Memory system, controller, and control method

Abstract

Error correction is performed using a simpler configuration. The memory system includes: memory and a controller. The memory stores data encoded by error correction codes used to correct errors of t bits or less. The controller uses received characters read from the memory to calculate t checksums. By performing variable transformations on the checksums, it calculates (t-1) key information, which is used to obtain a first error pattern. This first error pattern includes a combination of multiple transformed positions obtained by performing variable transformations on multiple error positions when the number of error bits is (t+1). Using the corresponding information, it obtains the first error pattern corresponding to the key information. It performs inverse variable transformations on the transformed positions included in the first error pattern to calculate the error positions, and obtains a list containing a second error pattern, which includes combinations of error positions. It then performs list decoding using the list.

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