function y=ovrlpadd(x,h,M)
lenx=length(x);N=length(h);
L=lenx+N-1;
h=[h,zeros(1,L-N)];
H=fft(h,L);
K=floor((lenx)/(M)); 
K=K+1;
x=[x,zeros(1,K*M-lenx)];
Y=zeros(K,L);
Y1=zeros(1,L);
for k=0:1:K-1
    xk1=x(k*M+1:k*M+M);
    xk2=[zeros(1,k*M),xk1,zeros(1,L-k*M-M)]; 
    XK=fft(xk2,L);
    X=XK.*H;
    Y(k+1,:)=ifft(X,L);
end
for z=1:1:K
    Y1=Y1+Y(z,:);
end
y=Y1(:);