From d4f46f4d52b3d51c2eb59a4aa818d4f23f14203d Mon Sep 17 00:00:00 2001 From: Michael Orlitzky Date: Sun, 2 May 2010 15:19:00 -0400 Subject: [PATCH] Add a None constructor for Octets. Return Octet.None when an octet is created from an invalid Int. --- src/Octet.hs | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/src/Octet.hs b/src/Octet.hs index f8af4df..e0a4bf6 100644 --- a/src/Octet.hs +++ b/src/Octet.hs @@ -5,14 +5,14 @@ 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 } +data Octet = None | 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 @@ -30,10 +30,10 @@ octet_to_int x = 0 * (bit_to_int (b8 x)) --- Supply an integer greater than 255 at your own risk. + octet_from_int :: Int -> Octet octet_from_int x - | (x < 0) = min_octet + | (x < 0) || (x > 255) = Octet.None | otherwise = (Octet a1 a2 a3 a4 a5 a6 a7 a8) where a1 = if (x `mod` 128) > 0 then One else Zero -- 2.44.2