Circuitry for detecting excessive runs of similar bits of data in a data
stream is provided. The data stream is typically received as serial data operating
in a serial clock domain. Run-length detection circuitry checks the received data
for run-length violations while operating in a slower parallel clock domain, as
opposed to the faster serial clock domain. An advantage of operating run-length
detection circuitry in the parallel domain is that longer length run-length violations
can be searched for in the received data, as compared to run-length detectors that
operate in the serial domain. Another advantage offered by the circuitry is that
the run-length violation signal can be provided to utilization circuitry asynchronously.
This enables utilization circuitry to quickly capture the signal despite differences
in clock domains (i.e., the clock domain of the detection circuitry and the clock
domain of the utilization circuitry).
