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sv2v/src/Language/SystemVerilog/AST/Expr.hs

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{- sv2v
- Author: Zachary Snow <zach@zachjs.com>
- Initial Verilog AST Author: Tom Hawkins <tomahawkins@gmail.com>
-
- SystemVerilog expressions
-}
module Language.SystemVerilog.AST.Expr
( Expr (..)
, Range
, TypeOrExpr
, ExprOrRange
, Args (..)
, PartSelectMode (..)
, DimsFn (..)
, DimFn (..)
, showAssignment
, showRanges
, showExprOrRange
, simplify
, rangeSize
, rangeSizeHiLo
, endianCondExpr
, endianCondRange
, dimensionsSize
, readNumber
) where
import Data.List (intercalate)
import Text.Printf (printf)
import Text.Read (readMaybe)
import Language.SystemVerilog.AST.Op
import Language.SystemVerilog.AST.ShowHelp
import {-# SOURCE #-} Language.SystemVerilog.AST.Type
type Range = (Expr, Expr)
type TypeOrExpr = Either Type Expr
type ExprOrRange = Either Expr Range
data Expr
= String String
| Number String
| Time String
| Ident Identifier
| PSIdent Identifier Identifier
| Range Expr PartSelectMode Range
| Bit Expr Expr
| Repeat Expr [Expr]
| Concat [Expr]
| Stream StreamOp Expr [Expr]
| Call Expr Args
| UniOp UniOp Expr
| BinOp BinOp Expr Expr
| Mux Expr Expr Expr
| Cast TypeOrExpr Expr
| DimsFn DimsFn TypeOrExpr
| DimFn DimFn TypeOrExpr Expr
| Dot Expr Identifier
| Pattern [(Identifier, Expr)]
| Inside Expr [ExprOrRange]
| MinTypMax Expr Expr Expr
| Nil
deriving (Eq, Ord)
instance Show Expr where
show (Nil ) = ""
show (Number str ) = str
show (Time str ) = str
show (Ident str ) = str
show (PSIdent x y ) = printf "%s::%s" x y
show (String str ) = printf "\"%s\"" str
show (Bit e b ) = printf "%s[%s]" (show e) (show b)
show (Range e m r) = printf "%s[%s%s%s]" (show e) (show $ fst r) (show m) (show $ snd r)
show (Repeat e l ) = printf "{%s {%s}}" (show e) (commas $ map show l)
show (Concat l ) = printf "{%s}" (commas $ map show l)
show (Stream o e l) = printf "{%s %s%s}" (show o) (show e) (show $ Concat l)
show (UniOp o e ) = printf "%s%s" (show o) (showUniOpPrec e)
show (BinOp o a b) = printf "%s %s %s" (showBinOpPrec a) (show o) (showBinOpPrec b)
show (Dot e n ) = printf "%s.%s" (show e) n
show (Mux c a b) = printf "(%s ? %s : %s)" (show c) (show a) (show b)
show (Call e l ) = printf "%s%s" (show e) (show l)
show (Cast tore e ) = printf "%s'(%s)" (showEither tore) (show e)
show (DimsFn f v ) = printf "%s(%s)" (show f) (showEither v)
show (DimFn f v e) = printf "%s(%s, %s)" (show f) (showEither v) (show e)
show (Inside e l ) = printf "(%s inside { %s })" (show e) (intercalate ", " strs)
where
strs = map showExprOrRange l
show (Pattern l ) =
printf "'{\n%s\n}" (indent $ intercalate ",\n" $ map showPatternItem l)
where
showPatternItem :: (Identifier, Expr) -> String
showPatternItem ("" , e) = show e
showPatternItem (':' : n, e) = showPatternItem (n, e)
showPatternItem (n , e) = printf "%s: %s" n (show e)
show (MinTypMax a b c) = printf "(%s : %s : %s)" (show a) (show b) (show c)
