fft moving window problem

I'd like to perform moving window fft on my signal. I'd like to use hamming window first, and then try hanning. I started writing the code, however I dont know how to save and merge data from each fft in the loop. I'll be very grateful to any suggestions. The code is:

x = sig;         % my signal
  nx = length(x);                           % size of signal
  w = hamming(32);                          % hamming window
  nw = length(w);                           % size of window
  pos=1;

    while (pos+nw <= nx)                      % while enough signal left
            y = x(pos:pos+nw-1).*w;           % make window y

            %%%% process window y %%%%
            yy = fft(y,32);
            pos = pos + nw/2;                 % next window

    end

thanks in advance, KK