using System;

public class Program

{

    static ulong Expand(byte b)

{

    ulong shift = 0x0000040810204081ul; // bits set: 0, 7, 14, 21, 28, 35, 42

    ulong mask = 0x0001010101010101ul; // bits set: 0, 8, 16, 24, 32, 40, 48

    return (ulong)(b & 127) * shift & mask | (ulong)(b & 128) << 49;

}

    public static void Main()

    {

        var i = Expand(255);

        Console.WriteLine("{0:X4}", i);

    }

}