index.js
1.15 KB
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
export default function parse(input) {
input = input.toUpperCase();
var splitIndex = input.indexOf("P");
var mantissa, exponent;
if (splitIndex !== -1) {
mantissa = input.substring(0, splitIndex);
exponent = parseInt(input.substring(splitIndex + 1));
} else {
mantissa = input;
exponent = 0;
}
var dotIndex = mantissa.indexOf(".");
if (dotIndex !== -1) {
var integerPart = parseInt(mantissa.substring(0, dotIndex), 16);
var sign = Math.sign(integerPart);
integerPart = sign * integerPart;
var fractionLength = mantissa.length - dotIndex - 1;
var fractionalPart = parseInt(mantissa.substring(dotIndex + 1), 16);
var fraction = fractionLength > 0 ? fractionalPart / Math.pow(16, fractionLength) : 0;
if (sign === 0) {
if (fraction === 0) {
mantissa = sign;
} else {
if (Object.is(sign, -0)) {
mantissa = -fraction;
} else {
mantissa = fraction;
}
}
} else {
mantissa = sign * (integerPart + fraction);
}
} else {
mantissa = parseInt(mantissa, 16);
}
return mantissa * (splitIndex !== -1 ? Math.pow(2, exponent) : 1);
}