{-# LANGUAGE CPP               #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TypeFamilies      #-}

module HaskellWorks.Data.Simd.Comparison.Avx2 where

import Control.Monad
import Data.Monoid   ((<>))
import Data.Word

import qualified Data.ByteString                         as BS
import qualified Data.Vector.Storable                    as DVS
import qualified Foreign.ForeignPtr                      as F
import qualified Foreign.Marshal.Unsafe                  as F
import qualified Foreign.Ptr                             as F
import qualified HaskellWorks.Data.ByteString            as BS
import qualified HaskellWorks.Data.Simd.Internal.Foreign as F
import qualified HaskellWorks.Data.Vector.AsVector8      as V
import qualified HaskellWorks.Data.Vector.Storable       as DVS

{-# ANN module ("HLint: ignore Redundant do"        :: String) #-}

class CmpEqWord8s a where
  type Target a
  cmpEqWord8s :: Word8 -> a -> Target a

instance CmpEqWord8s (DVS.Vector Word8) where
  type Target (DVS.Vector Word8) = DVS.Vector Word8
  cmpEqWord8s w8 v = F.unsafeLocalState $ do
    tgtFptr <- F.mallocForeignPtrBytes bufLen
    F.withForeignPtr srcFptr $ \srcPtr -> do
      F.withForeignPtr tgtFptr $ \tgtPtr -> do
        _ <- F.avx2Cmpeq8 (fromIntegral w8) (F.castPtr tgtPtr) (fromIntegral w64sLen) (srcPtr `F.plusPtr` srcOffset)
        when (disalignment /= 0) $ do
          let ending = DVS.padded ((DVS.length v + 63) `div` 64)  (DVS.drop alignment v)
          let (endFptr, _, _) = DVS.unsafeToForeignPtr ending
          F.withForeignPtr endFptr $ \endPtr -> do
            void $ F.avx2Cmpeq8 (fromIntegral w8) (tgtPtr `F.plusPtr` (w64sLen * 64)) (fromIntegral w64sLen) (F.castPtr endPtr)

        return $ DVS.unsafeFromForeignPtr tgtFptr 0 tgtLen
    where (srcFptr, srcOffset, srcLen) = DVS.unsafeToForeignPtr v
          bufLen        = (srcLen + 63) `div` 8
          tgtLen        = (srcLen + 7) `div` 8
          w64sLen       = srcLen `div` 64
          alignment     = w64sLen * 64
          disalignment  = srcLen - alignment
  {-# INLINE cmpEqWord8s #-}

instance CmpEqWord8s (DVS.Vector Word64) where
  type Target (DVS.Vector Word64) = DVS.Vector Word64
  cmpEqWord8s w8 v = case DVS.unsafeCast v :: DVS.Vector Word8 of
    u -> case DVS.unsafeToForeignPtr u of
      (srcFptr, srcOffset, srcLength) -> if disalignment == 0
        then F.unsafeLocalState $ do
          targetFptr <- F.mallocForeignPtrBytes srcLength
          F.withForeignPtr srcFptr $ \srcPtr -> do
            F.withForeignPtr targetFptr $ \targetPtr -> do
              _ <- F.avx2Cmpeq8
                (fromIntegral w8)
                (F.castPtr targetPtr)
                (fromIntegral w64sLen)
                (F.castPtr srcPtr `F.plusPtr` srcOffset)
              return $ DVS.unsafeFromForeignPtr targetFptr 0 w64sLen
        else error $ "Unaligned byte string: " <> show disalignment
        where w64sLen       = srcLength `div` 64
              disalignment  = srcLength - w64sLen * 64
  {-# INLINE cmpEqWord8s #-}

instance CmpEqWord8s [DVS.Vector Word64] where
  type Target [DVS.Vector Word64] = [DVS.Vector Word64]
  cmpEqWord8s w8 vs = cmpEqWord8s w8 <$> vs
  {-# INLINE cmpEqWord8s #-}

instance CmpEqWord8s [DVS.Vector Word8] where
  type Target [DVS.Vector Word8] = [DVS.Vector Word8]
  cmpEqWord8s w8 vs = cmpEqWord8s w8 <$> vs
  {-# INLINE cmpEqWord8s #-}

instance CmpEqWord8s [BS.ByteString] where
  type Target [BS.ByteString] = [BS.ByteString]
  cmpEqWord8s w8 vs = BS.toByteString . cmpEqWord8s w8 . V.asVector8 <$> vs
  {-# INLINE cmpEqWord8s #-}

-- instance CmpEqWord8s CS.ChunkString where
--   type Target CS.ChunkString = CS.ChunkString
--   cmpEqWord8s w8 = CS.toChunkString . cmpEqWord8s w8 . BS.toByteStrings
--   {-# INLINE cmpEqWord8s #-}