using System;

using System.Text;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        byte[] atrByteArray = new byte[] {59, 5, 0, 2 , 241, 6, 115};

        var cardNumber = FromByteArray(atrByteArray, 0, 1, 16);

        var facilityCode = FromByteArray(atrByteArray, 0, 17, 8);

        Console.WriteLine(string.Format("Card number is: {0} and facility code is: {1}", cardNumber, facilityCode));

    }

    /// call example: FromByteArray(atrByteArray, byteOffset: 0, int bitOffset: 1, int numberOfBits: 16)

    /// call example: FromByteArray(atrByteArray, byteOffset: 0, int bitOffset: 17, int numberOfBits: 8)

    public static long FromByteArray(byte[] atrByteArray, int byteOffset, int bitOffset, int numberOfBits)

    {

        var hexString = ByteArrayToString(atrByteArray);

        var start_number = Int64.Parse( hexString, NumberStyles.HexNumber );

        Int64 a_26_only = start_number & 0x3FFFFFF; //26 bits, 11 1111 1111 1111 1111 1111 1111             

        Int64 result = (a_26_only >> bitOffset) & (long)(Math.Pow(2,numberOfBits)-1);       

        return result;

    }

    public static string ByteArrayToString(byte[] ba)

    {

      StringBuilder hex = new StringBuilder(ba.Length * 2);

      foreach (byte b in ba)

        hex.AppendFormat("{0:x2}", b);

      return hex.ToString();

    }

}

​

​

​

/// call example: FromByteArray(atrByteArray, byteOffset: 0, int bitOffset: 1, int numberOfBits: 16)

    /*public static int FromByteArray(byte[] atrByteArray, int byteOffset, int bitOffset, int numberOfBits)

    {

        var hexString = ByteArrayToString(atrByteArray);

        var start_number = Int64.Parse( hexString, NumberStyles.HexNumber );

        Int64 a_26_only = start_number & 0x3FFFFFF; //26 bits, 11 1111 1111 1111 1111 1111 1111     

        //Then, per the spec, the right-most bit is a parity bit, so after checking it you can discard it:

        Int64 a_without_parity = a_26_only >> 1;        

        //Finally, the card number is the right-most 16 bits:

        Int64 card_number = a_without_parity & 0xffff;      

        //And the facility code is the next 8 bits:

        Int64 facility_code = (a_without_parity >> 16 ) & 0xff;

        return 0;

    }*/