Adaptec, Inc.

Stmicroelectronics Gmbh

John T Gill, Iii

Honda Yang

A system and method are disclosed for providing error correction coding having a selectively variable degree of redundancy. The system and method include generating extended check symbols by performing a Reed-Solomon operation on unused check symbols that do not form a portion of an interleaved code word. An extended check symbol is generated from the unused check symbols appearing in a column of the unused check symbols. The extended check symbols are stored with the interleaved code words in a data storage device. The extended check symbols are retrieved from the data storage device with the corresponding interleaved code words. Following the decoding of the interleaved code words and the identification of uncorrectable errors therein, the extended check symbols are decoded to recover the corresponding unused check symbols for the previously uncorrectable interleaved code words. The recovered unused check symbols are added to the previously uncorrectable interleaved code words so as to increase the error correcting capability thereof. The previously uncorrectable interleaved code words having the recovered unused check symbols are then decoded and errors therein corrected accordingly.

System and method for providing error correction coding with selectively variable redundancy

Disclosed is a thermal asperity pointer processing apparatus and method for processing apparatus for generating erasure locations from a thermal asperity signal. The thermal asperity signal indicates an error burst in an interleaved data sector. The apparatus includes a thermal asperity pointer recorder, a storage unit, and a thermal asperity pointer processing unit. The thermal asperity pointer recorder is adapted to receive a thermal asperity signal and is configured to generate a thermal asperity event information associated with the thermal asperity signal. The thermal asperity event information includes a thermal asperity duration, a starting interleave number, and a starting interleave address of the thermal asperity signal in the interleaved data sector. The storage unit is configured to receive the thermal asperity event information from the thermal asperity pointer recorder and is configured to store the thermal asperity duration, starting interleave number, and starting interleave address associated with the thermal asperity signal. The thermal asperity pointer processing unit is coupled to receive the thermal asperity event information from the storage unit and is adapted to generate the erasure locations for interleaves corresponding to the error burst in the data sector.

Apparatus and method for generating interleave erasure locations from thermal asperity erasure pointers

Disclosed is a Chien search circuit for determining roots to an error locator polynomial that is defined by a set of coefficients. The circuit includes N sub-Chien search circuits, each of which is configured to sequentially evaluate a subset of field elements from a specified set of field elements. Each sub-Chien search circuit includes a set of storage elements, a set of constant multipliers, an adder, and a comparator. The set of storage elements stores a set of values, and receives and stores the set of coefficients as the set of values. One storage element is associated with each coefficient. The set of constant multipliers is coupled to receive the set of values from the set of storage elements. One constant multiplier is associated with one storage element. Each of the constant multipliers is associated with a constant field element and is configured to multiply the received value and the constant field element to generate a product. Each of the constant multipliers is coupled to feed the product back to the associated storage element for storage. The adder is coupled to receive the stored set of values from the set of storage elements for generating a sum of the set of values for a current field element being evaluated. The comparator is coupled to receive the sum for comparing the sum to a specified constant value. The comparator generates a signal indicating that the current field element is a root when the sum is equal to the specified constant value.

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Stanford, CA, United States of America

John T Gill, Iii