A run-length limited (RLL) DC-free encoder includes a determination module
that receives input words and that determines whether each input word is
a member of one of a first input set and a second input set, a first
mapping module that maps the first ones of the input words of the first
input set to corresponding output words that are run-length limited and
DC-free, a second mapping module that maps the second ones of the input
words of the second input set to corresponding output words that are
run-length limited and have a negative digital sum, and an inverter
module that selectively inverts the output words from the second mapping
module based on a cumulative digital sum of the output words.