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{-# LANGUAGE ScopedTypeVariables, Unsafe #-}
{-# OPTIONS_GHC -Wall #-}
-- | Efficient, but unsafe 'Get' and 'Putter' for
-- "Data.Vector.Storable" vectors. The serialized format is an 'Int64'
-- representing the length of the 'Vector', followed by the raw
-- bytes. Therefore behavior may be unpredictable if serialized data
-- is transferred between machines with different word size or
-- endianness.
module Data.Vector.Storable.UnsafeSerialize (
unsafeGetVector
, unsafePutVector
) where
import Control.Monad (when)
import qualified Data.ByteString.Internal as BS
import Data.Int (Int64)
import Data.Serialize (Get, getBytes, putByteString, Putter, Serialize(..))
import Data.Vector.Storable ( unsafeFromForeignPtr0
, unsafeToForeignPtr0
, Vector)
import Data.Vector.Storable.Internal (updPtr)
import Foreign.ForeignPtr (castForeignPtr)
import Foreign.Marshal.Array (advancePtr)
import Foreign.Storable (Storable, sizeOf)
-- | Get a 'Vector' in host order, endian form, and word width.
unsafeGetVector :: forall a. Storable a => Get (Vector a)
{-# INLINE unsafeGetVector #-}
unsafeGetVector = do
len64 <- get :: Get Int64
when (len64 > fromIntegral (maxBound :: Int)) $
fail "Host can't deserialize a Vector longer than (maxBound :: Int)"
let len = fromIntegral len64
nbytes = len * sizeOf (undefined :: a)
bs <- getBytes nbytes
let (fp, off, _) = BS.toForeignPtr bs
fp' | off /= 0 = updPtr (`advancePtr` off) fp
| otherwise = fp
return $ unsafeFromForeignPtr0 (castForeignPtr fp') len
-- | Put a 'Vector' in host order, endian form, and word width.
unsafePutVector :: forall a. Storable a => Putter (Vector a)
{-# INLINE unsafePutVector #-}
unsafePutVector v = do
let (fp, len) = unsafeToForeignPtr0 v
nbytes = len * sizeOf (undefined :: a)
bs = BS.fromForeignPtr (castForeignPtr fp) 0 nbytes
put (fromIntegral len :: Int64)
putByteString bs
|
