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bundled/Crypto/Internal/CompatPrim.hs

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+-- |
+-- Module      : Crypto.Internal.CompatPrim
+-- License     : BSD-style
+-- Maintainer  : Vincent Hanquez <vincent@snarc.org>
+-- Stability   : stable
+-- Portability : Compat
+--
+-- This module tries 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 #-}
+{-# LANGUAGE UnboxedTuples #-}
+module Crypto.Internal.CompatPrim
+    ( be32Prim
+    , le32Prim
+    , byteswap32Prim
+    , booleanPrim
+    , convert4To32
+    ) where
+
+#if !defined(ARCH_IS_LITTLE_ENDIAN) && !defined(ARCH_IS_BIG_ENDIAN)
+import Data.Memory.Endian (getSystemEndianness, Endianness(..))
+#endif
+
+#if __GLASGOW_HASKELL__ >= 902
+import GHC.Prim
+#else
+import GHC.Prim hiding (Word32#)
+type Word32# = Word#
+#endif
+
+-- | Byteswap Word# to or from Big Endian
+--
+-- On a big endian machine, this function is a nop.
+be32Prim :: Word32# -> Word32#
+#ifdef ARCH_IS_LITTLE_ENDIAN
+be32Prim = byteswap32Prim
+#elif defined(ARCH_IS_BIG_ENDIAN)
+be32Prim = id
+#else
+be32Prim w = if getSystemEndianness == LittleEndian then byteswap32Prim w else w
+#endif
+
+-- | Byteswap Word# to or from Little Endian
+--
+-- On a little endian machine, this function is a nop.
+le32Prim :: Word32# -> Word32#
+#ifdef ARCH_IS_LITTLE_ENDIAN
+le32Prim w = w
+#elif defined(ARCH_IS_BIG_ENDIAN)
+le32Prim = byteswap32Prim
+#else
+le32Prim w = if getSystemEndianness == LittleEndian then w else byteswap32Prim w
+#endif
+
+-- | Simple compatibility for byteswap the lower 32 bits of a Word#
+-- at the primitive level
+byteswap32Prim :: Word32# -> Word32#
+#if __GLASGOW_HASKELL__ >= 902
+byteswap32Prim w = wordToWord32# (byteSwap32# (word32ToWord# w))
+#else
+byteswap32Prim w = byteSwap32# w
+#endif
+
+-- | Combine 4 word8 [a,b,c,d] to a word32 representing [a,b,c,d]
+convert4To32 :: Word# -> Word# -> Word# -> Word#
+             -> Word#
+convert4To32 a b c d = or# (or# c1 c2) (or# c3 c4)
+  where
+#ifdef ARCH_IS_LITTLE_ENDIAN
+        !c1 = uncheckedShiftL# a 24#
+        !c2 = uncheckedShiftL# b 16#
+        !c3 = uncheckedShiftL# c 8#
+        !c4 = d
+#elif defined(ARCH_IS_BIG_ENDIAN)
+        !c1 = uncheckedShiftL# d 24#
+        !c2 = uncheckedShiftL# c 16#
+        !c3 = uncheckedShiftL# b 8#
+        !c4 = a
+#else
+        !c1
+            | getSystemEndianness == LittleEndian = uncheckedShiftL# a 24#
+            | otherwise                           = uncheckedShiftL# d 24#
+        !c2
+            | getSystemEndianness == LittleEndian = uncheckedShiftL# b 16#
+            | otherwise                           = uncheckedShiftL# c 16#
+        !c3
+            | getSystemEndianness == LittleEndian = uncheckedShiftL# c 8#
+            | otherwise                           = uncheckedShiftL# b 8#
+        !c4
+            | getSystemEndianness == LittleEndian = d
+            | otherwise                           = a
+#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