From d88c516d33c7aef93e3f6b594596adc513329c07 Mon Sep 17 00:00:00 2001
From: Zachary Snow <zach@zachjs.com>
Date: Sun, 12 Jul 2020 15:06:27 -0600
Subject: [PATCH] enhanced handling of number literals

- number literals are parsed rather than stored as strings
- fix array query functions used on non-trivial number literals
- more efficient expression simplification recursion
- expanded constant folding scenarios
---
 src/Convert/DimensionQuery.hs                 |  50 ++-
 src/Convert/EmptyArgs.hs                      |   2 +-
 src/Convert/Enum.hs                           |   9 +-
 src/Convert/ExprUtils.hs                      | 199 ++++++++++++
 src/Convert/ForDecl.hs                        |   2 +-
 src/Convert/Foreach.hs                        |   6 +-
 src/Convert/Jump.hs                           |  13 +-
 src/Convert/Logic.hs                          |   4 +-
 src/Convert/MultiplePacked.hs                 |  11 +-
 src/Convert/ParamType.hs                      |   5 +-
 src/Convert/Simplify.hs                       |  57 ++--
 src/Convert/SizeCast.hs                       |  50 +--
 src/Convert/Stream.hs                         |  13 +-
 src/Convert/Struct.hs                         |  27 +-
 src/Convert/Traverse.hs                       |  42 ++-
 src/Convert/TypeOf.hs                         |  29 +-
 src/Convert/UnbasedUnsized.hs                 |  32 +-
 src/Convert/Wildcard.hs                       |   9 +-
 src/Language/SystemVerilog/AST.hs             |   2 +
 src/Language/SystemVerilog/AST/Expr.hs        | 188 +----------
 src/Language/SystemVerilog/AST/Number.hs      | 298 ++++++++++++++++++
 src/Language/SystemVerilog/AST/Type.hs        |   8 +-
 src/Language/SystemVerilog/Parser/Lex.x       |   6 +-
 src/Language/SystemVerilog/Parser/Parse.y     |  39 ++-
 .../SystemVerilog/Parser/ParseDecl.hs         |   8 +-
 src/Language/SystemVerilog/Parser/Tokens.hs   |   1 +
 sv2v.cabal                                    |   2 +
 test/basic/dimensions.sv                      |   8 +
 test/basic/dimensions.v                       |   8 +
 test/basic/div.sv                             |   8 +
 test/basic/div.v                              |   1 +
 test/lex/number.sv                            |  41 +++
 test/lex/number.v                             |   1 +
 33 files changed, 813 insertions(+), 366 deletions(-)
 create mode 100644 src/Convert/ExprUtils.hs
 create mode 100644 src/Language/SystemVerilog/AST/Number.hs
 create mode 100644 test/basic/div.sv
 create mode 100644 test/basic/div.v
 create mode 100644 test/lex/number.sv
 create mode 100644 test/lex/number.v

diff --git a/src/Convert/DimensionQuery.hs b/src/Convert/DimensionQuery.hs
index f81aee4..885d367 100644
--- a/src/Convert/DimensionQuery.hs
+++ b/src/Convert/DimensionQuery.hs
@@ -19,8 +19,7 @@
 
 module Convert.DimensionQuery (convert) where
 
-import Data.List (elemIndex)
-
+import Convert.ExprUtils
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
@@ -37,9 +36,9 @@ elaborateType (IntegerAtom t sg) =
     IntegerVector TLogic sg [(hi, lo)]
     where
         size = atomSize t
-        hi = Number $ show (size - 1)
-        lo = Number "0"
-        atomSize :: IntegerAtomType -> Int
+        hi = RawNum $ size - 1
+        lo = RawNum 0
+        atomSize :: IntegerAtomType -> Integer
         atomSize TByte = 8
         atomSize TShortint = 16
         atomSize TInt = 32
@@ -59,32 +58,32 @@ convertExpr (DimFn fn (Right e) d) =
     DimFn fn (Left $ TypeOf e) d
 convertExpr (orig @ (DimsFn FnUnpackedDimensions (Left t))) =
     case t of
-        UnpackedType _ rs -> Number $ show $ length rs
+        UnpackedType _ rs -> RawNum $ fromIntegral $ length rs
         TypeOf{} -> orig
-        _ -> Number "0"
+        _ -> RawNum 0
 convertExpr (orig @ (DimsFn FnDimensions (Left t))) =
     case t of
-        IntegerAtom{} -> Number "1"
+        IntegerAtom{} -> RawNum 1
         Alias{} -> orig
         PSAlias{} -> orig
         CSAlias{} -> orig
         TypeOf{} -> orig
         UnpackedType t' rs ->
             BinOp Add
-                (Number $ show $ length rs)
+                (RawNum $ fromIntegral $ length rs)
                 (DimsFn FnDimensions $ Left t')
-        _ -> Number $ show $ length $ snd $ typeRanges t
+        _ -> RawNum $ fromIntegral $ length $ snd $ typeRanges t
 
