## Copyright (C) 2004-2012 John W. Eaton
##
## This file is part of Octave.
##
## Octave is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or (at
## your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn  {Function File} {[@var{c}, @var{maxsize}, @var{endian}] =} computer ()
## @deftypefnx {Function File} {@var{arch} =} computer ("arch")
## Print or return a string of the form @var{cpu}-@var{vendor}-@var{os}
## that identifies the kind of computer Octave is running on.  If invoked
## with an output argument, the value is returned instead of printed.  For
## example:
##
## @example
## @group
## computer ()
##      @print{} i586-pc-linux-gnu
##
## x = computer ()
##      @result{} x = "i586-pc-linux-gnu"
## @end group
## @end example
##
## If two output arguments are requested, also return the maximum number
## of elements for an array.
##
## If three output arguments are requested, also return the byte order
## of the current system as a character (@code{"B"} for big-endian or
## @code{"L"} for little-endian).
##
## If the argument @code{"arch"} is specified, return a string
## indicating the architecture of the computer on which Octave is
## running.
## @end deftypefn

function [c, maxsize, endian] = computer (a)

  if (nargin == 1 && ischar (a) && strcmpi (a, "arch"))
    tmp = strsplit (octave_config_info ("canonical_host_type"), "-");
    if (numel (tmp) == 4)
      c = sprintf ("%s-%s-%s", tmp{4}, tmp{3}, tmp{1});
    else
      c = sprintf ("%s-%s", tmp{3}, tmp{1});
    endif
  elseif (nargin == 0)
    msg = octave_config_info ("canonical_host_type");

    if (strcmp (msg, "unknown"))
      msg = "Hi Dave, I'm a HAL-9000";
    endif

    if (nargout == 0)
      printf ("%s\n", msg);
    else
      c = msg;
      if (strcmp (octave_config_info ("USE_64_BIT_IDX_T"), "true"))
        maxsize = 2^63-1;
      else
        maxsize = 2^31-1;
      endif
      if (octave_config_info ("words_big_endian"))
        endian = "B";
      elseif (octave_config_info ("words_little_endian"))
        endian = "L";
      else
        endian = "?";
      endif
    endif
  else
    print_usage ();
  endif

endfunction

%!assert((ischar (computer ())
%! && computer () == octave_config_info ("canonical_host_type")));
%!assert(ischar (computer ("arch")));
%!error computer (2);