TM4C1294NCPDT UIP例程 MAC地址如何设置，有何规则？？

参考如下代码：

//
// Read the MAC address from the user registers.
//
MAP_FlashUserGet(&ui32User0, &ui32User1);
if((ui32User0 == 0xffffffff) || (ui32User1 == 0xffffffff))
{
//
// We should never get here. This is an error if the MAC address has
// not been programmed into the device. Exit the program.
//
UpdateStatus("MAC Address Not Programmed!");
while(1)
{
}
}

//
// Convert the 24/24 split MAC address from NV ram into a 32/16 split MAC
// address needed to program the hardware registers, then program the MAC
// address into the Ethernet Controller registers.
//
sTempAddr.addr[0] = ((ui32User0 >> 0) & 0xff);
sTempAddr.addr[1] = ((ui32User0 >> 8) & 0xff);
sTempAddr.addr[2] = ((ui32User0 >> 16) & 0xff);
sTempAddr.addr[3] = ((ui32User1 >> 0) & 0xff);
sTempAddr.addr[4] = ((ui32User1 >> 8) & 0xff);
sTempAddr.addr[5] = ((ui32User1 >> 16) & 0xff);