A method includes generating a first subset of codeword symbols by processing, during each of a plurality of iterations, a first input and a second input. The first input is a function of (i) an output, during a respective one of the plurality of iterations, of a last processing stage of a first plurality of processing stages and (ii) a symbol, of a first subset of original symbols, corresponding to the respective iteration. The second input is a function of (i) an output, during the respective iteration, of a last processing stage of the second plurality of processing stages and (ii) a symbol, of a second subset of original symbols, corresponding to the respective iteration. The method also includes generating a second subset of codeword symbols by processing, during each of the plurality of iterations, the first input and the second input.