Out of Context constraints are needed for timing driven synthesis as for
avoiding critical warnings due clock queries.
The memory from the FIFO is inferred in different ways for high clock
speeds. Assume the highest frequency for all projects.
The grey coder/decoder function was limited to 10 bits, and this
resulted an unwanted limitation of the FIFO size. Using this
module, the coder/decoder data width can be adjusted to the current
address width.