An additive version of the SISO algorithm for the dual code

We show that by changing in a proper way the representation of the soft information passed from one decoder to the other in the iterative decoding process, the SISO module of the decoder based on the dual code becomes equal to that used for the original code. The additive version of the SISO algorithm (ASISO) can also be extended, with some care in the definition of the max/sup */ operator, to the dual code.