So I figured it out in the end, it was just a typo in my redshift.h file causing all the includes to break xD. Then I needed to add an '-lm' flag into the makefile as shown here:
https://github.com/AuroraWright/Lum...a24c#diff-df3b0b90e9112ef9de99f7fb6e99c1acR16 to sort some "undefined reference to" errors.
Anyway, on to the good part...
I've attached firms for N3DS and O3DS - so please use the correct one! The only reason for the difference is that Luma chops the top menu option off for O3DS (to stop you accessing the "New 3DS menu..."). However, I wanted the redshift option to be top of the list so I could easily select it with my eyes closed.
The minor changes to Sono's original module implementation are all just my personal preferences:
- SELECT now toggles LEDs (LEDs also toggle upon opening menu)
- B instead returns to previous menu
- UP/DOWN now navigate, RIGHT/LEFT change values
- X applies changes to top screen
- Text change from Luma blue to red/white
Big thanks to Sono for giving us CTR_Redshift in the first place and the Luma team for making it possible to add modules.