forked from bonzini/smalltalk
-
Notifications
You must be signed in to change notification settings - Fork 0
/
ldexpl.c
92 lines (83 loc) · 2.92 KB
/
ldexpl.c
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
/******************************** -*- C -*- ****************************
*
* Emulation for ldexpl
*
*
***********************************************************************/
/***********************************************************************
*
* Copyright 2002, 2006 Free Software Foundation, Inc.
* Written by Paolo Bonzini.
*
* This file is part of GNU Smalltalk.
*
* GNU Smalltalk 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 2, or (at your option) any later
* version.
*
* Linking GNU Smalltalk statically or dynamically with other modules is
* making a combined work based on GNU Smalltalk. Thus, the terms and
* conditions of the GNU General Public License cover the whole
* combination.
*
* In addition, as a special exception, the Free Software Foundation
* give you permission to combine GNU Smalltalk with free software
* programs or libraries that are released under the GNU LGPL and with
* independent programs running under the GNU Smalltalk virtual machine.
*
* You may copy and distribute such a system following the terms of the
* GNU GPL for GNU Smalltalk and the licenses of the other code
* concerned, provided that you include the source code of that other
* code when and as the GNU GPL requires distribution of source code.
*
* Note that people who make modified versions of GNU Smalltalk are not
* obligated to grant this special exception for their modified
* versions; it is their choice whether to do so. The GNU General
* Public License gives permission to release a modified version without
* this exception; this exception also makes it possible to release a
* modified version which carries forward this exception.
*
* GNU Smalltalk 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
* GNU Smalltalk; see the file COPYING. If not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
***********************************************************************/
#include <float.h>
#include <math.h>
#include "mathl.h"
long double
ldexpl(long double x, int exp)
{
long double factor;
int bit;
/* Check for zero, nan and infinity. */
if (x != x || x + x == x )
return x;
if (exp < 0)
{
exp = -exp;
factor = 0.5L;
}
else
factor = 2.0L;
for (bit = 1; bit <= exp; bit <<= 1, factor *= factor)
if (exp & bit)
x *= factor;
return x;
}
#if 0
int
main()
{
long double x;
int y;
for (y = 0; y < 29; y++)
printf ("%5d %.16Lg %.16Lg\n", y, ldexpl(0.8L, y), ldexpl(0.8L, -y) * ldexpl(0.8L, y));
}
#endif