function a=ats(a)
%Reading Alive Technologies .ats files
%   ats;
%   a=ats('AT000083.ats')
%   a.noscaling=1 %use with large files to return uint8
%   a.file='AT00083.ats'
%   a=ats(a)
%
%Based on Bluetooth Heart Monitor Data Format, August 2006
%   Jussi.Virkkala@neuroupdate.com
%   2007-10-21 Noscaling option, uint8
%   2007-10-19 Dialog, data block 0, extra header data, plot
%   2007-08-15 First version, no GPS information?

%File
%2007-10-19 Filename as parameter
if nargin==0,a='';end
if isstr(a) | isempty(a),
    if isempty(a)
        [f p]=uigetfile('*.ats','Select Alivetec ats file');
        a.file=[p f];
    else
        a.file=a;
    end
end

f=fopen(a.file,'r','b');
%Header
a.id=char(fread(f,5,'uint8'))';
if ~strcmp(a.id,['ATSF' char(0)]), %ATFS
    a=[a.file ', unknown ats header:' a.id];
    fclose(f);
    return;
end
a.header=fread(f,1,'uint16');
a.channels=fread(f,1,'uint8');
a.blocks=fread(f,1,'uint32');
a.blocklength=fread(f,1,'uint16');
%date
a.year=fread(f,1,'uint16');
a.month=fread(f,1,'uint8');
a.day=fread(f,1,'uint8');
%time
a.hour=fread(f,1,'uint8');
a.minute=fread(f,1,'uint8');
a.second=fread(f,1,'uint8');
%reserved
reserved=fread(f,107,'uint8');

%2007-10-19 If zero block, use file size to determine
%if ~a.blocks,
    fseek(f,0,'eof');
    s=ftell(f)-128-32*a.channels;
    a.blocks=fix(s/a.blocklength)-1;
    fseek(f,128,'bof');
%end

%Channels
%ECG 0xAA(170), Status 0x11(17), 2 Axis 0x55(85), 3 Axis 0x56(86)
for i=1:a.channels,
    a.type(i)=fread(f,1,'uint8');
    a.format(i)=fread(f,1,'uint8');   
    a.length(i)=fread(f,1,'uint16');
    switch a.type(i)
        case 170 %ECG
            a.ecg=zeros(1,a.length(i)*a.blocks,'uint8');
            switch a.format(i)
                case 1
                    a.ecg_sr=150;
                case 2
                    a.ecg_sr=300;
                otherwise
                a=[a.file ', unknown ecg format' int2str(a.format(i))];
            end
        case 17 %Status
            a.but=zeros(a.length(i)/2,a.blocks,'uint8');
            a.bat=a.but;
        case 85 %2 axes
            a.x=zeros(a.length(i)/2,a.blocks,'uint8');
            a.y=a.x;
        case 86 %3 axes
            a.x=zeros(a.length(i)/3,a.blocks,'uint8');
            a.y=a.x;
            a.z=a.x;
        otherwise
            a=[a.file ', unknown ats type:' int2str(a.type(i))];
            fclose(f);
            return
    end        
    reserved=fread(f,28,'uint8');    %5-32
end
a.acc_sr=75;

%2007-10-19 extra bytes
fseek(f,a.header-128-32*a.channels,'cof');
extra=a.blocklength-sum(a.length);

%Blocks
for b=1:a.blocks,
    for i=1:a.channels,
        switch a.type(i)
            case 170 %ECG
                a.ecg((1:a.length(i))+(b-1)*a.length(i))=fread(f,a.length(i),'uint8');
            case 17 %status
                d=fread(f,a.length(i),'uint8');
                d=reshape(d,2,a.length(i)/2)';
                a.but(:,b)=d(:,1);
                a.bat(:,b)=d(:,2);
            case 85 %2 axes
                d=fread(f,a.length(i),'uint8');
                d=reshape(d,2,a.length(i)/2)';
                a.x(:,b)=d(:,1);
                a.y(:,b)=d(:,2);
            case 86 %3 axes
                d=fread(f,a.length(i),'uint8');
                d=reshape(d,3,a.length(i)/3)';
                a.x(:,b)=d(:,1);
                a.y(:,b)=d(:,2);
                a.z(:,b)=d(:,3);
        end     
    end
%2007-10-19 Extra zeros ignored
    fseek(f,extra,'cof');
end
fclose(f);

%Scaling
%2007-10-21 No scaling 
if ~isfield(a,'noscaling'),
    for i=1:a.channels,
        switch a.type(i)
        case 170 %ECG
            a.ecg=2*2.66*double(a.ecg(:)')/255-2.66;
        case 17
            a.but=a.but(:);
            a.bat=a.bat(:)/2;
        case 85
            a.x=2*2*double(a.x(:)')/255-2;
            a.y=2*2*double(a.y(:)')/255-2;
        case 86
            a.x=2*2.7*double(a.x(:)')/255-2.7;
            a.y=2*2.7*double(a.y(:)')/255-2.7;
            a.z=2*2.7*double(a.z(:)')/255-2.7;
        end
    end
else
    a.ecg=a.ecg(:);    
    a.bat=a.bat/2;
    a.x=a.x(:)';
    a.y=a.y(:)';
    if isfield(a,'z'),a.z=a.z(:)';end
end

%2007-10-19
if nargout==0,
    te=(1:length(a.ecg))/a.ecg_sr;
    ta=(1:length(a.x))/a.acc_sr;
    if isfield(a,'z'),
        plot(te,a.ecg+3,'k',ta,a.x,'k',ta,a.y,'b',ta,a.z,'r');
    else
        plot(te,a.ecg+3,'k',ta,a.x,'k',ta,a.y,'b')
    end
    xlabel('s');
    ylabel('Ecg+3 mV, x (black), y (blue), z (red) g')
end
%end of ats.m