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|
{-# LANGUAGE MagicHash, UnboxedTuples, ScopedTypeVariables #-}
-- |
-- Module : Data.Vector.Storable.Internal
-- Copyright : (c) Roman Leshchinskiy 2009-2010
-- License : BSD-style
--
-- Maintainer : Roman Leshchinskiy <rl@cse.unsw.edu.au>
-- Stability : experimental
-- Portability : non-portable
--
-- Ugly internal utility functions for implementing 'Storable'-based vectors.
--
module Data.Vector.Storable.Internal (
ptrToOffset, offsetToPtr
) where
import Control.Monad.Primitive ( unsafeInlineIO )
import Foreign.Storable
import Foreign.ForeignPtr
import Foreign.Ptr
import Foreign.Marshal.Array ( advancePtr )
import GHC.Base ( quotInt )
distance :: forall a. Storable a => Ptr a -> Ptr a -> Int
{-# INLINE distance #-}
distance p q = (p `minusPtr` q) `quotInt` sizeOf (undefined :: a)
ptrToOffset :: Storable a => ForeignPtr a -> Ptr a -> Int
{-# INLINE ptrToOffset #-}
ptrToOffset fp q = unsafeInlineIO
$ withForeignPtr fp $ \p -> return (distance p q)
offsetToPtr :: Storable a => ForeignPtr a -> Int -> Ptr a
{-# INLINE offsetToPtr #-}
offsetToPtr fp i = unsafeInlineIO
$ withForeignPtr fp $ \p -> return (advancePtr p i)
|
