The source of truth is in the link to the Core source code provided by @J-M-L. UX2 is used when it can be used.
(Ugh. I really wish the Arduino folks would fix the wide register accesses.)
The source of truth is in the link to the Core source code provided by @J-M-L. UX2 is used when it can be used.
(Ugh. I really wish the Arduino folks would fix the wide register accesses.)