src/RMCA/Translator/Note.hs

   1 {-# LANGUAGE Arrows #-}
   2
   3 module RMCA.Translator.Note where
   4
   5 import Data.Ratio
   6 import FRP.Yampa
   7 import RMCA.Global.Clock
   8 import RMCA.Semantics
   9 import RMCA.Translator.Message
  10
  11 messageToNote :: Message -> Note
  12 messageToNote (NoteOn _ p s) = Note { notePch = p
  13                                     , noteStr = s
  14                                     , noteDur = 1 % 4
  15                                     , noteOrn = noOrn
  16                                     }
  17 messageToNote m = error $ "In messageToNote: the message "
  18                   ++ show m ++ " is not a note message"
  19
  20 -- noteToMessage gives a pair of two time-stamped messages. The one on
  21 -- the left is a note message, the other a note off.
  22 noteToMessages :: LTempo
  23                -> SampleRate
  24                -> Int -- Channel number
  25                -> (Frames,Note) -- Note to convert
  26                -> [(Frames,Message)]
  27 noteToMessages layTempo sr chan =
  28   proc (t,n@Note { noteDur = d }) -> do
  29     nm <- noteOnToMessage chan -< n
  30     let dt :: Double
  31         dt = fromRational (d * toRational (tempoToQNoteIvl layTempo))
  32         dn :: Int
  33         dn = floor $ dt * fromIntegral sr
  34     returnA -< [(t,nm),(t + dn,switchOnOff nm)]
  35
  36 noteOnToMessage :: Int -> Note -> Message
  37 noteOnToMessage c Note { notePch = p
  38                        , noteStr = s
  39                        } = NoteOn (makeChannel c) p s