namespace Nikse.SubtitleEdit.Core.TransportStream
{
    internal class HummingDecoder
    {
        private static byte[] _unhammingTable = new byte[256]
        {
          0x01, 0xff, 0x81, 0x01, 0xff, 0x00, 0x01, 0xff, 0xff, 0x02, 0x01, 0xff, 0x0a, 0xff, 0xff, 0x07,
          0xff, 0x00, 0x01, 0xff, 0x00, 0x80, 0xff, 0x00, 0x06, 0xff, 0xff, 0x0b, 0xff, 0x00, 0x03, 0xff,
          0xff, 0x0c, 0x01, 0xff, 0x04, 0xff, 0xff, 0x07, 0x06, 0xff, 0xff, 0x07, 0xff, 0x07, 0x07, 0x87,
          0x06, 0xff, 0xff, 0x05, 0xff, 0x00, 0x0d, 0xff, 0x86, 0x06, 0x06, 0xff, 0x06, 0xff, 0xff, 0x07,
          0xff, 0x02, 0x01, 0xff, 0x04, 0xff, 0xff, 0x09, 0x02, 0x82, 0xff, 0x02, 0xff, 0x02, 0x03, 0xff,
          0x08, 0xff, 0xff, 0x05, 0xff, 0x00, 0x03, 0xff, 0xff, 0x02, 0x03, 0xff, 0x03, 0xff, 0x83, 0x03,
          0x04, 0xff, 0xff, 0x05, 0x84, 0x04, 0x04, 0xff, 0xff, 0x02, 0x0f, 0xff, 0x04, 0xff, 0xff, 0x07,
          0xff, 0x05, 0x05, 0x85, 0x04, 0xff, 0xff, 0x05, 0x06, 0xff, 0xff, 0x05, 0xff, 0x0e, 0x03, 0xff,
          0xff, 0x0c, 0x01, 0xff, 0x0a, 0xff, 0xff, 0x09, 0x0a, 0xff, 0xff, 0x0b, 0x8a, 0x0a, 0x0a, 0xff,
          0x08, 0xff, 0xff, 0x0b, 0xff, 0x00, 0x0d, 0xff, 0xff, 0x0b, 0x0b, 0x8b, 0x0a, 0xff, 0xff, 0x0b,
          0x0c, 0x8c, 0xff, 0x0c, 0xff, 0x0c, 0x0d, 0xff, 0xff, 0x0c, 0x0f, 0xff, 0x0a, 0xff, 0xff, 0x07,
          0xff, 0x0c, 0x0d, 0xff, 0x0d, 0xff, 0x8d, 0x0d, 0x06, 0xff, 0xff, 0x0b, 0xff, 0x0e, 0x0d, 0xff,
          0x08, 0xff, 0xff, 0x09, 0xff, 0x09, 0x09, 0x89, 0xff, 0x02, 0x0f, 0xff, 0x0a, 0xff, 0xff, 0x09,
          0x88, 0x08, 0x08, 0xff, 0x08, 0xff, 0xff, 0x09, 0x08, 0xff, 0xff, 0x0b, 0xff, 0x0e, 0x03, 0xff,
          0xff, 0x0c, 0x0f, 0xff, 0x04, 0xff, 0xff, 0x09, 0x0f, 0xff, 0x8f, 0x0f, 0xff, 0x0e, 0x0f, 0xff,
          0x08, 0xff, 0xff, 0x05, 0xff, 0x0e, 0x0d, 0xff, 0xff, 0x0e, 0x0f, 0xff, 0x0e, 0x8e, 0xff, 0x0e,
        };

        public static int Decode2418(byte[] data, int offset)
        {
            return ((data[offset + 2] & 0x7F) << 11) |
                ((data[offset + 1] & 0x7F) << 4) |
                ((data[offset] & 0x70) >> 3) |
                ((data[offset] & 0x4) >> 2);
        }

        public static byte Decode84(byte[] data, int offset)
        {
            return Decode(data[offset]);
        }

        public static byte Decode(byte b1, byte b2)
        {
            return (byte)((_unhammingTable[b2] << 4) | (_unhammingTable[b1] & 0xF));
        }

        public static byte Decode(byte b)
        {
            return (byte)(_unhammingTable[b] & 0xF);
        }

    }
}