data Args
= Args [Maybe Expr] [(Identifier, Maybe Expr)]
deriving (Eq, Ord)
instance Show Args where
show (Args pnArgs kwArgs) = "(" ++ (commas strs) ++ ")"
where
strs = (map showPnArg pnArgs) ++ (map showKwArg kwArgs)
showPnArg = maybe "" show
showKwArg (x, me) = printf ".%s(%s)" x (showPnArg me)
data PartSelectMode
= NonIndexed
| IndexedPlus
| IndexedMinus
deriving (Eq, Ord)
instance Show PartSelectMode where
show NonIndexed = ":"
show IndexedPlus = "+:"
show IndexedMinus = "-:"
data DimsFn
= FnBits
| FnDimensions
| FnUnpackedDimensions
deriving (Eq, Ord)
data DimFn
= FnLeft
| FnRight
| FnLow
| FnHigh
| FnIncrement
| FnSize
deriving (Eq, Ord)
instance Show DimsFn where
show FnBits = "$bits"
show FnDimensions = "$dimensions"
show FnUnpackedDimensions = "$unpacked_dimensions"
instance Show DimFn where
show FnLeft = "$left"
show FnRight = "$right"
show FnLow = "$low"
show FnHigh = "$high"
show FnIncrement = "$increment"
show FnSize = "$size"
showAssignment :: Show a => Maybe a -> String
showAssignment Nothing = ""
showAssignment (Just val) = " = " ++ show val
showRanges :: [Range] -> String
showRanges [] = ""
showRanges l = " " ++ (concatMap showRange l)
showRange :: Range -> String
showRange (h, l) = printf "[%s:%s]" (show h) (show l)
showExprOrRange :: ExprOrRange -> String
showExprOrRange (Left x) = show x
showExprOrRange (Right x) = show x
clog2Help :: Int -> Int -> Int
clog2Help p n = if p >= n then 0 else 1 + clog2Help (p*2) n
clog2 :: Int -> Int
clog2 n = if n < 2 then 0 else clog2Help 1 n
readNumber :: String -> Maybe Int
readNumber n =
readMaybe n' :: Maybe Int
where
n' = case n of
'3' : '2' : '\'' : 'd' : rest -> rest
'\'' : 'd' : rest -> rest
_ -> n
showUniOpPrec :: Expr -> String
showUniOpPrec (e @ UniOp{}) = printf "(%s)" (show e)
showUniOpPrec (e @ BinOp{}) = printf "(%s)" (show e)
showUniOpPrec e = show e
showBinOpPrec :: Expr -> String
showBinOpPrec (e @ BinOp{}) = printf "(%s)" (show e)
showBinOpPrec e = show e
-- basic expression simplfication utility to help us generate nicer code in the
-- common case of ranges like `[FOO-1:0]`
simplify :: Expr -> Expr
simplify (UniOp LogNot (Number "1")) = Number "0"
simplify (UniOp LogNot (Number "0")) = Number "1"
simplify (orig @ (UniOp UniSub (Number n))) =
case readNumber n of
Nothing -> orig
Just x -> Number $ show (-x)
simplify (orig @ (Repeat (Number n) exprs)) =
case readNumber n of
Nothing -> orig
Just 0 -> Concat []
Just 1 -> Concat exprs
Just x ->
if x < 0
then error $ "negative repeat count: " ++ show orig
else orig
simplify (Concat [expr]) = expr
simplify (Concat exprs) =
Concat $ filter (/= Concat []) exprs
simplify (orig @ (Call (Ident "$clog2") (Args [Just (Number n)] []))) =
case readNumber n of
Nothing -> orig
Just x -> Number $ show $ clog2 x
simplify (Mux cc e1 e2) =
case cc' of
Number "1" -> e1'
Number "0" -> e2'
_ -> Mux cc' e1' e2'
where
cc' = simplify cc
e1' = simplify e1
e2' = simplify e2
simplify (Range e NonIndexed r) = Range e NonIndexed r