 -- conversion for array dimension functions on types
-convertExpr (DimFn f (Left t) (Number str)) =
-    if dm == Nothing || isUnresolved t then
-        DimFn f (Left t) (Number str)
-    else if d <= 0 || fromIntegral d > length rs then
-        Number "'x"
+convertExpr (DimFn f (Left t) (Number n)) =
+    if isUnresolved t then
+        DimFn f (Left t) (Number n)
+    else if d <= 0 || d > length rs then
+        Number $ UnbasedUnsized 'x'
     else case f of
         FnLeft -> fst r
         FnRight -> snd r
-        FnIncrement -> endianCondExpr r (Number "1") (UniOp UniSub $ Number "1")
+        FnIncrement -> endianCondExpr r (RawNum 1) (UniOp UniSub $ RawNum 1)
         FnLow -> endianCondExpr r (snd r) (fst r)
         FnHigh -> endianCondExpr r (fst r) (snd r)
         FnSize -> rangeSize r
@@ -93,9 +92,10 @@ convertExpr (DimFn f (Left t) (Number str)) =
             UnpackedType tInner rsOuter ->
                 rsOuter ++ (snd $ typeRanges $ elaborateType tInner)
             _ -> snd $ typeRanges $ elaborateType t
-        dm = readNumber str
-        Just d = dm
-        r = rs !! (fromIntegral $ d - 1)
+        d = case numberToInteger n of
+            Just value -> fromIntegral value
+            Nothing -> 0
+        r = rs !! (d - 1)
         isUnresolved :: Type -> Bool
         isUnresolved Alias{} = True
         isUnresolved PSAlias{} = True
@@ -117,7 +117,7 @@ convertBits (Left t) =
         Struct   _ fields rs ->
             BinOp Mul
                 (dimensionsSize rs)
-                (foldl (BinOp Add) (Number "0") fieldSizes)
+                (foldl (BinOp Add) (RawNum 0) fieldSizes)
             where fieldSizes = map (DimsFn FnBits . Left . fst) fields
         UnpackedType  t'  rs ->
             BinOp Mul
@@ -127,17 +127,13 @@ convertBits (Left t) =
 convertBits (Right e) =
     case e of
         Concat exprs ->
-            foldl (BinOp Add) (Number "0") $
+            foldl (BinOp Add) (RawNum 0) $
             map (convertBits . Right) $
             exprs
         Stream _ _ exprs -> convertBits $ Right $ Concat exprs
-        Number n ->
-            case elemIndex '\'' n of
-                Nothing -> Number "32"
-                Just 0  -> Number "32"
-                Just idx -> Number $ take idx n
+        Number n -> RawNum $ numberBitLength n
         Range expr mode range ->
-            BinOp Mul size $ convertBits $ Right $ Bit expr (Number "0")
+            BinOp Mul size $ convertBits $ Right $ Bit expr (RawNum 0)
             where
                 size = case mode of
                     NonIndexed   -> rangeSize range
diff --git a/src/Convert/EmptyArgs.hs b/src/Convert/EmptyArgs.hs
index fc18b71..8166085 100644
--- a/src/Convert/EmptyArgs.hs
+++ b/src/Convert/EmptyArgs.hs
@@ -49,6 +49,6 @@ convertExpr :: Idents -> Expr -> Expr
 convertExpr functions (Call (Ident func) (Args [] [])) =
     Call (Ident func) (Args args [])
     where args = if Set.member func functions
-            then [Number "0"]
+            then [RawNum 0]
             else []
 convertExpr _ other = other
diff --git a/src/Convert/Enum.hs b/src/Convert/Enum.hs
index f893ba9..5719b19 100644
--- a/src/Convert/Enum.hs
+++ b/src/Convert/Enum.hs
@@ -23,6 +23,7 @@ import Control.Monad.Writer
 import Data.List (elemIndices)
 import qualified Data.Set as Set
 
