src/Octet.hs

   1 module Octet where
   2
   3 import Bit
   4
   5 -- An Octet consists of eight bits. For our purposes, the most
   6 -- significant bit will come "first." That is, b1 is in the 2^7
   7 -- place while b8 is in the 2^0 place.
   8 data Octet = Octet { b1 :: Bit,
   9                      b2 :: Bit,
  10                      b3 :: Bit,
  11                      b4 :: Bit,
  12                      b5 :: Bit,
  13                      b6 :: Bit,
  14                      b7 :: Bit,
  15                      b8 :: Bit }
  16            deriving (Eq, Show)
  17
  18 -- Convert each bit to its integer value, and multiply by the
  19 -- appropriate power of two. Sum them up, and we should get an integer
  20 -- between 0 and 255.
  21 octet_to_int :: Octet -> Int
  22 octet_to_int x =
  23     128 * (bit_to_int (b1 x)) +
  24     64  * (bit_to_int (b2 x)) +
  25     32  * (bit_to_int (b3 x)) +
  26     16  * (bit_to_int (b4 x)) +
  27     8   * (bit_to_int (b5 x)) +
  28     4   * (bit_to_int (b6 x)) +
  29     2   * (bit_to_int (b7 x)) +
  30     0   * (bit_to_int (b8 x))
  31
  32
  33 -- The octet with the least possible value.
  34 min_octet :: Octet
  35 min_octet = Octet Zero Zero Zero Zero Zero Zero Zero Zero
  36
  37
  38 -- The octet with the greatest possible value.
  39 max_octet :: Octet
  40 max_octet = Octet One One One One One One One One