tornadocontrib/noble-curves
1
0
Fork 0
forked from tornado-packages/noble-curves
Code Pull Requests Activity

Merge pull request #83 from arobsn/main

Browse Source 
Improve `hexToBytes` performance
This commit is contained in:
Paul Miller 2023-09-14 00:17:42 +02:00 committed by GitHub
commit 728b485cd8
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 23 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
src/abstract/utils.ts
View File

@ -44,6 +44,23 @@ export function hexToNumber(hex: string): bigint {
return BigInt(hex === '' ? '0' : `0x${hex}`);
}
// We use very optimized technique to convert hex string to byte array
const enum HexC {
ZERO = 48, // 0
NINE = 57, // 9
A_UP = 65, // A
F_UP = 70, // F
A_LO = 97, // a
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');
}
/**
* @example hexToBytes('cafe0123') // Uint8Array.from([0xca, 0xfe, 0x01, 0x23])
*/
@ -51,13 +68,12 @@ export function hexToBytes(hex: string): Uint8Array {
if (typeof hex !== 'string') throw new Error('hex string expected, got ' + typeof hex);
const len = hex.length;
if (len % 2) throw new Error('padded hex string expected, got unpadded hex of length ' + len);
const array = new Uint8Array(len / 2);
for (let i = 0; i < array.length; i++) {
const j = i * 2;
const hexByte = hex.slice(j, j + 2);
const byte = Number.parseInt(hexByte, 16);
if (Number.isNaN(byte) || byte < 0) throw new Error('Invalid byte sequence');
array[i] = byte;
const al = len / 2;
const array = new Uint8Array(al);
for (let i = 0, j = 0; i < al; i++) {
const n1 = charCodeToBase16(hex.charCodeAt(j++));
const n2 = charCodeToBase16(hex.charCodeAt(j++));
array[i] = n1 * 16 + n2;
}
return array;
}