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utils: refactor hexToBytes a bit

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Paul Miller 2023-09-25 17:21:18 +00:00
parent d0294bb2a6
commit f58002e6d4
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GPG Key ID: 697079DA6878B89B
1 changed files with 14 additions and 17 deletions
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31
src/abstract/utils.ts
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@ -44,21 +44,13 @@ export function hexToNumber(hex: string): bigint {
return BigInt(hex === '' ? '0' : `0x${hex}`); return BigInt(hex === '' ? '0' : `0x${hex}`);
} }
// We use very optimized technique to convert hex string to byte array // We use optimized technique to convert hex string to byte array
const enum HexC { const asciis = { _0: 48, _9: 57, _A: 65, _F: 70, _a: 97, _f: 102 } as const;
ZERO = 48, // 0 function asciiToBase16(char: number): number | undefined {
NINE = 57, // 9 if (char >= asciis._0 && char <= asciis._9) return char - asciis._0;
A_UP = 65, // A if (char >= asciis._A && char <= asciis._F) return char - (asciis._A - 10);
F_UP = 70, // F if (char >= asciis._a && char <= asciis._f) return char - (asciis._a - 10);
A_LO = 97, // a return;
F_LO = 102, // f
}
function charCodeToBase16(char: number) {
if (char >= HexC.ZERO && char <= HexC.NINE) return char - HexC.ZERO;
else if (char >= HexC.A_UP && char <= HexC.F_UP) return char - (HexC.A_UP - 10);
else if (char >= HexC.A_LO && char <= HexC.F_LO) return char - (HexC.A_LO - 10);
throw new Error('Invalid byte sequence');
} }
/** /**
@ -71,8 +63,13 @@ export function hexToBytes(hex: string): Uint8Array {
const al = len / 2; const al = len / 2;
const array = new Uint8Array(al); const array = new Uint8Array(al);
for (let i = 0, j = 0; i < al; i++) { for (let i = 0, j = 0; i < al; i++) {
const n1 = charCodeToBase16(hex.charCodeAt(j++)); const n1 = asciiToBase16(hex.charCodeAt(j++));
const n2 = charCodeToBase16(hex.charCodeAt(j++)); const n2 = asciiToBase16(hex.charCodeAt(j++));
if (n1 === undefined || n2 === undefined) {
const index = j - 2;
const chr = hex[index] + hex[index + 1];
throw new Error('hex string expected, got non-hex character "' + chr + '" at index ' + index);
}
array[i] = n1 * 16 + n2; array[i] = n1 * 16 + n2;
} }
return array; return array;