rsc_encode.m
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- function y = rsc_encode(g, x, terminated)
- % Copyright Nov. 1998 Yufei Wu
- % MPRG lab, Virginia Tech.
- % for academic use only
- % encodes a block of data x (0/1)with a recursive systematic
- % convolutional code with generator vectors in g, and
- % returns the output in y (0/1).
- % if terminated>0, the trellis is perfectly terminated
- % if terminated<0, it is left unterminated;
- % determine the constraint length (K), memory (m), and rate (1/n)
- % and number of information bits.
- [n,K] = size(g);
- m = K - 1;
- if terminated>0
- L_info = length(x);
- L_total = L_info + m;
- else
- L_total = length(x);
- L_info = L_total - m;
- end
- % initialize the state vector
- state = zeros(1,m);
- % generate the codeword
- for i = 1:L_total
- if terminated<0 | (terminated>0 & i<=L_info)
- d_k = x(1,i);
- elseif terminated>0 & i>L_info
- % terminate the trellis
- d_k = rem( g(1,2:K)*state', 2 );
- end
-
- a_k = rem( g(1,:)*[d_k state]', 2 );
- [output_bits, state] = encode_bit(g, a_k, state);
- % since systematic, first output is input bit
- output_bits(1,1) = d_k;
- y(n*(i-1)+1:n*i) = output_bits;
- end