[Internal] properly handle big endian architecture

add a CompatPrim module to handle all the primitive compatibility needed,
instead of putting all in Compat.

Crypto/Internal/CompatPrim.hs

@@ -0,0 +1,40 @@
+-- |
+-- Module      : Crypto.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 MagicHash #-}
+module Crypto.Internal.CompatPrim
+    ( be32Prim
+    , byteswap32Prim
+    ) where
+
+import GHC.Prim
+
+#ifdef ARCH_IS_LITTLE_ENDIAN
+be32Prim :: Word# -> Word#
+be32Prim = byteswap32Prim
+#else
+be32Prim w = w
+#endif
+
+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

Crypto/Internal/WordArray.hs

@@ -35,6 +35,7 @@ module Crypto.Internal.WordArray
 import Data.Word
 import Data.Bits (xor)
 import Crypto.Internal.Compat
+import Crypto.Internal.CompatPrim
 import GHC.Prim
 import GHC.Types
 import GHC.Word
@@ -102,9 +103,8 @@ mutableArray32FromAddrBE (I# n) a = IO $ \s ->
         loop i st mb
             | booleanPrim (i ==# n) = (# st, MutableArray32 mb #)
             | otherwise             =
-                let st' = writeWord32Array# mb i (be (indexWord32OffAddr# a i)) st
+                let st' = writeWord32Array# mb i (be32Prim (indexWord32OffAddr# a i)) st
                  in loop (i +# 1#) st' mb
-        be = byteSwap32#
 
 mutableArray32Freeze :: MutableArray32 -> IO Array32
 mutableArray32Freeze (MutableArray32 mb) = IO $ \st ->

cryptonite.cabal

@@ -126,6 +126,7 @@ Library
                      Crypto.PubKey.Internal
                      Crypto.PubKey.ElGamal
                      Crypto.Internal.Compat
+                     Crypto.Internal.CompatPrim
                      Crypto.Internal.Bytes
                      Crypto.Internal.Endian
                      Crypto.Internal.Imports