% This programm reads ECG data which are saved in format 212.

% (e.g., 100.dat from MIT-BIH-DB, cu01.dat from CU-DB,...)

% The data are displayed in a figure together with the annotations.

% The annotations are saved in the vector ANNOT, the corresponding

% times (in seconds) are saved in the vector ATRTIME.

% The annotations are saved as numbers, the meaning of the numbers can

% be found in the codetable "ecgcodes.h" available at www.physionet.org.

%

% ANNOT only contains the most important information, which is displayed

% with the program rdann (available on www.physionet.org) in the 3rd row.

% The 4th to 6th row are not saved in ANNOT.

%

%

%      created on Feb. 27, 2003 by

%      Robert Tratnig (Vorarlberg University of Applied Sciences)

%      (email: rtratnig@gmx.at),

%

%      algorithm is based on a program written by

%      Klaus Rheinberger (University of Innsbruck)

%      (email: klaus.rheinberger@uibk.ac.at)

%

%-------------------------------------------------------------------------

clc; clear all;

%------ SPECIFY DATA ------------------------------------------------------

%------ 指定数据文件 -------------------------------------------------------

PATH= 'F:\MATLAB\MIT-BIH'; % 指定数据的储存路径

HEADERFILE= '100.hea';      % .hea 格式，头文件，可用记事本打开

ATRFILE= '100.atr';         % .atr 格式，属性文件，数据格式为二进制数

DATAFILE='100.dat';         % .dat ¸ñʽ£¬ECG Êý¾Ý

SAMPLES2READ=1800;          % 指定需要读入的样本数

                            % 若.dat文件中存储有两个通道的信号:

                            % 则读入 2*SAMPLES2READ 个数据 

%------ LOAD HEADER DATA --------------------------------------------------

%------ 读入头文件数据 -----------------------------------------------------

%

% 示例：用记事本打开的117.hea 文件的数据

%

%      117 2 360 650000

%      117.dat 212 200 11 1024 839 31170 0 MLII

%      117.dat 212 200 11 1024 930 28083 0 V2

%      # 69 M 950 654 x2

%      # None

%

%-------------------------------------------------------------------------

fprintf(1,'\\n$> WORKING ON %s ...\n', HEADERFILE); % 在Matlab命令行窗口提示当前工作状态

% 

% 【注】函数 fprintf 的功能将格式化的数据写入到指定文件中。

% ±í´ïʽ£ºcount = fprintf(fid,format,A,...)

% 在字符串'format'的控制下，将矩阵A的实数数据进行格式化，并写入到文件对象fid中。该函数返回所写入数据的字节数 count。

% fid 是通过函数 fopen 获得的整型文件标识符。fid=1，表示标准输出（即输出到屏幕显示）；fid=2，表示标准偏差。

%

signalh= fullfile(PATH, HEADERFILE);    % 通过函数 fullfile 获得头文件的完整路径

fid1=fopen(signalh,'r');    % 打开头文件，其标识符为 fid1 ，属性为'r'--“只读”

z= fgetl(fid1);             % 读取头文件的第一行数据，字符串格式

A= sscanf(z, '%*s %d %d %d',[1,3]); % 按照格式 '%*s %d %d %d' 转换数据并存入矩阵 A 中

nosig= A(1);    % 信号通道数目

sfreq=A(2);     % 数据采样频率

clear A;        % 清空矩阵 A ，准备获取下一行数据

for k=1:nosig           % 读取每个通道信号的数据信息

    z= fgetl(fid1);

    A= sscanf(z, '%*s %d %d %d %d %d',[1,5]);

    dformat(k)= A(1);           % 信号格式; 这里只允许为 212 格式

    gain(k)= A(2);              % 每 mV 包含的整数个数

    bitres(k)= A(3);            % 采样精度（位分辨率）

    zerovalue(k)= A(4);         % ECG 信号零点相应的整数值

    firstvalue(k)= A(5);        % 信号的第一个整数值 (用于偏差测试)

end;

fclose(fid1);

clear A;

%------ LOAD BINARY DATA --------------------------------------------------

%------ 读取 ECG 信号二值数据 ----------------------------------------------

%

if dformat~= [212,212], error('this script does not apply binary formats different to 212.'); end;

signald= fullfile(PATH, DATAFILE);            % 读入 212 格式的 ECG 信号数据

fid2=fopen(signald,'r');