+import Convert.ExprUtils
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
@@ -72,12 +73,12 @@ traverseType (Enum (Implicit sg rl) v rs) =
         -- default to a 32 bit logic
         t' = IntegerVector TLogic sg rl'
         rl' = if null rl
-            then [(Number "31", Number "0")]
+            then [(RawNum 31, RawNum 0)]
             else rl
 traverseType (Enum t v rs) = do
     let (tf, rl) = typeRanges t
     rlParam <- case rl of
-        [ ] -> return [(Number "0", Number "0")]
+        [ ] -> return [(RawNum 0, RawNum 0)]
         [_] -> return rl
         _   -> error $ "unexpected multi-dim enum type: " ++ show (Enum t v rs)
     tell $ Set.singleton (tf rlParam, v) -- type of localparams
@@ -93,10 +94,10 @@ makeEnumItems (itemType, l) =
                 ++ show (zip keys vals)
     where
         keys = map fst l
-        vals = tail $ scanl step (UniOp UniSub $ Number "1") (map snd l)
+        vals = tail $ scanl step (UniOp UniSub $ RawNum 1) (map snd l)
         noDuplicates = all (null . tail . flip elemIndices vals) vals
         step :: Expr -> Expr -> Expr
-        step expr Nil = simplify $ BinOp Add expr (Number "1")
+        step expr Nil = simplify $ BinOp Add expr (RawNum 1)
         step _ expr = expr
         toPackageItem :: Identifier -> Expr -> PackageItem
         toPackageItem x v =
diff --git a/src/Convert/ExprUtils.hs b/src/Convert/ExprUtils.hs
new file mode 100644
index 0000000..50ed802
--- /dev/null
+++ b/src/Convert/ExprUtils.hs
@@ -0,0 +1,199 @@
+{-# LANGUAGE PatternSynonyms #-}
+{- sv2v
+ - Author: Zachary Snow <zach@zachjs.com>
+ -
+ - Utilities for expressions and ranges
+ -}
+
+module Convert.ExprUtils
+    ( simplify
+    , simplifyStep
+    , rangeSize
+    , rangeSizeHiLo
+    , endianCondExpr
+    , endianCondRange
+    , dimensionsSize
+    ) where
+
+import Data.Bits (shiftL, shiftR)
+
+import Convert.Traverse
+import Language.SystemVerilog.AST
+
+simplify :: Expr -> Expr
+simplify = simplifyStep . traverseSinglyNestedExprs simplify . simplifyStep
+
+simplifyStep :: Expr -> Expr
+
+simplifyStep (UniOp LogNot (Number n)) =
+    case numberToInteger n of
+        Just 0 -> bool True
+        Just _ -> bool False
+        Nothing -> UniOp LogNot $ Number n
+simplifyStep (UniOp LogNot (BinOp Eq a b)) = BinOp Ne a b
+simplifyStep (UniOp LogNot (BinOp Ne a b)) = BinOp Eq a b
+
+simplifyStep (UniOp UniSub (UniOp UniSub e)) = e
+simplifyStep (UniOp UniSub (BinOp Sub e1 e2)) = BinOp Sub e2 e1
+
+simplifyStep (Concat [e]) = e
+simplifyStep (Concat es) = Concat $ filter (/= Concat []) es
+simplifyStep (Repeat (Dec 0) _) = Concat []
+simplifyStep (Repeat (Dec 1) es) = Concat es
+simplifyStep (Mux (Number n) e1 e2) =
+    case numberToInteger n of
+        Just 0 -> e2
+        Just _ -> e1
+        Nothing -> Mux (Number n) e1 e2
+
+simplifyStep (Call (Ident "$clog2") (Args [Dec k] [])) =
+    toDec $ clog2 k
+    where
+        clog2Help :: Integer -> Integer -> Integer
+        clog2Help p n = if p >= n then 0 else 1 + clog2Help (p*2) n
+        clog2 :: Integer -> Integer
+        clog2 n = if n < 2 then 0 else clog2Help 1 n
+
+simplifyStep (BinOp op e1 e2) = simplifyBinOp op e1 e2
+simplifyStep other = other
+
+
+simplifyBinOp :: BinOp -> Expr -> Expr -> Expr
+
+simplifyBinOp Add (Dec 0) e = e
+simplifyBinOp Add e (Dec 0) = e
+simplifyBinOp Sub e (Dec 0) = e
+simplifyBinOp Sub (Dec 0) e = UniOp UniSub e
+simplifyBinOp Mul (Dec 0) _ = toDec 0
+simplifyBinOp Mul (Dec 1) e = e
+simplifyBinOp Mul _ (Dec 0) = toDec 0
+simplifyBinOp Mul e (Dec 1) = e
+
+simplifyBinOp Add e1 (UniOp UniSub e2) = BinOp Sub e1 e2
+simplifyBinOp Add (UniOp UniSub e1) e2 = BinOp Sub e2 e1
+simplifyBinOp Sub e1 (UniOp UniSub e2) = BinOp Add e1 e2
+simplifyBinOp Sub (UniOp UniSub e1) e2 = UniOp UniSub $ BinOp Add e1 e2
+
+simplifyBinOp Sub (n1 @ Number{}) (BinOp Sub (n2 @ Number{}) e) =
+    BinOp Add (BinOp Sub n1 n2) e
+simplifyBinOp Sub (n1 @ Number{}) (BinOp Sub e (n2 @ Number{})) =
+    BinOp Sub (BinOp Add n1 n2) e
+simplifyBinOp Sub (BinOp Add e (n1 @ Number{})) (n2 @ Number{}) =
+    BinOp Add e (BinOp Sub n1 n2)
+simplifyBinOp Add (n1 @ Number{}) (BinOp Add (n2 @ Number{}) e) =
