-module Octet where
-
-import Bit
-
--- An Octet consists of eight bits. For our purposes, the most
--- significant bit will come "first." That is, b1 is in the 2^7
--- place while b8 is in the 2^0 place.
-data Octet = Octet { b1 :: Bit,
- b2 :: Bit,
- b3 :: Bit,
- b4 :: Bit,
- b5 :: Bit,
- b6 :: Bit,
- b7 :: Bit,
- b8 :: Bit }
- deriving (Eq, Show)
-
--- Convert each bit to its integer value, and multiply by the
--- appropriate power of two. Sum them up, and we should get an integer
--- between 0 and 255.
+module Octet
+where
+
+import Data.Maybe (fromJust)
+
+import Test.HUnit (assertEqual)
+import Test.Framework (Test, testGroup)
+import Test.Framework.Providers.HUnit (testCase)
+
+import Test.QuickCheck (Arbitrary(..), Gen)
+
+import Bit as B
+import Maskable
+import Maskbits
+
+-- | An Octet consists of eight bits. For our purposes, the most
+-- significant bit will come "first." That is, b1 is in the 2^7
+-- place while b8 is in the 2^0 place.
+data Octet =
+ Octet { b1 :: Bit,
+ b2 :: Bit,
+ b3 :: Bit,
+ b4 :: Bit,
+ b5 :: Bit,
+ b6 :: Bit,
+ b7 :: Bit,
+ b8 :: Bit }
+ deriving (Eq)
+
+
+instance Show Octet where
+ show oct = show (octet_to_int oct)
+
+
+instance Arbitrary Octet where
+ arbitrary = do
+ a1 <- arbitrary :: Gen Bit
+ a2 <- arbitrary :: Gen Bit
+ a3 <- arbitrary :: Gen Bit
+ a4 <- arbitrary :: Gen Bit
+ a5 <- arbitrary :: Gen Bit
+ a6 <- arbitrary :: Gen Bit
+ a7 <- arbitrary :: Gen Bit
+ a8 <- arbitrary :: Gen Bit
+ return (Octet a1 a2 a3 a4 a5 a6 a7 a8)
+
+
+instance Maskable Octet where
+ apply_mask oct Eight _ = oct
+
+ apply_mask oct Seven bit =
+ oct { b8 = bit }
+
+ apply_mask oct Six bit =
+ oct { b8 = bit, b7 = bit }
+
+ apply_mask oct Five bit =
+ oct { b8 = bit, b7 = bit, b6 = bit }
+
+ apply_mask oct Four bit =
+ oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit }
+
+ apply_mask oct Three bit =
+ oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit, b4 = bit }
+
+ apply_mask oct Two bit =
+ oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit, b4 = bit, b3 = bit }
+
+ apply_mask oct Maskbits.One bit =
+ oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit,
+ b4 = bit, b3 = bit, b2 = bit }
+
+ apply_mask oct Maskbits.Zero bit =
+ oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit,
+ b4 = bit, b3 = bit, b2 = bit, b1 = bit }
+
+ -- The Maskbits must be in [Eight..ThirtyTwo].
+ apply_mask oct _ _ = oct
+
+
+-- | Convert each bit to its integer value, and multiply by the
+-- appropriate power of two. Sum them up, and we should get an integer
+-- between 0 and 255.
octet_to_int :: Octet -> Int
octet_to_int x =
- 128 * (bit_to_int (b1 x)) +
- 64 * (bit_to_int (b2 x)) +
- 32 * (bit_to_int (b3 x)) +
- 16 * (bit_to_int (b4 x)) +
- 8 * (bit_to_int (b5 x)) +
- 4 * (bit_to_int (b6 x)) +
- 2 * (bit_to_int (b7 x)) +
- 0 * (bit_to_int (b8 x))
+ 128 * (bit_to_int (b1 x)) +
+ 64 * (bit_to_int (b2 x)) +
+ 32 * (bit_to_int (b3 x)) +
+ 16 * (bit_to_int (b4 x)) +
+ 8 * (bit_to_int (b5 x)) +
+ 4 * (bit_to_int (b6 x)) +
+ 2 * (bit_to_int (b7 x)) +
+ 1 * (bit_to_int (b8 x))
+
+
+
+octet_from_int :: Int -> Maybe Octet
+octet_from_int x
+ | (x < 0) || (x > 255) = Nothing
+ | otherwise = Just (Octet a1 a2 a3 a4 a5 a6 a7 a8)
+ where
+ a1 = if (x >= 128) then B.One else B.Zero
+ a2 = if ((x `mod` 128) >= 64) then B.One else B.Zero
+ a3 = if ((x `mod` 64) >= 32) then B.One else B.Zero
+ a4 = if ((x `mod` 32) >= 16) then B.One else B.Zero
+ a5 = if ((x `mod` 16) >= 8) then B.One else B.Zero
+ a6 = if ((x `mod` 8) >= 4) then B.One else B.Zero
+ a7 = if ((x `mod` 4) >= 2) then B.One else B.Zero
+ a8 = if ((x `mod` 2) == 1) then B.One else B.Zero
+
+
+octet_from_string :: String -> Maybe Octet
+octet_from_string s =
+ case (reads s :: [(Int, String)]) of
+ [] -> Nothing
+ x:_ -> octet_from_int (fst x)
--- The octet with the least possible value.
+-- | The octet with the least possible value.
min_octet :: Octet
-min_octet = Octet Zero Zero Zero Zero Zero Zero Zero Zero
+min_octet =
+ Octet B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero
--- The octet with the greatest possible value.
+-- | The octet with the greatest possible value.
max_octet :: Octet
-max_octet = Octet One One One One One One One One
+max_octet =
+ Octet B.One B.One B.One B.One B.One B.One B.One B.One
+
+
+
+-- HUnit Tests
+test_octet_from_int1 :: Test
+test_octet_from_int1 =
+ testCase desc $ assertEqual desc oct1 oct2
+ where
+ desc = "octet_from_int 128 should parse as 10000000"
+ oct1 = Octet B.One B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero
+ oct2 = fromJust $ octet_from_int 128
+
+test_octet_mask1 :: Test
+test_octet_mask1 =
+ testCase desc $
+ assertEqual desc oct2 (apply_mask oct1 Four B.Zero)
+ where
+ desc = "The network bits of 255/4 should equal 240"
+ oct1 = fromJust $ octet_from_int 255
+ oct2 = fromJust $ octet_from_int 240
+
+
+test_octet_mask2 :: Test
+test_octet_mask2 =
+ testCase desc $
+ assertEqual desc oct2 (apply_mask oct1 Maskbits.One B.Zero)
+ where
+ desc = "The network bits of 255/1 should equal 128"
+ oct1 = fromJust $ octet_from_int 255
+ oct2 = fromJust $ octet_from_int 128
+
+
+octet_tests :: Test
+octet_tests =
+ testGroup "Octet Tests" [
+ test_octet_from_int1,
+ test_octet_mask1,
+ test_octet_mask2 ]
projects / hath.git / blobdiff