    {-# LANGUAGE MagicHash, Trustworthy, UnliftedFFITypes #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Data.Array.IO
    -- Copyright   :  (c) The University of Glasgow 2001
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  experimental
    -- Portability :  non-portable (uses Data.Array.MArray)
    --
    -- Mutable boxed and unboxed arrays in the IO monad.
    --
    -----------------------------------------------------------------------------

    module Data.Array.IO (
        -- * @IO@ arrays with boxed elements
        IOArray,             -- instance of: Eq, Typeable

        -- * @IO@ arrays with unboxed elements
        IOUArray,            -- instance of: Eq, Typeable

        -- * Overloaded mutable array interface
        module Data.Array.MArray,

        -- * Doing I\/O with @IOUArray@s
        hGetArray,           -- :: Handle -> IOUArray Int Word8 -> Int -> IO Int
        hPutArray,           -- :: Handle -> IOUArray Int Word8 -> Int -> IO ()
      ) where

    import Data.Array.Base
    import Data.Array.IO.Internals
    import Data.Array.MArray
    import System.IO.Error

    import Foreign
    import Foreign.C

    import GHC.Exts  (MutableByteArray#, RealWorld)
    import GHC.IO.Handle
    import GHC.IO.Exception

    -- ---------------------------------------------------------------------------
    -- hGetArray

    -- | Reads a number of 'Word8's from the specified 'Handle' directly
    -- into an array.
    hGetArray
            :: Handle               -- ^ Handle to read from
            -> IOUArray Int Word8   -- ^ Array in which to place the values
            -> Int                  -- ^ Number of 'Word8's to read
            -> IO Int
                    -- ^ Returns: the number of 'Word8's actually
                    -- read, which might be smaller than the number requested
                    -- if the end of file was reached.

    hGetArray :: Handle -> IOUArray Int Word8 -> Int -> IO Int
    hGetArray Handle
    handle (IOUArray (STUArray Int
    _l Int
    _u Int
    n MutableByteArray# RealWorld
    ptr)) Int
    count
      | Int
    count Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    0              = Int -> IO Int
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return Int
    0
      | Int
    count Int -> Int -> Bool
    forall a. Ord a => a -> a -> Bool
    < Int
    0 Bool -> Bool -> Bool
    || Int
    count Int -> Int -> Bool
    forall a. Ord a => a -> a -> Bool
    > Int
    n  = Handle -> String -> Int -> IO Int
    forall a. Handle -> String -> Int -> IO a
    illegalBufferSize Handle
    handle String
    "hGetArray" Int
    count
      | Bool
    otherwise = do
          -- we would like to read directly into the buffer, but we can't
          -- be sure that the MutableByteArray# is pinned, so we have to
          -- allocate a separate area of memory and copy.
          Int -> (Ptr Any -> IO Int) -> IO Int
    forall a b. Int -> (Ptr a -> IO b) -> IO b
    allocaBytes Int
    count ((Ptr Any -> IO Int) -> IO Int) -> (Ptr Any -> IO Int) -> IO Int
    forall a b. (a -> b) -> a -> b
    $ \Ptr Any
    p -> do
            r <- Handle -> Ptr Any -> Int -> IO Int
    forall a. Handle -> Ptr a -> Int -> IO Int
    hGetBuf Handle
    handle Ptr Any
    p Int
    count
            _ <- memcpy_ba_ptr ptr p (fromIntegral r)
            return r

    foreign import ccall unsafe "memcpy"
       memcpy_ba_ptr :: MutableByteArray# RealWorld -> Ptr a -> CSize -> IO (Ptr ())

    -- ---------------------------------------------------------------------------
    -- hPutArray

    -- | Writes an array of 'Word8' to the specified 'Handle'.
    hPutArray
            :: Handle                       -- ^ Handle to write to
            -> IOUArray Int Word8           -- ^ Array to write from
            -> Int                          -- ^ Number of 'Word8's to write
            -> IO ()

    hPutArray :: Handle -> IOUArray Int Word8 -> Int -> IO ()
    hPutArray Handle
    handle (IOUArray (STUArray Int
    _l Int
    _u Int
    n MutableByteArray# RealWorld
    raw)) Int
    count
      | Int
    count Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    0              = () -> IO ()
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return ()
      | Int
    count Int -> Int -> Bool
    forall a. Ord a => a -> a -> Bool
    < Int
    0 Bool -> Bool -> Bool
    || Int
    count Int -> Int -> Bool
    forall a. Ord a => a -> a -> Bool
    > Int
    n  = Handle -> String -> Int -> IO ()
    forall a. Handle -> String -> Int -> IO a
    illegalBufferSize Handle
    handle String
    "hPutArray" Int
    count
      | Bool
    otherwise = do
          -- as in hGetArray, we would like to use the array directly, but
          -- we can't be sure that the MutableByteArray# is pinned.
         Int -> (Ptr Any -> IO ()) -> IO ()
    forall a b. Int -> (Ptr a -> IO b) -> IO b
    allocaBytes Int
    count ((Ptr Any -> IO ()) -> IO ()) -> (Ptr Any -> IO ()) -> IO ()
    forall a b. (a -> b) -> a -> b
    $ \Ptr Any
    p -> do
           _ <- Ptr Any -> MutableByteArray# RealWorld -> CSize -> IO (Ptr ())
    forall a.
    Ptr a -> MutableByteArray# RealWorld -> CSize -> IO (Ptr ())
    memcpy_ptr_ba Ptr Any
    p MutableByteArray# RealWorld
    raw (Int -> CSize
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral Int
    count)
           hPutBuf handle p count

    foreign import ccall unsafe "memcpy"
       memcpy_ptr_ba :: Ptr a -> MutableByteArray# RealWorld -> CSize -> IO (Ptr ())

    -- ---------------------------------------------------------------------------
    -- Internal Utils

    illegalBufferSize :: Handle -> String -> Int -> IO a
    illegalBufferSize :: forall a. Handle -> String -> Int -> IO a
    illegalBufferSize Handle
    handle String
    fn Int
    sz =
            IOException -> IO a
    forall a. HasCallStack => IOException -> IO a
    ioException (IOException -> String -> IOException
    ioeSetErrorString
                         (IOErrorType
    -> String -> Maybe Handle -> Maybe String -> IOException
    mkIOError IOErrorType
    InvalidArgument String
    fn (Handle -> Maybe Handle
    forall a. a -> Maybe a
    Just Handle
    handle) Maybe String
    forall a. Maybe a
    Nothing)
                         (String
    "illegal buffer size " String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ Int -> Int -> String -> String
    forall a. Show a => Int -> a -> String -> String
    showsPrec Int
    9 (Int
    sz::Int) []))