Method and system for encoding and decoding information with modulation constraints and error control

A computer-implemented method of designing a parity-related constrained code for use with a sequence of normal constrained code words, the method comprising:

• (i) designing candidate code words of the parity-related constrained code using a finite state machine (FSM);
• (ii) computing parity-check bits of the candidate code words based on a given parity-check polynomial or parity-check matrix, and taking into account the length of a sequence comprising the normal constrained code words;
• (iii) distributing the candidate code words into a group of code word sets;
• (iv) concatenating the code word sets together;
• and
• (v) forming a code table for at least one of encoding and decoding of the parity-related constrained code;
• (vi) releasing a run-length constraint k prior to designing the candidate code words, and
• (vii) tightening the run-length constraint k by optimizing the code table through at least one of:
• (a) deleting candidate code words that start or end with long runs of 0's, and (b) increasing the number of states in the FSM.

An encoding apparatus for encoding user data from a data source, where an input segment of the user data has been partitioned into data words, the apparatus comprising:

• first encoder means for encoding one or more of the data words into one or more first component code words;
• second encoder means for encoding a data word into a second component code word;
• and
• concatenator means for concatenating the one or more first component code words with the second component code word to provide a combined code word, with a pre-determined parity-check constraint over the entire combined code word, the parity-check constraint defined by a parity-check polynomial or a parity-check matrix of a systematic linear block code;
• wherein the one or more first component code words comprise one or more normal constrained code words of a normal constrained code and the second component code word comprises a code word of a parity-related constrained code, and
• wherein the parity-related constrained code is selected from a candidate code word set.

An encoder for encoding user data from a data source, where an input segment of user data has been partitioned into data words, the encoder comprising:

• a plurality of first encoders for encoding the data words into first component code words;
• a second encoder for encoding a data word into a second component code word;
• and
• a concatenator for concatenating the first component code words with the second component code word to provide a combined code word, with a pre-determined parity-check constraint over the entire combined code word, the parity-check constraint being defined by a parity-check polynomial or a parity-check matrix of a systematic linear block code;
• wherein the first component code words comprise normal constrained code words of a normal constrained code and the second component code word comprises a p code word of a parity-related constrained code, the parity-related constrained code being selected from a candidate code word set.

A method of decoding a constrained parity-check code word into a segment of user data, the constrained parity-check code word comprising a concatenation of first component code words and a second component code word, the method implemented by a decoder and comprising:

• decoding a plurality of first component code words and the second component code word into a plurality of user data words;
• and
• combining state information indicated by the next code word with the knowledge of the current code word, the decoder uniquely determining the data words associated with the current code words,
• wherein the first component code words comprise normal constrained code words and the second component code word comprises a parity-related constrained code word, and
• wherein decoding the second component code word is based on the state information indicated by the next code word.

A decoder apparatus for decoding a constrained parity-check code word into a segment of user data, the code word comprising a concatenation of first component code words and a second component code word, the apparatus comprising:

• first decoder means for decoding the plurality of first component code words into a plurality of user data words;
• second decoder means for decoding the second component code word into a user data word;
• and
• means for combining the state information indicated by the next code word with knowledge of the current code word, the first and second decoder means uniquely determining the data words associated with the current code words,
• wherein the first component code words comprise normal constrained code words and the second component code word comprises a parity-related constrained code word,
• wherein the second decoder means is operable to decode the second component code word based on state information indicated by the next code word.