function [data_f, data, noise_f, noise_data, Zo] = SXPParse(DataFileName, fid_log);

% [data_f, data, noise_f, noise, Zo] = SXPParse(DataFileName, fid_log);
%
% reads .sxp file data in MDIF format (a.k.a. HPEEsof format)
%
% data is a PxPxF matrix of complex, data_f an F-size vector
%
% description of .sxp files :
% '!' is a comment line
% the specifier line is preceded by '#' : (and anything before it is ignored)
% # <freq units> <param_type> <data format> R <reference resistance value>
%
% permitted values :
% <freq units>                  GHz, Mhz, kHz, Hz
% <param_type>                  S, Z, Y, G, H (same as output data !)
% <data format>                 RI, MA, DB
% <reference resistance value>  alphanumeric
%
% examples of specifier line
% # GHz     S            RI  R 50 !(S in real and imaginary, 50ohm system)
% # MHz     S            MA  R 75 !(S in lin mag and angle <deg>, 75ohm system)
% # kHz     S            DB  R 50 !(S in log mag (dB) and angle <deg>, 50ohm system)
%
% (defaults : # MHz MA R 50)
%
% -------------------------------------------------
% format of data in file (*.s2p) is :
% f s11.1 s11.2 s21.1 s21.2 s12.1 s12.2 s22.1 s22.2
% -------------------------------------------------
%
% format of data in file (*.sxp) with x>2 is :
% -------------------------------------------------
% f s11.1 s11.2 s12.1 s12.2 ... s1x.1 s1x.2
%   s21.1 s21.2 s22.2 s22.2 ... s2x.1 s2x.2
%   ...
%   sx1.1 sx1.2 sx2.1 sx2.2 ... sxx.1 sxx.2
% -------------------------------------------------
%
% ver 1.1 : data in format complex (26feb99)
% ver 1.2 : zgomot adaugat (4martie99)
% ver 1.21: max. nr of ports increased from 9 to 99 (24.04.2002)
%
% written by tudor dima, tudima@zahoo.com, change the z into y


%------- read from file DataFileName -------
%format compact;
if nargin<2
   fid_log = 1; % daca nu vrei log se duce la screen (verifica fid_log inainte sa-l pasezi)
end;

raw_data = []; % FileReadOK = 0;
fid = fopen(DataFileName, 'rt');

if fid < 1 
   fprintf(fid_log, '%s \n %s', ' ... exiting...', ['Error : requested parameter file ' DataFileName ' not found ! ']);
end;

if fid > 0
   fprintf(fid_log, '\n %s', ['reading parameter data from file ' DataFileName ' ...']);
   
   % --- find out matrix order ---
   NoOfPorts = str2num(DataFileName(size(DataFileName,2)-1) );
   candidate_zeci = str2num(DataFileName(size(DataFileName,2)-2) );
   if ~isempty(candidate_zeci)
      NoOfPorts = NoOfPorts + 10*candidate_zeci;
   end; % ugly, works only up to 99, but still...
      
   buff = 'some dummy text';
   StartOptions = 0;
   StartData = 0;
   % --- read specifier line ---
   while ~isempty(buff) & ~StartData
      buff = fscanf(fid, '%s', 1 );
      if StartOptions & StartOptions <= 5
         l = size(buff,2);
         Specifier(StartOptions,(1:l)) = buff;
         StartOptions = StartOptions + 1;
      end;
      if strcmp(buff, '#')
         StartOptions = StartOptions + 1;
      end;
      if StartOptions == 6
         StartData = 1;
      end;
   end % {while}
   
   % --- read data one frequency at a time ---
   if StartData
      last_frequency = 0;
      noise_started = 0;
      freq_index = 0;
      noise_f_index = 0;
      NewFrequency = 1;
      while ~isempty(buff) 
         if NewFrequency
            buff = fscanf(fid, '%s', 1 );
            if ~isempty(buff)
               if str2num(buff) < last_frequency;
                  noise_started = 1;
               end;
               if noise_started
                  noise_f_index = noise_f_index +1;
                  noise_f(noise_f_index) = str2num(buff);               
                  NewFrequency = 0;   
               else
                  freq_index = freq_index + 1;
                  data_f(freq_index) = str2num(buff);
                  last_frequency = data_f(freq_index);
                  NewFrequency = 0;   
               end;   
            end;
         else
            if noise_started
               buff = fscanf(fid, '%s', 1 ); NFmin(noise_f_index) = str2num(buff);
               buff = fscanf(fid, '%s', 1 ); gamma1(noise_f_index) = str2num(buff);
               buff = fscanf(fid, '%s', 1 ); gamma2(noise_f_index) = str2num(buff);
               buff = fscanf(fid, '%s', 1 ); Rn(noise_f_index) = str2num(buff);
               NewFrequency = 1;            
            else
               for i=1:NoOfPorts
                  for j=1:2*NoOfPorts
                     buff = fscanf(fid, '%s', 1 );
                     raw_data(i,j, freq_index) = str2num(buff);
                  end;
               end;
               NewFrequency = 1;        
            end;
         end; % {if NewFrequency)
      end % {while}
   end; %{if StartData)
   % --- process specifiers ---
   
