Patent ID: 8418028

Claim:
A storage device comprising: a nonvolatile memory; and an error correction circuit that corrects an error included in first data read from the nonvolatile semiconductor memory with error-correcting code associated with the first data, the error correction circuit comprising: a first error correction unit that performs a first error correction process to the first data, and then performs an error detection process to the first data and outputs an error detection result; a second error correction unit that includes a chien search circuit for calculating an error position in the first data output from the first error correction unit, the chien search circuit comprising: a determination unit that determines an error-correction area and a non-error-correction area of the first data based on error detection result from the first error correction unit; a first processing unit that performs an error position search process to an error-correction area of the first data at least one-bit unit at one time; a second processing unit that performs a passing or skipping process to a non-error-correction area of the first data a first plurality of bits at one time.