Fan.Sys.Uri.hexNibble C# (CSharp) Method

        static int hexNibble(int ch)
        {
            if ((charMap[ch] & HEX) == 0) throw err("Invalid percent encoded hex: '" + (char)ch);
              if (ch <= '9') return ch - '0';
              if (ch <= 'Z') return (ch - 'A') + 10;
              return (ch - 'a') + 10;
        }