CONTROLLER OF NONVOLATILE SEMICONDUCTOR MEMORY

摘要

According to one embodiment, a controller includes a decoder, calculation section, table creation, and control section. The decoder converts ECC frames into likelihood information based on a set table, generates decoded ECC frames by decoding using the likelihood information and switches the set table when there is an ECC frame in which the decoding is unsuccessful. The calculation section generates calculation data based on an ECC frame of calculation target among the decoded ECC frames and its ECC frame before decoded. The table creation section sets the new table to the decoder based on the calculation data. The control section controls the calculation target so that a calculation in the calculation section is not repeated for an ECC frame in which the decoding is successful.

主权项

1. A controller comprising:
a decoder that converts a plurality of error correction code (ECC) frames read out from a nonvolatile semiconductor memory into likelihood information based on a set table among a plurality of tables, generates a plurality of decoded ECC frames by decoding using the likelihood information and switches the set table when there is an ECC frame in which the decoding is unsuccessful; a calculation section that generates calculation data based on an ECC frame of calculation target among the plurality of decoded ECC frames and an ECC frame before decoded, which corresponds to the ECC frame of the calculation target; a table creation section that creates a new table by executing statistical calculation based on the calculation data generated by the calculation section and sets the new table to the decoder; and a control section that controls the calculation target so that a calculation in the calculation section is not repeated for an ECC frame in which the decoding is successful.