convert method

Implementation

@override
List<int> convert(String input) {
  String str = input.replaceAll(" ", "");
  str = str.toLowerCase();
  if (str.length % 2 != 0) {
    str = "0$str";
  }
  final Uint8List result = Uint8List(str.length ~/ 2);
  for (int i = 0; i < result.length; i++) {
    final int firstDigit = _alphabet.indexOf(str[i * 2]);
    final int secondDigit = _alphabet.indexOf(str[i * 2 + 1]);
    if (firstDigit == -1 || secondDigit == -1) {
      throw FormatException("Non-hex character detected in $input");
    }
    result[i] = (firstDigit << 4) + secondDigit;
  }
  return result;
}