25 lines
528 B
JavaScript
25 lines
528 B
JavaScript
"use bigint"
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export function decodeVarint(buffer, offset) {
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let res = BigInt(0);
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let shift = 0;
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let byte = 0;
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do {
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if (offset >= buffer.length) {
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throw new RangeError("Index out of bound decoding varint");
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}
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byte = buffer[offset++];
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const multiplier = exponentiate(BigInt(2), BigInt(shift));
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const thisByteValue = multiply(BigInt(byte & 0x7f), multiplier);
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shift += 7;
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res = add(res, thisByteValue);
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} while (byte >= 0x80);
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return {
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value: res,
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length: shift / 7
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};
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}
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