+    BinOp Add (BinOp Add n1 n2) e
+simplifyBinOp Add (n1 @ Number{}) (BinOp Sub e (n2 @ Number{})) =
+    BinOp Add e (BinOp Sub n1 n2)
+simplifyBinOp Sub (BinOp Sub e (n1 @ Number{})) (n2 @ Number{}) =
+    BinOp Sub e (BinOp Add n1 n2)
+simplifyBinOp Add (BinOp Sub e (n1 @ Number{})) (n2 @ Number{}) =
+    BinOp Sub e (BinOp Sub n1 n2)
+simplifyBinOp Add (BinOp Sub (n1 @ Number{}) e) (n2 @ Number{}) =
+    BinOp Sub (BinOp Add n1 n2) e
+simplifyBinOp Ge (BinOp Sub e (Dec 1)) (Dec 0) = BinOp Ge e (toDec 1)
+
+simplifyBinOp ShiftAL (Dec x) (Dec y) = toDec $ shiftL x (fromIntegral y)
+simplifyBinOp ShiftAR (Dec x) (Dec y) = toDec $ shiftR x (fromIntegral y)
+simplifyBinOp ShiftL  (Dec x) (Dec y) = toDec $ shiftL x (fromIntegral y)
+simplifyBinOp ShiftR  (Dec x) (Dec y) = toDec $ shiftR x (fromIntegral y)
+
+simplifyBinOp op e1 e2 =
+    case (e1, e2) of
+        (Dec    x, Dec    y) -> constantFold orig op   x    y
+        (SizDec x, Dec    y) -> constantFold orig op   x    y
+        (Dec    x, SizDec y) -> constantFold orig op   x    y
+        (Bas    x, Dec    y) -> constantFold orig op   x    y
+        (Dec    x, Bas    y) -> constantFold orig op   x    y
+        (Bas    x, Bas    y) -> constantFold orig op   x    y
+        (NegDec x, Dec    y) -> constantFold orig op (-x)   y
+        (Dec    x, NegDec y) -> constantFold orig op   x  (-y)
+        (NegDec x, NegDec y) -> constantFold orig op (-x) (-y)
+        _ -> orig
+    where orig = BinOp op e1 e2
+
+
+-- attempt to constant fold a binary operation on integers
+constantFold :: Expr -> BinOp -> Integer -> Integer -> Expr
+constantFold _ Add x y = toDec (x + y)
+constantFold _ Sub x y = toDec (x - y)
+constantFold _ Mul x y = toDec (x * y)
+constantFold _ Div _ 0 = Number $ Based (-32) True Hex 0 bits
+    where bits = 2 ^ (32 :: Integer) - 1
+constantFold _ Div x y = toDec (x `quot` y)
+constantFold _ Mod x y = toDec (x `rem` y)
+constantFold _ Pow x y = toDec (x ^ y)
+constantFold _ Eq  x y = bool $ x == y
+constantFold _ Ne  x y = bool $ x /= y
+constantFold _ Gt  x y = bool $ x >  y
+constantFold _ Ge  x y = bool $ x >= y
+constantFold _ Lt  x y = bool $ x <  y
+constantFold _ Le  x y = bool $ x <= y
+constantFold fallback _ _ _ = fallback
+
+
+bool :: Bool -> Expr
+bool True = Number $ Decimal 1 False 1
+bool False = Number $ Decimal 1 False 0
+
+toDec :: Integer -> Expr
+toDec n =
+    if n < 0 then
+        UniOp UniSub $ toDec (-n)
+    else if n >= 4294967296 `div` 2 then
+        let size = fromIntegral $ bits $ n * 2
+        in Number $ Decimal (negate size) True n
+    else
+        RawNum n
+    where
+        bits :: Integer -> Integer
+        bits 0 = 0
+        bits v = 1 + bits (quot v 2)
+
+pattern Dec :: Integer -> Expr
+pattern Dec n <- Number (Decimal (-32) _ n)
+
+pattern SizDec :: Integer -> Expr
+pattern SizDec n <- Number (Decimal 32 _ n)
+
+pattern NegDec :: Integer -> Expr
+pattern NegDec n <- UniOp UniSub (Dec n)
+
+pattern Bas :: Integer -> Expr
+pattern Bas n <- Number (Based _ _ _ n 0)
+
+
+-- returns the size of a range
+rangeSize :: Range -> Expr
+rangeSize (s, e) =
+    endianCondExpr (s, e) a b
+    where
+        a = rangeSizeHiLo (s, e)
+        b = rangeSizeHiLo (e, s)
+
+-- returns the size of a range known to be ordered
+rangeSizeHiLo :: Range -> Expr
+rangeSizeHiLo (hi, lo) =
+    simplify $ BinOp Add (BinOp Sub hi lo) (RawNum 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)
+    )
+
+-- returns the total size of a set of dimensions
+dimensionsSize :: [Range] -> Expr
+dimensionsSize ranges =
+    simplify $
+    foldl (BinOp Mul) (RawNum 1) $
+    map rangeSize $
+    ranges
diff --git a/src/Convert/ForDecl.hs b/src/Convert/ForDecl.hs
index df7c563..8a37316 100644
--- a/src/Convert/ForDecl.hs
+++ b/src/Convert/ForDecl.hs
@@ -23,7 +23,7 @@ convertStmt (For (Left []) cc asgns stmt) =
     convertStmt $ For (Right []) cc asgns stmt
 convertStmt (For (Right []) cc asgns stmt) =
     convertStmt $ For inits cc asgns stmt
-    where inits = Left [dummyDecl $ Number "0"]
+    where inits = Left [dummyDecl $ RawNum 0]
 convertStmt (orig @ (For (Right [_]) _ _ _)) = orig
 
