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
|
/* $NetBSD: s_ilogbl.c,v 1.2 2013/02/09 22:56:00 matt Exp $ */
/*-
* Copyright (c) 2011 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Joerg Sonnenberger.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: s_ilogbl.c,v 1.2 2013/02/09 22:56:00 matt Exp $");
#include "namespace.h"
#include <float.h>
#include <math.h>
#include <machine/ieee.h>
#ifdef __HAVE_LONG_DOUBLE
#if LDBL_MANT_DIG == 64
#define FROM_UNDERFLOW 0x1p65L
#elif LDBL_MANT_DIG == 113
#define FROM_UNDERFLOW 0x1p114L
#else
#error Unsupported long double format
#endif
int
ilogbl(long double x)
{
union ieee_ext_u u;
if (x == 0.0L)
return FP_ILOGB0; /* ilogbl(0) = 0x80000001 */
u.extu_ld = x;
if (u.extu_ext.ext_exp == EXT_EXP_INFNAN)
return FP_ILOGBNAN; /* inf too */
if (u.extu_ext.ext_exp == 0) {
/*
* Scale denormalized numbers slightly,
* so that they are normal.
*/
u.extu_ld *= FROM_UNDERFLOW;
return u.extu_ext.ext_exp - EXT_EXP_BIAS - LDBL_MANT_DIG - 1;
}
return u.extu_ext.ext_exp - EXT_EXP_BIAS;
}
#endif
|
