using System;

public class OctetString 
{
    private byte[] m_bDataArray = null;

    public OctetString(byte[] data_i)
    {
        //copy input data
        m_bDataArray = new byte[data_i.Length];
        data_i.CopyTo(m_bDataArray, 0);
    }
	
	//...
	//checks if a bit on a specfied position is set
	public bool CheckIfBitOnPositionIsSet(int iPosition)
	{
		if (m_bDataArray.Length * 8 < iPosition)
		{
			return false;
		}

		int iByte = iPosition / 8;
		
		int iBit = iPosition % 8;

		byte bData = m_bDataArray[iByte];

		if((bData & (0x1 << iBit)) != 0)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}

public class Test
{
	public static void Main()
	{
		byte[] data = { 0xFF, 0x3F, 0x00 };
        OctetString octetString = new OctetString(data);
        bool isSet = octetString.CheckIfBitOnPositionIsSet(15);
        System.Console.Out.WriteLine("{0:d}", isSet);
	}
}