;;;
;;; A four-voice rendition of a second-order Markov process. The basic process is taken
;;; from chapter 8 of Computer Music by Dodge/Jerse.
;;;

(in-package :cm)

(merge stephen-foster ()
  (loop for i from -1 to 2 do     ; iterate 4 voices
        (let ((transp (* i 12)))  ; octave offset for each voice
          (algorithm nil midi-note (length 90 amplitude .5)
            (setf note 
                  (item
                   (markov
                     (b3  d4 -> d4)
                     (cs4 d4 -> (d4 .3125) (e4 .3125) (a4 .3125))
                     (d4  d4 -> (cs4 .125) (d4 .125) (e4 .5625) (fs4 .125) (a4 .0625))
                     (e4  d4 -> (b3 .0625) (d4 .0625) (e4 .25) (fs4 .3125) (a4 .0625) 
                                (cs5 .0625) (d5 .1875))
                     (fs4 d4 -> (e4 .75) (fs4 .1875) (g4 .0625))
                     (a4  d4 -> (e4 .6875) (fs4 .3125))
                     (b4  d4 -> d4)
                     
                     (d4  b3 -> d4)
                     
                     (d4  cs4 -> d4)
                     (e4  cs4 -> d4)
                     
                     (d4  e4 -> (d4 .1875) (e4 .25) (fs4 .5) (a4 .0625))
                     (e4  e4 -> (cs4 .0625) (d4 .75) (e4 .0625) (fs4 .125))
                     (fs4 e4 -> (cs4 .125) (d4 .4375) (e4 .1875) (fs4 .125) (a4 .0625) 
                                (d5 .0625))
                     
                     (d4  fs4 -> (e4 .4375) (fs4 .1875) (g4 .125) (a4 .25))
                     (e4  fs4 -> (d4 .0625) (e4 .1875) (fs4 .3125) (g4 .25) (a4 .0625)
                                 (b4 .0625)) 
                     (fs4 fs4 -> (d4 .1875) (e4 .25) (fs4 .3125) (g4 .125) (a4 .0625))
                     (g4  fs4 -> (e4 .5) (g4 .5))
                     (a4  fs4 -> (d4 .3125) (e4 .25) (fs4 .1875) (g4 .0625) (a4 .125) 
                                 (b4 .0625))
                     (b4  fs4 -> (e4 .6875) (fs4 .3125))
                     
                     (d4  g4 -> (fs4 .6875) (b4 .3125))
                     (fs4 g4 -> (fs4 .25) (g4 .1875) (a4 .3125) (b4 .1875))
                     (g4  g4 -> (g4 .5) (a4 .5))
                     (a4  g4 -> fs4)
                     (b4  g4 -> b4)
                     
                     (a4  gs4 -> a4)
                     
                     (d4  a4 -> (fs4 .25) (a4 .75))
                     (e4  a4 -> (a4 .8125) (b4 .1875))
                     (fs4 a4 -> (fs4 .125) (a4 .625) (b4 .1875) (d5 .0625))
                     (g4  a4 -> (d4 .125) (a4 .625) (d5 .25))
                     (gs4 a4 -> a4)
                     (a4  a4 -> (fs4 .25) (g4 .0625) (gs4 .0625) (a4 .3125) (b4 .3125)) 
                     (b4  a4 -> (d4 .0625) (fs4 .5625) (g4 .0625) (a4 .125) (b4 .0625)
                                (d5 .125))
                     (d5  a4 -> (fs4 .875) (a4 .125))
                     (e5  a4 -> a4)
                     
                     (fs4 b4 -> a4)
                     (g4  b4 -> a4)
                     (a4  b4 -> (d4 .0625) (fs4 .0625) (a4 .75) (b4 .0625) (b4 .0625))
                     (b4  b4 -> (fs4 .125) (a4 .75) (d5 .125))
                     (cs5 b4 -> a4)
                     (d5  b4 -> (g4 .0625) (a4 .3125) (b4 .3125) (d5 .25))
                     
                     (d4  cs5 -> d5)
                     (d5  cs5 -> (b4 .75) (d5 .25)) 
                     (e5  cs5 -> d5)
                     
                     (d4  d5 -> (a4 .125) (b4 .6875) (cs5 .1875) )
                     (e4  d5 -> cs5)
                     (a4  d5 -> (a4 .3125) (b4 .3125) (cs5 .1875) (d5 .125))
                     (b4  d5 -> (a4 .5625) (b4 .125) (cs5 .3125))
                     (cs5 d5 -> (b4 .3125) (e5 .625))
                     (d5  d5 -> b4)
                     
                     (d5 e5 -> (a4 .3125) (cs5 .6875)))))
            ;; transpose each algo to its own octave
            (setf note (transpose note transp)) 
            (setf rhythm
                  (item (items ((rhythms h h tempo 200) weight .125)
                               ((rhythms h h tempo 200) weight .25)
                               ((rhythms q for 4 tempo 200) weight .125)
                               ((rhythms h q q tempo 200) weight .125)
                               ((rhythms q q h tempo 200) weight .125)
                               ((rhythms q h q tempo 200) weight .125)
                               ((rhythms q h q tempo 200) weight .125)
                               ((rhythms w tempo 200) weight .125)
                               in random)))))))