 convertStmt (For (Left inits) cc asgns stmt) =
diff --git a/src/Convert/Foreach.hs b/src/Convert/Foreach.hs
index c261b3c..646f22d 100644
--- a/src/Convert/Foreach.hs
+++ b/src/Convert/Foreach.hs
@@ -22,16 +22,16 @@ convertStmt :: Stmt -> Stmt
 convertStmt (Foreach x idxs stmt) =
     (foldl (.) id $ map toLoop $ zip [1..] idxs) stmt
     where
-        toLoop :: (Int, Identifier) -> (Stmt -> Stmt)
+        toLoop :: (Integer, Identifier) -> (Stmt -> Stmt)
         toLoop (_, "") = id
         toLoop (d, i) =
             For (Left [idxDecl]) cmp [incr]
             where
-                queryFn f = DimFn f (Right $ Ident x) (Number $ show d)
+                queryFn f = DimFn f (Right $ Ident x) (RawNum d)
                 idxDecl = Variable Local (IntegerAtom TInteger Unspecified) i []
                     (queryFn FnLeft)
                 cmp =
-                    Mux (BinOp Eq (queryFn FnIncrement) (Number "1"))
+                    Mux (BinOp Eq (queryFn FnIncrement) (RawNum 1))
                         (BinOp Ge (Ident i) (queryFn FnRight))
                         (BinOp Le (Ident i) (queryFn FnRight))
                 incr = (LHSIdent i, AsgnOp Sub, queryFn FnIncrement)
diff --git a/src/Convert/Jump.hs b/src/Convert/Jump.hs
index d76ebfa..1fbec2b 100644
--- a/src/Convert/Jump.hs
+++ b/src/Convert/Jump.hs
@@ -276,23 +276,26 @@ convertLoop loop comp stmt = do
                 ]
 
