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
|
// Copyright (c) 2008, Fair Oaks Labs, Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * 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.
//
// * Neither the name of Fair Oaks Labs, Inc. nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
//
//
// Modifications to writeIEEE754 to support negative zeroes made by Brian White
exports.readIEEE754 = function(buffer, offset, isBE, mLen, nBytes) {
var e, m,
eLen = nBytes * 8 - mLen - 1,
eMax = (1 << eLen) - 1,
eBias = eMax >> 1,
nBits = -7,
i = isBE ? 0 : (nBytes - 1),
d = isBE ? 1 : -1,
s = buffer[offset + i];
i += d;
e = s & ((1 << (-nBits)) - 1);
s >>= (-nBits);
nBits += eLen;
for (; nBits > 0; e = e * 256 + buffer[offset + i], i += d, nBits -= 8);
m = e & ((1 << (-nBits)) - 1);
e >>= (-nBits);
nBits += mLen;
for (; nBits > 0; m = m * 256 + buffer[offset + i], i += d, nBits -= 8);
if (e === 0) {
e = 1 - eBias;
} else if (e === eMax) {
return m ? NaN : ((s ? -1 : 1) * Infinity);
} else {
m = m + Math.pow(2, mLen);
e = e - eBias;
}
return (s ? -1 : 1) * m * Math.pow(2, e - mLen);
};
exports.writeIEEE754 = function(buffer, value, offset, isBE, mLen, nBytes) {
var e, m, c,
eLen = nBytes * 8 - mLen - 1,
eMax = (1 << eLen) - 1,
eBias = eMax >> 1,
rt = (mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0),
i = isBE ? (nBytes - 1) : 0,
d = isBE ? -1 : 1,
s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0;
value = Math.abs(value);
if (isNaN(value) || value === Infinity) {
m = isNaN(value) ? 1 : 0;
e = eMax;
} else {
e = Math.floor(Math.log(value) / Math.LN2);
if (value * (c = Math.pow(2, -e)) < 1) {
e--;
c *= 2;
}
if (e + eBias >= 1) {
value += rt / c;
} else {
value += rt * Math.pow(2, 1 - eBias);
}
if (value * c >= 2) {
e++;
c /= 2;
}
if (e + eBias >= eMax) {
m = 0;
e = eMax;
} else if (e + eBias >= 1) {
m = (value * c - 1) * Math.pow(2, mLen);
e = e + eBias;
} else {
m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen);
e = 0;
}
}
for (; mLen >= 8; buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8);
e = (e << mLen) | m;
eLen += mLen;
for (; eLen > 0; buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8);
buffer[offset + i - d] |= s * 128;
};
|
