1 // IEEE754 conversions based on https://github.com/feross/ieee754
2 // eslint-disable-next-line no-shadow-restricted-names
6 var floor = Math.floor;
10 var pack = function (number, mantissaLength, bytes) {
11 var buffer = new Array(bytes);
12 var exponentLength = bytes * 8 - mantissaLength - 1;
13 var eMax = (1 << exponentLength) - 1;
14 var eBias = eMax >> 1;
15 var rt = mantissaLength === 23 ? pow(2, -24) - pow(2, -77) : 0;
16 var sign = number < 0 || number === 0 && 1 / number < 0 ? 1 : 0;
18 var exponent, mantissa, c;
20 // eslint-disable-next-line no-self-compare
21 if (number != number || number === Infinity) {
22 // eslint-disable-next-line no-self-compare
23 mantissa = number != number ? 1 : 0;
26 exponent = floor(log(number) / LN2);
27 if (number * (c = pow(2, -exponent)) < 1) {
31 if (exponent + eBias >= 1) {
34 number += rt * pow(2, 1 - eBias);
36 if (number * c >= 2) {
40 if (exponent + eBias >= eMax) {
43 } else if (exponent + eBias >= 1) {
44 mantissa = (number * c - 1) * pow(2, mantissaLength);
45 exponent = exponent + eBias;
47 mantissa = number * pow(2, eBias - 1) * pow(2, mantissaLength);
51 for (; mantissaLength >= 8; buffer[index++] = mantissa & 255, mantissa /= 256, mantissaLength -= 8);
52 exponent = exponent << mantissaLength | mantissa;
53 exponentLength += mantissaLength;
54 for (; exponentLength > 0; buffer[index++] = exponent & 255, exponent /= 256, exponentLength -= 8);
55 buffer[--index] |= sign * 128;
59 var unpack = function (buffer, mantissaLength) {
60 var bytes = buffer.length;
61 var exponentLength = bytes * 8 - mantissaLength - 1;
62 var eMax = (1 << exponentLength) - 1;
63 var eBias = eMax >> 1;
64 var nBits = exponentLength - 7;
65 var index = bytes - 1;
66 var sign = buffer[index--];
67 var exponent = sign & 127;
70 for (; nBits > 0; exponent = exponent * 256 + buffer[index], index--, nBits -= 8);
71 mantissa = exponent & (1 << -nBits) - 1;
73 nBits += mantissaLength;
74 for (; nBits > 0; mantissa = mantissa * 256 + buffer[index], index--, nBits -= 8);
77 } else if (exponent === eMax) {
78 return mantissa ? NaN : sign ? -Infinity : Infinity;
80 mantissa = mantissa + pow(2, mantissaLength);
81 exponent = exponent - eBias;
82 } return (sign ? -1 : 1) * mantissa * pow(2, exponent - mantissaLength);