www.pudn.com > turboprog.rar > encode_bit.m

function [output, state] = encode_bit(g, input, state) 
% Copyright 1996 Matthew C. Valenti 
% MPRG lab, Virginia Tech 
% for academic use only 
 
% This function takes as an input a single bit to be encoded, 
% as well as the coeficients of the generator polynomials and 
% the current state vector. 
% It returns as output n encoded data bits, where 1/n is the 
% code rate. 
 
% the rate is 1/n 
% k is the constraint length 
% m is the amount of memory 
[n,k] = size(g); 
m = k-1; 
 
% determine the next output bit 
for i=1:n 
   output(i) = g(i,1)*input;    % the first bit a_k's contribution to output  --yzh 
   for j = 2:k 
      output(i) = xor(output(i),g(i,j)*state(j-1)); % a_(k-j)'s contribution to output  --yzh 
      % why not use rem(g(i,j)*[input,state]'),j=1:k?  --yzh 
   end; 
end 
 
state = [input, state(1:m-1)];  % shift one bit  --yzh