Honored Contributor
Honored ContributorI suggest that you read the triple speed ethernet user guide (https://www.altera.com/en_us/pdfs/literature/ug/ug_ethernet.pdf). In chapter 5 you have a list of all the registers.
Page 5-3 describes the two registers used to define the MAC address. At offset 3 you have the register mac_0 which holds the 4 most significant bytes of the MAC address, and at offset 4 you have the 2 least significant. The line of codes you showed are one way to write to those TSE registers. I don't know how the rest of the tutorial is written, but if your CPU has a data cache you need to be careful when you use this way of talking to the hardware. You must either flush the cache when you are finished, or use an uncached access.
