Decoding block codes

A structure for processing soft information, comprising:

• a block code decoder receives a length n soft input vector, wherein said block code decoder creates a binary vector Y corresponding to the length n soft input vector;
• a hard input hard output decoder decodes each linear function Xi of Y and a test pattern Zi of one or more test patterns, wherein when the hard decoder is successful a codeword and an associated metric produced by the hard decoding of linear function Xi, are added to a set S;
• the block code decoder removes redundant codewords in S to form a reduced set S′ based on processing a number of errors found during the hard decoding of the linear function Xi, and a guaranteed error correcting capability t of the block code decoder;
• and
• the block code decoder generates n soft outputs based on c estimated soft output values and (n-c) non-estimated soft output values wherein the c estimated soft output values are computed from one or more positions of the length n soft input vector and one or more codewords in the set S′.