minor improvements

hs-leopard.cabal

@@ -66,7 +66,7 @@ Library
   ghc-options:          -fwarn-tabs -fno-warn-unused-matches -fno-warn-name-shadowing -fno-warn-unused-imports                        
 
   cc-options:           -x c++
-  cxx-options:          -O3 -std=c++11 -lm
+  cxx-options:          -O3 -std=c++11
   extra-libraries:      stdc++
 
 --------------------------------------------------------------------------------

src/Leopard/Binding.hs

@@ -28,8 +28,7 @@ import Leopard.Misc
 -- * error handling
 
 data LeopardResult
-  = Success                           -- ^ Operation succeeded
-  | NeedMoreData                      -- ^ Not enough recovery data received
+  = NeedMoreData                      -- ^ Not enough recovery data received
   | TooMuchData                       -- ^ Buffer counts are too high
   | InvalidSize                       -- ^ Buffer size must be a multiple of 64 bytes
   | InvalidCounts                     -- ^ Invalid counts provided
@@ -40,7 +39,8 @@ data LeopardResult
 
 instance Enum LeopardResult where
 
-  toEnum ( 0)  = Success             -- Operation succeeded
+  fromEnum _ = error "LeopardResult/fromEnum: not implemented"
+
   toEnum (-1)  = NeedMoreData        -- Not enough recovery data received
   toEnum (-2)  = TooMuchData         -- Buffer counts are too high
   toEnum (-3)  = InvalidSize         -- Buffer size must be a multiple of 64 bytes
@@ -48,21 +48,18 @@ instance Enum LeopardResult where
   toEnum (-5)  = InvalidInput        -- A function parameter was invalid
   toEnum (-6)  = Platform            -- Platform is unsupported
   toEnum (-7)  = CallInitialize      -- Call leo_init() first 
-
   toEnum _     = error "invalid leopard error code"
 
-  fromEnum _ = error "LeopardResult/fromEnum: not implemented"
 
-decodeLeopardResult :: LeopardResult -> Maybe String
+decodeLeopardResult :: LeopardResult -> String
 decodeLeopardResult result = case result of
-  Success        -> Nothing  -- "Operation succeeded"
-  NeedMoreData   -> Just "Not enough recovery data received"
-  TooMuchData    -> Just "Buffer counts are too high"
-  InvalidSize    -> Just "Buffer size must be a multiple of 64 bytes"
-  InvalidCounts  -> Just "Invalid counts provided"
-  InvalidInput   -> Just "A function parameter was invalid"
-  Platform       -> Just "Platform is unsupported"
-  CallInitialize -> Just "Call leo_init() first"
+  NeedMoreData   -> "Not enough recovery data received"
+  TooMuchData    -> "Buffer counts are too high"
+  InvalidSize    -> "Buffer size must be a multiple of 64 bytes"
+  InvalidCounts  -> "Invalid counts provided"
+  InvalidInput   -> "A function parameter was invalid"
+  Platform       -> "Platform is unsupported"
+  CallInitialize -> "Call leo_init() first"
 
 --------------------------------------------------------------------------------
 -- * C++ bindings
@@ -94,6 +91,8 @@ unsafeEncodeIOList ecParams inputChunks = do
 -- We assume that the chunks have a size which is a multiple of 64 bytes, as 
 -- the underlying `leopard` library assumes that too...
 --
+-- Also it is required that @K >= 2@
+--
 {-# NOINLINE unsafeEncodeIO #-}
 unsafeEncodeIO :: ECParams -> Array Int ByteString -> IO (Either LeopardResult (Array Int ByteString))
 unsafeEncodeIO ecParams@(ECParams k n) inputChunks = do

src/Leopard/Misc.hs

@@ -58,6 +58,9 @@ isDivisibleBy64 n = (mod n 64 == 0)
 roundUpToMultipleOf :: Int -> Int -> Int
 roundUpToMultipleOf size x = size * (ceilDiv x size)
 
+requiredPadToMultipleOf :: Int -> Int -> Int
+requiredPadToMultipleOf size x = roundUpToMultipleOf size x - x
+
 --------------------------------------------------------------------------------
 -- * Bytestrings
 

src/Leopard/Types.hs

@@ -16,7 +16,7 @@ import Leopard.Misc
 --------------------------------------------------------------------------------
 
 -- | Note: Recause of a restriction of the underlying Leopard library, you should have
--- @K >= 2@, @N <= 2*K@ and @N <= 65536@.
+-- @K >= 2@, @N <= 2*K@ and @N <= 65536@. 
 data ECParams = ECParams
   { _ecK :: Int             -- ^ @K@ is the number of original chunks
   , _ecN :: Int             -- ^ @N@ is the number of chunks after encoding
@@ -29,9 +29,18 @@ ecM params = _ecN params - _ecK params
 
 isValidECParams :: ECParams -> Bool
 isValidECParams (ECParams k n) = and
-  [ k >  1
+  [ k >= 1             -- note: while Leopard only allows `k >= 2`, we can just do replication ourselves for `k = 1`.
   , k <= 32768
-  , k <  n 
+  , k <= n             -- note: if `k == n`, we can simply not call Leopard at all 
+  , n <= 2 * k
+  ]
+
+-- | This version only accepts what Leopard should also accept 
+isValidECParamsStrict :: ECParams -> Bool
+isValidECParamsStrict (ECParams k n) = and
+  [ k >= 2     
+  , k <  n     
+  , n <= 65536
   , n <= 2 * k
   ]