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
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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})
+## 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