update packages

[CreaPhase.git] / octave_packages / m / miscellaneous / swapbytes.m

diff --git a/octave_packages/m/miscellaneous/swapbytes.m b/octave_packages/m/miscellaneous/swapbytes.m
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+## Copyright (C) 2007-2012 David Bateman
+##
+## 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} {} swapbytes (@var{x})
+## Swap the byte order on values, converting from little endian to big
+## endian and vice versa.  For example:
+##
+## @example
+## @group
+## swapbytes (uint16 (1:4))
+## @result{} [   256   512   768  1024]
+## @end group
+## @end example
+##
+## @seealso{typecast, cast}
+## @end deftypefn
+
+function y = swapbytes (x)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  clx = class (x);
+  if (strcmp (clx, "int8") || strcmp (clx, "uint8") || isempty (x))
+    y = x;
+  else
+    if (strcmp (clx, "int16") || strcmp (clx, "uint16"))
+      nb = 2;
+    elseif (strcmp (clx, "int32") || strcmp (clx, "uint32"))
+      nb = 4;
+    elseif (strcmp (clx, "int64") || strcmp (clx, "uint64")
+            || strcmp (clx, "double"))
+      nb = 8;
+    else
+      error ("swapbytes: invalid class of object");
+    endif
+    y = reshape (typecast (reshape (typecast (x(:), "uint8"), nb, numel (x))
+                           ([nb : -1 : 1], :) (:), clx), size(x));
+  endif
+
+endfunction
+
+
+%!assert (double (swapbytes (uint16 (1:4))), [256 512 768 1024])
+%!error (swapbytes ())
+%!error (swapbytes (1, 2))
+