function ft_realtime_fileproxy(cfg)

% FT_REALTIME_FILEPROXY reads continuous data from an EEG/MEG file and writes it to a

% FieldTrip buffer. This works for any file format that is supported by FieldTrip.

%

% The FieldTrip buffer is a network transparent server that allows the acquisition

% client to stream data to it. An analysis client can connect to read the data upon

% request. Multiple clients can connect simultaneously, each analyzing a specific

% aspect of the data concurrently.

%

% Use as

% ft_realtime_fileproxy(cfg)

% with the following configuration options

% cfg.minblocksize = number, in seconds (default = 0)

% cfg.maxblocksize = number, in seconds (default = 1)

% cfg.channel = cell-array, see FT_CHANNELSELECTION (default = 'all')

% cfg.jumptoeof = jump to end of file at initialization (default = 'no')

% cfg.readevent = whether or not to copy events (default = 'no'; event type can also be specified; e.g., 'UPPT002')

% cfg.speed = relative speed at which data is written (default = inf)

%

% The source of the data is configured as

% cfg.source.dataset = string

% or alternatively to obtain more low-level control as

% cfg.source.datafile = string

% cfg.source.headerfile = string

% cfg.source.eventfile = string

% cfg.source.dataformat = string, default is determined automatic

% cfg.source.headerformat = string, default is determined automatic

% cfg.source.eventformat = string, default is determined automatic

%

% The target to write the data to is configured as

% cfg.target.datafile = string, target destination for the data (default = 'buffer://localhost:1972')

% cfg.target.dataformat = string, default is determined automatic

%

% To stop this realtime function, you have to press Ctrl-C

%

% See also FT_REALTIME_SIGNALPROXY, FT_REALTIME_SIGNALVIEWER

% Copyright (C) 2008, Robert Oostenveld

%

% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org

% for the documentation and details.

%

% FieldTrip 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.

%

% FieldTrip 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 FieldTrip. If not, see <http://www.gnu.org/licenses/>.

%

% $Id$

% set the defaults

if ~isfield(cfg, 'source'), cfg.source = []; end

if ~isfield(cfg, 'target'), cfg.target = []; end

if ~isfield(cfg.source, 'headerformat'), cfg.source.headerformat = []; end % default is detected automatically

if ~isfield(cfg.source, 'dataformat'), cfg.source.dataformat = []; end % default is detected automatically

if ~isfield(cfg.target, 'headerformat'), cfg.target.headerformat = []; end % default is detected automatically

if ~isfield(cfg.target, 'dataformat'), cfg.target.dataformat = []; end % default is detected automatically

if ~isfield(cfg.target, 'datafile'), cfg.target.datafile = 'buffer://localhost:1972'; end

if ~isfield(cfg, 'minblocksize'), cfg.minblocksize = 0; end % in seconds

if ~isfield(cfg, 'maxblocksize'), cfg.maxblocksize = 1; end % in seconds

if ~isfield(cfg, 'channel'), cfg.channel = 'all'; end

if ~isfield(cfg, 'jumptoeof'), cfg.jumptoeof = 'no'; end % jump to end of file at initialization

if ~isfield(cfg, 'readevent'), cfg.readevent = 'no'; end % capture events?

if ~isfield(cfg, 'speed'), cfg.speed = inf ; end % inf -> run as fast as possible

% translate dataset into datafile+headerfile

cfg.source = ft_checkconfig(cfg.source, 'dataset2files', 'yes');

cfg.target = ft_checkconfig(cfg.target, 'dataset2files', 'yes');

ft_checkconfig(cfg.source, 'required', {'datafile' 'headerfile'});

ft_checkconfig(cfg.target, 'required', {'datafile' 'headerfile'});

if ~isfield(cfg.source,'eventfile') || isempty(cfg.source.eventfile)

cfg.source.eventfile = cfg.source.datafile;

end

if ~isfield(cfg.target,'eventfile') || isempty(cfg.target.eventfile)

cfg.target.eventfile = cfg.target.datafile;

end

% ensure that the persistent variables related to caching are cleared

clear ft_read_header

% read the header for the first time

hdr = ft_read_header(cfg.source.headerfile);

fprintf('updating the header information, %d samples available\n', hdr.nSamples*hdr.nTrials);

% define a subset of channels for reading

cfg.channel = ft_channelselection(cfg.channel, hdr.label);

chanindx = match_str(hdr.label, cfg.channel);

nchan = length(chanindx);

if nchan==0

ft_error('no channels were selected');

end

minblocksmp = round(cfg.minblocksize*hdr.Fs);

minblocksmp = max(minblocksmp, 1);

maxblocksmp = round(cfg.maxblocksize*hdr.Fs);

count = 0;

if strcmp(cfg.jumptoeof, 'yes')

prevSample = hdr.nSamples * hdr.nTrials;

else

prevSample = 0;

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% this is the general BCI loop where realtime incoming data is handled

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

evt = [];

while true

% determine number of samples available in buffer

hdr = ft_read_header(cfg.source.headerfile, 'cache', true);

% see whether new samples are available

newsamples = (hdr.nSamples*hdr.nTrials-prevSample);

if newsamples>=minblocksmp

begsample = prevSample+1;

endsample = prevSample+min(newsamples,maxblocksmp);

% remember up to where the data was read

count = count + 1;

fprintf('processing segment %d from sample %d to %d\n', count, begsample, endsample);

% read data segment

dat = ft_read_data(cfg.source.datafile,'header', hdr, 'dataformat', cfg.source.dataformat, 'begsample', begsample, 'endsample', endsample, 'chanindx', chanindx, 'checkboundary', false);

% it only makes sense to read those events associated with the currently processed data

if ~strcmp(cfg.readevent,'no')

evt = ft_read_event(cfg.source.eventfile, 'header', hdr, 'minsample', begsample, 'maxsample', endsample);

if ~strcmp(cfg.readevent,'yes')

evt = ft_filter_event(evt, 'type', cfg.readevent);

end

end

prevSample = endsample;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% from here onward it is specific to writing the data to another stream

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if count==1

% the input file may have a different offset than the output file

offset = begsample - 1;

% flush the file, write the header and subsequently write the data segment

ft_write_data(cfg.target.datafile, dat, 'header', hdr, 'dataformat', cfg.target.dataformat, 'chanindx', chanindx, 'append', false);

if ~strcmp(cfg.readevent,'no')

for i=1:numel(evt)

evt(i).sample = evt(i).sample - offset;

end

ft_write_event(cfg.target.eventfile,evt,'append',false);

end

else

% write the data segment

ft_write_data(cfg.target.datafile, dat, 'header', hdr, 'dataformat', cfg.target.dataformat, 'chanindx', chanindx, 'append', true);

if ~strcmp(cfg.readevent,'no')

for i=1:numel(evt)

evt(i).sample = evt(i).sample - offset;

end

ft_write_event(cfg.target.eventfile,evt,'append',true);

end

end % if count==1

% wait for a realistic amount of time

pause(((endsample-begsample+1)/hdr.Fs)/cfg.speed);

end % if enough new samples

end % while true