+flattenTopExpr ::
+ HsFunction
+ -> CoreExpr
+ -> FlattenState ([SignalMap], SignalMap)
+
+flattenTopExpr hsfunc expr = do
+ -- Flatten the expression
+ (args, res) <- flattenExpr [] expr
+
+ -- Join the signal ids and uses together
+ let zipped_args = zipWith zipValueMaps args (hsFuncArgs hsfunc)
+ let zipped_res = zipValueMaps res (hsFuncRes hsfunc)
+ -- Set the signal uses for each argument / result, possibly updating
+ -- argument or result signals.
+ args' <- mapM (Traversable.mapM $ hsUseToSigUse args_use) zipped_args
+ res' <- Traversable.mapM (hsUseToSigUse res_use) zipped_res
+ return (args', res')
+ where
+ args_use Port = SigPortIn
+ args_use (State n) = SigStateOld n
+ res_use Port = SigPortOut
+ res_use (State n) = SigStateNew n
+
+
+hsUseToSigUse ::
+ (HsValueUse -> SigUse) -- ^ A function to actually map the use value
+ -> (SignalId, HsValueUse) -- ^ The signal to look at and its use
+ -> FlattenState SignalId -- ^ The resulting signal. This is probably the
+ -- same as the input, but it could be different.
+hsUseToSigUse f (id, use) = do
+ info <- getSignalInfo id
+ id' <- case sigUse info of
+ -- Internal signals can be marked as different uses freely.
+ SigInternal -> do
+ return id
+ -- Signals that already have another use, must be duplicated before
+ -- marking. This prevents signals mapping to the same input or output
+ -- port or state variables and ports overlapping, etc.
+ otherwise -> do
+ duplicateSignal id
+ setSignalInfo id' (info { sigUse = f use})
+ return id'
+
+-- | Creates a new internal signal with the same type as the given signal
+copySignal :: SignalId -> FlattenState SignalId
+copySignal id = do
+ -- Find the type of the original signal
+ info <- getSignalInfo id
+ let ty = sigTy info
+ -- Generate a new signal (which is SigInternal for now, that will be
+ -- sorted out later on).
+ genSignalId SigInternal ty
+
+-- | Duplicate the given signal, assigning its value to the new signal.
+-- Returns the new signal id.
+duplicateSignal :: SignalId -> FlattenState SignalId
+duplicateSignal id = do
+ -- Create a new signal
+ id' <- copySignal id
+ -- Assign the old signal to the new signal
+ addDef $ UncondDef (Left id) id'
+ -- Replace the signal with the new signal
+ return id'
+