/usr/share/octave/packages/communications-1.2.1/golombdeco.m is in octave-communications-common 1.2.1-2.
This file is owned by root:root, with mode 0o644.
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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 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 | ## Copyright (C) 2006 Muthiah Annamalai <muthiah.annamalai@uta.edu>
##
## 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 -*-
## @deftypefn {Function File} {} golombdeco (@var{code}, @var{m})
##
## Returns the Golomb decoded signal vector using @var{code} and @var{m}.
## Compulsory m is need to be specified. A restrictions is that a
## signal set must strictly be non-negative. The value of code
## is a cell array of row-vectors which have the encoded Golomb value
## for a single sample. The Golomb algorithm is
## used to encode the "code" and only that can be meaningfully
## decoded. @var{code} is assumed to have been of format generated
## by the function @code{golombenco}. Also the parameter @var{m} need to
## be a non-zero number, unless which it makes divide-by-zero errors.
## This function works backward the Golomb algorithm see
## @code{golombenco} for more details on that.
## Reference: Solomon Golomb, Run length Encodings, 1966 IEEE Trans Info Theory
##
## An example of the use of @code{golombdeco} is
## @example
## @group
## golombdeco (golombenco (1:4, 2), 2)
## @result{} [1 2 3 4]
## @end group
## @end example
## @seealso{golombenco}
## @end deftypefn
##! /usr/bin/octave -q
#A stress test routine
#for i=1:100
# sig=abs(randint(1,10,[0,255]));
# k=mod(i,10)+1;
# code=golombenco(sig,k);
# assert(golombdeco(code,k),sig)
#endfor
#
#for k=1:10;
# assert(golombdeco(golombenco(4:10,k),k),[4:10]);
#endfor
#
function sig_op = golombdeco (code, m)
if (nargin != 2 || ! iscell (code) || m <= 0)
print_usage ();
endif
L = length (code);
C = ceil (log2 (m));
partition_limit = 2**C - m;
power_seq = [2.^(ceil (log2 (m)) - 1:-1:0)];
power_seq_mod = power_seq(2:end);
for j = 1:L
word = code{j};
WL = length (word);
idx = find (word == 0)(1);
q = sum (word(1:idx));
idx2 = (WL-idx);
word_tail = word(idx+1:end);
if (length (word_tail) == C)
r = sum (word_tail.*power_seq);
r = r- (partition_limit);
else
r = sum (word_tail.*power_seq_mod);
endif
quot(j) = q;
rem(j) = r;
endfor
sig_op = quot.*m + rem;
endfunction
%!assert (golombdeco (golombenco (1:4, 2), 2), [1:4])
%% Test input validation
%!error golombdeco ()
%!error golombdeco (1)
%!error golombdeco (1, 2)
%!error golombdeco ({}, 0)
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