Grumpy_Mike:
Somehow it auto detects the Uno or Mega.
No. Don't be silly.
That code uses direct port addressing, that will only work on the Atmel xx8 sort of chips. On other chips the I/O ports are at different addresses. So it won't work on boards with other processors.
I wasn't trying to be silly. The comments claim the code would auto detect the board type and I didn't understand how that could work.
The Yun has two processors. The first is the Atmel ATMega32u4. Can that do direct port addressing? Is it just a matter of finding out the correct ports and edit the code to use those ports for that controller chip?
The Yun also has a second processor running Linux. That should not matter since the I/O pins are attached to the Atmel AtMega32u4 chip.