1/* Test of splitting a double into fraction and mantissa.
2   Copyright (C) 2007-2010 Free Software Foundation, Inc.
3
4   This program is free software: you can redistribute it and/or modify
5   it under the terms of the GNU General Public License as published by
6   the Free Software Foundation; either version 3 of the License, or
7   (at your option) any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12   GNU General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
16
17/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
18
19#include <config.h>
20
21#include "printf-frexp.h"
22
23#include <float.h>
24
25#include "macros.h"
26
27static double
28my_ldexp (double x, int d)
29{
30  for (; d > 0; d--)
31    x *= 2.0;
32  for (; d < 0; d++)
33    x *= 0.5;
34  return x;
35}
36
37int
38main ()
39{
40  int i;
41  /* The use of 'volatile' guarantees that excess precision bits are dropped
42     when dealing with denormalized numbers.  It is necessary on x86 systems
43     where double-floats are not IEEE compliant by default, to avoid that the
44     results become platform and compiler option dependent.  'volatile' is a
45     portable alternative to gcc's -ffloat-store option.  */
46  volatile double x;
47
48  for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
49    {
50      int exp = -9999;
51      double mantissa = printf_frexp (x, &exp);
52      ASSERT (exp == i - 1);
53      ASSERT (mantissa == 1.0);
54    }
55  for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
56    {
57      int exp = -9999;
58      double mantissa = printf_frexp (x, &exp);
59      ASSERT (exp == i - 1);
60      ASSERT (mantissa == 1.0);
61    }
62  for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
63    {
64      int exp = -9999;
65      double mantissa = printf_frexp (x, &exp);
66      ASSERT (exp == DBL_MIN_EXP - 1);
67      ASSERT (mantissa == my_ldexp (1.0, i - DBL_MIN_EXP));
68    }
69
70  for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0)
71    {
72      int exp = -9999;
73      double mantissa = printf_frexp (x, &exp);
74      ASSERT (exp == i - 1);
75      ASSERT (mantissa == 1.01);
76    }
77  for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5)
78    {
79      int exp = -9999;
80      double mantissa = printf_frexp (x, &exp);
81      ASSERT (exp == i - 1);
82      ASSERT (mantissa == 1.01);
83    }
84  for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
85    {
86      int exp = -9999;
87      double mantissa = printf_frexp (x, &exp);
88      ASSERT (exp == DBL_MIN_EXP - 1);
89      ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
90      ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
91      ASSERT (mantissa == my_ldexp (x, - exp));
92    }
93
94  for (i = 1, x = 1.73205; i <= DBL_MAX_EXP; i++, x *= 2.0)
95    {
96      int exp = -9999;
97      double mantissa = printf_frexp (x, &exp);
98      ASSERT (exp == i - 1);
99      ASSERT (mantissa == 1.73205);
100    }
101  for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5)
102    {
103      int exp = -9999;
104      double mantissa = printf_frexp (x, &exp);
105      ASSERT (exp == i - 1);
106      ASSERT (mantissa == 1.73205);
107    }
108  for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
109    {
110      int exp = -9999;
111      double mantissa = printf_frexp (x, &exp);
112      ASSERT (exp == DBL_MIN_EXP - 1);
113      ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
114      ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
115      ASSERT (mantissa == my_ldexp (x, - exp));
116    }
117
118  return 0;
119}
120