function a=ats(a)
%Reading Alive Technologies .ats files
%   a.file='AT000083.ats'
%   a=ats(a);
%   subplot(211);plot(a.ecg)
%   subplot(212);plot(a.x)
%
%Based on Bluetooth Heart Monitor Data Format, August 2006
%   Jussi.Virkkala@neuroupdate.com
%   2007-08-15 First version, no GPS information?

%File
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');

%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(a.length(i),a.blocks);
        case 17 %Status
            a.but=zeros(a.length(i)/2,a.blocks);
            a.bat=a.but;
        case 85 %2 axes
            a.x=zeros(a.length(i)/2,a.blocks);
            a.y=a.x;
        case 86 %3 axes
            a.x=zeros(a.length(i)/3,a.blocks);
            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

%Blocks
for b=1:a.blocks,
    for i=1:a.channels,
        switch a.type(i)
            case 170 %ECG
                a.ecg(:,b)=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
end

%Scaling
for i=1:a.channels,
    switch a.type(i)
        case 170 %ECG
            a.ecg=2*2.66*a.ecg(:)/255-2.66;
    case 17
            a.but=a.but(:);
            a.bat=a.bat(:)/2;
    case 85
            a.x=2*2*a.x(:)/255-2;
            a.y=2*2*a.y(:)/255-2;
    case 86
            a.x=2*2.7*a.x(:)/255-2.7;
            a.y=2*2.7*a.y(:)/255-2.7;
            a.z=2*2.7*a.z(:)/255-2.7;
    end
end
fclose(f);

%end of ats.m