content: {-# LANGUAGE Trustworthy #-}
  {-# LANGUAGE NoImplicitPrelude
             , BangPatterns
             , NondecreasingIndentation
             , MagicHash
             , UnboxedTuples
    #-}
  {-# OPTIONS_GHC  -funbox-strict-fields #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  GHC.Internal.IO.Encoding.UTF32
  -- Copyright   :  (c) The University of Glasgow, 2009
  -- License     :  see libraries/base/LICENSE
  --
  -- Maintainer  :  libraries@haskell.org
  -- Stability   :  internal
  -- Portability :  non-portable
  --
  -- UTF-32 Codecs for the IO library
  --
  -- Portions Copyright   : (c) Tom Harper 2008-2009,
  --                        (c) Bryan O'Sullivan 2009,
  --                        (c) Duncan Coutts 2009
  --
  -----------------------------------------------------------------------------
  
  module GHC.Internal.IO.Encoding.UTF32 (
    utf32, mkUTF32,
    utf32_decode,
    utf32_encode,
  
    utf32be, mkUTF32be,
    utf32be_decode,
    utf32be_encode,
  
    utf32le, mkUTF32le,
    utf32le_decode,
    utf32le_encode,
    ) where
  
  import GHC.Internal.Base
  import GHC.Internal.Real
  import GHC.Internal.Num
  -- import GHC.Internal.IO
  import GHC.Internal.IO.Buffer
  import GHC.Internal.IO.Encoding.Failure
  import GHC.Internal.IO.Encoding.Types
  import GHC.Internal.Word
  import GHC.Internal.Data.Bits
  import GHC.Internal.IORef
  
  -- -----------------------------------------------------------------------------
  -- The UTF-32 codec: either UTF-32BE or UTF-32LE with a BOM
  
  utf32  :: TextEncoding
  utf32 = mkUTF32 ErrorOnCodingFailure
  
  -- | @since base-4.4.0.0
  mkUTF32 :: CodingFailureMode -> TextEncoding
  mkUTF32 cfm = TextEncoding { textEncodingName = "UTF-32",
                               mkTextDecoder = utf32_DF cfm,
                               mkTextEncoder = utf32_EF cfm }
  
  utf32_DF :: CodingFailureMode -> IO (TextDecoder (Maybe DecodeBuffer#))
  utf32_DF cfm = do
    seen_bom <- newIORef Nothing
    return (BufferCodec# {
               encode#   = utf32_decode seen_bom,
               recover#  = recoverDecode# cfm,
               close#    = return (),
               getState# = readIORef seen_bom,
               setState# = writeIORef seen_bom
            })
  
  utf32_EF :: CodingFailureMode -> IO (TextEncoder Bool)
  utf32_EF cfm = do
    done_bom <- newIORef False
    return (BufferCodec# {
               encode#   = utf32_encode done_bom,
               recover#  = recoverEncode# cfm,
               close#    = return (),
               getState# = readIORef done_bom,
               setState# = writeIORef done_bom
            })
  
  utf32_encode :: IORef Bool -> EncodeBuffer#
  utf32_encode done_bom input
    output@Buffer{ bufRaw=oraw, bufL=_, bufR=ow, bufSize=os }
    st0
   = do
    let !(# st1, b #) = unIO (readIORef done_bom) st0
    if b then utf32_native_encode input output st1
         else if os - ow < 4
                 then (# st1,OutputUnderflow,input,output #)
                 else do
                 let !(# st2, () #) = unIO (writeIORef done_bom True) st1
                     !(# st3, () #) = unIO (writeWord8Buf oraw ow     bom0) st2
                     !(# st4, () #) = unIO (writeWord8Buf oraw (ow+1) bom1) st3
                     !(# st5, () #) = unIO (writeWord8Buf oraw (ow+2) bom2) st4
                     !(# st6, () #) = unIO (writeWord8Buf oraw (ow+3) bom3) st5
                 utf32_native_encode input output{ bufR = ow+4 } st6
  
