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