Apparatus and method for low density parity check code decoding in a first processing device, wherein the method includes receiving a first bit-word of a first length related to a log-likelihood ratio of a bit of a signal; obtaining a second bit-word of a second length that is shorter than the first length, wherein obtaining the second bit-word comprises applying a correction to the first bit-word; and determining a message depending on a set of second bit-words, wherein the set of second bit-words includes the second bit-word.

An apparatus for data storage includes an interface and a processor. The interface is configured to communicate with a memory device that includes (i) a plurality of memory cells and (ii) a data compression module. The processor is configured to determine a maximal number of errors that are required to be corrected by applying a soft decoding scheme to data retrieved from the memory cells, and based on the maximal number of errors, to determine an interval between multiple read thresholds for reading Code Words (CWs) stored in the memory cells for processing by the soft decoding scheme, so as to meet following conditions: (i) the soft decoding scheme achieves a specified decoding capability requirement, and (ii) a compression rate of the compression module when applied to confidence levels corresponding to readouts of the CWs, achieves a specified readout throughput requirement.

A method and apparatus for decoding quasi-cyclic LDPC codes using a vertical layered iterative message passing algorithm. The algorithm of the method improves the efficiency of the check node update by using one or more additional magnitudes, predicted with predictive magnitude maps, for the computation of messages and update of the check node states. The method allows reducing the computational complexity, as well as the storage requirements, of the processing units in the check node update. Several embodiments for the apparatus are presented, using one or more predictive magnitude maps, targeting significant savings in resource usage and power consumption, while minimizing the impact on the error correction performance loss.

Embodiments of this application disclose a polar coding method, apparatus, and device, so as to reduce storage overheads of a system. A sequence for polar coding is obtained based on a length M of a target polar code, wherein the sequence comprises L sequence numbers, ordering of the L sequence numbers in the sequence is the same as ordering of the L sequence numbers in a maximum mother code sequence, wherein the maximum mother code sequence is obtained by sorting N sequence numbers of N polarized channels in ascending order or descending order of reliability metrics, wherein L and N are integer power of 2, M is smaller than or equal to L, L is smaller than or equal to N.

Embodiments of this application disclose a polar coding method, apparatus, and device, so as to reduce storage overheads of a system. A sequence for polar coding is obtained based on a length M of a target polar code, wherein the sequence comprises L sequence numbers, ordering of the L sequence numbers in the sequence is the same as ordering of the L sequence numbers in a maximum mother code sequence, wherein the maximum mother code sequence is obtained by sorting N sequence numbers of N polarized channels in ascending order or descending order of reliability metrics, wherein L and N are integer power of 2, M is smaller than or equal to L, L is smaller than or equal to N.

Designs of controllers for flash memory array are described. A controller is designed to form data packs of a predefined size with compressed data segments in different sizes. The data packs are encoded with ECC in two dimensions. When the data packs are read out, the ECC is applied in two dimensions, possibly repeated, to detect and correct errors that can be corrected by the ECC.

A compression engine calculates replacement CRC codes, in predetermined data lengths, for DIF-in cleartext data including cleartext data and multiple CRC codes based on the cleartext data. The compression engine generates headered compressed-text data in which a header including the replacement CRC codes is added to compressed-text data in which the cleartext data is compressed, and generates code-in compressed-text data by calculating multiple CRC codes based on the headered compressed-text data to add the calculated CRC codes to the headered compressed-text data.

A low-density parity check (LDPC) decoder includes a variable node unit (VNU) comprising a plurality of variable nodes configured to perform sums. A first message mapper of the LDPC decoder receives first n1-bit indices from likelihood ratio (LLR) input and maps the first n1-bit indices to first numerical values that are input to the variable nodes of the VNU. A second message mapper of the LDPC decoder receives second n2-bit indices from a check node unit (CNU) and maps the second n2-bit indices to second numerical values that are input to the variable nodes of the VNU. The CNU includes a plurality of check nodes that perform parity check operations. The first and second numerical values having ranges that are larger than what can be represented in n1-bit and n2-bit binary, respectively.

An apparatus for data storage includes an interface and a processor. The interface is configured to communicate with a memory device that includes (i) a plurality of memory cells and (ii) a data compression module. The processor is configured to determine a maximal number of errors that are required to be corrected by applying a soft decoding scheme to data retrieved from the memory cells, and based on the maximal number of errors, to determine an interval between multiple read thresholds for reading Code Words (CWs) stored in the memory cells for processing by the soft decoding scheme, so as to meet following conditions: (i) the soft decoding scheme achieves a specified decoding capability requirement, and (ii) a compression rate of the compression module when applied to confidence levels corresponding to readouts of the CWs, achieves a specified readout throughput requirement.

Designs of controllers for flash memory array are described. A controller is designed to form data packs of a predefined size with compressed data segments in different sizes. The data packs are encoded with ECC in two dimensions. When the data packs are read out, the ECC is applied in two dimensions to detect and correct errors that can be corrected by the ECC.