1 files changed, 54 insertions, 0 deletions
diff --git a/compiler/utils/FastMutInt.lhs b/compiler/utils/FastMutInt.lhs
new file mode 100644
index 0000000000..b483a1428e
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+++ b/compiler/utils/FastMutInt.lhs
@@ -0,0 +1,54 @@
+{-# OPTIONS -cpp #-}
+--
+-- (c) The University of Glasgow 2002
+--
+-- Unboxed mutable Ints
+
+\begin{code}
+module FastMutInt(
+	FastMutInt, newFastMutInt,
+	readFastMutInt, writeFastMutInt
+  ) where
+
+#include "MachDeps.h"
+
+#ifndef SIZEOF_HSINT
+#define SIZEOF_HSINT  INT_SIZE_IN_BYTES
+#endif
+
+
+#if __GLASGOW_HASKELL__ < 503
+import GlaExts
+import PrelIOBase
+#else
+import GHC.Base
+import GHC.IOBase
+#endif
+
+#if __GLASGOW_HASKELL__ < 411
+newByteArray# = newCharArray#
+#endif
+\end{code}
+
+\begin{code}
+#ifdef __GLASGOW_HASKELL__
+data FastMutInt = FastMutInt (MutableByteArray# RealWorld)
+
+newFastMutInt :: IO FastMutInt
+newFastMutInt = IO $ \s ->
+  case newByteArray# size s of { (# s, arr #) ->
+  (# s, FastMutInt arr #) }
+  where I# size = SIZEOF_HSINT
+
+readFastMutInt :: FastMutInt -> IO Int
+readFastMutInt (FastMutInt arr) = IO $ \s ->
+  case readIntArray# arr 0# s of { (# s, i #) ->
+  (# s, I# i #) }
+
+writeFastMutInt :: FastMutInt -> Int -> IO ()
+writeFastMutInt (FastMutInt arr) (I# i) = IO $ \s ->
+  case writeIntArray# arr 0# i s of { s ->
+  (# s, () #) }
+\end{code}
+#endif
+