{-
Split a number into 64-bit blocks
-}
import Data.Bits ((.&.), (.|.), shiftR, shiftL)

-- !
-- Shift operations
(.<<) :: Integer -> Int -> Integer
(.<<) = shiftL

(>>.) :: Integer -> Int -> Integer
(>>.) = shiftR

split_in_u64s :: Integer -> (Integer, Integer, Integer, Integer)
split_in_u64s i = (x3, x2, x1, x0)
  where mask = (1 .<< 64) - 1
        x3   = (i >>. 192) .&. mask
        x2   = (i >>. 128) .&. mask
        x1   = (i >>. 64) .&. mask
        x0   =  i .&. mask

split_ex = split_in_u64s (x*y)
  where x = (2 .<< 64) .|. (2 .<< 32)
        y = (1 .<< 128) - 3

combine_u64s :: (Integer, Integer, Integer, Integer) -> Integer
combine_u64s (x3, x2, x1, x0) = (x3 .<< 192) .|. (x2 .<< 128) .|. (x1 .<< 64) .|. x0

div_split :: Integer -> Integer -> ((Integer, Integer, Integer, Integer), (Integer, Integer))
div_split x y = (split_in_u64s q, (r1, r0))
  where (_, _, r1, r0) = split_in_u64s r
        r = x `mod` y
	q = x `div` y

div_tricky :: ((Integer, Integer, Integer, Integer), (Integer, Integer))
div_tricky = div_split x y
  where x = combine_u64s (2338623232362770208, 2968197749036490859, 9499753957944579205, 10687495549587570827)
	y = (18446744073709551615 .<< 64) .|. 18446744073709551610