+-- | How is a given (single) value in a function's type (ie, argument or
+-- return value) used?
+data HsValueUse =
+ Port -- ^ Use it as a port (input or output)
+ | State Int -- ^ Use it as state (input or output). The int is used to
+ -- match input state to output state.
+ deriving (Show, Eq)
+
+useAsPort :: Type -> HsUseMap
+useAsPort = fst . (mkHsValueMap (\(ty, s) -> (Single Port, s)) 0)
+useAsState :: Type -> HsUseMap
+useAsState = fst . (mkHsValueMap (\(ty, s) -> (Single $ State s, s + 1)) 0)
+
+type HsUseMap = HsValueMap HsValueUse
+
+-- | This type describes a particular use of a Haskell function and is used to
+-- look up an appropriate hardware description.
+data HsFunction = HsFunction {
+ hsName :: String, -- ^ What was the name of the original Haskell function?
+ hsArgs :: [HsUseMap], -- ^ How are the arguments used?
+ hsRes :: HsUseMap -- ^ How is the result value used?
+} deriving (Show, Eq)
+
+-- | Translate a function application to a HsFunction. i.e., which function
+-- do you need to translate this function application.
+appToHsFunction ::
+ Var.Var -- ^ The function to call
+ -> [CoreExpr] -- ^ The function arguments
+ -> Type -- ^ The return type
+ -> HsFunction -- ^ The needed HsFunction
+
+appToHsFunction f args ty =
+ HsFunction hsname hsargs hsres
+ where
+ hsargs = map (useAsPort . CoreUtils.exprType) args
+ hsres = useAsPort ty
+ hsname = getOccString f
+
+-- | Translate a top level function declaration to a HsFunction. i.e., which
+-- interface will be provided by this function. This function essentially
+-- defines the "calling convention" for hardware models.
+mkHsFunction ::
+ Var.Var -- ^ The function defined
+ -> Type -- ^ The function type (including arguments!)
+ -> HsFunction -- ^ The resulting HsFunction
+
+mkHsFunction f ty =
+ HsFunction hsname hsargs hsres
+ where
+ hsname = getOccString f
+ (arg_tys, res_ty) = Type.splitFunTys ty
+ -- The last argument must be state
+ state_ty = last arg_tys
+ state = useAsState state_ty
+ -- All but the last argument are inports
+ inports = map useAsPort (init arg_tys)
+ hsargs = inports ++ [state]
+ hsres = case splitTupleType res_ty of
+ -- Result type must be a two tuple (state, ports)
+ Just [outstate_ty, outport_ty] -> if Type.coreEqType state_ty outstate_ty
+ then
+ Tuple [state, useAsPort outport_ty]
+ else
+ error $ "Input state type of function " ++ hsname ++ ": " ++ (showSDoc $ ppr state_ty) ++ " does not match output state type: " ++ (showSDoc $ ppr outstate_ty)
+ otherwise -> error $ "Return type of top-level function " ++ hsname ++ " must be a two-tuple containing a state and output ports."
+