I might recommend the tracker Art of Noise over, say, ProTracker due to its wavetable synth capabilities giving it very little CPU overhead with very little RAM overhead if you use the synth routines on your FM samples.
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I seem to recall it functions something like the wave offset command (9xx) but with short loops, also it has a simple FM synth built in if being able to model a sound from within the editor is desired... And the replayer code is part of the archive I think. I know it can save executable code that you just call from within your code as I have done so.