42 lines
1.1 KiB
JavaScript
42 lines
1.1 KiB
JavaScript
export default function parse(input) {
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input = input.toUpperCase();
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var splitIndex = input.indexOf("P");
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var mantissa, exponent;
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if (splitIndex !== -1) {
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mantissa = input.substring(0, splitIndex);
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exponent = parseInt(input.substring(splitIndex + 1));
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} else {
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mantissa = input;
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exponent = 0;
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}
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var dotIndex = mantissa.indexOf(".");
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if (dotIndex !== -1) {
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var integerPart = parseInt(mantissa.substring(0, dotIndex), 16);
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var sign = Math.sign(integerPart);
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integerPart = sign * integerPart;
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var fractionLength = mantissa.length - dotIndex - 1;
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var fractionalPart = parseInt(mantissa.substring(dotIndex + 1), 16);
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var fraction = fractionLength > 0 ? fractionalPart / Math.pow(16, fractionLength) : 0;
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if (sign === 0) {
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if (fraction === 0) {
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mantissa = sign;
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} else {
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if (Object.is(sign, -0)) {
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mantissa = -fraction;
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} else {
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mantissa = fraction;
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}
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}
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} else {
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mantissa = sign * (integerPart + fraction);
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}
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} else {
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mantissa = parseInt(mantissa, 16);
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}
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return mantissa * (splitIndex !== -1 ? Math.pow(2, exponent) : 1);
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} |