34 lines
927 B
JavaScript
Vendored
34 lines
927 B
JavaScript
Vendored
/* eslint no-bitwise: "off" */
|
|
// Credit: https://github.com/paulmillr/es6-shim/
|
|
|
|
"use strict";
|
|
|
|
var pow = Math.pow;
|
|
|
|
module.exports = function (bytes, ebits, fbits) {
|
|
// Bytes to bits
|
|
var bits = [], i, j, bit, str, bias, sign, e, fraction;
|
|
|
|
for (i = bytes.length; i; i -= 1) {
|
|
bit = bytes[i - 1];
|
|
for (j = 8; j; j -= 1) {
|
|
bits.push(bit % 2 ? 1 : 0);
|
|
bit >>= 1;
|
|
}
|
|
}
|
|
bits.reverse();
|
|
str = bits.join("");
|
|
|
|
// Unpack sign, exponent, fraction
|
|
bias = (1 << (ebits - 1)) - 1;
|
|
sign = parseInt(str.substring(0, 1), 2) ? -1 : 1;
|
|
e = parseInt(str.substring(1, 1 + ebits), 2);
|
|
fraction = parseInt(str.substring(1 + ebits), 2);
|
|
|
|
// Produce number
|
|
if (e === (1 << ebits) - 1) return fraction === 0 ? sign * Infinity : NaN;
|
|
if (e > 0) return sign * pow(2, e - bias) * (1 + fraction / pow(2, fbits));
|
|
if (fraction !== 0) return sign * pow(2, -(bias - 1)) * (fraction / pow(2, fbits));
|
|
return sign < 0 ? -0 : 0;
|
|
};
|