Importance

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Abstract

In an optical disk storage device capable of reading compact disks (CDs) and digital video disks (DVDs), the latency of an error correction system is significantly reduced by sharing a syndrome buffer between CD and DVD modes of operation. In CD mode, user data read from the disk is stored in the syndrome buffer and corrected using C1/C2 redundancy of a Cross-Interleaved Reed-Solomon Code (CIRC). In DVD mode, user data read from the disk is stored in a data buffer and the syndrome buffer stores: intermediate values for generating the ECC syndromes for use in correcting the user data, and data CRC and error CRC syndromes for use in verifying the validity and completeness of the corrections. Two aspects of the present invention which significantly increase throughput are (1) the ECC syndromes are generated concurrently for the row (Q) and column (P) codewords of the CD and DVD product codes, and (2) the CRC validation syndrome is generated concurrent with correcting the product code. In this manner, the ECC syndromes for the entire product code can be generated during the first horizontal pass over the row codewords, thereby avoiding the latency in generating the ECC syndromes for the column codewords during the subsequent vertical pass. In addition, the CRC validation syndrome is available immediately after correcting a data sector--it is not necessary to read the entire data sector from the data buffer after correction in order to generate the CRC validation syndrome, as in the prior art.

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First Claim