module Data.Digest.Adler32 (
Adler32, adler32, adler32Update
) where
import Foreign
import Foreign.C.Types
import Foreign.ForeignPtr
import GHC.Ptr
import qualified Data.ByteString as S
import qualified Data.ByteString.Internal as BI
import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString.Lazy.Internal as LI
class Adler32 a where
adler32 :: a -> Word32
adler32 = adler32Update 0
adler32Update :: Word32 -> a -> Word32
instance Adler32 S.ByteString where
adler32Update = adler32_s_update
instance Adler32 L.ByteString where
adler32Update = adler32_l_update
instance Adler32 [Word8] where
adler32Update n = (adler32Update n) . L.pack
adler32_s_update :: Word32 -> S.ByteString -> Word32
adler32_s_update n s = adler32_l_update n (LI.Chunk s LI.Empty)
adler32_l_update :: Word32 -> L.ByteString -> Word32
adler32_l_update n = LI.foldlChunks updateAdler n
where updateAdler adler bs = fromIntegral $ adler32_c (fromIntegral adler) buf (fromIntegral len)
where (ptr, offset, len) = BI.toForeignPtr bs
buf = (unsafeForeignPtrToPtr ptr) `plusPtr` offset
foreign import ccall unsafe "zlib.h adler32"
adler32_c :: CInt -> Ptr Word8 -> CInt -> CInt