US Patent 7519897 Decoding apparatus and decoding method

To provide a decoder and decoding method capable of reducing the number of times received data is decoded. A decoder according to the present invention includes: a Viterbi decoder decoding received data; a decode data length storage area storing a decode data length; a decoded data temporary storage area storing temporary storage data as decoded data up to a decode data length; a maximum data storage memory storing maximum decoded data as decoded data up to a maximum data length; a maximum-likelihood detection circuit selecting a decode data length based on likelihood information; and a decoded data reconstruction circuit replacing a part of maximum decoded data with temporary decoded data.