Create working parser

app/Parser.hs

@@ -0,0 +1,28 @@
+module Parser (
+  parse
+) where
+
+import Data.Word
+import qualified Data.ByteString as B
+import qualified Data.Map as Map
+
+import qualified Instruction as I
+import qualified Util as U
+
+parse :: B.ByteString -> Either String [I.Command]
+parse = parseCommands . B.unpack
+
+parseCommands :: [Word8] -> Either String [I.Command]
+parseCommands [] = Right []
+parseCommands code@(x:_) = case parseCommand code of
+  Just (cmd, rest) -> parseCommands rest >>= (\r -> return $ cmd : r)                              
+  Nothing          -> Left $ "Unparseable byte: " ++ U.byteStr x ++ "\nIn following sequence:\n" ++ U.bytesStr 16 code
+
+parseCommand :: [Word8] -> Maybe (I.Command, [Word8])
+parseCommand [] = Nothing
+parseCommand (opByte:xs) = do
+  let op = toEnum . fromIntegral $ opByte :: I.Op
+  instruction <- Map.lookup op I.instructionByOp
+  let noParams = I.noParams instruction
+  let params = map fromIntegral $ take noParams xs :: [Int]
+  return (I.Command instruction params, drop noParams xs)