{-# LANGUAGE MagicHash #-}

module Data.Text.Utf16 where

import GHC.Exts
import GHC.Word

import Data.Word

chr2 :: Word16 -> Word16 -> Char
chr2 (W16# a#) (W16# b#) = C# (chr# (upper# +# lower# +# 0x10000#))
    where
      x# = word2Int# a#
      y# = word2Int# b#
      upper# = uncheckedIShiftL# (x# -# 0xD800#) 10#
      lower# = y# -# 0xDC00#
{-# INLINE chr2 #-}

validate1    :: Word16 -> Bool
validate1 x1 = (x1 >= 0 && x1 < 0xD800) || (x1 > 0xDFFF && x1 < 0x10000)

validate2       ::  Word16 -> Word16 -> Bool
validate2 x1 x2 = (x1 >= 0xD800 && x1 <= 0xDBFF) &&
                  (x2 >= 0xDC00 && x2 <= 0xDFFF)