function [HDR,H1,h2] = sopen(arg1,PERMISSION,CHAN,MODE,arg5,arg6)
% SOPEN opens signal files for reading and writing and returns 
%       the header information. 
%       Many different data formats are supported.
%
% HDR = sopen(Filename, PERMISSION, [, CHAN [, MODE]]);
% [S,HDR] = sread(HDR, NoR, StartPos);
% HDR = sclose(HDR);
%
% PERMISSION is one of the following strings 
%	'r'	read header
%	'w'	write header
%
% CHAN defines a list of selected Channels
%   Alternative CHAN can be also a Re-Referencing Matrix ReRefMx
%       (i.e. a spatial filter). 
%   E.g. the following command returns the difference and 
%       the mean of the first two channels. 
%   HDR = sopen(Filename, 'r', [[1;-1],[.5,5]]);
%   [S,HDR] = sread(HDR, NoR, StartPos);
%   HDR = sclose(HDR);
%
% HDR contains the Headerinformation and internal data
% S 	returns the signal data 
%
% see also: SOPEN, SREAD, SSEEK, STELL, SCLOSE, SWRITE, SEOF


% 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 2
% 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, write to the Free Software
% Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

%	$Revision: 1.65 $
%	$Id: sopen.m,v 1.65 2004/09/13 17:27:26 schloegl Exp $
%	(C) 1997-2004 by Alois Schloegl <a.schloegl@ieee.org>	
%    	This is part of the BIOSIG-toolbox http://biosig.sf.net/


if isnan(str2double('1, 3'));
        fprintf(2,'Warning BIOSIG: incorrect version of STR2DOUBLE.\n');
        fprintf(2,'- Its recommended to update STR2DOUBLE. Contact Alois!\n');
end;

if nargin<2, 
        PERMISSION='rb'; 
elseif ~any(PERMISSION=='b');
        PERMISSION = [PERMISSION,'b']; % force binary open. Needed for Octave
end;
if nargin<3, CHAN = 0; end; 
if all(size(CHAN)>1) | any(floor(CHAN)~=CHAN) | (any(CHAN<0) & prod(size(CHAN))>1),
        ReRefMx = CHAN; 
        CHAN = find(any(CHAN,2));
end
if nargin<4, MODE = ''; end;

if ~isstruct(arg1),
        HDR.FileName = arg1;
else
        HDR = arg1;
end;

if isempty(MODE), MODE=' '; end;	% Make sure MODE is not empty -> FINDSTR

[pfad,file,FileExt] = fileparts(HDR.FileName);
HDR.FILE.Name = file;
HDR.FILE.Path = pfad;
HDR.FILE.Ext  = FileExt(2:length(FileExt));
HDR.FILE.OPEN = 0;
HDR.FILE.FID  = -1;
if ~isfield(HDR.FILE,'stderr'),
        HDR.FILE.stderr = 2;
end;
if ~isfield(HDR.FILE,'stdout'),
        HDR.FILE.stdout = 1;
end;	

% test for type of file 
if any(PERMISSION=='r'),
        HDR = getfiletype(HDR);
end;

%% Initialization
if ~isfield(HDR,'NS');
        HDR.NS = NaN; 
end;
if ~isfield(HDR,'SampleRate');
        HDR.SampleRate = NaN; 
end;
if ~isfield(HDR,'Label');
        HDR.Label = []; 
end;
if ~isfield(HDR,'PhysDim');
        HDR.PhysDim = ''; 
end;
if ~isfield(HDR,'T0');
        HDR.T0 = repmat(nan,1,6);
end;
if ~isfield(HDR,'Filter');
        HDR.Filter.LowPass  = NaN; 
        HDR.Filter.HighPass = NaN; 
end;
if ~isfield(HDR,'FLAG');
        HDR.FLAG.UCAL = ~isempty(findstr(MODE,'UCAL'));   % FLAG for UN-CALIBRATING
        HDR.FLAG.FILT = 0; 	% FLAG if any filter is applied; 
        HDR.FLAG.TRIGGERED = 0; % the data is untriggered by default
end;
if ~isfield(HDR,'EVENT');
        HDR.EVENT.N   = 0; 
        HDR.EVENT.TYP = []; 
        HDR.EVENT.POS = []; 
end;

if strcmp(HDR.TYPE,'EDF') | strcmp(HDR.TYPE,'GDF') | strcmp(HDR.TYPE,'BDF'),
        if any(PERMISSION=='w');
                HDR = eegchkhdr(HDR);
        end;
        if nargin<4,
                HDR = sdfopen(HDR,PERMISSION,CHAN);
        else
                HDR = sdfopen(HDR,PERMISSION,CHAN,MODE);
        end;
        
elseif strcmp(HDR.TYPE,'BKR'),
        HDR = bkropen(HDR,PERMISSION,CHAN);
        
        
elseif strmatch(HDR.TYPE,['CNT';'AVG';'EEG']),
        if any(PERMISSION=='r');
                [HDR,H1,h2] = cntopen(HDR,PERMISSION,CHAN);
                
