Apparatus and method for correcting errors in data accessed from a memory device

摘要

An apparatus and method for correcting errors in data accessed from a memory device. A plurality of read symbols are read from a memory device. Syndrome information is then determined from the n data symbols and associated m error correction code symbols. Error correction circuitry uses the syndrome information in order to attempt to locate each read symbol containing an error and to correct the errors in each of those located read symbols. Error tracking circuitry tracks which memory regions the located read symbols containing an error originate from, and, on detecting an error threshold condition, sets at least one memory region as an erasure memory region. The correction circuitry treats each read symbol as a located read symbol containing an error, such that the read symbols to be located are not all randomly distributed and more than PMAX read symbols containing errors can be corrected.

主权项

1. An apparatus comprising:
a memory device comprising multiple memory regions, and configured to store data symbols and associated error correction code (ECC) symbols; read circuitry configured to perform a read operation in order to output a plurality of read symbols from said memory device, said read symbols comprising n data symbols and an associated m error correction code symbols, and comprising more than one read symbol from each memory region, both n and m being integer values greater than 1; a syndrome decoder configured to determine syndrome information from the n data symbols and associated m error correction code symbols; error correction circuitry configured to be responsive to said syndrome information indicating that an error exists in at least one read symbol, to perform an error correction process to seek to locate each read symbol containing an error and to correct the errors in each of those located read symbols, if the read symbols containing an error are randomly distributed amongst the plurality of read symbols, the error correction circuitry being configured to locate and correct those errors using the error correction process if no more than PMAX read symbols of said plurality of read symbols contain errors, where PMAX is equal to a maximum number of errors that can be located and corrected; and error tracking circuitry configured to track which memory regions the located read symbols containing an error originate from, and on detecting an error threshold condition being reached, to set at least one memory region from said multiple memory regions as an erasure memory region; the error correction circuitry being responsive to the erasure memory region being set by the error tracking circuitry, to treat each read symbol from said erasure memory region as a located read symbol containing an error, such that when the error correction process is performed the read symbols to be located are not all randomly distributed and the error correction circuitry is configured to locate and correct the errors if no more than x read symbols of said plurality of read symbols contain errors, where x is greater than PMAX.