31 lines
877 B
TypeScript
31 lines
877 B
TypeScript
const SHORT_TO_HEX: { [key: number]: string } = {};
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const HEX_TO_SHORT: Record<string, number> = {};
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for (let i = 0; i < 256; i++) {
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let encodedByte = i.toString(16).toLowerCase();
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if (encodedByte.length === 1) {
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encodedByte = `0${encodedByte}`;
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}
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SHORT_TO_HEX[i] = encodedByte;
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HEX_TO_SHORT[encodedByte] = i;
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}
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export function fromHex(encoded: string): Uint8Array {
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if (encoded.length % 2 !== 0) {
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throw new Error("Hex encoded strings must have an even number length");
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}
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const out = new Uint8Array(encoded.length / 2);
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for (let i = 0; i < encoded.length; i += 2) {
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const encodedByte = encoded.slice(i, i + 2).toLowerCase();
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if (encodedByte in HEX_TO_SHORT) {
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out[i / 2] = HEX_TO_SHORT[encodedByte];
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} else {
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throw new Error(`Cannot decode unrecognized sequence ${encodedByte} as hexadecimal`);
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}
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}
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return out;
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}
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