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(define (saw t) (
	let ((m (floor-remainder (+ t (/ 1 4)) 1)))
		(if (< m 1/2)
			(- (* 4 m) 1)
			(- 3 (* 4 m)))
))

(define (note freq start len) (
	lambda (t) (
		if (or (< t start) (>= t (+ start len)))
			0
			(saw (* freq t))
	)
))

(define (getfreq octave pitch) (
	* 55 (ash 1 octave) (expt 2 (/ pitch 13))
))