1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
/* Test of splitting a double into fraction and mantissa.
Copyright (C) 2007-2008 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
#include <config.h>
#include "printf-frexp.h"
#include <float.h>
#include <stdio.h>
#include <stdlib.h>
#define ASSERT(expr) \
do \
{ \
if (!(expr)) \
{ \
fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
fflush (stderr); \
abort (); \
} \
} \
while (0)
static double
my_ldexp (double x, int d)
{
for (; d > 0; d--)
x *= 2.0;
for (; d < 0; d++)
x *= 0.5;
return x;
}
int
main ()
{
int i;
/* The use of 'volatile' guarantees that excess precision bits are dropped
when dealing with denormalized numbers. It is necessary on x86 systems
where double-floats are not IEEE compliant by default, to avoid that the
results become platform and compiler option dependent. 'volatile' is a
portable alternative to gcc's -ffloat-store option. */
volatile double x;
for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.0);
}
for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.0);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == DBL_MIN_EXP - 1);
ASSERT (mantissa == my_ldexp (1.0, i - DBL_MIN_EXP));
}
for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.01);
}
for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.01);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == DBL_MIN_EXP - 1);
ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
ASSERT (mantissa == my_ldexp (x, - exp));
}
for (i = 1, x = 1.73205; i <= DBL_MAX_EXP; i++, x *= 2.0)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.73205);
}
for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == i - 1);
ASSERT (mantissa == 1.73205);
}
for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
{
int exp = -9999;
double mantissa = printf_frexp (x, &exp);
ASSERT (exp == DBL_MIN_EXP - 1);
ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
ASSERT (mantissa == my_ldexp (x, - exp));
}
return 0;
}
|
