view scripts/general/bitget.m @ 4920:b22a7a1db0d5

[project @ 2004-07-27 18:15:25 by jwe]
author jwe
date Tue, 27 Jul 2004 18:16:18 +0000
parents c45f14873b5e
children 0896307b1b48
line wrap: on
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## Copyright (C) 2004 David BAteman
##
## This program 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 2 of the License, or
## (at your option) any later version.
##
## This program 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 this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

## -*- texinfo -*-
## @deftypefn {Function File} {@var{X} =} bitget (@var{a},@var{n})
## Return the status of bit(s) @var{n} of unsigned integers in @var{a}
## the lowest significant bit is @var{n} = 1.
##
## @example
## bitget (100, 8:-1:1)
## @result{} 0  1  1  0  0  1  0  0 
## @end example
## @seealso{bitand, bitor, bitxor, bitset, bitcmp, bitshift, bitmax}
## @end deftypefn

## Liberally based of the version by Kai Habel from octave-forge

function X = bitget (A, n)

  if (nargin != 2)
    usage ("bitget (A, n)");
  endif

  cname = class (A);
  if (strcmp (cname, "double"))
    Amax = log2 (bitmax) + 1;
  elseif strcmp ("uint", substr (cname, 1, 4))
    Amax = eval ([cname, " (log2 (double (intmax (cname))) + 1);"]);
  else
    Amax = eval ([cname, " (log2 (double (intmax (cname))) + 2);"]);
  endif

  Aone = eval ([ cname, "(1);"]);
  m = eval ([cname, " (n(:));"]);
  if (any (m < Aone) || any (m > Amax))
    error ("n must be in the range [1,%d]", Amax);
  endif

  X = eval (["bitand (A, ", cname, " (2) .^ (", cname, " (n) - Aone)) != ", cname, "(0);"]);

endfunction