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bundled/Data/Memory/Internal/CompatPrim.hs

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+-- |
+-- Module      : Data.Memory.Internal.CompatPrim
+-- License     : BSD-style
+-- Maintainer  : Vincent Hanquez <vincent@snarc.org>
+-- Stability   : stable
+-- Portability : Compat
+--
+-- This module try to keep all the difference between versions of ghc primitive
+-- or other needed packages, so that modules don't need to use CPP.
+--
+-- Note that MagicHash and CPP conflicts in places, making it "more interesting"
+-- to write compat code for primitives
+--
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE MagicHash #-}
+module Data.Memory.Internal.CompatPrim
+    ( be32Prim
+    , le32Prim
+    , byteswap32Prim
+    , booleanPrim
+    ) where
+
+import GHC.Prim
+
+-- | byteswap Word# to or from Big Endian
+--
+-- on a big endian machine, this function is a nop.
+be32Prim :: Word# -> Word#
+#ifdef ARCH_IS_LITTLE_ENDIAN
+be32Prim = byteswap32Prim
+#else
+be32Prim w = w
+#endif
+
+-- | byteswap Word# to or from Little Endian
+--
+-- on a little endian machine, this function is a nop.
+le32Prim :: Word# -> Word#
+#ifdef ARCH_IS_LITTLE_ENDIAN
+le32Prim w = w
+#else
+le32Prim = byteswap32Prim
+#endif
+
+-- | Simple compatibility for byteswap the lower 32 bits of a Word#
+-- at the primitive level
+byteswap32Prim :: Word# -> Word#
+#if __GLASGOW_HASKELL__ >= 708
+byteswap32Prim w = byteSwap32# w
+#else
+byteswap32Prim w =
+    let !a =       uncheckedShiftL# w 24#
+        !b = and# (uncheckedShiftL# w 8#) 0x00ff0000##
+        !c = and# (uncheckedShiftRL# w 8#) 0x0000ff00##
+        !d = and# (uncheckedShiftRL# w 24#) 0x000000ff##
+     in or# a (or# b (or# c d))
+#endif
+
+-- | Simple wrapper to handle pre 7.8 and future, where
+-- most comparaison functions don't returns a boolean
+-- anymore.
+#if __GLASGOW_HASKELL__ >= 708
+booleanPrim :: Int# -> Bool
+booleanPrim v = tagToEnum# v
+#else
+booleanPrim :: Bool -> Bool
+booleanPrim b = b
+#endif
+{-# INLINE booleanPrim #-}