BitArray 64bit

class BitArray64 : IEnumerable<int>
{
    private ulong bits;
    private const int Max = 63;

    public BitArray64(ulong bits)
    {
        this.bits = bits;
    }

    public int this [int index]
    {
        get
        {
            if (index < 0 || index > Max)
            {
                throw new IndexOutOfRangeException("Index must be >= 0 and <= 63");
            }
            if ( (bits & (ulong)1 << index  ) == 0)
            {
                return 0;
            }
            else
            {
                return 1;
            }
        }
        set
        {
            if (index < 0 || index > Max)
            {
                throw new IndexOutOfRangeException("Index must be >= 0 and <= 63");
            }
            if (value != 0 && value != 1)
            {
                throw new ArgumentException("Value must be 1 or 0");
            }

            if (value == 1)
            {
                this.bits = this.bits | ((ulong)1 << index);
            }
            else
            {
                this.bits = this.bits & (~((ulong)1 << index));
            }
        }
    }

    public override int GetHashCode()
    {
        return this.GetHashCode();
    }


    public static bool operator ==(BitArray64 bit1, BitArray64 bit2)
    {
        return (BitArray64.Equals(bit1, bit2));
    }
    public static bool operator !=(BitArray64 bit1, BitArray64 bit2)
    {
        return !(BitArray64.Equals(bit1, bit2));
    }

    public override bool Equals(object obj)
    {
        if (obj == null)
        {
            return false;
        }
        BitArray64 value = obj as BitArray64;
        return this.bits == value.bits;
    }
    //enumerator
    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }

    public IEnumerator<int> GetEnumerator()
    {
        for (int i = Max; i >= 0; i--)
        {
            yield return this[i];
        }
    }

}