[e9d0dc]: bitshift.m  Maximize  Restore  History

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83``` ```## Copyright (C) 2000 Kai Habel ## ## 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} =} bitshift (@var{a},@var{k}) ## @deftypefnx {Function File} {@var{X} =} bitshift (@var{a},@var{k},@var{n}) ## return a @var{k} bit shift of @var{n}- digit unsigned ## integers in @var{a}. A positive @var{k} leads to a left shift. ## A negative value to a right shift. If @var{N} is omitted it defaults ## to log2(bitmax)+1. ## @var{N} must be in range [1,log2(bitmax)+1] usually [1,33] ## ## ## @example ## bitshift(eye(3),1)) ## @result{} ## @group ## 2 0 0 ## 0 2 0 ## 0 0 2 ## @end group ## ## bitshift(10,[-2, -1, 0, 1, 2]) ## @result{} 2 5 10 20 40 ## ## bitshift ([1, 10],2,[3,4]) ## @result{} 4 8 ## @end example ## ## @seealso{bitand,bitor,bitxor,bitset,bitget,bitcmp,bitmax} ## @end deftypefn ## Author: Kai Habel ## Bug fixed by Paul Kienzle ## log2(bitmax) must be rounded to nearest integer function X = bitshift (A,k,n) if ((nargin < 2) | (nargin > 3)) usage ("bitshift(A,n,k)"); endif if (nargin == 3) n = fix (n); if ( is_scalar(n) & (!is_scalar(k)) ) if (!is_scalar (A) & ((ndims (A) != ndims (k)) || any(size (A) != size (k)))) error ("size of A and k must match"); endif n = n .* ones (size (k)); elseif (!is_scalar (n)) & is_scalar (k) if (!is_scalar (A) & ((ndims (A) != ndims (n)) || any(size (A) != size (n)))) error ("size of A and n must match"); endif k = fix (k) .* ones (size (n)); elseif ((ndims (n) != ndims (n)) || any(size (n) != size (n))) error ("size of n and k must match"); endif else n = round (log2 (bitmax) * ones (size (k))); endif if !(is_matrix (A)) || is_complex (A) error ("first argument must be a real value"); else X = fix (A .* pow2 (k)); X = bitand (X, pow2 (n) - 1); endif endfunction ```