add Endian module

Crypto/Internal/Endian.hs

@@ -0,0 +1,41 @@
+-- |
+-- Module      : Crypto.Internal.Endian
+-- License     : BSD-style
+-- Maintainer  : Vincent Hanquez <vincent@snarc.org>
+-- Stability   : stable
+-- Portability : good
+--
+{-# LANGUAGE CPP #-}
+module Crypto.Internal.Endian
+    ( fromBE64, toBE64
+    , fromLE64, toLE64
+    ) where
+
+import Crypto.Internal.Compat (byteSwap64)
+import Data.Word (Word64)
+
+#ifndef ARCH_IS_LITTLE_ENDIAN
+fromLE64 :: Word64 -> Word64
+fromLE64 = id
+
+toLE64 :: Word64 -> Word64
+toLE64 = id
+
+fromBE64 :: Word64 -> Word64
+fromBE64 = byteSwap64
+
+toBE64 :: Word64 -> Word64
+toBE64 = byteSwap64
+#else
+fromLE64 :: Word64 -> Word64
+fromLE64 = byteSwap64
+
+toLE64 :: Word64 -> Word64
+toLE64 = byteSwap64
+
+fromBE64 :: Word64 -> Word64
+fromBE64 = id
+
+toBE64 :: Word64 -> Word64
+toBE64 = id
+#endif