Wave.hs

{-
Reads wave file into raw structure, containing
meta and signal data. For detailed header structure
see the Wave format specification.
-}

module Signal.Wave (
    WaveHeader (..),
    RawSignal (..),
    Wave (..),
    Endianness (..),
    readWaveFromFile
) where

import Control.Applicative
import Data.Word
import Data.Binary.Get

import qualified Data.ByteString.Lazy as ByteStr

data Endianness = LittleEndian | BigEndian deriving (Eq, Show)

data WaveHeader = WaveHeader {
    header :: !Word32,
    fileSize :: !Word32,
    waveHeader :: !Word32,
    fmtHeader :: !Word32,
    waveMetaSize :: !Word32,
    waveFormat :: !Word16,
    channelsNum :: !Word16,
    frequency :: !Word32,
    bytesPerSec :: !Word32,
    bytesPerBlock :: !Word16,
    bitsPerSample :: !Word16,
    dataHeader :: !Word32,
    dataSize :: !Word32
} deriving (Eq, Show)

newtype RawSignal = RawSignal {
    waveContents :: ByteStr.ByteString
} deriving (Eq, Show)

data Wave = Wave {
    waveMeta :: !WaveHeader,
    rawSignal :: !RawSignal,
    endianness :: Endianness
} deriving (Eq, Show)

waveHeaderLength = 44

readWaveFromFile :: FilePath -> IO Wave
readWaveFromFile path =
    Wave <$> header <*> (RawSignal <$> dataString)
         <*> (getEndianness <$> header)
    where
        input = ByteStr.readFile path
        dataString = ByteStr.drop waveHeaderLength <$> input
        header = (runGet getWaveHeader . ByteStr.take waveHeaderLength) <$> input

getWaveHeader :: Get WaveHeader
getWaveHeader =
    WaveHeader <$> dw <*> dw <*> dw <*> dw <*> dw <*> w
               <*> w <*> dw <*> dw <*> w <*> w <*> dw <*> dw
    where
        w = getWord16le
        dw = getWord32le

--Endianness stub : TODO!
getEndianness :: WaveHeader -> Endianness
getEndianness _ = LittleEndian