Layered low density parity check decoder

A method comprising:

• initializing an LDPC code for use with a layered LDPC decoder configured with physical syndrome memories that store syndrome values until the syndrome values change due to a change in a codeword bit value, and
• configuring the layered LDPC decoder to reduce the number of syndrome memories by restricting the position of non-zero circulants in a matrix associated with the LDPC code so that a column in the matrix has no more than a threshold number of non-zero circulants per physical syndrome memory in the layered LDPC decoder.

A device, comprising:

• a layered, low density parity check (LDPC) decoder apparatus configured to decode a codeword, comprising:
• a plurality of hardware layers, where each hardware layer is configured to compute a syndrome value, where a syndrome value is computed as a function of one or more bit values in the codeword;
• a plurality of physical memories configured to store a plurality of syndrome values, where each physical memory is configured to store syndrome values computed by one or more of the hardware layers and persist the syndrome values until the syndrome values change due to a change in a codeword bit value, such that a first physical memory stores syndrome values computed for the codeword and a second physical memory stores syndrome values computed for the codeword.