        elseif any(PERMISSION=='w');
                % check header information
                if ~isfield(HDR,'NS'),
                        HDR.NS = 0;
                end;
                if ~isfinite(HDR.NS) | (HDR.NS<0)
                        fprintf(2,'Error SOPEN CNT-Write: HDR.NS not defined\n');
                        return;
                end;	
                if ~isfield(HDR,'SPR'),
                        HDR.SPR = 0;
                end;
                if ~isfinite(HDR.SPR)
                        HDR.SPR = 0;
                end;	
                type = 2;
                if strmatch(HDR.TYPE,'EEG'), type = 1;
                elseif strmatch(HDR.TYPE,'AVG'), type = 0;
                end;
                
                if ~isfield(HDR,'PID')
                        HDR.PID = char(repmat(32,1,20));
                elseif prod(size(HDR.PID))>20,
                        HDR.PID = HDR.PID(1:20);
                else 
                        HDR.PID = [HDR.PID(:)',repmat(32,1,20-length(HDR.PID(:)))];
                        %HDR.PID = [HDR.PID,repmat(32,1,20-length(HDR.PID))];
                end;
                
                if ~isfield(HDR,'Label')
                        HDR.Label = int2str((1:HDR.NS)');
                elseif iscell(HDR.Label),
                        HDR.Label = cat(1,HDR.Label);
                end;
                if size(HDR.Label,2)>10,
                        HDR.Label = HDR.Label(:,1:10);
                elseif size(HDR.Label,2)<10, 
                        HDR.Label = [HDR.Label,repmat(32,HDR.NS,10-size(HDR.Label,2))];
                end;
                
                if ~isfield(HDR,'Calib')
                        HDR.Cal = ones(HDR.NS,1);
                        e.sensitivity = ones(HDR.NS,1)*204.8;
                        HDR.Off = zeros(HDR.NS,1);
                else
                        HDR.Cal = diag(HDR.Calib(2:end,:));
                        e.sensitivity = ones(HDR.NS,1)*204.8;
                        HDR.Off = round(HDR.Calib(1,:)'./HDR.Cal);
                end;
                
                % open file 
                HDR.FILE.FID = fopen(HDR.FileName,PERMISSION,'ieee-le');
                if HDR.FILE.FID < 0,
                        return;
                end;
                HDR.FILE.OPEN = 2; 
                if any([HDR.SPR] <= 0);
                        HDR.FILE.OPEN = 3; 
                end;
                
                % write fixed header
                fwrite(HDR.FILE.FID,'Version 3.0','char');
                fwrite(HDR.FILE.FID,zeros(2,1),'uint32');
                fwrite(HDR.FILE.FID,type,'uchar');
                fwrite(HDR.FILE.FID,HDR.PID,'uchar');
                
                fwrite(HDR.FILE.FID,repmat(0,1,900-ftell(HDR.FILE.FID)),'uchar')
                
                % write variable header
                for k = 1:HDR.NS,
                        count = fwrite(HDR.FILE.FID,HDR.Label(k,:),'uchar');
                        count = fwrite(HDR.FILE.FID,zeros(5,1),'uchar');
                        count = fwrite(HDR.FILE.FID, 0, 'ushort');
                        count = fwrite(HDR.FILE.FID,zeros(2,1),'uchar');
                        
                        count = fwrite(HDR.FILE.FID,zeros(7,1),'float');
                        count = fwrite(HDR.FILE.FID,HDR.Off(k),'short');
                        count = fwrite(HDR.FILE.FID,zeros(2,1),'uchar');
                        count = fwrite(HDR.FILE.FID,[zeros(2,1),e.sensitivity(k)],'float');
                        count = fwrite(HDR.FILE.FID,zeros(3,1),'char');
                        count = fwrite(HDR.FILE.FID,zeros(4,1),'uchar');
                        count = fwrite(HDR.FILE.FID,zeros(1,1),'char');
                        count = fwrite(HDR.FILE.FID,HDR.Cal(k),'short');
                end;	
                
                HDR.HeadLen = ftell(HDR.FILE.FID);
                if HDR.HeadLen ~= (900+75*HDR.NS),
                        fprintf(2,'Error SOPEN CNT-Write: Headersize does not fit\n');
                end;
        end;
        
        
elseif strcmp(HDR.TYPE,'FEF'),		% FEF/Vital format included
        HDR.FILE.FID = fopen(HDR.FileName,PERMISSION,HDR.Endianity);
        fseek(HDR.FILE.FID,32,'bof'); 	% skip preamble
        
        if exist('fefopen','file'),
                HDR = fefopen(HDR);
        end;
        
        fprintf(2,'Warning SOPEN: Implementing Vital/FEF format not completed yet. Contact <a.schloegl@ieee.org> if you are interested in this feature.\n');
        HDR.FILE.FID = -1;
        return;        

        
elseif strcmp(HDR.TYPE,'SCP'),	%
        HDR = scpopen(HDR,PERMISSION);        
        HDR.Calib = sparse(2:HDR.NS+1,1:HDR.NS,1);
        
        
elseif strcmp(HDR.TYPE,'EBS'),
        HDR.FILE.FID = fopen(HDR.FileName,PERMISSION,'ieee-be');
        
        fprintf(2,'Warning SOPEN: Implementing EBS format not completed yet. Contact <a.schloegl@ieee.org> if you are interested in this feature.\n');
        
        %%%%% (1) Fixed Header (32 bytes) %%%%%
        HDR.VERSION = fread(HDR.FILE.FID,[1,8],'char');	%