decode method
Implementation
int decode(String hex) {
int value = 0;
if (hex.isNotEmpty) {
var array = hex.split('');
var i = 0;
for (int count = hex.length - 1; count >= 0; count--) {
int a = int.tryParse(array[i]) ?? _charDecode(array[i]);
value += (a * pow(16, count)).round();
i++;
}
}
return value;
}