Patent ID: 7266748

Claim:
A system for error-erasure correcting modulated data reproduced from an optical disc, the system comprising: a demodulator for receiving channel code symbols and demodulating each valid channel code symbol into an information data symbol, providing an arbitrary information data symbol for each invalid channel code symbol, and setting a first single-bit erasure flag for each invalid channel code symbol; a first buffer in signal communication with the demodulator for receiving the information data symbols and corresponding first erasure flags, and composing a first code word including a plurality of information data symbols and their corresponding first erasure flags; and a first error-erasure decoder in signal communication with the first buffer for receiving the first code word, checking for erasures by performing a single-bit operation on all of the first single-bit erasure flags of the received first code word, and if any erasures are detected, correcting up to a first maximum number of correctable erasures and then correcting a number of actual errors not to exceed one half of the first maximum number of correctable erasures reduced by one half of the number of corrected erasures, and if no erasures are detected, correcting only actual errors of the first code word.