tonalisa/lib/sndlib/moog.scm

;;; Moog style four pole lowpass filter clm unit generator
;;;   low pass, 24db/Oct, variable resonance, warm, analog sound ;-)
;;;   [all this digital wizardry and we're back where we started!]
;;;
;;; original C instrument by Tim Stilson
;;; translation into clm and tuning by 
;;;   Fernando Lopez-Lezcano, nando@ccrma.stanford.edu
;;;   http://ccrma.stanford.edu/~nando/clm/moog
;;;
;;; translated to Snd scheme function by Bill,
;;;   changed 21-Sep-10 to use defgenerator

(provide 'snd-moog.scm)

(if (provided? 'snd)
    (require snd-ws.scm)
    (require sndlib-ws.scm))

(define moog-gaintable (float-vector 0.999969 0.990082 0.980347 0.970764 0.961304 0.951996 0.94281 0.933777 0.924866 0.916077 
			    0.90741 0.898865 0.890442 0.882141  0.873962 0.865906 0.857941 0.850067 0.842346 0.834686
			    0.827148 0.819733 0.812378 0.805145 0.798004 0.790955 0.783997 0.77713 0.770355 0.763672
			    0.75708  0.75058 0.744141 0.737793 0.731537 0.725342 0.719238 0.713196 0.707245 0.701355
			    0.695557 0.689819 0.684174 0.678558 0.673035 0.667572 0.66217 0.65686 0.651581 0.646393
			    0.641235 0.636169 0.631134 0.62619 0.621277 0.616425 0.611633 0.606903 0.602234 0.597626
			    0.593048 0.588531 0.584045 0.579651 0.575287  0.570953 0.566681 0.562469 0.558289 0.554169
			    0.550079 0.546051 0.542053 0.538116 0.53421 0.530334 0.52652 0.522736 0.518982 0.515289
			    0.511627 0.507996  0.504425 0.500885 0.497375 0.493896 0.490448 0.487061 0.483704 0.480377
			    0.477081 0.473816 0.470581 0.467377 0.464203 0.46109 0.457977 0.454926 0.451874 0.448883
			    0.445892 0.442932 0.440033 0.437134 0.434265 0.431427 0.428619 0.425842 0.423096 0.42038
			    0.417664 0.415009 0.412354 0.409729 0.407135 0.404572 0.402008 0.399506 0.397003 0.394501
			    0.392059 0.389618 0.387207 0.384827 0.382477 0.380127 0.377808 0.375488 0.37323 0.370972
			    0.368713 0.366516 0.364319 0.362122 0.359985 0.357849 0.355713 0.353607 0.351532 0.349457
			    0.347412 0.345398 0.343384 0.34137 0.339417 0.337463 0.33551 0.333588 0.331665 0.329773
			    0.327911 0.32605 0.324188 0.322357 0.320557 0.318756 0.316986 0.315216 0.313446 0.311707
			    0.309998 0.308289 0.30658 0.304901 0.303223 0.301575 0.299927 0.298309 0.296692 0.295074
			    0.293488 0.291931 0.290375 0.288818 0.287262 0.285736 0.284241 0.282715 0.28125 0.279755
			    0.27829 0.276825 0.275391 0.273956 0.272552 0.271118 0.269745 0.268341 0.266968 0.265594
			    0.264252 0.262909 0.261566 0.260223 0.258911 0.257599 0.256317 0.255035 0.25375))

(define moog-freqtable
    '(0 -1
      0.03311111 -0.9
      0.06457143 -0.8
      0.0960272 -0.7
      0.127483 -0.6
      0.1605941 -0.5
      0.1920544 -0.4
      0.22682086 -0.3
      0.2615873 -0.2
      0.29801363 -0.1
      0.33278003 -0.0
      0.37086168 0.1
      0.40893877 0.2
      0.4536417 0.3
      0.5 0.4
      0.5463583 0.5
      0.5943719 0.6
      0.6556281 0.7
      0.72185487 0.8
      0.8096009 0.9
      0.87913835 0.95
      0.9933787 1
      1 1))

;;; moog struct is a list (freq res arr a)
;;;   freq: cutoff frequency in Hertz
;;;   Q: resonance, 0->no resonance, 1->oscilates at freq
;;;
;;; Note: the relation between freq and the actual cutoff is not exactly linear but
;;;       I prefered to translate Hz into the internal parameter rather than controlling
;;;       the cutoff frequency in terms of a number that goes between -1 and 1. 