  utf32_decode :: IORef (Maybe DecodeBuffer#) -> DecodeBuffer#
  utf32_decode seen_bom
    input@Buffer{  bufRaw=iraw, bufL=ir, bufR=iw,  bufSize=_  }
    output
    st0
   = do
     let !(# st1, mb #) = unIO (readIORef seen_bom) st0
     case mb of
       Just decode -> decode input output st1
       Nothing ->
         if iw - ir < 4 then (# st1,InputUnderflow,input,output #) else do
         let !(# st2, c0 #) = unIO (readWord8Buf iraw  ir   ) st1
             !(# st3, c1 #) = unIO (readWord8Buf iraw (ir+1)) st2
             !(# st4, c2 #) = unIO (readWord8Buf iraw (ir+2)) st3
             !(# st5, c3 #) = unIO (readWord8Buf iraw (ir+3)) st4
         case () of
          _ | c0 == bom0 && c1 == bom1 && c2 == bom2 && c3 == bom3 ->
                 let !(# st6, () #) = unIO (writeIORef seen_bom (Just utf32be_decode)) st5
                 in utf32be_decode input{ bufL= ir+4 } output st6
          _ | c0 == bom3 && c1 == bom2 && c2 == bom1 && c3 == bom0 ->
                 let !(# st6, () #) = unIO (writeIORef seen_bom (Just utf32le_decode)) st5
                 in utf32le_decode input{ bufL= ir+4 } output st6
            | otherwise ->
                 let !(# st6, () #) = unIO (writeIORef seen_bom (Just utf32_native_decode)) st5
                 in utf32_native_decode input output st6
  
  
  bom0, bom1, bom2, bom3 :: Word8
  bom0 = 0
  bom1 = 0
  bom2 = 0xfe
  bom3 = 0xff
  
  -- choose UTF-32BE by default for UTF-32 output
  utf32_native_decode :: DecodeBuffer#
  utf32_native_decode = utf32be_decode
  
  utf32_native_encode :: EncodeBuffer#
  utf32_native_encode = utf32be_encode
  
  -- -----------------------------------------------------------------------------
  -- UTF32LE and UTF32BE
  
  utf32be :: TextEncoding
  utf32be = mkUTF32be ErrorOnCodingFailure
  
  -- | @since base-4.4.0.0
  mkUTF32be :: CodingFailureMode -> TextEncoding
  mkUTF32be cfm = TextEncoding { textEncodingName = "UTF-32BE",
                                 mkTextDecoder = utf32be_DF cfm,
                                 mkTextEncoder = utf32be_EF cfm }
  
  utf32be_DF :: CodingFailureMode -> IO (TextDecoder ())
  utf32be_DF cfm =
    return (BufferCodec# {
               encode#   = utf32be_decode,
               recover#  = recoverDecode# cfm,
               close#    = return (),
               getState# = return (),
               setState# = const $ return ()
            })
  
  utf32be_EF :: CodingFailureMode -> IO (TextEncoder ())
  utf32be_EF cfm =
    return (BufferCodec# {
               encode#   = utf32be_encode,
               recover#  = recoverEncode# cfm,
               close#    = return (),
               getState# = return (),
               setState# = const $ return ()
            })
  
  
  utf32le :: TextEncoding
  utf32le = mkUTF32le ErrorOnCodingFailure
  
  -- | @since base-4.4.0.0
  mkUTF32le :: CodingFailureMode -> TextEncoding
  mkUTF32le cfm = TextEncoding { textEncodingName = "UTF-32LE",
                                 mkTextDecoder = utf32le_DF cfm,
                                 mkTextEncoder = utf32le_EF cfm }
  
  utf32le_DF :: CodingFailureMode -> IO (TextDecoder ())
  utf32le_DF cfm =
    return (BufferCodec# {
               encode#   = utf32le_decode,
               recover#  = recoverDecode# cfm,
               close#    = return (),
               getState# = return (),
               setState# = const $ return ()
            })
  