simplify (Range e _ (i, Number "0")) = Bit e i
simplify (BinOp Sub (Number n1) (BinOp Sub (Number n2) e)) =
simplify $ BinOp Add (BinOp Sub (Number n1) (Number n2)) e
simplify (BinOp Sub (Number n1) (BinOp Sub e (Number n2))) =
simplify $ BinOp Sub (BinOp Add (Number n1) (Number n2)) e
simplify (BinOp Add (BinOp Sub (Number n1) e) (Number n2)) =
case (readNumber n1, readNumber n2) of
(Just x, Just y) ->
simplify $ BinOp Sub (Number $ show (x + y)) e'
_ -> nochange
where
e' = simplify e
nochange = BinOp Add (BinOp Sub (Number n1) e') (Number n2)
simplify (BinOp op e1 e2) =
case (op, e1', e2') of
(Add, Number "0", e) -> e
(Add, e, Number "0") -> e
(Mul, _, Number "0") -> Number "0"
(Mul, Number "0", _) -> Number "0"
(Mul, e, Number "1") -> e
(Mul, Number "1", e) -> e
(Sub, e, Number "0") -> e
(Add, BinOp Sub e (Number "1"), Number "1") -> e
(Add, e, BinOp Sub (Number "0") (Number "1")) -> BinOp Sub e (Number "1")
(_ , Number a, Number b) ->
case (op, readNumber a :: Maybe Int, readNumber b :: Maybe Int) of
(Add, Just x, Just y) -> Number $ show (x + y)
(Sub, Just x, Just y) -> Number $ show (x - y)
(Mul, Just x, Just y) -> Number $ show (x * y)
(Div, Just _, Just 0) -> Number "x"
(Div, Just x, Just y) -> Number $ show (x `quot` y)
(Eq , Just x, Just y) -> bool $ x == y
(Ne , Just x, Just y) -> bool $ x /= y
(Gt , Just x, Just y) -> bool $ x > y
(Ge , Just x, Just y) -> bool $ x >= y
(Lt , Just x, Just y) -> bool $ x < y
(Le , Just x, Just y) -> bool $ x <= y
_ -> BinOp op e1' e2'
(Add, BinOp Add e (Number a), Number b) ->
case (readNumber a, readNumber b) of
(Just x, Just y) -> BinOp Add e $ Number $ show (x + y)
_ -> BinOp op e1' e2'
(Sub, e, Number "-1") -> BinOp Add e (Number "1")
_ -> BinOp op e1' e2'
where
e1' = simplify e1
e2' = simplify e2
bool True = Number "1"
bool False = Number "0"
simplify other = other
rangeSize :: Range -> Expr
rangeSize (s, e) =
endianCondExpr (s, e) a b
where
a = rangeSizeHiLo (s, e)
b = rangeSizeHiLo (e, s)
rangeSizeHiLo :: Range -> Expr
rangeSizeHiLo (hi, lo) =
simplify $ BinOp Add (BinOp Sub hi lo) (Number "1")
-- chooses one or the other expression based on the endianness of the given
-- range; [hi:lo] chooses the first expression
endianCondExpr :: Range -> Expr -> Expr -> Expr
endianCondExpr r e1 e2 = simplify $ Mux (uncurry (BinOp Ge) r) e1 e2
-- chooses one or the other range based on the endianness of the given range,
-- but in such a way that the result is itself also usable as a range even if
-- the endianness cannot be resolved during conversion, i.e. if it's dependent
-- on a parameter value; [hi:lo] chooses the first range
endianCondRange :: Range -> Range -> Range -> Range
endianCondRange r r1 r2 =
( endianCondExpr r (fst r1) (fst r2)
, endianCondExpr r (snd r1) (snd r2)
)
dimensionsSize :: [Range] -> Expr
dimensionsSize ranges =
simplify $
foldl (BinOp Mul) (Number "1") $
map rangeSize $
ranges
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