1 files changed, 58 insertions, 0 deletions
diff --git a/src/FastMutInt.hs b/src/FastMutInt.hs
new file mode 100644
index 00000000..6b25e360
--- /dev/null
+++ b/src/FastMutInt.hs
@@ -0,0 +1,58 @@
+{-# OPTIONS -cpp #-}
+--
+-- (c) The University of Glasgow 2002
+--
+-- Unboxed mutable Ints
+
+module FastMutInt(
+	FastMutInt, newFastMutInt,
+	readFastMutInt, writeFastMutInt,
+	incFastMutInt, incFastMutIntBy
+  ) where
+
+#include "MachDeps.h"
+
+#ifndef SIZEOF_HSINT
+#define SIZEOF_HSINT  INT_SIZE_IN_BYTES
+#endif
+
+
+import GlaExts
+import PrelIOBase
+
+#if __GLASGOW_HASKELL__ < 411
+newByteArray# = newCharArray#
+#endif
+
+#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, () #) }
+
+incFastMutInt :: FastMutInt -> IO Int	-- Returns original value
+incFastMutInt (FastMutInt arr) = IO $ \s ->
+  case readIntArray# arr 0# s of { (# s, i #) ->
+  case writeIntArray# arr 0# (i +# 1#) s of { s ->
+  (# s, I# i #) } }
+
+incFastMutIntBy :: FastMutInt -> Int -> IO Int	-- Returns original value
+incFastMutIntBy (FastMutInt arr) (I# n) = IO $ \s ->
+  case readIntArray# arr 0# s of { (# s, i #) ->
+  case writeIntArray# arr 0# (i +# n) s of { s ->
+  (# s, I# i #) } }
+#endif
+