  utf32le_EF :: CodingFailureMode -> IO (TextEncoder ())
  utf32le_EF cfm =
    return (BufferCodec# {
               encode#   = utf32le_encode,
               recover#  = recoverEncode# cfm,
               close#    = return (),
               getState# = return (),
               setState# = const $ return ()
            })
  
  
  utf32be_decode :: DecodeBuffer#
  utf32be_decode
    input@Buffer{  bufRaw=iraw, bufL=ir0, bufR=iw,  bufSize=_  }
    output@Buffer{ bufRaw=oraw, bufL=_,   bufR=ow0, bufSize=os }
    st
   = let
         loop :: Int -> Int -> DecodingBuffer#
         loop !ir !ow st0
           | ow >= os    = done OutputUnderflow ir ow st0
           | iw - ir < 4 = done InputUnderflow  ir ow st0
           | otherwise = do
                let !(# st1, c0 #) = unIO (readWord8Buf iraw ir    ) st0
                    !(# st2, c1 #) = unIO (readWord8Buf iraw (ir+1)) st1
                    !(# st3, c2 #) = unIO (readWord8Buf iraw (ir+2)) st2
                    !(# st4, c3 #) = unIO (readWord8Buf iraw (ir+3)) st3
                let x1 = chr4 c0 c1 c2 c3
                if not (validate x1) then invalid st4 else do
                let !(# st5, ow' #) = unIO (writeCharBuf oraw ow x1) st4
                loop (ir+4) ow' st5
           where
             invalid :: DecodingBuffer#
             invalid st' = done InvalidSequence ir ow st'
  
         -- lambda-lifted, to avoid thunks being built in the inner-loop:
         {-# NOINLINE done #-}
         done :: CodingProgress -> Int -> Int -> DecodingBuffer#
         done why !ir !ow st' =
           let !ri = if ir == iw then input{ bufL=0, bufR=0 } else input{ bufL=ir }
               !ro = output{ bufR=ow }
           in  (# st', why, ri, ro #)
      in
      loop ir0 ow0 st
  
  utf32le_decode :: DecodeBuffer#
  utf32le_decode
    input@Buffer{  bufRaw=iraw, bufL=ir0, bufR=iw,  bufSize=_  }
    output@Buffer{ bufRaw=oraw, bufL=_,   bufR=ow0, bufSize=os }
    st
   = let
         loop :: Int -> Int -> DecodingBuffer#
         loop !ir !ow st0
           | ow >= os    = done OutputUnderflow ir ow st0
           | iw - ir < 4 = done InputUnderflow  ir ow st0
           | otherwise = do
                let !(# st1, c0 #) = unIO (readWord8Buf iraw ir    ) st0
                    !(# st2, c1 #) = unIO (readWord8Buf iraw (ir+1)) st1
                    !(# st3, c2 #) = unIO (readWord8Buf iraw (ir+2)) st2
                    !(# st4, c3 #) = unIO (readWord8Buf iraw (ir+3)) st3
                let x1 = chr4 c3 c2 c1 c0
                if not (validate x1) then invalid st4 else do
                let !(# st5, ow' #) = unIO (writeCharBuf oraw ow x1) st4
                loop (ir+4) ow' st5
           where
             invalid :: DecodingBuffer#
             invalid st' = done InvalidSequence ir ow st'
  
         -- lambda-lifted, to avoid thunks being built in the inner-loop:
         {-# NOINLINE done #-}
         done :: CodingProgress -> Int -> Int -> DecodingBuffer#
         done why !ir !ow st' =
           let !ri = if ir == iw then input{ bufL=0, bufR=0 } else input{ bufL=ir }
               !ro = output{ bufR=ow }
           in  (# st', why, ri, ro #)
      in
      loop ir0 ow0 st
  
