function inoutsig = adaptloop(inoutsig,fs,varargin);
%ADAPTLOOP   Adaptation loops
%   Usage: outsig = adaptloop(insig,fs,limit,minlvl,tau);
%          outsig = adaptloop(insig,fs,limit,minlvl);
%          outsig = adaptloop(insig,fs,limit);
%          outsig = adaptloop(insig,fs);
%
%   `adaptloop(insig,fs,limit,minlvl,tau)` applies non-linear adaptation to an
%   input signal *insig* sampled at a sampling frequency of *fs* Hz. *limit* is
%   used to limit the overshoot of the output, *minlvl* determines the lowest
%   audible threshhold of the signal (in dB SPL) and *tau* are time constants
%   involved in the adaptation loops. The number of adaptation loops is
%   determined by the length of *tau*.
%
%   `adaptloop(insig,fs,limit,minlvl)` does as above, but uses the values for
%   tau determined in Dau. et al (1996a).
%
%   `adaptloop(insig,fs,limit)` does as above with a minimum threshhold *minlvl*
%   equal to 0 dB SPL.
%
%   `adaptloop(insig,fs)` does as above with an overshoot limit of $limit=10$.
%
%   `adaptloop` takes the following flags at the end of the line of input
%   arguments:
%
%     'adt_dau'        Choose the parameters as in the Dau 1996 and 1997
%                      models. This consists of 5 adaptation loops with
%                      an overshoot limit of 10 and a minimum level of
%                      1e-5. This is a correction in regard to the model
%                      described in Dau et al. (1996a), which did not use 
%                      overshoot limiting. The adaptation loops have an 
%                      exponential spacing. This flag is the default.
%
%     'adt_puschel'    Choose the parameters as in the original Puschel 1988
%                      model. This consists of 5 adaptation loops without
%                      overshoot limiting. The adapation loops have a linear spacing.
%
%     'adt_breebaart'  As `'puschel'`, but with overshoot limiting.
%
%     'dim',d          Do the computation along dimension *d* of the input. 
%
%   See also: auditoryfilterbank, drnl
%
%   Demos: demo_adaptloop
%
%   References: puschel1988pza dau1996qmeI  breebaart2001a

% Copyright (c) 1999 - 2004 Stephan Ewert. All rights reserved.

%   AUTHOR : Stephan Ewert, Morten L. Jepsen, Peter L. Søndergaard

% ------ Checking of input parameters and default parameters ---------

if nargin<2
  error('Too few input parameters.');
end;

definput.import = {'adaptloop'};
definput.keyvals.dim=[];
[flags,keyvals,limit,minlvl_db,tau]  = ltfatarghelper({'limit','minlvl','tau'},definput,varargin);

% Convert minlvl from dB SPL to numerical value
minlvl=setdbspl(minlvl_db);

if ~isnumeric(tau) || ~isvector(tau) || any(tau<=0)
  error('%s: tau must be a vector with positive values.',upper(mfilename));
end;

if ~isnumeric(minlvl) || ~isscalar(minlvl) || minlvl<=0
  error('%s: minlvl must be a positive scalar.',upper(mfilename));
end;

if ~isnumeric(limit) || ~isscalar(limit) 
  error('%s: "limit" must be a scalar.',upper(mfilename));
end;  

% -------- Computation ------------------

[inoutsig,siglen,dummy,nsigs,dim,permutedsize,order]=assert_sigreshape_pre(inoutsig,[],keyvals.dim, ...
                                                  upper(mfilename));

% The current implementation of the adaptation loops works with
% dboffset=100, so we must change to this setting.
% The output is always the same, so there is no need for changing back.
 
% Obtain the dboffset currently used.
dboffset=dbspl(1);

% Switch the minimum level and signal to the correct scaling.
minlvl=gaindb(minlvl,dboffset-100);
inoutsig=gaindb(inoutsig,dboffset-100);

inoutsig=comp_adaptloop(inoutsig,fs,limit,minlvl,tau);

inoutsig=assert_sigreshape_post(inoutsig,dim,permutedsize,order);