Helpers.hs

-- |
-- Module      :  Codec.Audio.FLAC.StreamDecoder.Internal.Helpers
-- Copyright   :  © 2016–2017 Mark Karpov
-- License     :  BSD 3 clause
--
-- Maintainer  :  Mark Karpov <markkarpov@openmailbox.org>
-- Stability   :  experimental
-- Portability :  portable
--
-- Wrappers around helpers written to help work with stream decoder.

module Codec.Audio.FLAC.StreamDecoder.Internal.Helpers
  ( decoderInitHelper )
where

import Codec.Audio.FLAC.StreamDecoder.Internal.Types
import Codec.Audio.FLAC.Util
import Data.Void
import Foreign
import Foreign.C.String
import Foreign.C.Types

-- | Initialize decoder to decode FLAC file and register buffer where
-- decoded audio data will go (which must be big enough). Return
-- 'DecoderInitStatus'.

decoderInitHelper
  :: Decoder           -- ^ 'Decoder' to use
  -> FilePath          -- ^ FLAC file to decode
  -> Ptr Void          -- ^ Buffer where to write decoded audio data
  -> IO DecoderInitStatus
     -- ^ Sample rate, bits per sample, channels
decoderInitHelper decoder ipath buffer =
  withCString ipath $ \ipathPtr ->
    toEnum' <$> c_decoder_init_helper
      decoder          -- stream decoder
      ipathPtr         -- name of FLAC file to decode
      buffer           -- output buffer

foreign import ccall unsafe "FLAC__stream_decoder_init_helper"
  c_decoder_init_helper
    :: Decoder
    -> CString
    -> Ptr Void
    -> IO CUInt