#!r6rs
(library (rsc3 supercollider spec)
(export make-spec* spec-map spec-unmap symbol->spec)
(import (rnrs)
	(only (rsc3 collection list) append-map)
	(only (rsc3 math clip) clip)
	(only (rsc3 math constants) two-pi)
	(rsc3 supercollider warp))

;; An interface to the warp procedures.

(define-record-type spec (fields minima maxima warp range ratio))

(define (make-spec* minima maxima warp)
  (let ((w (if (symbol? warp) (symbol->warp warp) warp)))
    (make-spec minima maxima (w minima maxima)
	       (- maxima minima) (/ maxima minima))))

(define (spec-map s value)
  ((spec-warp s) 'map (clip 0.0 1.0 value)))

(define (spec-unmap s value)
  (clip 0.0 1.0 ((spec-warp s) 'unmap value)))

(define (symbol->spec s)
  (case s
    ((unipolar)       (make-spec  0.0 1.0     'linear))
    ((bipolar pan)    (make-spec -1.0 1.0     'linear))
    ((freq frequency) (make-spec 20.0 20000.0 'linear))
    ((phase)          (make-spec  0.0 two-pi  'linear))
    (else             (error 'symbol->spec "illegal value" s))))

)