I am playing with some assembly language in the Arduino environment and are looking to do the same in the Arduboy environment.
I am making progress with the actual code itself on a ‘bare-bones’ Arduino but struggling to understand how I move this to the Arduboy environment. Obviously I can use the
asm volatile command and code away but how do I know what registers are being used at the point in time so I do not overwrite values that may still be needed?
I can see in the Arduboy2 docs that R28 and R29 are being used in the draw…() functions. How were these determined to be free? I assume that I can use them too but what if I need more?