🚀 go-pugleaf

Hi, I have just subscribed here as I am looking for algorithms or even some helpful
pointers on real-time pitch shifting using DSPs.

I having some specialist hardware built for a pet-project I have the input will be
a single guitar string sound wave (from a standard magnetic pickup).

What I need to know is:
- if I sample at x Khz and I may assume the frequency of the note, Is there an
  easy-ish way to bend this to any semi-tone to +/- 1 octave?
- does not knowing the frequency overly complicate the computation? (other than
  waiting for 1 cycle to determine it.
- can any algorithms handle doing this to a single note that varies in pitch over
  time (the result must vary accordingly, i.e. if I shift an A440 down 2 semitones
  then the pitch of the input goes up 2 semitones I get an A440).

Please post or mail ANY helpful hints and/or locations for sources and/or sources
(any language). I am a baby DSP programmer, hints are welcome.

Thank you for your time,
Andrew Longhorn.