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
|
/*-
* Copyright (c) 2007 David Schultz
* All rights reserved.
*
* 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 AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <sys/endian.h>
#include <ctype.h>
#include <float.h>
#include <math.h>
#include <stdint.h>
#include <strings.h>
#include "math_private.h"
/* digittoint is in the FreeBSD C library, but not Bionic at this point */
static int
digittoint(char ch)
{
int d;
d = ch - '0';
if ((unsigned)d < 10) {
return d;
}
d = ch - 'a';
if ((unsigned)d < 6) {
return d + 10;
}
d = ch - 'A';
if ((unsigned)d < 6) {
return d + 10;
}
return -1;
}
/*
* Scan a string of hexadecimal digits (the format nan(3) expects) and
* make a bit array (using the local endianness). We stop when we
* encounter an invalid character, NUL, etc. If we overflow, we do
* the same as gcc's __builtin_nan(), namely, discard the high order bits.
*
* The format this routine accepts needs to be compatible with what is used
* in contrib/gdtoa/hexnan.c (for strtod/scanf) and what is used in
* __builtin_nan(). In fact, we're only 100% compatible for strings we
* consider valid, so we might be violating the C standard. But it's
* impossible to use nan(3) portably anyway, so this seems good enough.
*/
void
_scan_nan(uint32_t *words, int num_words, const char *s)
{
int si; /* index into s */
int bitpos; /* index into words (in bits) */
bzero(words, num_words * sizeof(uint32_t));
/* Allow a leading '0x'. (It's expected, but redundant.) */
if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
s += 2;
/* Scan forwards in the string, looking for the end of the sequence. */
for (si = 0; isxdigit(s[si]); si++)
;
/* Scan backwards, filling in the bits in words[] as we go. */
#if _BYTE_ORDER == _LITTLE_ENDIAN
for (bitpos = 0; bitpos < 32 * num_words; bitpos += 4) {
#else
for (bitpos = 32 * num_words - 4; bitpos >= 0; bitpos -= 4) {
#endif
if (--si < 0)
break;
words[bitpos / 32] |= digittoint(s[si]) << (bitpos % 32);
}
}
double
nan(const char *s)
{
union {
double d;
uint32_t bits[2];
} u;
_scan_nan(u.bits, 2, s);
#if _BYTE_ORDER == _LITTLE_ENDIAN
u.bits[1] |= 0x7ff80000;
#else
u.bits[0] |= 0x7ff80000;
#endif
return (u.d);
}
float
nanf(const char *s)
{
union {
float f;
uint32_t bits[1];
} u;
_scan_nan(u.bits, 1, s);
u.bits[0] |= 0x7fc00000;
return (u.f);
}
#if (LDBL_MANT_DIG == 53)
__weak_alias(nanl, nan);
#endif
|
