Where do your common.h and os.h libraries come from?

Vogtinator,

I am fairly new to programming , and the only languages that I've had experience with are Java and the Arduino's language. I managed to make a capacitive-sensor piano with the Arduino, but it is rather clunky. I realized that the Ti-inspire calculator already has a built-in keypad and that I might be able to play tones with the nspire. I was wondering if you have any directions, tips, or references that would help me with this project. Also, should I be using Assembly or Lua? I would also like to mention that in the future, I would like to add a synthesizer as well, where I might be able to use waveform equations to creates the timbre and/or the ability to draw the wave. Any information that you could give me would be helpful!

Sincerely,
InvX