  utf32be_encode :: EncodeBuffer#
  utf32be_encode
    input@Buffer{  bufRaw=iraw, bufL=ir0, bufR=iw,  bufSize=_  }
    output@Buffer{ bufRaw=oraw, bufL=_,   bufR=ow0, bufSize=os }
    st
   = let
        {-# NOINLINE done #-}
        done :: CodingProgress -> Int -> Int -> EncodingBuffer#
        done why !ir !ow st' =
          let !ri = if ir == iw then input{ bufL=0, bufR=0 } else input{ bufL=ir }
              !ro = output{ bufR=ow }
          in  (# st', why, ri, ro #)
        loop :: Int -> Int -> EncodingBuffer#
        loop !ir !ow st0
          | ir >= iw    = done InputUnderflow  ir ow st0
          | os - ow < 4 = done OutputUnderflow ir ow st0
          | otherwise = do
             let !(# st1, (c,ir') #) = unIO (readCharBuf iraw ir) st0
             if isSurrogate c then done InvalidSequence ir ow st1 else do
               let (c0,c1,c2,c3) = ord4 c
                   !(# st2, () #) = unIO (writeWord8Buf oraw ow     c0) st1
                   !(# st3, () #) = unIO (writeWord8Buf oraw (ow+1) c1) st2
                   !(# st4, () #) = unIO (writeWord8Buf oraw (ow+2) c2) st3
                   !(# st5, () #) = unIO (writeWord8Buf oraw (ow+3) c3) st4
               loop ir' (ow+4) st5
      in
      loop ir0 ow0 st
  
  utf32le_encode :: EncodeBuffer#
  utf32le_encode
    input@Buffer{  bufRaw=iraw, bufL=ir0, bufR=iw,  bufSize=_  }
    output@Buffer{ bufRaw=oraw, bufL=_,   bufR=ow0, bufSize=os }
    st
   = let
        done :: CodingProgress -> Int -> Int -> EncodingBuffer#
        done why !ir !ow st' =
          let !ri = if ir == iw then input{ bufL=0, bufR=0 } else input{ bufL=ir }
              !ro = output{ bufR=ow }
          in  (# st', why, ri, ro #)
        loop :: Int -> Int -> EncodingBuffer#
        loop !ir !ow st0
          | ir >= iw    = done InputUnderflow  ir ow st0
          | os - ow < 4 = done OutputUnderflow ir ow st0
          | otherwise = do
             let !(# st1, (c,ir') #) = unIO (readCharBuf iraw ir) st0
             if isSurrogate c then done InvalidSequence ir ow st1 else do
               let (c0,c1,c2,c3) = ord4 c
                   !(# st2, () #) = unIO (writeWord8Buf oraw ow     c3) st1
                   !(# st3, () #) = unIO (writeWord8Buf oraw (ow+1) c2) st2
                   !(# st4, () #) = unIO (writeWord8Buf oraw (ow+2) c1) st3
                   !(# st5, () #) = unIO (writeWord8Buf oraw (ow+3) c0) st4
               loop ir' (ow+4) st5
      in
      loop ir0 ow0 st
  
  chr4 :: Word8 -> Word8 -> Word8 -> Word8 -> Char
  chr4 (W8# x1#) (W8# x2#) (W8# x3#) (W8# x4#) =
      C# (chr# (z1# +# z2# +# z3# +# z4#))
      where
        !y1# = word2Int# (word8ToWord# x1#)
        !y2# = word2Int# (word8ToWord# x2#)
        !y3# = word2Int# (word8ToWord# x3#)
        !y4# = word2Int# (word8ToWord# x4#)
        !z1# = uncheckedIShiftL# y1# 24#
        !z2# = uncheckedIShiftL# y2# 16#
        !z3# = uncheckedIShiftL# y3# 8#
        !z4# = y4#
  {-# INLINE chr4 #-}
  
  ord4 :: Char -> (Word8,Word8,Word8,Word8)
  ord4 c = (fromIntegral (x `shiftR` 24),
            fromIntegral (x `shiftR` 16),
            fromIntegral (x `shiftR` 8),
            fromIntegral x)
    where
      x = ord c
  {-# INLINE ord4 #-}
  
  
  validate    :: Char -> Bool
  validate c = (x1 >= 0x0 && x1 < 0xD800) || (x1 > 0xDFFF && x1 <= 0x10FFFF)
     where x1 = ord c
  {-# INLINE validate #-}
  