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{-# LANGUAGE BangPatterns, MagicHash, UnboxedTuples #-}
{-# OPTIONS_GHC -O2 #-}
-- We always optimise this, otherwise performance of a non-optimised
-- compiler is severely affected
--
-- (c) The University of Glasgow 2002-2006
--
-- Unboxed mutable Ints
module GHC.Data.FastMutInt(
FastMutInt, newFastMutInt,
readFastMutInt, writeFastMutInt
) where
import GHC.Prelude
import Data.Bits
import GHC.Base
newFastMutInt :: IO FastMutInt
readFastMutInt :: FastMutInt -> IO Int
writeFastMutInt :: FastMutInt -> Int -> IO ()
data FastMutInt = FastMutInt (MutableByteArray# RealWorld)
newFastMutInt = IO $ \s ->
case newByteArray# size s of { (# s, arr #) ->
(# s, FastMutInt arr #) }
where !(I# size) = finiteBitSize (0 :: Int) `unsafeShiftR` 3
readFastMutInt (FastMutInt arr) = IO $ \s ->
case readIntArray# arr 0# s of { (# s, i #) ->
(# s, I# i #) }
writeFastMutInt (FastMutInt arr) (I# i) = IO $ \s ->
case writeIntArray# arr 0# i s of { s ->
(# s, () #) }
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