{-# LANGUAGE NoImplicitPrelude #-}
{- | Noise and random processes. -}
module Synthesizer.State.Noise where

import qualified Synthesizer.State.Signal as Sig

import qualified Algebra.RealRing              as RealRing
import qualified Algebra.Ring                  as Ring

import System.Random (Random, RandomGen, randomR, mkStdGen, )
import qualified System.Random as Rnd

import NumericPrelude.Numeric
import NumericPrelude.Base


{-|
Deterministic white noise, uniformly distributed between -1 and 1.
That is, variance is 1\/3.
-}
{-# INLINE white #-}
white :: (Ring.C y, Random y) =>
   Sig.T y
white :: forall y. (C y, Random y) => T y
white = forall y g. (C y, Random y, RandomGen g) => g -> T y
whiteGen (Int -> StdGen
mkStdGen Int
12354)

{-# INLINE whiteGen #-}
whiteGen ::
   (Ring.C y, Random y, RandomGen g) =>
   g -> Sig.T y
whiteGen :: forall y g. (C y, Random y, RandomGen g) => g -> T y
whiteGen = forall y g. (C y, Random y, RandomGen g) => (y, y) -> g -> T y
randomRs (-y
1,y
1)


{- |
Approximates normal distribution with variance 1
by a quadratic B-spline distribution.
-}
{-# INLINE whiteQuadraticBSplineGen #-}
whiteQuadraticBSplineGen ::
   (Ring.C y, Random y, RandomGen g) =>
   g -> Sig.T y
whiteQuadraticBSplineGen :: forall y g. (C y, Random y, RandomGen g) => g -> T y
whiteQuadraticBSplineGen g
g =
   let (g
g0,g
gr) = forall g. RandomGen g => g -> (g, g)
Rnd.split g
g
       (g
g1,g
g2) = forall g. RandomGen g => g -> (g, g)
Rnd.split g
gr
   in  forall y g. (C y, Random y, RandomGen g) => g -> T y
whiteGen g
g0 forall a. C a => T a -> T a -> T a
`Sig.mix`
       forall y g. (C y, Random y, RandomGen g) => g -> T y
whiteGen g
g1 forall a. C a => T a -> T a -> T a
`Sig.mix`
       forall y g. (C y, Random y, RandomGen g) => g -> T y
whiteGen g
g2


{-# INLINE randomPeeks #-}
randomPeeks :: (RealRing.C y, Random y) =>
      Sig.T y    {- ^ momentary densities, @p@ means that there is about one peak
                      in the time range of @1\/p@ samples -}
   -> Sig.T Bool {- ^ Every occurence of 'True' represents a peak. -}
randomPeeks :: forall y. (C y, Random y) => T y -> T Bool
randomPeeks =
   forall y g. (C y, Random y, RandomGen g) => g -> T y -> T Bool
randomPeeksGen (Int -> StdGen
mkStdGen Int
876)

{-# INLINE randomPeeksGen #-}
randomPeeksGen :: (RealRing.C y, Random y, RandomGen g) =>
      g
   -> Sig.T y
   -> Sig.T Bool
randomPeeksGen :: forall y g. (C y, Random y, RandomGen g) => g -> T y -> T Bool
randomPeeksGen =
   forall a b c. (a -> b -> c) -> T a -> T b -> T c
Sig.zipWith forall a. Ord a => a -> a -> Bool
(<) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall y g. (C y, Random y, RandomGen g) => (y, y) -> g -> T y
randomRs (y
0,y
1)



{-# INLINE randomRs #-}
randomRs ::
   (Ring.C y, Random y, RandomGen g) =>
   (y,y) -> g -> Sig.T y
randomRs :: forall y g. (C y, Random y, RandomGen g) => (y, y) -> g -> T y
randomRs (y, y)
bnd = forall acc y. (acc -> Maybe (y, acc)) -> acc -> T y
Sig.unfoldR (forall a. a -> Maybe a
Just forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a g. (Random a, RandomGen g) => (a, a) -> g -> (a, g)
randomR (y, y)
bnd)