function [data,varNames] = gaussread(FMT_DHT_FileName , DAT_FileName)
%GAUSSREAD Import GAUSS binary files.
%   Read either of two common GAUSS binary file formats:
%   (1) Binary GAUSS matrix files created with the GAUSS command SAVE. The
%       SAVE command will generate a file with a .FMT file extension, in which 
%       a single matrix is stored in double-precision.
%   (2) Binary GAUSS data set files created with the GAUSS command CREATE or
%       SAVED. The CREATE commands will generate a pair of files: The first is 
%       a descriptor file with .DHT extension that stores header and variable 
%       name information; the second file stores a matrix in either 2-byte 
%       signed integer, 4-byte single-precision, or 8-byte double-precision.
%
%   [DataMatrix , VarNames] = gaussread(FMT_DHT_FileName)
%   [DataMatrix , VarNames] = gaussread(FMT_DHT_FileName , DAT_FileName)
%
%   Optional Input: DAT_FileName
%
% Input:
%   FMT_DHT_FileName - String containing the name of the binary GAUSS matrix 
%     file (usually .FMT extension), or data set descriptor file (.DHT 
%     extension) to read. If the file resides in a directory that is not on 
%     the MATLAB path, then this string must include the full path of the file 
%     (e.g., 'C:\mydata\datasets\DATA.DHT').
%
% Optional Input:
%   DAT_FileName - String containing the name of the binary GAUSS data set 
%     file (probably .DAT extension) associated with the .DHT descriptor file 
%     specified above in 'FMT_DHT_FileName'. If the file resides in a directory
%     that is not on your MATLAB path, then this string must also include the 
%     full path of the file (e.g., 'C:\mydata\datasets\DATA.DAT').
%
% Outputs:
%   DataMatrix - A MATLAB matrix containing the contents of a GAUSS matrix or
%     data set file.
%
%   VarNames - Cell array of variable names associated with each of the columns
%     of the GAUSS data set. Valid ONLY for GAUSS data set files.
%
% Notes:
%   (1) If the required 'FMT_DHT_FileName' file is a GAUSS matrix file, then 
%       'DAT_FileName' is unnecessary and will be ignored even if specified.
%   (2) If the required 'FMT_DHT_FileName' input file is a GAUSS data set
%       descriptor (.DHT) file, then 'DAT_FileName' will be opened and read
%       if it is specified. If 'DAT_FileName' is unspecified, then the .DAT
%       file associated with the .DHT descriptor file will be constructed from 
%       the .DHT file by replacing .DHT extension with .DAT, thus retaining the
%       same filename. For example, if 'DAT_FileName' is not specified and 
%       FMT_DHT_FileName = 'mydata.dht', then DAT_FileName = 'mydata.dat'.
%
% See also PATH, FREAD, FOPEN.

% Copyright 1999-2002 The MathWorks, Inc.   
% $Revision: 1.7 $   $ Date: 1998/01/30 13:45:34 $

%
% Open the specified GAUSS binary file.
%

fid  =  fopen(FMT_DHT_FileName , 'r');

if fid == -1
   error(sprintf(' Cannot open specified ''%s'' GAUSS file.\n' , FMT_DHT_FileName))
end

%
% Read the first 2 bytes of the header to determine the type of file:
%
%     'DDDD' HEX = Simple   Matrix   File Format (.FMT matrix with <= 8190 elements)
%     'EEDD' HEX = Extended Matrix   File Format (.FMT matrix with >  8190 elements)
%
%     'DADA' HEX = Simple   Data Set File Format (.DHT data set with <= 8175 columns)
%     'EEDA' HEX = Extended Data Set File Format (.DHT data set with >  8175 columns)
%
% Reference: GAUSS Volume I: System & Graphics Manual, Chapter 9, page 127-138.
%

[fileFormat , count]  =  fread(fid , 1 , 'uint16');

%
% Call the appropriate decoding function for this type of binary GAUSS file.
%

switch fileFormat

   case {hex2dec('DDDD') , hex2dec('EEDD')}    % FMT matrix files.

