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Z%
% (c) The University of Glasgow, 2000-2006
%
\section{Fast functions}
\begin{code}
module FastFunctions (
unsafeChr, inlinePerformIO, unsafeDupableInterleaveIO,
indexWord8OffFastPtr,
indexWord8OffFastPtrAsFastChar, indexWord8OffFastPtrAsFastInt,
global, Global
) where
#include "HsVersions.h"
import FastTypes
import Data.IORef
import System.IO.Unsafe
#if defined(__GLASGOW_HASKELL__)
import GHC.Exts
import GHC.Word
import GHC.Base (unsafeChr)
import GHC.IO (IO(..), unsafeDupableInterleaveIO)
-- Just like unsafePerformIO, but we inline it.
{-# INLINE inlinePerformIO #-}
inlinePerformIO :: IO a -> a
inlinePerformIO (IO m) = case m realWorld# of (# _, r #) -> r
indexWord8OffFastPtr p i = W8# (indexWord8OffAddr# p i)
indexWord8OffFastPtrAsFastChar p i = indexCharOffAddr# p i
indexWord8OffFastPtrAsFastInt p i = word2Int# (indexWord8OffAddr# p i)
-- or ord# (indexCharOffAddr# p i)
#else /* ! __GLASGOW_HASKELL__ */
import Foreign.Ptr
import Data.Word
-- hey, no harm inlining it, :-P
{-# INLINE inlinePerformIO #-}
inlinePerformIO :: IO a -> a
inlinePerformIO = unsafePerformIO
unsafeDupableInterleaveIO :: IO a -> IO a
unsafeDupableInterleaveIO = unsafeInterleaveIO
-- truly, these functions are unsafe: they assume
-- a certain immutability of the pointer's target area.
indexWord8OffFastPtr p i = inlinePerformIO (peekByteOff p n) :: Word8
indexWord8OffFastPtrAsFastInt p i =
iUnbox (fromIntegral (inlinePerformIO (peekByteOff p n) :: Word8))
indexWord8OffFastPtrAsFastChar p i =
fastChr (iUnbox (fromIntegral (inlinePerformIO (peekByteOff p n) :: Word8)))
#endif /* ! __GLASGOW_HASKELL__ */
--just so we can refer to the type clearly in a macro
type Global a = IORef a
global :: a -> Global a
global a = unsafePerformIO (newIORef a)
indexWord8OffFastPtr :: FastPtr Word8 -> FastInt -> Word8
indexWord8OffFastPtrAsFastChar :: FastPtr Word8 -> FastInt -> FastChar
indexWord8OffFastPtrAsFastInt :: FastPtr Word8 -> FastInt -> FastInt
\end{code}
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