 jumpStateType :: Type
-jumpStateType = IntegerVector TBit Unspecified [(Number "0", Number "1")]
+jumpStateType = IntegerVector TBit Unspecified [(RawNum 0, RawNum 1)]
 
 jumpState :: String
 jumpState = "_sv2v_jump"
 
+jsVal :: Integer -> Expr
+jsVal n = Number $ Based 2 False Binary n 0
+
 -- keep running the loop/function normally
 jsNone :: Expr
-jsNone = Number "2'b00"
+jsNone = jsVal 0
 -- skip to the next iteration of the loop (continue)
 jsContinue :: Expr
-jsContinue = Number "2'b01"
+jsContinue = jsVal 1
 -- stop running the loop immediately (break)
 jsBreak :: Expr
-jsBreak = Number "2'b10"
+jsBreak = jsVal 2
 -- stop running the function immediately (return)
 jsReturn :: Expr
-jsReturn = Number "2'b11"
+jsReturn = jsVal 3
 
 
 assertMsg :: Bool -> String -> State Info ()
diff --git a/src/Convert/Logic.hs b/src/Convert/Logic.hs
index b082aef..f9d9a22 100644
--- a/src/Convert/Logic.hs
+++ b/src/Convert/Logic.hs
@@ -134,7 +134,7 @@ traverseModuleItem ports scopes =
                         tmp = "sv2v_tmp_" ++ instanceName ++ "_" ++ portName
                         tmpExpr = Ident tmp
                         t = Net (NetType TWire) Unspecified
-                                [(DimsFn FnBits $ Right expr, Number "1")]
+                                [(DimsFn FnBits $ Right expr, RawNum 1)]
                         items =
                             [ MIPackageItem $ Decl $ Variable Local t tmp [] Nil
                             , AlwaysC AlwaysComb $ Asgn AsgnOpEq Nothing lhs tmpExpr]
@@ -182,7 +182,7 @@ rewriteDeclM (Variable d t x a e) = do
     return $ Variable d' t' x a e
 rewriteDeclM (Param s (IntegerVector _ sg []) x e) =
     return $ Param s (Implicit sg [(zero, zero)]) x e
-    where zero = Number "0"
+    where zero = RawNum 0
 rewriteDeclM (Param s (IntegerVector _ sg rs) x e) =
     return $ Param s (Implicit sg rs) x e
 rewriteDeclM decl = return decl
diff --git a/src/Convert/MultiplePacked.hs b/src/Convert/MultiplePacked.hs
index 5ad1c4a..92f3cd0 100644
--- a/src/Convert/MultiplePacked.hs
+++ b/src/Convert/MultiplePacked.hs
@@ -26,6 +26,7 @@
 
 module Convert.MultiplePacked (convert) where
 
+import Convert.ExprUtils
 import Control.Monad ((>=>))
 import Data.Tuple (swap)
 import Data.Maybe (isJust)
@@ -110,7 +111,7 @@ combineRanges r1 r2 = r
                 size2 = rangeSizeHiLo (s2, e2)
                 lower = BinOp Add e2 (BinOp Mul e1 size2)
                 upper = BinOp Add (BinOp Mul size1 size2)
-                            (BinOp Sub lower (Number "1"))
+                            (BinOp Sub lower (RawNum 1))
 
