New byte error correcting codes with simple decoding for reliable cache design

Abstract

Most cache designs support single or double bit-level error detection and correction in cache lines. However, a single error may distort a whole byte or even more, resulting in much higher decoding complexity than that of bit-level distortions. Thereby this paper proposes a new group testing based error correcting code (GTB code) for byte-level error locating and correcting which provides much stronger protection for memories. This new class of non-binary GTB codes is generated from binary superimposed codes. Since it is encoded and decoded by binary matrices, no complicated Galois Field computations in GF(Q) such as multiplications and inversions are involved. Comparing with popular non-binary error correcting codes (ECC) such as Hamming, Reed-Solomon and interleaved codes, the GTB codes achieves up to 42% reduction of the decoding complexity (hardware cost × latency) for single-byte error correction, and up to 98% reduction for double-byte error correction. Moreover, given the length of codewords (e.g. 512 bits for cache lines), as the size of each Q-ary digit (byte) increases, the saving increases.