function [L,R]=nffc(s,ptr,winlen,lmin,lmax,thr)
%
% Syntax: [L,R]=nffc(s,ptr,winlen,lmin,lmax,thr)
%
% Computes pitch using normalized cross-correlation method.
% s is the ENTIRE signal with lmax zeros added before (for the 1st frame)
% ptr is pointer pointing to the beginning sample of a frame. 
% winlen if the length of frame. 
% lmin is minimal lag in samples
% lmax is maximal lag in samples
% thr  is a          threshold Rmax >= thr => voiced
%                              Rmax < thr  => unvoiced
% L is  lag in samples for voiced, 0 for unvoiced frame
% R (facultative) is the vector of NCCF coefficients

% nonshifted frame
x = s(ptr:(ptr+winlen-1)); 
e1 = sum(x.^2); 

R = zeros (1,lmax+1); 
% shifted versions
for ii=0:lmax,    % want them all from 0 ... 
  xs = s((ptr-ii):(ptr+winlen-1-ii)); 
  e2 = sum(xs.^2); 
  ncc = sum (xs .* x) / sqrt(e1 * e2); 
  R(ii+1) = ncc; 
end

[Rmax,ii]=max(R(lmin+1:lmax+1));

if Rmax >= thr,
  L=ii+lmin-1;
else
  L=0;
end