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
|
/* Returns the unbiased exponent of the passed _Decimal32 value as an int
Copyright (C) 2006 IBM Corporation.
Copyright (C) 2007-2015 Free Software Foundation, Inc.
This file is part of the Decimal Floating Point C Library.
Author(s): Joseph Kerian <jkerian@us.ibm.com>
The Decimal Floating Point C Library is free software; you can
redistribute it and/or modify it under the terms of the GNU Lesser
General Public License version 2.1.
The Decimal Floating Point C 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 version 2.1 for more details.
You should have received a copy of the GNU Lesser General Public
License version 2.1 along with the Decimal Floating Point C Library;
if not, write to the Free Software Foundation, Inc., 59 Temple Place,
Suite 330, Boston, MA 02111-1307 USA.
Please see libdfp/COPYING.txt for more information. */
#ifndef _DECIMAL_SIZE
# include <decimal32.h>
# define _DECIMAL_SIZE 32
#endif
#ifndef _RETURN_TYPE
# define _RETURN_TYPE int
#endif
#ifndef _MAX_VALUE
# define _MAX_VALUE INT_MAX
#endif
#ifndef _MIN_VALUE
# define _MIN_VALUE INT_MIN
#endif
#ifndef _FBLOG0
# define _FBLOG0 FP_ILOGB0
#endif
#ifndef _FBLOGNAN
# define _FBLOGNAN FP_ILOGBNAN
#endif
#include <decContext.h>
#include <decNumber.h>
#include <math.h>
#include <limits.h>
#include <errno.h>
#include <decNumberMath.h>
#ifndef FUNCTION_NAME
# define FUNCTION_NAME ilogb
#endif
#include <dfpmacro.h>
_RETURN_TYPE
INTERNAL_FUNCTION_NAME (DEC_TYPE x)
{
DEC_TYPE result;
decContext context;
decNumber dn_result;
decNumber dn_x;
decNumber dn_absx;
decNumber dn_logx;
decNumber dn_one;
decNumber dn_cmp;
enum rounding round;
FUNC_CONVERT_TO_DN (&x, &dn_x);
if (decNumberIsZero (&dn_x))
{
DFP_EXCEPT (FE_INVALID);
DFP_ERRNO (EDOM);
return _FBLOG0;
}
if (decNumberIsInfinite (&dn_x))
{
DFP_EXCEPT (FE_INVALID);
DFP_ERRNO (EDOM);
return decNumberIsNegative (&dn_x) ? _MIN_VALUE : _MAX_VALUE;
}
if (decNumberIsNaN (&dn_x))
{
DFP_EXCEPT (FE_INVALID);
DFP_ERRNO (EDOM);
return _FBLOGNAN;
}
decContextDefault (&context, DEFAULT_CONTEXT);
decNumberAbs (&dn_absx, &dn_x, &context);
/* For DFP, we use radix 10 instead of whatever FLT_RADIX happens to be */
decNumberLog10 (&dn_logx, &dn_absx, &context);
/* Capture the case where truncation will return the wrong result,
by rounding up if -1.0 < x < 1.0 */
round = DEC_ROUND_DOWN;
decNumberFromInt32 (&dn_one, 1);
decNumberCompare (&dn_cmp, &dn_x, &dn_one, &context);
if (-decNumberIsNegative(&dn_cmp))
{
decNumberFromInt32 (&dn_one, -1);
decNumberCompare (&dn_cmp, &dn_x, &dn_one, &context);
if (!decNumberIsNegative(&dn_cmp) && !decNumberIsZero(&dn_cmp))
round = DEC_ROUND_UP;
}
context.round = round;
decNumberToIntegralValue (&dn_result, &dn_logx, &context);
FUNC_CONVERT_FROM_DN (&dn_result, &result, &context);
/* Use _Decimal* to int casting. */
return (_RETURN_TYPE) result;
}
weak_alias (INTERNAL_FUNCTION_NAME, EXTERNAL_FUNCTION_NAME)
|
