content: {-# LANGUAGE BangPatterns #-}
  {-# LANGUAGE MagicHash #-}
  {-# LANGUAGE UnboxedTuples #-}
  
  module Main where
  
  import Data.Int
  import Data.List
  import GHC.Prim
  import GHC.Exts
  
  main :: IO ()
  main = do
  
      --
      -- Check if passing Int8# on the stack works (16 parameter function will
      -- need to use stack for some of the them)
      --
      let input =
              [ ( (a + 0), (a + 1), (a + 2), (a + 3),
                  (a + 4), (a + 5), (a + 6), (a + 7),
                  (a + 8), (a + 9), (a + 10), (a + 11),
                  (a + 12), (a + 13), (a + 14), (a + 15) )
              | a <- allInt8
              ]
          expected =
              [ toInt8
                    (a + b + c + d + e + f + g + h +
                     i + j + k + l + m + n + o + p)
              | (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) <- input
              ]
          actual =
              [ addMany a b c d e f g h i j k l m n o p
              | (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) <- input
              ]
      checkResults "passing Int8# on the stack" input expected actual
  
      --
      -- negateInt8#
      --
      let input = allInt8
          expected = [ toInt8 (negate a) | a <- input ]
          actual = [ apply1 negateInt8# a | a <- input ]
      checkResults "negateInt8#" input expected actual
  
      --
      -- plusInt8#
      --
      let input = [ (a, b) | a <- allInt8, b <- allInt8 ]
          expected = [ toInt8 (a + b) | (a, b) <- input ]
          actual = [ apply2 plusInt8# a b | (a, b) <- input ]
      checkResults "plusInt8#" input expected actual
  
      --
      -- subInt8#
      --
      let input = [ (a, b) | a <- allInt8, b <- allInt8 ]
          expected = [ toInt8 (a - b) | (a, b) <- input ]
          actual = [ apply2 subInt8# a b | (a, b) <- input ]
      checkResults "subInt8#" input expected actual
  
      --
      -- timesInt8#
      --
      let input = [ (a, b) | a <- allInt8, b <- allInt8 ]
          expected = [ toInt8 (a * b) | (a, b) <- input ]
          actual = [ apply2 timesInt8# a b | (a, b) <- input ]
      checkResults "timesInt8#" input expected actual
  
      --
      -- remInt8#
      --
      let input =
              [ (a, b) | a <- allInt8, b <- allInt8
              -- Don't divide by 0 or cause overflow
              , b /= 0, not (a == -128 && b == -1)
              ]
          expected = [ toInt8 (a `rem` b) | (a, b) <- input ]
          actual = [ apply2 remInt8# a b | (a, b) <- input ]
      checkResults "remInt8#" input expected actual
  
      --
      -- quotInt8#
      --
      let input =
              [ (a, b) | a <- allInt8, b <- allInt8
              , b /= 0, not (a == -128 && b == -1)
              ]
          expected = [ toInt8 (a `quot` b) | (a, b) <- input ]
          actual = [ apply2 quotInt8# a b | (a, b) <- input ]
      checkResults "quotInt8#" input expected actual
  
      --
      -- quotRemInt8#
      --
      let input =
              [ (a, b) | a <- allInt8, b <- allInt8
              , b /= 0, not (a == -128 && b == -1)
              ]
          expected =
              [ (toInt8 q, toInt8 r)  | (a, b) <- input
              , let (q, r) = a `quotRem` b
              ]
          actual = [ apply3 quotRemInt8# a b | (a, b) <- input ]
      checkResults "quotRemInt8#" input expected actual
  
  
  checkResults
      :: (Eq a, Eq b, Show a, Show b) => String -> [a] -> [b] -> [b] -> IO ()
  checkResults test inputs expected actual =
      case findIndex (\(e, a) -> e /= a) (zip expected actual) of
          Nothing -> putStrLn $ "Pass: " ++ test
          Just i -> error $
              "FAILED: " ++ test ++ " for input: " ++ show (inputs !! i)
                ++ " expected: " ++ show (expected !! i)
                ++ " but got: " ++ show (actual !! i)
  
  allInt8 :: [Int]
  allInt8 = [ minInt8 .. maxInt8 ]
  
  minInt8 :: Int
  minInt8 = fromIntegral (minBound :: Int8)
  
  maxInt8 :: Int
  maxInt8 = fromIntegral (maxBound :: Int8)
  
