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https://github.com/urbit/shrub.git
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Got this working except there is a mistake in my approach.
I am traversing each subtree even if it will eventually become a back reference. While, traversing, I insert any backreferences that I find. However, if the enclosing noun is a backreference, then all of the backreferences found in subtrees will be invalid.
This commit is contained in:
Benjamin Summers
parent
89b2cccae7
commit
a089cfea12
@ -52,7 +52,7 @@ data PutResult a = PutResult {-# UNPACK #-} !S !a
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deriving Functor
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newtype Put a = Put
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{ runPut :: H.LinearHashTable Noun Word
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{ runPut :: H.LinearHashTable Word Word
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-> S
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-> IO (PutResult a)
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}
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@ -60,14 +60,8 @@ newtype Put a = Put
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--------------------------------------------------------------------------------
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{-# INLINE getRef #-}
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getRef :: Noun -> Put (Maybe Word)
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getRef n = Put \tbl s -> do
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pos <- pure (pos s)
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traceM ("getRef: " <> show n <> " @" <> show pos)
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res <- H.lookup tbl n
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pure $ PutResult s $ case res of
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Just w | w<pos -> Just w
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_ -> Nothing
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getRef :: Put (Maybe Word)
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getRef = Put \tbl s -> PutResult s <$> H.lookup tbl (pos s)
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{-
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1. Write the register to the output, and increment the output pointer.
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@ -110,7 +104,7 @@ putS s = Put $ \tbl _ -> pure (PutResult s ())
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{-# INLINE writeBit #-}
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writeBit :: Bool -> Put ()
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writeBit b = Put $ \tbl s@S{..} -> do
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-- traceM ("writeBit: " <> show b)
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traceM ("writeBit: " <> show b)
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let s' = s { reg = (if b then setBit else clearBit) reg off
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, off = (off + 1) `mod` 64
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, pos = pos + 1
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@ -130,7 +124,7 @@ writeBit b = Put $ \tbl s@S{..} -> do
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{-# INLINE writeWord #-}
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writeWord :: Word -> Put ()
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writeWord wor = do
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-- traceM ("writeWord: " <> show wor)
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traceM ("writeWord: " <> show wor)
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S{..} <- getS
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setReg (reg .|. shiftL wor off)
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flush
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@ -155,7 +149,7 @@ writeBitsFromWord :: Int -> Word -> Put ()
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writeBitsFromWord wid wor = do
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wor <- pure (takeBitsWord wid wor)
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-- traceM ("writeBitsFromWord: " <> show wid <> ", " <> show wor)
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traceM ("writeBitsFromWord: " <> show wid <> ", " <> show wor)
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oldSt <- getS
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@ -175,7 +169,7 @@ writeBitsFromWord wid wor = do
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{-# INLINE writeAtomWord# #-}
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writeAtomWord# :: Word# -> Put ()
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writeAtomWord# w = do
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-- traceM "writeAtomWord"
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traceM "writeAtomWord"
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writeBitsFromWord (I# (word2Int# (wordBitWidth# w))) (W# w)
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{-# INLINE writeAtomWord #-}
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@ -240,10 +234,12 @@ instance Monad Put where
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--------------------------------------------------------------------------------
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doPut :: Map Noun Word -> Word -> Put () -> ByteString
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doPut :: H.LinearHashTable Word Word -> Word -> Put () -> ByteString
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doPut tbl sz m =
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unsafePerformIO $ do
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tbl <- H.fromListWithSizeHint (M.size tbl) (mapToList tbl)
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traceM ""
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H.toList tbl >>= traceM . show . sort
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traceM ""
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buf <- callocBytes (fromIntegral $ 4 * wordSz*8)
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_ <- runPut (m >> mbFlush) tbl (S buf 0 0 0)
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BS.unsafePackCStringFinalizer (castPtr buf) (2*byteSz) (free buf)
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@ -265,15 +261,28 @@ doPut tbl sz m =
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-}
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writeNoun :: Noun -> Put ()
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writeNoun n = do
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-- traceM "writeNoun"
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p <- pos <$> getS
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traceM ("writeNoun: " <> show p)
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traceM ("\t" <> show n)
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mRef <- getRef n
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-- getRef >>= \case
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-- Nothing -> pure ()
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-- Just rf -> do
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-- p <- pos <$> getS
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-- traceM ("backref: " <> show p <> "-> " <> show rf)
