One-shot state transition probability encoder and decoder

An apparatus, comprising a processing circuit, the processing circuit comprising:

• an error correction decoder that decodes an N-bit codeword based on data read from a storage media;
• and
• a modulation decoder operable to:
• receive the codeword;
• read a first D-bits of the codeword to determine a stitching location d within the codeword, the stitching location identifying a start bit of unencoded data in the codeword;
• perform a decoding of the codeword into an output buffer for user data comprising L bits, L<N wherein parameters of the modulation decoder are set before the decoding, the setting of the parameters including setting a number of expected decoded bits to d and a length of the codeword to N−L+d, the decoding including decoding the d bits based on a set of state transition probabilities and copying decoded bits into the output buffer;
• copy the unencoded data to an end of the output buffer;
• and
• sending the output buffer as recovered user data to a host.

A method, comprising:

• encoding user data into a codeword at a modulation encoder, the codeword having a length N ∈[Nmin, Nmax],
• receiving the codeword at a low-density parity check (LDPC) encoder, the LDPC encoder having an LDPC graph with a maximum of K input nodes, K≥Nmax;
• determining a minimum number of parity bits P for the LDPC graph, P≥Nmax−Nmin, the LDPC encoder producing an LDPC codeword of maximum length M, M≤Nmin+P;
• determining N<K and in response thereto, zero-filling a remaining K−N information bits of the input nodes with zeros;
• generating an intermediate LDPC codeword with length K+P;
• puncturing out the K−N zero-filled information bits and N+P−M of the parity bits from the intermediate codeword to maintain a final LDPC codeword with length of M;
• and
• storing the final LDPC codeword to a recording media.