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// Credit: https://github.com/paulmillr/es6-shim/
'use strict';
var abs = Math.abs, floor = Math.floor, log = Math.log, min = Math.min
, pow = Math.pow, LN2 = Math.LN2
, roundToEven;
roundToEven = function (n) {
var w = floor(n), f = n - w;
if (f < 0.5) return w;
if (f > 0.5) return w + 1;
return w % 2 ? w + 1 : w;
};
module.exports = function (v, ebits, fbits) {
var bias = (1 << (ebits - 1)) - 1, s, e, f, i, bits, str, bytes;
// Compute sign, exponent, fraction
if (isNaN(v)) {
// NaN
// http://dev.w3.org/2006/webapi/WebIDL/#es-type-mapping
e = (1 << ebits) - 1;
f = pow(2, fbits - 1);
s = 0;
} else if (v === Infinity || v === -Infinity) {
e = (1 << ebits) - 1;
f = 0;
s = (v < 0) ? 1 : 0;
} else if (v === 0) {
e = 0;
f = 0;
s = (1 / v === -Infinity) ? 1 : 0;
} else {
s = v < 0;
v = abs(v);
if (v >= pow(2, 1 - bias)) {
e = min(floor(log(v) / LN2), 1023);
f = roundToEven(v / pow(2, e) * pow(2, fbits));
if (f / pow(2, fbits) >= 2) {
e = e + 1;
f = 1;
}
if (e > bias) {
// Overflow
e = (1 << ebits) - 1;
f = 0;
} else {
// Normal
e = e + bias;
f = f - pow(2, fbits);
}
} else {
// Subnormal
e = 0;
f = roundToEven(v / pow(2, 1 - bias - fbits));
}
}
// Pack sign, exponent, fraction
bits = [];
for (i = fbits; i; i -= 1) {
bits.push(f % 2 ? 1 : 0);
f = floor(f / 2);
}
for (i = ebits; i; i -= 1) {
bits.push(e % 2 ? 1 : 0);
e = floor(e / 2);
}
bits.push(s ? 1 : 0);
bits.reverse();
str = bits.join('');
// Bits to bytes
bytes = [];
while (str.length) {
bytes.push(parseInt(str.substring(0, 8), 2));
str = str.substring(8);
}
return bytes;
};
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