/usr/share/octave/packages/interval-3.1.0/@infsupdec/bitunpack.m is in octave-interval 3.1.0-5.
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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 | ## Copyright 2014-2016 Oliver Heimlich
##
## 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 3 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, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @documentencoding UTF-8
## @defmethod {@@infsupdec} bitunpack (@var{X})
## @comment DO NOT SYNCHRONIZE DOCUMENTATION STRING
##
## Encode decorated interval @var{X} in interchange format.
##
## The result is a raw bit pattern of length 136 that derive from two binary64
## numbers plus 8 bit for the decoration. Bits are in increasing order.
## Byte order depends on the system's endianness. First 8 bytes come from the
## lower interval boundary, next 8 bytes come from the upper interval boundary,
## last byte comes from the decoration.
##
## The result is a row vector if @var{X} is a row vector; otherwise, it is a
## column vector.
##
## For all scalar intervals the following equation holds:
## @code{@var{X} == interval_bitpack (bitunpack (@var{X}))}.
##
## @seealso{interval_bitpack}
## @end defmethod
## Author: Oliver Heimlich
## Keywords: interval
## Created: 2014-12-23
function result = bitunpack (x)
if (nargin ~= 1)
print_usage ();
return
endif
bare = bitunpack (x.infsup);
d = bitunpack (x.dec);
## The exchange representation of [NaI] is (NaN, NaN, ill).
if (any (isnai (x)(:)))
bare(vec (1:128) + 128 .* vec (find (isnai (x)) - 1, 2)) = ...
[bitunpack(nan (sum (isnai (x)), 2))];
endif
## Initialize result vector
result = zeros (1, length (bare) + length (d), 'logical');
if (not (isrow (bare)))
result = result';
endif
## Merge alternating 128 bit blocks from bare and 8 bit blocks from d together
## into result.
target_bare = reshape (1 : length (result), 8, length (result) / 8);
target_d = target_bare (:, 17 : 17 : size (target_bare, 2));
target_bare(:, 17 : 17 : size (target_bare, 2)) = [];
result(target_bare) = bare;
result(target_d) = d;
endfunction
%!test
%! littleendian = bitunpack (uint16 (1))(1);
%! b = zeros (1, 136);
%! if (littleendian)
%! b([52, 63, 117, 127, 133]) = 1;
%! else
%! b([7, 12, 71, 77, 133]) = 1;
%! endif
%! assert (bitunpack (infsupdec (3, 4)), logical (b));
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