Decoding apparatus, decoding method, data-receiving apparatus and data-receiving method

A decoding apparatus for performing a maximum-likelihood decoding process based on a Viterbi algorithm on a data train completing a convolution-encoding process, said decoding apparatus comprising:

• computation means for performing a trellis computation for decoding said data train completing said convolution-encoding process;
• control means for controlling said trellis computation to be performed by said computation means with a plurality of processing timings in a plurality of processing units each corresponding to a process performed on n bits of pre-encoding data, wherein each of said plurality of processing units performs parallel processing performed on a plurality of computation results obtained for 2n states with one of said plurality of processing timings immediately preceding a present timing of said plurality of processing timings to obtain computation results for said 2n states;
• and
• memory means for storing said computation results obtained with said immediately preceding processing timing and said present processing timing, wherein during each of said processing units said computation results obtained for said 2n states with said immediately preceding processing timing are read from a storage area of said memory means and said computation results found with said present processing timing for said 2n states are stored in said storage area, wherein said computation results include metric values and path-metric values and
• said storage area is divided into two portions used as areas for storing the metric values and the path-metric values, respectively.