{-# LANGUAGE MagicHash           #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Data.BA where

import GHC.Exts
import Control.Monad.Primitive
import Data.Primitive.Types
import Data.Primitive.ByteArray

-- | WARNING: Unsafe to use this on packed C structs.
writeAtByte :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -> Int -> a -> m ()
writeAtByte buf offset a = writeByteArray buf (div offset $ I# (sizeOf# a)) a
{-# INLINE writeAtByte #-}

readAtByte :: forall a m. (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -> Int -> m a
readAtByte buf offset = readByteArray buf (div offset $ I# (sizeOf# (undefined :: a)))
{-# INLINE readAtByte #-}