A= fread(fid2, [3, SAMPLES2READ], 'uint8')';  % matrix with 3 rows, each 8 bits long, = 2*12bit

fclose(fid2);

% 通过一系列的移位（bitshift）、位与（bitand）运算，将信号由二值数据转换为十进制数

M2H= bitshift(A(:,2), -4);        %字节向右移四位，即取字节的高四位

M1H= bitand(A(:,2), 15);          %取字节的低四位

PRL=bitshift(bitand(A(:,2),8),9);     % sign-bit   取出字节低四位中最高位，向右移九位

PRR=bitshift(bitand(A(:,2),128),5);   % sign-bit   取出字节高四位中最高位，向右移五位

M( : , 1)= bitshift(M1H,8)+ A(:,1)-PRL;

M( : , 2)= bitshift(M2H,8)+ A(:,3)-PRR;

if M(1,:) ~= firstvalue, error('inconsistency in the first bit values'); end;

switch nosig

case 2

    M( : , 1)= (M( : , 1)- zerovalue(1))/gain(1);

    M( : , 2)= (M( : , 2)- zerovalue(2))/gain(2);

    TIME=(0:(SAMPLES2READ-1))/sfreq;

case 1

    M( : , 1)= (M( : , 1)- zerovalue(1));

    M( : , 2)= (M( : , 2)- zerovalue(1));

    M=M';

    M(1)=[];

    sM=size(M);

    sM=sM(2)+1;

    M(sM)=0;

    M=M';

    M=M/gain(1);

    TIME=(0:2*(SAMPLES2READ)-1)/sfreq;

otherwise  % this case did not appear up to now!

    % here M has to be sorted!!!

    disp('Sorting algorithm for more than 2 signals not programmed yet!');

end;

clear A M1H M2H PRR PRL;

fprintf(1,'\\n$> LOADING DATA FINISHED \n');

%------ LOAD ATTRIBUTES DATA ----------------------------------------------

atrd= fullfile(PATH, ATRFILE);      % attribute file with annotation data

fid3=fopen(atrd,'r');

A= fread(fid3, [2, inf], 'uint8')';

fclose(fid3);

ATRTIME=[];

ANNOT=[];

sa=size(A);

saa=sa(1);

i=1;

while i<=saa

    annoth=bitshift(A(i,2),-2);

    if annoth==59

        ANNOT=[ANNOT;bitshift(A(i+3,2),-2)];

        ATRTIME=[ATRTIME;A(i+2,1)+bitshift(A(i+2,2),8)+...

                bitshift(A(i+1,1),16)+bitshift(A(i+1,2),24)];

        i=i+3;

    elseif annoth==60

        % nothing to do!

    elseif annoth==61

        % nothing to do!

    elseif annoth==62

        % nothing to do!

    elseif annoth==63

        hilfe=bitshift(bitand(A(i,2),3),8)+A(i,1);

        hilfe=hilfe+mod(hilfe,2);

        i=i+hilfe/2;

    else

        ATRTIME=[ATRTIME;bitshift(bitand(A(i,2),3),8)+A(i,1)];

        ANNOT=[ANNOT;bitshift(A(i,2),-2)];

   end;

   i=i+1;

end;

ANNOT(length(ANNOT))=[];       % last line = EOF (=0)

ATRTIME(length(ATRTIME))=[];   % last line = EOF

clear A;

ATRTIME= (cumsum(ATRTIME))/sfreq;

ind= find(ATRTIME <= TIME(end));

ATRTIMED= ATRTIME(ind);

ANNOT=round(ANNOT);

ANNOTD= ANNOT(ind);

%------ DISPLAY DATA ------------------------------------------------------

figure(1); clf, box on, hold on

plot(TIME, M(:,1),'r');

if nosig==2

    plot(TIME, M(:,2),'b');

end;

for k=1:length(ATRTIMED)

    text(ATRTIMED(k),0,num2str(ANNOTD(k)));

end;

xlim([TIME(1), TIME(end)]);

xlabel('Time / s'); ylabel('Voltage / mV');

string=['ECG signal ',DATAFILE];

title(string);

fprintf(1,'\\n$> DISPLAYING DATA FINISHED \n');

% -------------------------------------------------------------------------

fprintf(1,'\\n$> ALL FINISHED \n');