Sentinel-65X VS corundum

You might find the Sentinel 65X interesting in that the guy behind it basically said "the X16 is big and clunky and expensive, let's cut out that stuff".

https://github.com/studio8502/Sentinel-65X

It's not yet a deliverable product but watching the developers work on it has been an entertaining part of my doomscrolling diet.

The GPU uses this: https://github.com/alexforencich/verilog-pcie . And there is an open-source 100G NIC here, including open source 10G/25G MACs: https://github.com/corundum/corundum

Well, I did build this: https://github.com/corundum/corundum

I would look into 10GbE PCS/MAC packet processors implemented under AXI Stream interfaces for example. There are open source examples https://github.com/corundum/corundum and https://netfpga.org/ .

I built my own 100 Gbps capable NIC, along with driver: https://github.com/corundum/corundum. You're welcome to ask if you have any questions, though it is quite a different animal from a 100 Mbps NIC you might have on a microcontroller.

If you're looking for resources, here's one rather comprehensive example of a high-performance FPGA design with a fully custom DMA engine and driver, that runs on both Xilinx and Intel FPGAs: https://github.com/corundum/corundum

I have no idea, but you're welcome to build the design and look at it yourself: https://github.com/corundum/corundum/tree/master/fpga/mqnic/NetFPGA_SUME/fpga. The barrel shifters are in the DMA engine, both the read DMA and write DMA engines have wide barrel shifters.

Dive right into the slack channel and introduce yourself. There is also a new contributor guide. /u/alexforencich/ is on these reddits and he may be able to chime in and give you more concrete suggestions.