how to find stair sinusoidal wave form as shown in attached file?

i have generated stair phase but i have no idea about desired result so please help my code is

% step-1 stair phase m=1000; n=1000; p=64; N=4; for i= 1:m for j=1:n SP(i,j)=-pi+floor((mod(i-1,p*N)/p))*(2*pi/N-1); end

end plot(SP); please find attachment