private static uint GetDirectExchangingCode(uint charCode, uint keyCharCode, CustomEncoding encoding) => charCode >= encoding.Count - keyCharCode ? charCode - encoding.Count + keyCharCode : charCode + keyCharCode;
private static uint GetReverseExchangingCode(uint charCode, uint keyCharCode, CustomEncoding encoding) => charCode < keyCharCode ? encoding.Count + charCode - keyCharCode : charCode - keyCharCode;