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Decode 32/64-bit float from bytes in JavaScript
// Derived from http://stackoverflow.com/a/8545403/106786
function decodeFloat(bytes, signBits, exponentBits, fractionBits, eMin, eMax, littleEndian) {
var totalBits = (signBits + exponentBits + fractionBits);
var binary = "";
for (var i = 0, l = bytes.length; i < l; i++) {
var bits = bytes[i].toString(2);
while (bits.length < 8)
bits = "0" + bits;
if (littleEndian)
binary = bits + binary;
else
binary += bits;
}
var sign = (binary.charAt(0) == '1')?-1:1;
var exponent = parseInt(binary.substr(signBits, exponentBits), 2) - eMax;
var significandBase = binary.substr(signBits + exponentBits, fractionBits);
var significandBin = '1'+significandBase;
var i = 0;
var val = 1;
var significand = 0;
if (exponent == -eMax) {
if (significandBase.indexOf('1') == -1)
return 0;
else {
exponent = eMin;
significandBin = '0'+significandBase;
}
}
while (i < significandBin.length) {
significand += val * parseInt(significandBin.charAt(i));
val = val / 2;
i++;
}
return sign * significand * Math.pow(2, exponent);
}
// Sample usage
ReadSingle: function () {
var bytes = this.ReadBytes(4);
return this.$decodeFloat(bytes, 1, 8, 23, -126, 127, true);
},
ReadDouble: function () {
var bytes = this.ReadBytes(8);
return this.$decodeFloat(bytes, 1, 11, 52, -1022, 1023, true);
},
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