A method and system for decoding low density parity check (“LDPC”) codes. An LDPC code decoder includes LDPC decoding circuitry comprising a Q message generator and a P sum adder array. The Q message generator combines an R message from a previous iteration with a P message to produce a Q message. The P sum adder array adds the P message to a difference of an R message from a current iteration and the R message from the previous iteration to produce an updated P message.