% Author: C. Talarico
% File name: ltsExp2Matlab.m
% ltsExp2Matlab.m reads an LTspice sim. exported as textfile into Matlab
% This version of the function supports DC sweep analysis, TRAN analysis
% and AC analysis
%
% Calling Convention:
%        [nvars blocks points PDATA] = ltsExp2Matlab( FILENAME ) 
%
% nvars  - number of sim. variables plotted      
% blocks - number of sim. "steps" (number of data sets = blocks*nvars)
% points - number of points in each data set
% PDATA  - processed data (mR x nR Matrix)
%                          mR = blocks*nvars, nR = points

function [nvars blocks points PDATA] = ltsExp2Matlab( FILENAME )

format LONGG;

countsteps  = 0;
countpoints = 0;
fid = fopen(FILENAME);
tline = fgetl(fid);
fline = tline; % keep the first line
while isstr(tline)
  S = tline;
  [num,ok] = str2num(S);
  if (ok == 0)
    R = regexp(S,'Step','match');
    if (strcmp(R,'Step'))
      countsteps = countsteps + 1;
      disp(tline);
    end
  end
  if (ok == 1)
    countpoints = countpoints + 1;
    % NEED TO PARSE THE STRING INTO ITS FIELDS THEN VECTORIZE THE FIELDS
    str = S;
    A=strread(str,'%s'); % default delimiter: one or more spaces
    [mA nA] = size(A); % m is the number of variables we observe
    % check if the variables are real numbers or complex numbers    
    % NOTE: str2num has issues, use str2double instead 
    for l=1:mA
      a = char(A(l)); % need a type casting
      occ = findstr(a,','); % real and imag part are separated by a comma 
      if (isempty(occ) == 1) % it is a real number    
        data(countpoints,l) = str2double(a);
      else % it is a complex number
        cnum = strsplit(a,','); % complex number string
        re = str2double(cnum(1));
        im = str2double(cnum(2));
        c = complex(re,im);
        data(countpoints,l) = c;
      end  
    end
  end
  tline = fgetl(fid);
end
if countsteps == 0 
    blocks = 1;
else
    blocks = countsteps;
end
fclose(fid);

nvars   = mA;                  % number of variables observed
totpoints = countpoints;       % total number of data points per variable
points    = totpoints/blocks;  % number of points per step
blocks;                        % number of steps

s1 = ['number of variables plotted is ', num2str(nvars), ':']; 
fprintf('\n%s \t %s \n\n', s1, fline);
s2 = ['total data points: ', num2str(totpoints), ' x ', num2str(nvars)];
fprintf('%s \t\t\t \n\n', s2);
s3 = ['simulation steps: ', num2str(blocks)];
fprintf('%s \t\t\t \n\n', s3);
s4 = ['data points per simulation step: ', num2str(points), ' x ', ...
    num2str(nvars)];
fprintf('%s \t\t\t \n\n', s4);

tdata = transpose(data);
tdatasize = size(tdata); % totpoints x nvars

PDATA = zeros(blocks*nvars,points);
[mR nR] = size(PDATA);

vindex = 0; % nvars's index counter
for i=1:mR
  bindex = ceil(i/nvars); % block's index
  vindex = vindex + 1;
  if vindex > nvars
    vindex = 1; % reset the vindex counter
  end
  % vindex 
  % 1+points*(bindex-1)
  % points*bindex
  PDATA(i,:) = tdata(vindex,1+points*(bindex-1):points*bindex);
  tdata(vindex,1+points*(bindex-1):points*bindex);
end

% PDATA