/usr/share/octave/packages/communications-1.1.1/golombdeco.m is in octave-communications-common 1.1.1-1.
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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 | ## 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 detials on that.
## Reference: Solomon Golomb, Run length Encodings, 1966 IEEE Trans Info' Theory
##
## An exmaple of the use of @code{golombdeco} is
## @example
## @group
## golombdeco(golombenco(1:4,2),2)
## @end group
## @end example
## @end deftypefn
## @seealso{golombenco}
##! /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)
#end
#
#for k=1:10;
# assert(golombdeco(golombenco(4:10,k),k),[4:10]);
#end
#
function sig_op=golombdeco(code,m)
if ( nargin < 2 ) || (strcmp(class(code),"cell")~=1 || m<=0)
error('usage: golombdeco(code,m)');
end
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);
end
quot(j)=q;
rem(j)=r;
end
sig_op=quot.*m + rem;
return
end
%!
%! assert(golombdeco(golombenco(1:4,2),2),[1:4])
%!
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