test suite.  If not, see https://www.gnu.org/licenses/.  */
     19 
     20 #include <stdio.h>
     21 #include <stdlib.h>
     22 #include "gmp-impl.h"
     23 #include "tests.h"
     24 
     25 
     26 void
     27 check_data (void)
     28 {
     29   static const struct {
     30     double     d;
     31     mp_size_t  want_size;
     32     mp_limb_t  want_data[2];
     33   } data[] = {
     34 
     35     {  0.0,  0 },
     36     {  1.0,  1, { 1 } },
     37     { -1.0, -1, { 1 } },
     38 
     39     {  123.0,  1, { 123 } },
     40     { -123.0, -1, { 123 } },
     41 
     42     { 1e-1, 0, { 0 } },
     43     { -1e-1, 0, { 0 } },
     44     { 2.328306436538696e-10, 0, { 0 } },
     45     { -2.328306436538696e-10, 0, { 0 } },
     46     { 5.421010862427522e-20, 0, { 0 } },
     47     { -5.421010862427522e-20, 0, { 0 } },
     48     { 2.938735877055719e-39, 0, { 0 } },
     49     { -2.938735877055719e-39, 0, { 0 } },
     50   };
     51 
     52   mpz_t  z;
     53   int    i;
     54 
     55   for (i = 0; i < numberof (data); i++)
     56     {
     57       mpz_init (z);
     58       mpz_set_d (z, data[i].d);
     59       MPZ_CHECK_FORMAT (z);
     60       if (z->_mp_size != data[i].want_size
     61           || refmpn_cmp_allowzero (z->_mp_d, data[i].want_data,
     62                                    ABS (data[i].want_size)) != 0)
     63         {
     64           printf ("mpz_set_d wrong on data[%d]\n", i);
     65         bad:
     66           d_trace   ("  d  ", data[i].d);
     67           printf    ("  got  size %ld\n", (long) z->_mp_size);
     68           printf    ("  want size %ld\n", (long) data[i].want_size);
     69           mpn_trace ("  got  z", z->_mp_d, z->_mp_size);
     70           mpn_trace ("  want z", data[i].want_data, data[i].want_size);
     71           abort();
     72         }
     73       mpz_clear (z);
     74 
     75       mpz_init_set_d (z, data[i].d);
     76       MPZ_CHECK_FORMAT (z);
     77       if (z->_mp_size != data[i].want_size
     78           || refmpn_cmp_allowzero (z->_mp_d, data[i].want_data,
     79                                    ABS (data[i].want_size)) != 0)
     80         {
     81           printf ("mpz_init_set_d wrong on data[%d]\n", i);
     82           goto bad;
     83         }
     84       mpz_clear (z);
     85     }
     86 }
     87 
     88 /* Try mpz_set_d on values 2^i+1, while such a value fits a double. */
     89 void
     90 check_2n_plus_1 (void)
     91 {
     92   volatile double  p, d, diff;
     93   mpz_t  want, got;
     94   int    i;
     95 
     96   mpz_init (want);
     97   mpz_init (got);
     98 
     99   p = 1.0;
    100   mpz_set_ui (want, 2L);  /* gives 3 on first step */
    101 
    102   for (i = 1; i < 500; i++)
    103     {
    104       mpz_mul_2exp (want, want, 1L);
    105       mpz_sub_ui (want, want, 1L);   /* want = 2^i+1 */
    106 
    107       p *= 2.0;  /* p = 2^i */
    108       d = p + 1.0;
    109       diff = d - p;
    110       if (diff != 1.0)
    111         break;   /* rounding occurred, stop now */
    112 
    113       mpz_set_d (got, d);
    114       MPZ_CHECK_FORMAT (got);
    115       if (mpz_cmp (got, want) != 0)
    116         {
    117           printf ("mpz_set_d wrong on 2^%d+1\n", i);
    118           d_trace   ("  d ", d);
    119           mpz_trace ("  got  ", got);
    120           mpz_trace ("  want ", want);
    121           abort ();
    122         }
    123     }
    124 
    125   mpz_clear (want);
    126   mpz_clear (got);
    127 }
    128 
    129 int
    130 main (void)
    131 {
    132   tests_start ();
    133 
    134   check_data ();
    135   check_2n_plus_1 ();
    136 
    137   tests_end ();
    138   exit (0);
    139 }
    140