   multiplier = 1; format = 2; % defaults : <MHz>, MA
   freq_units = Specifier(1,:);
   
   switch freq_units 
   case 'GHz';				multiplier = 1e9;
   case 'MHz';				multiplier = 1e6;
   case 'kHz';				multiplier = 1e3;
   case {'Hz', 'HZ'};	multiplier = 1;
   end;
   
   data_f = data_f * multiplier;
   
   type = Specifier(3,1); % not used yet; assumed to be S for now;
   Zo = str2num(Specifier(5,:));
   if (strcmp(Specifier(3,1),'R') | strcmp(Specifier(3,1),'r')) & (strcmp(Specifier(3,2),'I') | strcmp(Specifier(3,2),'i'))
      format = 1;
   elseif (strcmp(Specifier(3,1),'M') | strcmp(Specifier(3,1),'m')) & (strcmp(Specifier(3,2),'A') | strcmp(Specifier(3,2),'a'))
      format = 2;
   elseif (strcmp(Specifier(3,1),'D') | strcmp(Specifier(3,1),'d')) & (strcmp(Specifier(3,2),'B') | strcmp(Specifier(3,2),'b'))
      format = 3;
   end;
   % --- swap data for stupi 2nd order exception ---
   if NoOfPorts == 2
      buff_r(1:freq_index) = raw_data(1, 3, 1:freq_index);
      buff_i(1:freq_index) = raw_data(1, 4, 1:freq_index);
      raw_data(1, 3, 1:freq_index) = raw_data(2, 1, 1:freq_index);
      raw_data(1, 4, 1:freq_index) = raw_data(2, 2, 1:freq_index);
      raw_data(2, 1, 1:freq_index) = buff_r(1:freq_index);
      raw_data(2, 2, 1:freq_index) = buff_i(1:freq_index);
   end;
   
   switch format
   case 1
      for i =1:NoOfPorts
         for j=1:NoOfPorts
            Re = raw_data(i, 2*j-1, 1:freq_index) ;
            Im = raw_data(i, 2*j, 1:freq_index) ;
            data(i,j, 1:freq_index) = Re + sqrt(-1)*Im;
         end;
      end;
   case 2
      for i =1:NoOfPorts
         for j=1:NoOfPorts
            Re = raw_data(i, 2*j-1, 1:freq_index) .* cos(raw_data(i, 2*j, 1:freq_index)*pi/180);
            Im = raw_data(i, 2*j-1, 1:freq_index) .* sin(raw_data(i, 2*j, 1:freq_index)*pi/180);
            data(i,j, 1:freq_index) = Re + sqrt(-1)*Im;
         end;
      end;
   case 3
      for i =1:NoOfPorts
         for j=1:NoOfPorts
            Re = 10.^(raw_data(i, 2*j-1, 1:freq_index)/20) .* cos(raw_data(i, 2*j, 1:freq_index)*pi/180);
            Im = 10.^(raw_data(i, 2*j-1, 1:freq_index)/20) .* sin(raw_data(i, 2*j, 1:freq_index)*pi/180);
            data(i,j, 1:freq_index) = Re + sqrt(-1)*Im;
         end;
      end;
   end;
   
   if noise_started
      noise_f = noise_f * multiplier;
      switch format
      case 1 
         gamma = gamma1 + sqrt(-1)*gamma2;
      case 2
         gamma = gamma1.*(cos(gamma2*pi/180) + sqrt(-1)*sin(gamma2*pi/180));
      case 3
         gamma = 10.^(gamma1/20)*(cos(gamma2*pi/180) + sqrt(-1)*sin(gamma2*pi/180));
      end;
      for i=1:noise_f_index
         noise_data(i,1) = NFmin(i);
         noise_data(i,2) = gamma(i);
         noise_data(i,3) = Rn(i);
      end;
   else
      noise_data = [];
      noise_f = [];
   end;
   fclose(fid);
   FileReadOK = 1;
   fprintf(fid_log, '\n %s\n', '...done');
else
   data_f = [0]; data = zeros(2); Zo = 0;
end;