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case (mRef, n) of
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(Nothing, Atom a) -> writeAtom a
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(Nothing, Cell h t) -> writeCell h t
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(Just bk, Atom a) | bitWidth a <= wordBitWidth bk -> writeAtom a
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(Just bk, _) -> writeBackRef bk
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-- case n of
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-- Atom a -> writeAtom a
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-- Cell h t -> writeCell h t
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getRef >>= \case
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Just bk -> do
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p <- pos <$> getS
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traceM $ mconcat (force ["backref: (", show p, " -> ", show bk, ")\n\t", show n])
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writeBackRef bk
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Nothing -> case n of
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Atom a -> writeAtom a
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Cell h t -> writeCell h t
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{-# INLINE writeMat #-}
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writeMat :: Atom -> Put ()
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@ -318,8 +327,10 @@ writeBackRef a = do
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jamBS :: Noun -> ByteString
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jamBS n = trace (show $ sort $ swap <$> mapToList tbl)
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$ doPut tbl sz (writeNoun n)
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-- $ trace (show $ sort $ swap <$> unsafePerformIO (H.toList ht))
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$ doPut ht (size shn) (writeNoun n)
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where (sz, tbl) = preJam n
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(shn, ht) = unsafePerformIO (preJam' n)
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jam :: Noun -> Atom
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jam = view (to jamBS . from atomBS)
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@ -403,6 +414,10 @@ instance Hashable SHN where
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instance Eq SHN where
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x == y = (size x == size y) && (noun x == noun y)
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{-
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This is slightly different that the stock `jam`, since we use
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backreferences if-and-only-if they save space.
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-}
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preJam' :: Noun -> IO (SHN, H.LinearHashTable Word Word)
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preJam' top = do
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nodes :: H.LinearHashTable SHN Word <- H.new
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@ -410,38 +425,32 @@ preJam' top = do
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let goAtom :: Word -> Atom -> IO SHN
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goAtom pos a@(MkAtom nat) = do
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let atmSz = matSz a
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let res = SHN (1+atmSz) (1+atmSz) (Hash.hash nat) (Atom a)
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H.lookup nodes res >>= \case
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Nothing -> do
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H.insert nodes res pos
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pure (traceShowId res)
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Just bak -> do
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let refSz = matSz (toAtom bak)
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if refSz < atmSz
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then do H.insert backs pos bak
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pure (traceShowId (res{jmSz=2+refSz}))
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else pure (traceShowId res)
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let atmSz = 1 + matSz a
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pure $ SHN atmSz atmSz (Hash.hash nat) (Atom a)
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goCell :: Word -> Noun -> Noun -> IO SHN
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goCell pos h t = do
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SHN hSz hJmSz hHash _ <- go (pos+2) h
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SHN tSz tJmSz tHash _ <- go (pos+2+hSz) t
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SHN tSz tJmSz tHash _ <- go (pos+2+hJmSz) t
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let sz = 2+hSz+tSz
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let jmSz = 2+hJmSz+tJmSz
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let res = SHN sz jmSz (combine hHash tHash) (Cell h t)
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H.lookup nodes res >>= \case
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Nothing -> do
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H.insert nodes res pos
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pure (traceShowId res)
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Just bak -> do
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let refSz = matSz (toAtom bak)
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H.insert backs pos bak
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pure (traceShowId (res{jmSz=2+refSz}))
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pure $ SHN sz jmSz (combine hHash tHash) (Cell h t)
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go :: Word -> Noun -> IO SHN
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go p (Atom a) = goAtom p a
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go p (Cell h t) = goCell p h t
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go p n = do
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res <- case n of Atom a -> goAtom p a
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Cell h t -> goCell p h t
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H.lookup nodes res >>= \case
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Nothing -> do
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H.insert nodes res p
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pure res
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Just bak -> do
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let refSz = 2 + matSz (toAtom bak)
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if (refSz < jmSz res)
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then do H.insert backs p bak
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pure (res { jmSz = refSz })
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else pure res
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res <- go 0 top
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pure (res, backs)
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