Anyone know of an available Ethernet 100BASE-FX PCS/PMA IP Block to go into a Xilinx FPGA?

I know this is usually done in an external PHY but I have an existing board that has an external dumb SerDes between the FPGA and SFP. This port is usually used for SDH but the SerDes will support Fast Ethernet clock rates, but I would need the PCS block to be in the FPGA.

I don't fancy designing the 4b/5b encoding/decoding, scrambler/descrambler and Auto-Neg stuff myself if I can get my hands on an IP core. Doesn't have to be free.

Thanks!

Have you tried Mantaro's 40/100G Cores? http://www.mantaro.com/products/fpga_ip_cores/downloads/Ethernet%20100G40G%20Product%20Brief.pdf