Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / communications-1.1.1 / ricedeco.m

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+## 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} {} ricedeco (@var{code}, @var{K})
+##
+## Returns the Rice decoded signal vector using @var{code} and @var{K}. 
+## Compulsory K 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 rice value for a single sample. The Rice 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{riceenco}.
+##
+## Reference: Solomon Golomb, Run length Encodings, 1966 IEEE Trans Info' Theory
+##
+## An exmaple of the use of @code{ricedeco} is
+## @example
+## @group
+##   ricedec(riceenco(1:4,2),2) 
+##  
+## @end group
+## @end example
+## @end deftypefn
+## @seealso{riceenco}
+
+##
+##
+##! /usr/bin/octave -q
+##A stress test routine
+##for i=1:100
+##  sig=abs(randint(1,10,[0,255]));
+##  [code,k]=riceenco(sig)
+##  sig_d=ricedeco(code,k)
+##  if(isequal(sig_d,sig)~=1)
+##    error('Some mistake in ricedeco/enco pair');
+##  end
+##end
+##
+function sig_op=ricedeco(code,K)
+  if ( nargin < 2 ) || (strcmp(class(code),"cell")~=1)
+    error('usage: ricedeco(code,K)');
+  end
+
+  L=length(code);
+  
+  K_pow_2=2**K;
+
+  if(K ~= 0)
+    power_seq=[2.^((K-1):-1:0)];
+    for j=1:L
+      word=code{j};
+      idx=find(word==0)(1);
+      val=sum(word(1:idx));
+      sig_op(j)=val*K_pow_2 + sum(word(idx+1:end).*power_seq);
+    end
+  else
+    for j=1:L
+      sig_op(j)=sum(code{j});
+    end
+  end
+  
+  return
+end
+%! 
+%! assert(ricedeco(riceenco(1:4,2),2),[1:4])
+%!