  toInt8 :: Int -> Int
  toInt8 a = fromIntegral (fromIntegral a :: Int8)
  
  addMany#
      :: Int8# -> Int8# -> Int8# -> Int8#
      -> Int8# -> Int8# -> Int8# -> Int8#
      -> Int8# -> Int8# -> Int8# -> Int8#
      -> Int8# -> Int8# -> Int8# -> Int8#
      -> Int8#
  addMany# a b c d e f g h i j k l m n o p =
      a `plusInt8#` b `plusInt8#` c `plusInt8#` d `plusInt8#`
      e `plusInt8#` f `plusInt8#` g `plusInt8#` h `plusInt8#`
      i `plusInt8#` j `plusInt8#` k `plusInt8#` l `plusInt8#`
      m `plusInt8#` n `plusInt8#` o `plusInt8#` p
  {-# NOINLINE addMany# #-}
  
  addMany
      :: Int -> Int -> Int -> Int
      -> Int -> Int -> Int -> Int
      -> Int -> Int -> Int -> Int
      -> Int -> Int -> Int -> Int
      -> Int
  addMany (I# a) (I# b) (I# c) (I# d)
          (I# e) (I# f) (I# g) (I# h)
          (I# i) (I# j) (I# k) (I# l)
          (I# m) (I# n) (I# o) (I# p)
              = I# (extendInt8# int8)
    where
      !int8 = addMany#
                  (narrowInt8# a) (narrowInt8# b) (narrowInt8# c) (narrowInt8# d)
                  (narrowInt8# e) (narrowInt8# f) (narrowInt8# g) (narrowInt8# h)
                  (narrowInt8# i) (narrowInt8# j) (narrowInt8# k) (narrowInt8# l)
                  (narrowInt8# m) (narrowInt8# n) (narrowInt8# o) (narrowInt8# p)
  {-# NOINLINE addMany #-}
  
  -- Convenient and also tests higher order functions on Int8#
  apply1 :: (Int8# -> Int8#) -> Int -> Int
  apply1 opToTest (I# a) = I# (extendInt8# (opToTest (narrowInt8# a)))
  {-# NOINLINE apply1 #-}
  
  apply2 :: (Int8# -> Int8# -> Int8#) -> Int -> Int -> Int
  apply2 opToTest (I# a) (I# b) =
      let (# sa, sb #) = (# narrowInt8# a, narrowInt8# b #)
          r = opToTest sa sb
      in I# (extendInt8# r)
  {-# NOINLINE apply2 #-}
  
  apply3 :: (Int8# -> Int8# -> (# Int8#, Int8# #)) -> Int -> Int -> (Int, Int)
  apply3 opToTest (I# a) (I# b) =
      let (# sa, sb #) = (# narrowInt8# a, narrowInt8# b #)
          (# ra, rb #) = opToTest sa sb
      in (I# (extendInt8# ra), I# (extendInt8# rb))
  {-# NOINLINE apply3 #-}
  
  instance
          (Eq a, Eq b, Eq c, Eq d, Eq e, Eq f, Eq g, Eq h,
           Eq i, Eq j, Eq k, Eq l, Eq m, Eq n, Eq o, Eq p)
        => Eq (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) where
      (a1, b1, c1, d1, e1, f1, g1, h1, i1, j1, k1, l1, m1, n1, o1, p1) ==
          (a2, b2, c2, d2, e2, f2, g2, h2, i2, j2, k2, l2, m2, n2, o2, p2) =
              a1 == a2 && b1 == b2 && c1 == c2 && d1 == d2 &&
              e1 == e2 && f1 == f2 && g1 == g2 && h1 == h2 &&
              i1 == i2 && j1 == j2 && k1 == k2 && l1 == l2 &&
              m1 == m2 && n1 == n2 && o1 == o2 && p1 == p2
  
  instance
          (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h,
           Show i, Show j, Show k, Show l, Show m, Show n, Show o, Show p)
        => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) where
      show (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) =
          "(" ++ show a ++ "," ++ show b ++ "," ++ show c ++ "," ++ show d ++
          "," ++ show e ++ "," ++ show f ++ "," ++ show g ++ "," ++ show h ++
          "," ++ show i ++ "," ++ show j ++ "," ++ show k ++ "," ++ show l ++
          "," ++ show m ++ "," ++ show n ++ "," ++ show o ++ "," ++ show p ++
          ")"
  