Hi,
as a newbie to AVR programming, I am porting Arduino Core code to modern
C++17. I wanted to get rid of ugly large lookup tables that in PROGMEM
that require separate assembly macro magic to access by normal C++ code.
My naïve assumption was that the compiler-generated tables for switch
statement would end up in flash memory, because they are immutable.
It turns out, that avr-gcc or the linker for the Arduino processor that
I have access to, generate code to copy .rodata to .data in RAM. This is
bad, and may have been the reason for these PROGMEM tables.
For some of the smaller processors the smaller switch statements would
not end up using the table lookup, but especially the ATmega2560 has
dense large number of cases.
Any ideas to circumvent it with standard code?
I am using avr-gcc 9.3.0
Regards
Peter.
--
Peter Sommerlad
Better Software: Consulting, Training, Reviews
Modern, Safe & Agile C++
peter....@sommerlad.ch
+41 79 432 23 32
