gray-extended 1.3 → 1.4

raw patch · 2 files changed

+19/−1 lines, 2 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• gray-extended.cabal +1/−1
• src/Codec/Gray.hs +18/−0

@@ -1,5 +1,5 @@ name:           gray-extended-version:        1.3+version:        1.4 synopsis:       Gray encoding schemes description:    Gray codes satisfy the property that two successive values                  differ in only one digit. Usually the term \"Gray code\"

@@ -17,10 +17,13 @@ module Codec.Gray    (     grayCodes,+    integralToGray,+    grayToIntegral,     naryGrayCodes   ) where  import Data.List (foldl')+import Data.Bits (Bits, shiftR, xor)  -- | @'grayCodes' k@ generates the list of Binary Reflected Gray Code --   (BRGC) numbers of length k. This code is cyclic.@@ -29,6 +32,21 @@ grayCodes k =    let xs = grayCodes (k-1) in map (False:) xs ++ map (True:) (reverse xs) +-- | @'integralToGray' n@ encodes @n@ using a BRGC, and returns the+--   resulting bits as an integer. For example, encoding @17@ in BRGC+--   results in @11001@, or 25. So @integralToGray 17@ returns @25@.+integralToGray :: Bits a => a -> a+integralToGray n = (n `shiftR` 1) `xor` n++-- | @'grayToIntegral' n@ decodes @n@ using a BRGC, and returns the+--   resulting integer. For example, 25 is @11001@, which is the code+--   for 17. So @grayToIntegral 25@ returns @17@.+--   (see @'integralToGray'@ for +grayToIntegral :: (Num a, Bits a) => a -> a+grayToIntegral n = f n (n `shiftR` 1)+  where f k m | m /= 0     = f (k `xor` m) (m `shiftR` 1)+              | otherwise = k+   -- | @'naryGrayCodes' xs k@ generates a non-Boolean (or n-ary) Gray code --   of length @k@ using the elements of @x@ as "digits". This code is --   cyclic.