FIR2LONG - Extend FIR window to LONG

function gout=fir2long(gin,Llong);
%FIR2LONG   Extend FIR window to LONG
%   Usage:  g=fir2long(g,Llong);
%
%   FIR2LONG(g,Llong) will extend the FIR window g to a length Llong*
%   window by inserting zeros. Note that this is a slightly different
%   behaviour than MIDDLEPAD.
%
%   FIR2LONG can also be used to extend a FIR window to a longer FIR
%   window, for instance in order to satisfy the usual requirement that the
%   window length should be divisible by the number of channels.
%
%   If the input to FIR2LONG is a cell, FIR2LONG will recurse into
%   the cell array.
%
%   See also:  long2fir, middlepad
%
%   Url: http://ltfat.github.io/doc/sigproc/fir2long.html

% Copyright (C) 2005-2023 Peter L. Soendergaard <peter@sonderport.dk> and others.
% This file is part of LTFAT version 2.6.0
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program.  If not, see <http://www.gnu.org/licenses/>.

complainif_argnonotinrange(nargin,2,2,mfilename);

if iscell(gin)
    gout=cellfun(@(x) fir2long(x,Llong),gin,'UniformOutput',false);    
else
    
    Lfir=length(gin);
    
    if Lfir>Llong
        error('Llong must be larger than length of window.');
    end;
    
    if rem(Lfir,2)==0
        % HPE middlepad works the same way as the FIR extension (e.g. just
        % inserting zeros) for even-length signals.
        gout=middlepad(gin,Llong,'hp');
    else
        % WPE middlepad works the same way as the FIR extension (e.g. just
        % inserting zeros) for odd-length signals.
        gout=middlepad(gin,Llong);
    end;
    
end;