8 -- An Octet consists of eight bits. For our purposes, the most
9 -- significant bit will come "first." That is, b1 is in the 2^7
10 -- place while b8 is in the 2^0 place.
11 data Octet = None | Octet { b1 :: Bit,
22 instance Show Octet where
23 show Octet.None = "None"
24 show oct = show (octet_to_int oct)
27 instance Arbitrary Octet where
29 a1 <- arbitrary :: Gen Bit
30 a2 <- arbitrary :: Gen Bit
31 a3 <- arbitrary :: Gen Bit
32 a4 <- arbitrary :: Gen Bit
33 a5 <- arbitrary :: Gen Bit
34 a6 <- arbitrary :: Gen Bit
35 a7 <- arbitrary :: Gen Bit
36 a8 <- arbitrary :: Gen Bit
37 return (Octet a1 a2 a3 a4 a5 a6 a7 a8)
39 coarbitrary _ = variant 0
42 -- Convert each bit to its integer value, and multiply by the
43 -- appropriate power of two. Sum them up, and we should get an integer
45 octet_to_int :: Octet -> Int
47 128 * (bit_to_int (b1 x)) +
48 64 * (bit_to_int (b2 x)) +
49 32 * (bit_to_int (b3 x)) +
50 16 * (bit_to_int (b4 x)) +
51 8 * (bit_to_int (b5 x)) +
52 4 * (bit_to_int (b6 x)) +
53 2 * (bit_to_int (b7 x)) +
54 1 * (bit_to_int (b8 x))
58 octet_from_int :: Int -> Octet
60 | (x < 0) || (x > 255) = Octet.None
61 | otherwise = (Octet a1 a2 a3 a4 a5 a6 a7 a8)
63 a1 = if (x >= 128) then One else Zero
64 a2 = if ((x `mod` 128) >= 64) then One else Zero
65 a3 = if ((x `mod` 64) >= 32) then One else Zero
66 a4 = if ((x `mod` 32) >= 16) then One else Zero
67 a5 = if ((x `mod` 16) >= 8) then One else Zero
68 a6 = if ((x `mod` 8) >= 4) then One else Zero
69 a7 = if ((x `mod` 4) >= 2) then One else Zero
70 a8 = if ((x `mod` 2) == 1) then One else Zero
73 octet_from_string :: String -> Octet
75 case (reads s :: [(Int, String)]) of
77 x:_ -> octet_from_int (fst x)
80 -- The octet with the least possible value.
82 min_octet = Octet Zero Zero Zero Zero Zero Zero Zero Zero
85 -- The octet with the greatest possible value.
87 max_octet = Octet One One One One One One One One
92 test_octet_from_int1 :: Test
93 test_octet_from_int1 =
94 TestCase $ assertEqual "octet_from_int 128 should parse as 10000000" oct1 (octet_from_int 128)
96 oct1 = Octet One Zero Zero Zero Zero Zero Zero Zero
100 octet_tests = [ test_octet_from_int1 ]