rs_decoder_154a.m

source Matlab traites the UWB

%
% function dec_data = rs_decoder_154a(rx_data,interleave_seed)
%
function dec_data = rs_decoder_154a(rx_data,interleaver_seed)

if ~isempty(interleaver_seed)
  fprintf('[RS decoder] deinterleaving\n');
  rx_data = randdeintrlv(rx_data,interleaver_seed);
end

% We are in GF(2^6)
m = 6;
k = 55;
n = k+8;
% Note: rsgenpoly(n,k) and rsgenpoly(n,k,67) are the same

DATALENGTH = length(rx_data);
nblock = ceil(DATALENGTH/378);
fprintf('[RS decoder] Number of blocks = %d\n',nblock);

dec_data = [];
for l = 1:nblock
  fprintf('[RS decoder] block = %d, (%d,%d)\n',...
          l,1+(l-1)*378,min(l*378,DATALENGTH));

  rx_data_block = rx_data(1+(l-1)*378:min(l*378,DATALENGTH));
  BLOCKLENGTH = length(rx_data_block);
  fprintf('[RS decoder] BLOCKLENGTH = %d\n',BLOCKLENGTH);
  % Now, prepare for decoding
  if rx_data_block < 378
    fprintf('[RS decoder] zero padding\n');
    rx_data_block = [zeros(1,378-BLOCKLENGTH) rx_data_block];
  end
  % Conversion from bit to symbol in GF(2^6)
  rx_data_block = permute(reshape(rx_data_block,m,n),[2 1]);
  rx_symbols = bi2de(rx_data_block,'left-msb');
  % Actually decode
  dec_symbols = rsdec(gf(rx_symbols',m),n,k);
  % And convert back to bit
  dec_symbols = dec_symbols(end-(BLOCKLENGTH/m-8)+1:end);
  dec_data_block = de2bi(double(dec_symbols.x),m,'left-msb');
  dec_data_block = ...
      reshape(permute(dec_data_block,[2 1]),1,size(dec_data_block,1)*m);

  dec_data = [dec_data dec_data_block];
end

return;