Hex to binary

Benchmark created on August 3, 2024

Setup

const string = 'C0ffeeFeee';

const fromHexString = (hexString) =>
  Uint8Array.from(hexString.match(/.{1,2}/g).map((byte) => parseInt(byte, 16)));
  
  function h2b_efficient(hex) {
  const binary = new Uint8Array(hex.length >> 1);
  let char;

  for (let i = 0; i < hex.length; i++) {
    char = hex.charCodeAt(i);

    if (char >= 48 && char <= 57) {
      char -= 48;
    } else if (char >= 65 && char <= 70) {
      char -= 55;
    } else if (char >= 97 && char <= 102) {
      char -= 87;
    } else {
      continue;
    }

    if (i & 1) {
      binary[i >> 1] <<= 4;
      binary[i >> 1] |= char;
    } else {
      binary[i >> 1] = char;
    }
  }

  return binary;
}

const HEX_STRINGS = "0123456789abcdef";
const MAP_HEX = {
  0: 0, 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6,
  7: 7, 8: 8, 9: 9, a: 10, b: 11, c: 12, d: 13,
  e: 14, f: 15, A: 10, B: 11, C: 12, D: 13,
  E: 14, F: 15
};

function fromHex(hexString) {
  const bytes = new Uint8Array(Math.floor((hexString || "").length / 2));
  let i;
  for (i = 0; i < bytes.length; i++) {
    const a = MAP_HEX[hexString[i * 2]];
    const b = MAP_HEX[hexString[i * 2 + 1]];
    if (a === undefined || b === undefined) {
      break;
    }
    bytes[i] = (a << 4) | b;
  }
  return i === bytes.length ? bytes : bytes.slice(0, i);
}

Test runner

let coffee = h2b_efficient(string)

let coffee = fromHex(string)

let coffee = fromHexString(string)

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

• Revision 1: published on August 3, 2024