Internal.hs

{-# LANGUAGE CApiFFI #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE UnliftedFFITypes #-}

-- |
-- Module      : Hash.MD5.Internal
-- License     : BSD-3
--
module Hash.Md5.Internal
  ( c_md5_init
  , c_md5_update_unsafe
  , c_md5_finalize
  ) where

import GHC.Exts (ByteArray#, MutableByteArray#,RealWorld,Int#)
import Data.Word
import Foreign.C.Types
import Foreign.Ptr

-- MD5 Context
--
-- The context data is exactly 88 bytes long, however
-- the data in the context is stored depends on host-endianness.
--
-- The context data is made up of
--
--  * a 'Word64' representing the number of bytes already feed to hash algorithm so far,
--  * a 64-element 'Word8' buffer holding partial input-chunks, and finally
--  * a 4-element 'Word32' array holding the current work-in-progress digest-value.
--
-- Consequently, a MD5 digest as produced by 'finalize' is 16 bytes long.
foreign import capi unsafe "md5.h hs_byteverse_md5_init"
    c_md5_init ::
         MutableByteArray# RealWorld -- ctx, updated
      -> IO ()

foreign import capi unsafe "md5.h hs_byteverse_md5_update"
    c_md5_update_unsafe ::
         MutableByteArray# RealWorld -- ctx, updated
      -> ByteArray# -- bytes that are hashed
      -> Int -- offset into bytes, often zero
      -> Int -- length of bytes
      -> IO ()

foreign import capi unsafe "md5.h hs_byteverse_md5_finalize"
    c_md5_finalize ::
         MutableByteArray# RealWorld -- ctx
      -> MutableByteArray# RealWorld -- output buffer, must be 16 bytes
      -> Int -- output buffer offset
      -> IO ()