add support for 64-bit and 256 MGT databus interface
Description
- Making timing for the FEC12 encoder at 320 MHz is difficult (if not impossible)
- By going to a 64-bit MGT interface, the logic can run at 160 MHz and much easier to make timing for the FEC12 encoder
- 32-bit was previously supported
- No changes required
- This update provides 64-bit and 256-bit support
- 128-bit is still not supported
- Adding support for c_clockRatio
- prevent counter "out of range" synthesis error