#|
(defgenerator moog freq Q s y fc gain sig)

(define make-moog-filter 
  (let ((documentation "(make-moog-filter frequency Q) makes a new moog-filter generator. 'frequency' is the cutoff in Hz,
'Q' sets the resonance: 0 = no resonance, 1: oscillates at 'frequency'"))
    (lambda (frequency Q)
      (let ((frq (envelope-interp (/ frequency (* *clm-srate* 0.5)) moog-freqtable)))
	(make-moog :freq frequency 
		   :Q Q 
		   :s (make-float-vector 4) 
		   :y 0.0 
		   :fc frq
		   :gain (* Q (array-interp moog-gaintable (+ 99.0 (* frq 99.0)))))))))
    

(define moog-frequency
  (dilambda
   (let ((documentation "(moog-frequency gen) accesses the cutoff frequency of the Moog filter 'gen'"))
     (lambda (gen)
       (gen 'freq)))
   (lambda (gen frq)
     (let ((fr (envelope-interp (/ frq (* *clm-srate* 0.5)) moog-freqtable)))
       (set! (gen 'freq) frq)
       (set! (gen 'fc) fr)
       (set! (gen 'gain) (* (gen 'Q) (array-interp moog-gaintable (+ 99.0 (* fr 99.0)))))))))


(define moog-filter 
  (let ((documentation "(moog-filter m sig) is the generator associated with make-moog-filter"))
    (lambda (m sig)
      (let-set! m 'sig sig)
      (with-let m
	(let ((A (* 0.25 (- sig y)))
	      (st 0.0))
	  (do ((cell 0 (+ 1 cell)))
	      ((= cell 4))
	    (set! st (float-vector-ref s cell))
	    (set! A (min 0.95 (max -0.95 (+ A (* fc (- A st))))))
	    (float-vector-set! s cell A)
	    (set! A (min 0.95 (max -0.95 (+ A st)))))
	  (set! y (* A gain))
	  A)))))
    
;;; (let ((gen (make-moog-filter 500.0 .1))) (map-channel (lambda (y) (moog-filter gen y))))

|#

;;; faster version?

(defgenerator moog freq Q s0 s1 s2 s3 y fc gain sig)

(define make-moog-filter 
  (let ((documentation "(make-moog-filter frequency Q) makes a new moog-filter generator. 'frequency' is the cutoff in Hz,
'Q' sets the resonance: 0 = no resonance, 1: oscillates at 'frequency'"))
    (lambda (frequency Q)
      (let ((frq (envelope-interp (/ frequency (* *clm-srate* 0.5)) moog-freqtable)))
	(make-moog :freq frequency 
		   :Q Q 
		   :y 0.0 :s0 0.0 :s1 0.0 :s2 0.0 :s3 0.0
		   :fc frq
		   :gain (* Q (array-interp moog-gaintable (+ 99.0 (* frq 99.0)))))))))
    

(define moog-frequency
  (dilambda
   (let ((documentation "(moog-frequency gen) accesses the cutoff frequency of the Moog filter 'gen'"))
     (lambda (gen)
       (gen 'freq)))
   (lambda (gen frq)
     (let ((fr (envelope-interp (/ frq (* *clm-srate* 0.5)) moog-freqtable)))
       (set! (gen 'freq) frq)
       (set! (gen 'fc) fr)
       (set! (gen 'gain) (* (gen 'Q) (array-interp moog-gaintable (+ 99.0 (* fr 99.0)))))))))


(define moog-filter 
  (let ((documentation "(moog-filter m sig) is the generator associated with make-moog-filter"))
    (lambda (m sig)
					;  see below for the "saturate" option
      (let-set! m 'sig sig)
      (with-let m
	(let ((A (* 0.25 (- sig y)))
	      (st s0))
	  
	  (set! s0 (+ A (* fc (- A st))))
	  (set! A (+ s0 st))
	  
	  (set! st s1)
	  (set! s1 (+ A (* fc (- A st))))
	  (set! A (+ s1 st))
	  
	  (set! st s2)
	  (set! s2 (+ A (* fc (- A st))))
	  (set! A (+ s2 st))
	  
	  (set! st s3)
	  (set! s3 (+ A (* fc (- A st))))
	  (set! A (+ s3 st))
	  
	  (set! y (* A gain))
	  A)))))

(define moog-filter-saturated 
  (let ((documentation "(moog-filter-saturated m sig) is the generator associated with make-moog-filter with internal saturation"))
    (lambda (m sig)
      (let-set! m 'sig sig)
      (with-let m
	(let ((A (* 0.25 (- sig y)))
	      (st s0))
	  
	  (set! s0 (min 0.95 (max -0.95 (+ A (* fc (- A st))))))
	  (set! A (min 0.95 (max -0.95 (+ s0 st))))
	  
	  (set! st s1)
	  (set! s1 (min 0.95 (max -0.95 (+ A (* fc (- A st))))))
	  (set! A (min 0.95 (max -0.95 (+ s1 st))))
	  
	  (set! st s2)
	  (set! s2 (min 0.95 (max -0.95 (+ A (* fc (- A st))))))
	  (set! A (min 0.95 (max -0.95 (+ s2 st))))
	  
	  (set! st s3)
	  (set! s3 (min 0.95 (max -0.95 (+ A (* fc (- A st))))))
	  (set! A (min 0.95 (max -0.95 (+ s3 st))))
	  
	  (set! y (* A gain))
	  A)))))