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{-# LANGUAGE MagicHash, UnboxedTuples #-}
-- |
-- Module : Data.Primitive.Addr
-- Copyright : (c) Roman Leshchinskiy 2009-2010
-- License : BSD-style
--
-- Maintainer : Roman Leshchinskiy <rl@cse.unsw.edu.au>
-- Portability : non-portable
--
-- Primitive operations on machine addresses
--
module Data.Primitive.Addr (
Addr(..),
nullAddr, plusAddr, minusAddr, remAddr,
indexOffAddr, readOffAddr, writeOffAddr
) where
import Control.Monad.Primitive
import Data.Primitive.Types
import GHC.Base ( Int(..) )
import GHC.Prim
-- | The null address
nullAddr :: Addr
nullAddr = Addr nullAddr#
infixl 6 `plusAddr`, `minusAddr`
infixl 7 `remAddr`
-- | Offset an address by the given number of bytes
plusAddr :: Addr -> Int -> Addr
plusAddr (Addr a#) (I# i#) = Addr (plusAddr# a# i#)
-- | Distance in bytes between two addresses. The result is only valid if the
-- difference fits in an 'Int'.
minusAddr :: Addr -> Addr -> Int
minusAddr (Addr a#) (Addr b#) = I# (minusAddr# a# b#)
remAddr :: Addr -> Int -> Int
remAddr (Addr a#) (I# i#) = I# (remAddr# a# i#)
-- | Read a value from a memory position given by an address and an offset.
-- The memory block the address refers to must be immutable. The offset is in
-- elements of type @a@ rather than in bytes.
indexOffAddr :: Prim a => Addr -> Int -> a
{-# INLINE indexOffAddr #-}
indexOffAddr (Addr addr#) (I# i#) = indexOffAddr# addr# i#
-- | Read a value from a memory position given by an address and an offset.
-- The offset is in elements of type @a@ rather than in bytes.
readOffAddr :: (Prim a, PrimMonad m) => Addr -> Int -> m a
{-# INLINE readOffAddr #-}
readOffAddr (Addr addr#) (I# i#) = primitive (readOffAddr# addr# i#)
-- | Write a value to a memory position given by an address and an offset.
-- The offset is in elements of type @a@ rather than in bytes.
writeOffAddr :: (Prim a, PrimMonad m) => Addr -> Int -> a -> m ()
{-# INLINE writeOffAddr #-}
writeOffAddr (Addr addr#) (I# i#) x = primitive_ (writeOffAddr# addr# i# x)
|
