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|
-----------------------------------------------------------------------------
-- |
-- Module : Data.Array.Storable
-- 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
--
-- A storable array is an IO-mutable array which stores its
-- contents in a contiguous memory block living in the C
-- heap. Elements are stored according to the class Storable.
-- You can obtain the pointer to the array contents to manipulate
-- elements from languages like C.
--
-- It's similar to IOUArray but slower. Its advantage is that
-- it's compatible with C.
--
-----------------------------------------------------------------------------
module Data.Array.Storable (
-- Array type:
StorableArray, -- data StorableArray index element
-- -- index type must be in class Ix
-- -- element type must be in class Storable
-- Module MArray provides the interface of storable arrays.
-- They are instances of class MArray (with IO monad).
module Data.Array.MArray,
-- The pointer to the array contents is obtained by withStorableArray.
-- The idea is similar to ForeignPtr (used internally here). The
-- pointer should be used only during execution of the IO action
-- retured by the function passed as argument to withStorableArray:
withStorableArray, -- :: StorableArray i e -> (Ptr e -> IO a) -> IO a
-- If you want to use it afterwards, ensure that you
-- touchStorableArray after the last use of the pointer,
-- so the array is not freed too early:
touchStorableArray -- :: StorableArray i e -> IO ()
)
where
import Prelude
import Data.Array.Base
import Data.Array.MArray
import Foreign hiding (newArray)
data StorableArray i e = StorableArray !i !i !(ForeignPtr e)
instance HasBounds StorableArray where
bounds (StorableArray l u _) = (l,u)
instance Storable e => MArray StorableArray e IO where
newArray (l,u) init = do
fp <- mallocForeignPtrArray size
withForeignPtr fp $ \a ->
sequence_ [pokeElemOff a i init | i <- [0..size-1]]
return (StorableArray l u fp)
where
size = rangeSize (l,u)
newArray_ (l,u) = do
fp <- mallocForeignPtrArray (rangeSize (l,u))
return (StorableArray l u fp)
unsafeRead (StorableArray _ _ fp) i =
withForeignPtr fp $ \a -> peekElemOff a i
unsafeWrite (StorableArray _ _ fp) i e =
withForeignPtr fp $ \a -> pokeElemOff a i e
withStorableArray :: StorableArray i e -> (Ptr e -> IO a) -> IO a
withStorableArray (StorableArray _ _ fp) f = withForeignPtr fp f
touchStorableArray :: StorableArray i e -> IO ()
touchStorableArray (StorableArray _ _ fp) = touchForeignPtr fp
|
