Mercurial > hg > octave-lyh
diff scripts/general/bitget.m @ 4916:c45f14873b5e
[project @ 2004-07-26 14:35:12 by jwe]
author | jwe |
---|---|
date | Mon, 26 Jul 2004 14:37:05 +0000 |
parents | |
children | b22a7a1db0d5 |
line wrap: on
line diff
new file mode 100644 --- /dev/null +++ b/scripts/general/bitget.m @@ -0,0 +1,53 @@ +## 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}) +## returns 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