Multichannel.hs

{-# OPTIONS_GHC -fglasgow-exts #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Numeric.Signal.Multichannel
-- Copyright   :  (c) Alexander Vivian Hugh McPhail 2010
-- License     :  GPL-style
--
-- Maintainer  :  haskell.vivian.mcphail <at> gmail <dot> com
-- Stability   :  provisional
-- Portability :  uses Concurrency
--
-- Signal processing functions, multichannel datatype
--
-- link with '-threaded' and run with +RTS Nn, where n is the number of CPUs
--
-----------------------------------------------------------------------------

module Numeric.Signal.Multichannel (
                       Multichannel,
                       mapConcurrently
                ) where

-----------------------------------------------------------------------------

--import qualified Numeric.Signal as S

--import Complex

import qualified Data.Array.IArray as I

import Control.Concurrent
import Control.Concurrent.MVar

import System.IO.Unsafe(unsafePerformIO)

--import qualified Data.List as L

import Data.Packed.Vector
--import Data.Packed(Container(..))

import Foreign.Storable
--import Numeric.GSL.Vector

--import Numeric.LinearAlgebra.Algorithms

--import qualified Numeric.GSL.Fourier as F

--import Prelude hiding(filter)

-----------------------------------------------------------------------------

data Multichannel a = MC {
                          _sampling_rate :: Int -- ^ sampling rate
                          , _precision   :: Int -- ^ bits of precision
                          , _channels    :: Int -- ^ number of channels
                          , _length      :: Int -- ^ length in samples
                          , _data        :: I.Array Int (Vector a) -- ^ data
                         }

-----------------------------------------------------------------------------


-- | map a function executed concurrently
mapConcurrently :: Storable b => Multichannel a  -- ^ input data
                -> (Vector a -> Vector b)        -- ^ the function to be mapped
                -> Multichannel b                -- ^ output data
mapConcurrently (MC sr p c _ d) f = unsafePerformIO $ do
                                    results <- newMVar []
                                    mapM_ (forkIO . applyFunction results f) $ I.assocs d
                                    vectors <- takeMVar results
                                    return $ MC sr p c (dim $ snd $ head vectors) (I.array (1,c) vectors)
    where applyFunction results f' (i,e) = do
                                          let o = f' e
                                          modifyMVar_ results (\x -> return ((i,o):x))
                                    
-----------------------------------------------------------------------------