Patent ID: 7218256

Claim:
A method comprising: (a) receiving a sequence of code words, wherein each code word comprises an encoded data word and an indicator bit, wherein the encoded data word corresponds to an unencoded data word and wherein the indicator bit has a first binary value if a sign of a running digital sum (RDS) of the unencoded data word is different than a sign of a current RDS of the sequence of code words, and has a second, different binary value if the sign of the RDS of the unencoded data word is the same as the sign of the current RDS of the sequence of code words; and (b) decoding the sequence of code words into a sequence of data words according to a code in which the encoded data word is extracted unchanged into the unencoded data word if the indicator bit has the first binary value and is extracted into the unencoded data word and then complemented if the indicator bit has the second, opposite binary value.