public static async Task<EncodingHelper> GetDBCSEncoding(string name)
        {
            name = name.ToLower();
            EncodingHelper encoding = new EncodingHelper();
            encoding._webName = name;
            if (_cache.ContainsKey(name))
            {
                var tuple = _cache[name];
                encoding._dbcsToUnicode = tuple.Item1;
                encoding._unicodeToDbcs = tuple.Item2;
                return encoding;
            }

            var dbcsToUnicode = new char[0x10000];
            var unicodeToDbcs = new ushort[0x10000];

            using (Stream stream = await GetInstall())
            using (BinaryReader reader = new BinaryReader(stream))
            {
                for (int i = 0; i < 0xffff; i++)
                {
                    ushort u = reader.ReadUInt16();
                    unicodeToDbcs[i] = u;
                }
                for (int i = 0; i < 0xffff; i++)
                {
                    ushort u = reader.ReadUInt16();
                    dbcsToUnicode[i] = (char)u;
                }
            }

            _cache[name] = new Tuple<char[], ushort[]>(dbcsToUnicode, unicodeToDbcs);
            encoding._dbcsToUnicode = dbcsToUnicode;
            encoding._unicodeToDbcs = unicodeToDbcs;
            return encoding;
        }
 public DBCSDecoder(EncodingHelper encoding)
 {
     _encoding = encoding;
 }