% SAVE_IT Saves an IT++ file to disk.
%
% SAVE_IT fname.it saves all workspace variables to the IT++ file 'fname.it'.
% SAVE_IT fname.it x y z saves variables x, y, and z to the IT++ file 'fname.it'.
%
% save_it.m,v 1.1.1.1 2001/10/10 13:31:08 tonyottosson Exp
%
% See also LOAD_IT

function save_it(fname, varargin)


if (nargin > 1)
  vars = varargin;
  
else
  vars = evalin('caller', 'who(''*'')')';
end


endianity = 1; % Always big endian for now...
file_version = 1; % The current file-version of it_file

if (endianity == 0)
  [fid, err_msg] = fopen(fname, 'wb', 'ieee-le');
else
  [fid, err_msg] = fopen(fname, 'wb', 'ieee-be');
end

if (fid == -1)
  error(err_msg);
end


% Writes a file header consisting of "IT++" and an char containing the file version number
fprintf(fid, 'IT++%c', file_version);

% Should a vector with only one element be saved as a scalar in IT++ or as a vector?

for vname=vars
  vname = char(vname);
  v = evalin('caller', vname);

  if (isa(v, 'double')) % double precision floating point type
    is_scalar = (size(v,1)==1 & size(v,2)==1); % true if scalar (for future use)
    is_vector = (size(v,1)==1 | size(v,2)==1); % true if a vector (or a scalar)


    % Writes a char telling what binary format is used
    fwrite(fid, [endianity], 'char');

    if (isreal(v)) % Check if real values
      hdr_bytes = 1 + 3 * 4 + size(vname,2)+1 + 5;
      if (is_vector)
        data_bytes = 1 * 4 + 8 * prod(size(v));
      else % a matrix
        data_bytes = 2 * 4 + 8 * prod(size(v));
      end
      block_bytes = hdr_bytes + data_bytes;

      % Writes a header
      fwrite(fid, [hdr_bytes data_bytes block_bytes], 'uint32');
      % Writes variable name as string
      fprintf(fid, '%s%c', vname, 0);

      if (is_vector)
        fprintf(fid, 'dvec%c', 0);
        fwrite(fid, size(v(:),1), 'uint32');

      else % a matrix
        fprintf(fid, 'dmat%c', 0);
        fwrite(fid, size(v), 'uint32');
      end

      fwrite(fid, v, 'float64');

    else % complex values
      hdr_bytes = 1 + 3 * 4 + size(vname,2)+1 + 6;  % 3*4 is for sized, 6 is for type (dcvec)
      if (is_vector)
        data_bytes = 1 * 4 + 2 * 8 * prod(size(v));
      else % a matrix
        data_bytes = 2 * 4 + 2 * 8 * prod(size(v));
      end
      block_bytes = hdr_bytes + data_bytes;

      % Writes a header
      fwrite(fid, [hdr_bytes data_bytes block_bytes], 'uint32');
      % Writes variable name as string
      fprintf(fid, '%s%c', vname, 0);

      if (is_vector)
        fprintf(fid, 'dcvec%c', 0);
        fwrite(fid, size(v(:),1), 'uint32');
        for i=1:size(v(:),1)
          fwrite(fid, real(v(i)), 'float64');
          fwrite(fid, imag(v(i)), 'float64');
        end

      else % a matrix
        fprintf(fid, 'dcmat%c', 0);
        fwrite(fid, size(v), 'uint32');
        for j=1:size(v,2)
          for i=1:size(v,1)
            fwrite(fid, real(v(i,j)), 'float64');
            fwrite(fid, imag(v(i,j)), 'float64');
          end
        end
      end

    end % real or complex

  else
    warning(['Variable ''' vname ''' is not a vector or matrix.  Not saved.']);
  end

end