Patent ID: 7213190

Claim:
A data processing apparatus for processing data read out from an information storage medium, data to be recorded on the information storage medium for respective recording units being a data block with sync codes, the data block being a block generated by inserting sync codes at predetermined intervals for sector data, the sector data being generated from some data of the data block with error correction codes, the data block containing data in row and column directions, one data sequence containing a first sync frame and a second sync frame; the first sync frame containing a first sync code and some data of the sector data, the second sync frame containing a second sync code and some data of the sector data, a demodulated data sequence obtained by removing the first and second sync codes from one data sequence being data that contains the error correction codes, and error correction being able to be attained for each demodulated data sequence, the data processing apparatus comprising: a demodulation unit configured to output the demodulated data sequence on the basis of data in the information storage medium and output address information corresponding to the demodulated data sequence; and a syndrome calculation unit configured to calculate a syndrome of the demodulated data sequence containing a first demodulated data sequence and a second demodulated data sequence, wherein the syndrome calculation unit enables a syndrome calculation of the demodulated data sequence by detecting a data loss in the first sync frame and the second sync frame on the basis of the address information, performing switching on the basis of the detection of the first demodulated data sequence corresponding to the first sync frame, calculating a first syndrome of the first demodulated data sequence by a first calculation, performing switching on the basis of the detection of the second demodulated data sequence corresponding to the second sync frame, calculating a second syndrome of the second demodulated data sequence by a second calculation, setting the first syndrome as binary 0 on the basis of a loss detection of the first demodulated data sequence, setting the second syndrome as binary 0 on the basis of a loss detection of the second demodulated data sequence, and outputting the syndrome of the demodulated data sequence on the basis of the first syndrome and the second syndrome.