function [outsig, obj] = hohmann2002_process(obj, insig)
%HOHMANN2002_PROCESS  Process input signal by filterbank object
%   Usage: [outsig, obj] = hohmann2002_process(obj, insig);
%
%   Input parameters:
%     obj      : An object created within the HOHMANN2002 filterbank framework by
%                one of the following funtions: HOHMANN2002,
%                HOHMANN2002_FILTER, HOHMANN2002_DELAY,
%                HOHMANN2002_SYNTH, HOHMANN2002_MIXER.
%     insig    : Input signal to be processed [time channels].
%
%   Output parameters:
%     outsig   : A matrix containing the processed output signals [time channels].
%                The columns correspond to the filter bands.
%     obj      : The original object with updated filter states.
%
%   HOHMANN2002_PROCESS applies the processing given by obj retrieved from the
%   HOHMANN2002 filterbank framework to the input signal.
%
%   See also: exp_hohmann2002 demo_hohmann2002
%
%   References:
%     V. Hohmann. Frequency analysis and synthesis using a gammatone
%     filterbank. Acta Acustica united with Acoustica, 88(3):433--442, 2002.
%     
%
%   Url: http://amtoolbox.org/amt-1.2.0/doc/modelstages/hohmann2002_process.php

% Copyright (C) 2009-2022 Piotr Majdak, Clara Hollomey, and the AMT team.
% This file is part of Auditory Modeling Toolbox (AMT) version 1.2.0
%
% 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/>.

%

% author   : Universitaet Oldenburg, tp (Jan 2002, Jan, Sep 2003, Nov 2006, Jan 2007)
% Adapted to AMT (PM, Jan 2016) from function gfb_*_process

if ~isfield(obj,'type'), error('Type of the object missing'); end

switch(obj.type)
  case 'gfb_Filter'    
    factor = obj.normalization_factor;

    % for compatibility of the filter state with the MEX extension, we
    % have to multiply the filter state with the filter coefficient before the
    % call to filter:
    filter_state = obj.state * obj.coefficient;

    insig=insig.';
    
    for i = 1:obj.gamma_order
      [insig, filter_state(i)] = ...
          filter(factor, [1, -obj.coefficient], ...
                 insig, filter_state(i));
      factor = 1;
    end

    outsig = insig;

    % for compatibility of the filter state with the MEX extension, we
    % have to divide the filter state by the filter coefficient after the
    % call to filter:
    obj.state = filter_state / obj.coefficient;
    outsig=outsig.';

  case 'gfb_analyzer'
    if (obj.fast)
      % use matlab extension for fast computation.
%       [outsig, obj] = gfb_analyzer_fprocess(obj, insig);
      warning('fast computation not available');
    end
%     insig=insig';
    number_of_bands = length(obj.center_frequencies_hz);
    outsig = zeros(size(insig,1), number_of_bands);
    for band = 1:number_of_bands
      [tmp, obj.filters(band)] = hohmann2002_process(obj.filters(band), insig(:, min(band,size(insig,2))) );
      outsig(:,band) = tmp;
    end
%     outsig=outsig';

  case 'gfb_Delay'
    insig=insig.';
    [number_of_bands, number_of_samples] = size(insig);
    if (number_of_bands ~= length(obj.delays_samples))
      error('Input rows must match the number of bands');
    end
    outsig = zeros(number_of_bands, number_of_samples);
    for band = 1:number_of_bands
      if (obj.delays_samples(band) == 0)
        outsig(band,:) = real(insig(band,:) * obj.phase_factors(band));
      else
        tmp_out = [obj.memory(band,1:obj.delays_samples(band)), ...
                   real(insig(band,:) * obj.phase_factors(band))];
        obj.memory(band,1:obj.delays_samples(band)) = tmp_out(number_of_samples+1:length(tmp_out));
        outsig(band,:) = tmp_out(1:number_of_samples);
      end
    end
    outsig=outsig.';

  case 'gfb_Synthesizer'
    [outsig, obj.delay] = hohmann2002_process(obj.delay, insig);
    [outsig, obj.mixer] = hohmann2002_process(obj.mixer, outsig);

  case 'gfb_mixer'
    insig=insig.';
    outsig = obj.gains * insig;
    outsig=outsig.';
  otherwise
    error('Unknown type of HOHMANN2002 filter object');
end