fix: faster hex to byte implementation (#6596)

* faster hex to byte implementation

Signed-off-by: Marin Petrunic <marin.petrunic@gmail.com>

* Apply suggestions from code review

Co-authored-by: Muhammad Altabba <24407834+Muhammad-Altabba@users.noreply.github.com>

* fix tiny linting issue

---------

Signed-off-by: Marin Petrunic <marin.petrunic@gmail.com>
Co-authored-by: Muhammad Altabba <24407834+Muhammad-Altabba@users.noreply.github.com>
Co-authored-by: Alex <alex.luu@mail.utoronto.ca>

packages/web3-validator/src/utils.ts

@@ -449,20 +449,49 @@ export function uint8ArrayToHexString(uint8Array: Uint8Array): string {
  return hexString;
 }
 
+// for optimized technique for hex to bytes conversion
+const charCodeMap = {
+ zero: 48,
+ nine: 57,
+ A: 65,
+ F: 70,
+ a: 97,
+ f: 102,
+ } as const
+
+ function charCodeToBase16(char: number) {
+ if (char >= charCodeMap.zero && char <= charCodeMap.nine)
+ return char - charCodeMap.zero
+ if (char >= charCodeMap.A && char <= charCodeMap.F)
+ return char - (charCodeMap.A - 10)
+ if (char >= charCodeMap.a && char <= charCodeMap.f)
+ return char - (charCodeMap.a - 10)
+ return undefined
+ }
+
 export function hexToUint8Array(hex: string): Uint8Array {
- let value;
- if (hex.toLowerCase().startsWith('0x')) {
- value = hex.slice(2);
- } else {
- value = hex;
+ let offset = 0;
+ if (hex.startsWith('0') && (hex[1] === 'x' || hex[1] === 'X')) {
+ offset = 2;
  }
- if (value.length % 2 !== 0) {
+ if (hex.length % 2 !== 0) {
  throw new InvalidBytesError(`hex string has odd length: ${hex}`);
  }
- const bytes = new Uint8Array(Math.ceil(value.length / 2));
- for (let i = 0; i < bytes.length; i += 1) {
- const byte = parseInt(value.substring(i * 2, i * 2 + 2), 16);
- bytes[i] = byte;
+ const length = (hex.length - offset) / 2;
+ const bytes = new Uint8Array(length);
+ for (let index = 0, j = offset; index < length; index+=1) {
+ // eslint-disable-next-line no-plusplus
+ const nibbleLeft = charCodeToBase16(hex.charCodeAt(j++))
+ // eslint-disable-next-line no-plusplus
+ const nibbleRight = charCodeToBase16(hex.charCodeAt(j++))
+ if (nibbleLeft === undefined || nibbleRight === undefined) {
+ throw new InvalidBytesError(
+ `Invalid byte sequence ("${hex[j - 2]}${
+ hex[j - 1]
+ }" in "${hex}").`,
+ )
+ }
+ bytes[index] = nibbleLeft * 16 + nibbleRight
  }
- return bytes;
+ return bytes
 }