{-# LANGUAGE UnicodeSyntax, CPP #-}

module Data.Endian.Internal (
    EndianSensitive(swapEndian)
  ) where

import Data.Int
import Data.Word
import Data.Bits
import Foreign.C.Types
import Foreign.Ptr (IntPtr, WordPtr)
import System.Posix.Types (CSsize)

#include <HsBaseConfig.h>

-- | Raw, endian-sensitive data
class EndianSensitive α where
  -- | Invert the the endianness of the argument
  swapEndian ∷ α → α

instance EndianSensitive α ⇒ EndianSensitive [α] where
  swapEndian = map swapEndian

instance EndianSensitive Word16 where
  swapEndian = (`rotateR` 8)
  {-# INLINE swapEndian #-}

instance EndianSensitive Word32 where
  swapEndian x  =  (x                  `shiftR` 24)
               .|. ((x .&. 0x00FF0000) `shiftR` 8)
               .|. ((x .&. 0x0000FF00) `shiftL` 8)
               .|. (x                  `shiftL` 24)
  {-# INLINE swapEndian #-}

instance EndianSensitive Word64 where
  swapEndian x
#if WORD_SIZE_IN_BITS == 32
    =  fromIntegral (swapEndian hi)
   .|. (fromIntegral (swapEndian lo) `shiftL` 32)
      where lo, hi ∷ Word32
            lo = fromIntegral x
            hi = fromIntegral (x `shiftR` 32)
#else
    =  (x                          `shiftR` 56)
   .|. ((x .&. 0x00FF000000000000) `shiftR` 40)
   .|. ((x .&. 0x0000FF0000000000) `shiftR` 24)
   .|. ((x .&. 0x000000FF00000000) `shiftR` 8)
   .|. ((x .&. 0x00000000FF000000) `shiftL` 8)
   .|. ((x .&. 0x0000000000FF0000) `shiftL` 24)
   .|. ((x .&. 0x000000000000FF00) `shiftL` 40)
   .|. (x                          `shiftL` 56)
#endif
  {-# INLINE swapEndian #-}

instance EndianSensitive Int16 where
  swapEndian = (`rotateR` 8)
  {-# INLINE swapEndian #-}

instance EndianSensitive Int32 where
  swapEndian = fromIntegral . (swapEndian ∷ Word32 → Word32) . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive Int64 where
  swapEndian = fromIntegral . (swapEndian ∷ Word64 → Word64) . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CShort where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_SHORT → HTYPE_SHORT)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CUShort where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UNSIGNED_SHORT → HTYPE_UNSIGNED_SHORT)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CInt where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_INT → HTYPE_INT)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CUInt where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UNSIGNED_INT → HTYPE_UNSIGNED_INT)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CLong where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_LONG → HTYPE_LONG)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CULong where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UNSIGNED_LONG → HTYPE_UNSIGNED_LONG)
             . fromIntegral
  {-# INLINE swapEndian #-}

#ifdef HAVE_LONG_LONG
instance EndianSensitive CLLong where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_LONG_LONG → HTYPE_LONG_LONG)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CULLong where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UNSIGNED_LONG_LONG
                           → HTYPE_UNSIGNED_LONG_LONG)
             . fromIntegral
  {-# INLINE swapEndian #-}
#endif

instance EndianSensitive CSize where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_SIZE_T → HTYPE_SIZE_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CSsize where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_SSIZE_T → HTYPE_SSIZE_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CUIntPtr where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UINTPTR_T → HTYPE_UINTPTR_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CIntPtr where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_INTPTR_T → HTYPE_INTPTR_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CPtrdiff where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_PTRDIFF_T → HTYPE_PTRDIFF_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CUIntMax where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UINTMAX_T → HTYPE_UINTMAX_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive CIntMax where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_INTMAX_T → HTYPE_INTMAX_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive WordPtr where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_UINTPTR_T → HTYPE_UINTPTR_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

instance EndianSensitive IntPtr where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_INTPTR_T → HTYPE_INTPTR_T)
             . fromIntegral
  {-# INLINE swapEndian #-}

#ifdef HTYPE_WCHAR_T
instance EndianSensitive CWchar where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_WCHAR_T → HTYPE_WCHAR_T)
             . fromIntegral
  {-# INLINE swapEndian #-}
#endif

#ifdef HTYPE_WINT_T
instance EndianSensitive CWint where
  swapEndian = fromIntegral
             . (swapEndian ∷ HTYPE_WINT_T → HTYPE_WINT_T)
             . fromIntegral
  {-# INLINE swapEndian #-}
#endif