{-# LANGUAGE MultiParamTypeClasses #-} module Sound.File.Sndfile.Buffer ( MBuffer(..), checkSampleBounds, checkFrameBounds, interact ) where import C2HS import Control.Monad (liftM, when) import Data.Array.Base (unsafeRead, unsafeWrite) import Data.Array.MArray (Ix, MArray, getBounds) --import Data.Array.IArray (IArray) import Data.Ix (rangeSize) import Prelude hiding (interact) import Sound.File.Sndfile.Interface checkSampleBounds :: (Monad m) => Count -> Int -> Count -> m () checkSampleBounds size channels count | (count `mod` channels) /= 0 = throw (Exception ("invalid channel/count combination " ++ (show count))) | (count < 0) || (count > size) = throw (Exception "index out of bounds") | otherwise = return () checkFrameBounds :: (Monad m) => Count -> Int -> Count -> m () checkFrameBounds size channels count | (size `mod` channels) /= 0 = throw (Exception "invalid buffer size") | (count < 0) || (count > (size `quot` channels)) = throw (Exception "index out of bounds") | otherwise = return () -- |The class MBuffer is used for polymorphic I\/O on a 'Handle', and is -- parameterized on the mutable array type, the element type and the monad -- results are returned in. -- -- It is important to note that the data type used by the calling program and -- the data format of the file do not need to be the same. For instance, it is -- possible to open a 16 bit PCM encoded WAV file and read the data in -- floating point format. The library seamlessly converts between the two -- formats on-the-fly; the Haskell interface only supports reading and writing -- 'Double' or 'Float' values. -- -- When converting between integer data and floating point data, the following -- rules apply: The default behaviour when reading floating point data -- ('hGetSamples' or 'hGetFrames') from a file with integer data is -- normalisation. Regardless of whether data in the file is 8, 16, 24 or 32 -- bit wide, the data will be read as floating point data in the range -- [-1.0, 1.0]. Similarly, data in the range [-1.0, 1.0] will be written to an -- integer PCM file so that a data value of 1.0 will be the largest allowable -- integer for the given bit width. This normalisation can be turned on or off -- using the command interface [TODO: implementation missing in Haskell]. -- -- 'hGetSamples' and 'hGetFrames' return the number of items read. Unless the -- end of the file was reached during the read, the return value should equal -- the number of items requested. Attempts to read beyond the end of the file -- will not result in an error but will cause the read functions to return -- less than the number of items requested or 0 if already at the end of the -- file. class (MArray a e m) => MBuffer a e m where -- |Fill the destination array with the requested number of items. The 'count' -- parameter must be an integer product of the number of channels or an error -- will occur. hGetSamples :: Handle -> a Index e -> Count -> m Count -- |Fill the destination array with the requested number of frames of data. -- The array must be large enough to hold the product of frames and the number -- of channels or an error will occur. hGetFrames :: Handle -> a Index e -> Count -> m Count -- |Write 'count' samples from the source array to the stream. The 'count' -- parameter must be an integer product of the number of channels or an error -- will occur. -- -- 'hPutSamples' returns the number of items written (which should be the same -- as the 'count' parameter). hPutSamples :: Handle -> a Index e -> Count -> m Count -- |Write 'count' frames from the source array to the stream. -- The array must be large enough to hold the product of frames and the number -- of channels or an error will occur. -- -- 'hPutFrames' returns the number of frames written (which should be the same -- as the 'count' parameter). hPutFrames :: Handle -> a Index e -> Count -> m Count modifyArray :: (MArray a e m, Ix i) => (e -> e) -> a i e -> Int -> Int -> m () modifyArray f a i n | i >= n = return () | otherwise = do e <- unsafeRead a i unsafeWrite a i (f e) modifyArray f a (i+1) n interact :: (MBuffer a e m) => (e -> e) -> a Index e -> Handle -> Handle -> m () interact f buffer hIn hOut = do s <- liftM rangeSize $ getBounds buffer n <- hGetSamples hIn buffer s when (n > 0) $ do modifyArray f buffer 0 n hPutSamples hOut buffer n interact f buffer hIn hOut -- EOF