    -- |
    -- Module      : Crypto.Hash.Skein256
    -- License     : BSD-style
    -- Maintainer  : Vincent Hanquez <vincent@snarc.org>
    -- Stability   : experimental
    -- Portability : unknown
    --
    -- module containing the binding functions to work with the
    -- Skein256 cryptographic hash.
    --
    {-# LANGUAGE ForeignFunctionInterface #-}
    {-# LANGUAGE DeriveDataTypeable #-}
    module Crypto.Hash.Skein256
        (  Skein256_224 (..), Skein256_256 (..)
        ) where

    import           Crypto.Hash.Types
    import           Foreign.Ptr (Ptr)
    import           Data.Data
    import           Data.Typeable
    import           Data.Word (Word8, Word32)

    -- | Skein256 (224 bits) cryptographic hash algorithm
    data Skein256_224 = Skein256_224
        deriving (Show,Data,Typeable)

    instance HashAlgorithm Skein256_224 where
        hashBlockSize  _          = 32
        hashDigestSize _          = 28
        hashInternalContextSize _ = 96
        hashInternalInit p        = c_skein256_init p 224
        hashInternalUpdate        = c_skein256_update
        hashInternalFinalize p    = c_skein256_finalize p 224

    -- | Skein256 (256 bits) cryptographic hash algorithm
    data Skein256_256 = Skein256_256
        deriving (Show,Data,Typeable)

    instance HashAlgorithm Skein256_256 where
        hashBlockSize  _          = 32
        hashDigestSize _          = 32
        hashInternalContextSize _ = 96
        hashInternalInit p        = c_skein256_init p 256
        hashInternalUpdate        = c_skein256_update
        hashInternalFinalize p    = c_skein256_finalize p 256

    foreign import ccall unsafe "cryptonite_skein256_init"
        c_skein256_init :: Ptr (Context a) -> Word32 -> IO ()

    foreign import ccall "cryptonite_skein256_update"
        c_skein256_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()

    foreign import ccall unsafe "cryptonite_skein256_finalize"
        c_skein256_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()