I’m struggling with understanding the MATLAB open source about converting 2D (x, y) to 1D (d) via the Hilbert curve. The author used bitwise AND and XOR in lines 17-19:
link

        function d = from2d(x, y)
            
            d = 0;
            rx = 0;
            ry = 0;
            m =32;
            n = 2 ^ m;
            s = n / 2; 
  
            while s > 0 

                rx = bitand( uint64(x), uint64(s), 'uint64' ) > 0;
                ry = bitand( uint64(y), uint64(s), 'uint64' ) > 0;
                d = d + s * s * ( bitxor((3 * rx), ry, 'uint64'));

                if (ry == 0) 
                    
                    if (rx == 1) 
                        x = n - 1 - x;
                        y = n - 1 - y;
                    end

                    t = x;
                    x = y;
                    y = t;

                end

                s = s / 2;      

            end  
        end

Where m is the order of the Hilbert curve. I don’t understand the role of rx and ry.

Can you explain the idea behind the use of bitwise operations?
Thanks