Interfacing Stratix 10 PMA with custom PCS

Hi,

I am planning to develop custom PCS which supports Symbol encoding of 128b/132b and implements Scrambling and RS-FEC of different polynomials compared to existing native PHY IP for L-tile XCVR of Stratix 10. I know that I need to use PCS direct to use only PMA from the L-tile native PHY and the data width supported by PCS direct is 64-bit max. Considering the scenario that after encoding 128b/132b, data width of custom PCS will become 132bit wide. How I map the 132bit encoded data to 64bit PCS direct data width? Also, provide material references / documents/ example designs which guide me to interface a custom PCS to PMA block.

With regards,

HPB