      [data,errorFlag] =  readFMT(fid , fileFormat);

      fclose(fid);

      varNames  =  '';

      if errorFlag
         error (' Problem reading GAUSS binary matrix (FMT) file.')
      end

   case {hex2dec('DADA') , hex2dec('EEDA')}    % DHT/DAT data set files.

      if nargin == 1
%
%        Allow the convenience of NOT specifying the GAUSS data (.DAT) file
%        associated with the descriptor (.DHT) file. If the data file is NOT 
%        specified, assume it has the same name and is in the same directory 
%        as the descriptor file, except replace 'DHT' extension with 'DAT'.
%
         DAT_FileName  =  [strtok(FMT_DHT_FileName , '.') '.dat'];
         fDAT          =  fopen(DAT_FileName , 'r');

         if fDAT == -1
            error(' Cannot open GAUSS data set .DAT file')
         end

      else

         fDAT  =  fopen(DAT_FileName , 'r');

         if fDAT == -1
            fclose(fid);
            error(sprintf(' Cannot open specified ''%s'' GAUSS data set DAT file.\n' , DAT_FileName))
         end

      end

      [data,varNames,errorFlag]  =  readDHT(fid , fDAT , fileFormat);

      fclose(fid);
      fclose(fDAT);

      if errorFlag
         error (' Problem reading GAUSS data set (DHT/DAT) files.')
      end

   otherwise

      fclose(fid);

      error (' Invalid File Type: Neither matrix (FMT) nor data set descriptor (DHT) formats.')

end


%
% * * * * * * * * *  End of gauss2ML  * * * * * * * * *
%


function [data,errorFlag]  =  readFMT(fid , fileFormat)
%READFMT Read GAUSS binary matrix files (.FMT extension).
%
% [Data , ErrorFlag] = readFMT(FID , FileFormat)
%
% READFMT reads GAUSS binary matrix files created with the GAUSS command
% SAVE. The SAVE command will generate a file with a .FMT default file 
% extension, in which a single matrix is stored in double-precision. 
% The .FMT file extension may be changed by the user, so interpret any
% references to .FMT as a GAUSS binary matrix file.
%
% Inputs:   
%   FID: File handle of the GAUSS binary matrix (.FMT) file to read. Note 
%      that the main function GAUSS2ML has already opened the matrix file.
%
%   FileFormat: Type of .FMT matrix binary file: 'DDDD' HEX is a simple 
%      matrix file format; 'EEDD' HEX extended matrix file format.
%
% Output:
%   Data: Contents of GAUSS .FMT matrix file converted to a MATLAB matrix.
%
%   ErrorFlag: Error flag indicator = 0 if no error occurrs and = 1 if an
%      error occurred trying to read/decose the binary matrix file.
%

errorFlag  =  0;                       % Intialize to 'No Error' condition.
data       = [];                       % Intialize output matrix placeholder.


if fileFormat == hex2dec('DDDD')       % Simple matrix file format.

%
%  Read the matrix header information contained in the first 16-bytes. Each field is
%  an unsigned 2-byte integer:
%
%       Bytes  0-1  = DDDD HEX identification flag
%       Bytes  2-3  = Number of rows
%       Bytes  4-5  = Number of columns
%       Bytes  6-7  = Size of the file minus the 16-byte header
%       Bytes  8-9  = Data type: '0086' HEX for REAL matrices/'8086' HEX for COMPLEX matrices
%       Bytes 10-15 = Reserved (zero padded)
%

   [header , count]  =  fread(fid , 7 , 'uint16');

   rows      =  header(1);
   columns   =  header(2);
   bytes     =  header(3);
   data_type =  header(4);


elseif fileFormat == hex2dec('EEDD')   % Extended matrix file format.

%
%  Read the matrix header information contained in the first 16-bytes.
%
%       Bytes  0-1  = EEDD HEX identification flag                                            (unsigned 2-byte integer)
%       Bytes  2-3  = File type: '0086' HEX for REAL matrices/'8086' HEX for COMPLEX matrices (unsigned 2-byte integer)
%       Bytes  4-7  = Number of rows                                                          (unsigned 4-byte integer)
%       Bytes  8-11 = Number of columns                                                       (unsigned 4-byte integer)
%       Bytes 12-15 = Size of the file minus this 16-byte header                              (unsigned 4-byte integer)
%

   [data_type , count]  =  fread(fid , 1 , 'uint16');
   [header    , count]  =  fread(fid , 3 , 'uint32');

   rows     =  header(1);
   columns  =  header(2);
   bytes    =  header(3);

end

%
% Read the data & resize the matrix if data consistency exists between the header & body.
%

if data_type == hex2dec('0086')         % REAL Matrix

   [data , count]  =  fread(fid , (rows * columns) , 'double');

   if (rows * columns) == count

      data  =  reshape(data , columns , rows)';

   else

      disp (' ')
      disp (' ERROR: REAL Matrix Inconsistency between Header/Body Information.')
      disp ('        The number of matrix elements expected from the header    ')
      disp ('        does NOT match the number of elements actually read.      ')