Hi Adam.
In the snd[] vector I charge all data, first portion is the ethernet UDP nescesary data header, last four bytes are the CRC, in the middle of them, you simply charge your usefull data, take it out from SDRAM or any place, and load the snd[42] to snd[flenght-4] with it.
You also could modify your packet size, anyway, "How to get the data from SDRAM" is another thing, if SDRAM is your NIOS main memory, the data is in the SDRAM yet, if not,..... explain me better which is your case.
Recieve part is a nightmare still for me... and I've not free time to play with that this days. :(
Cheers.
Alberto.