 traverseStmtM :: Stmt -> Scoper TypeInfo Stmt
 traverseStmtM =
@@ -254,7 +255,7 @@ convertExpr scopes =
                 maybeDims = dims expr
                 exprOuter = Bit expr idxInner
                 baseDec = fst rangeOuter
-                baseInc = BinOp Sub (BinOp Add baseDec len) (Number "1")
+                baseInc = BinOp Sub (BinOp Add baseDec len) (RawNum 1)
                 base = endianCondExpr rangeOuter baseDec baseInc
                 len = rangeSize rangeOuter
                 range = (base, len)
@@ -277,7 +278,7 @@ convertExpr scopes =
                 base = endianCondExpr dimOuter baseDec baseInc
                 len = lenOuter
                 range' = (base, len)
-                one = Number "1"
+                one = RawNum 1
         rewriteExpr (orig @ (Range expr NonIndexed range)) =
             if isJust maybeDims && expr == rewriteExpr expr
                 then rewriteExpr $ Range expr IndexedMinus range'
@@ -285,7 +286,7 @@ convertExpr scopes =
             where
                 maybeDims = dims expr
                 baseDec = fst range
-                baseInc = BinOp Sub (BinOp Add baseDec len) (Number "1")
+                baseInc = BinOp Sub (BinOp Add baseDec len) (RawNum 1)
                 base = endianCondExpr range baseDec baseInc
                 len = rangeSize range
                 range' = (base, len)
@@ -299,7 +300,7 @@ convertExpr scopes =
                 sizeOuter = rangeSize dimOuter
                 offsetOuter = uncurry (endianCondExpr dimOuter) $ swap dimOuter
                 (baseOrig, lenOrig) = range
-                lenOrigMinusOne = BinOp Sub lenOrig (Number "1")
+                lenOrigMinusOne = BinOp Sub lenOrig (RawNum 1)
                 baseSwapped =
                     orientIdx dimInner $
                     case mode of
diff --git a/src/Convert/ParamType.hs b/src/Convert/ParamType.hs
index af7b0cf..cf60dff 100644
--- a/src/Convert/ParamType.hs
+++ b/src/Convert/ParamType.hs
@@ -13,6 +13,7 @@ import Data.Maybe (isJust, isNothing, fromJust)
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
 
+import Convert.ExprUtils
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
@@ -164,7 +165,7 @@ convert files =
                 idents = Set.toList identSet
                 toParam :: Identifier -> Decl
                 toParam ident =
-                    Param Parameter typ name (Number "0")
+                    Param Parameter typ name (RawNum 0)
                     where
                         typ = Alias (addedParamTypeName paramName ident) []
                         name = addedParamName paramName ident
@@ -225,7 +226,7 @@ exprToType (Bit e i) =
         Just t -> Just $ tf (rs ++ [r])
             where
                 (tf, rs) = typeRanges t
-                r = (simplify $ BinOp Sub i (Number "1"), Number "0")
+                r = (simplify $ BinOp Sub i (RawNum 1), RawNum 0)
 exprToType _ = Nothing
 
 -- checks where a type is sufficiently resolved to be substituted
diff --git a/src/Convert/Simplify.hs b/src/Convert/Simplify.hs
index 4ccf63b..6cfd73e 100644
--- a/src/Convert/Simplify.hs
+++ b/src/Convert/Simplify.hs
@@ -19,6 +19,7 @@ module Convert.Simplify (convert) where
 import Control.Monad.State
 import qualified Data.Map.Strict as Map
 
+import Convert.ExprUtils
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
@@ -66,44 +67,56 @@ traverseStmtM :: Stmt -> State Info Stmt
 traverseStmtM stmt = traverseStmtExprsM traverseExprM stmt
 
 traverseExprM :: Expr -> State Info Expr
-traverseExprM = traverseNestedExprsM $ stately convertExpr
+traverseExprM = stately convertExpr
 
 substituteExprM :: Expr -> State Info Expr
-substituteExprM = traverseNestedExprsM $ stately substitute
+substituteExprM = stately substitute
 
 convertExpr :: Info -> Expr -> Expr
 convertExpr info (Cast (Right c) e) =
-    Cast (Right c') e
+    Cast (Right c') e'
     where
-        c' = simplify $ substitute info c
+        c' = convertExpr info $ substitute info c
+        e' = convertExpr info e
 convertExpr info (DimFn f v e) =
     DimFn f v e'
-    where
-        e' = simplify $ substitute info e
+    where e' = convertExpr info $ substitute info e
 convertExpr info (Call (Ident "$clog2") (Args [e] [])) =
-    if clog2' == clog2
-        then clog2
-        else clog2'
+    if val' == val
+        then val
+        else val'
     where
-        e' = simplify $ substitute info e
-        clog2 = Call (Ident "$clog2") (Args [e'] [])
-        clog2' = simplify clog2
+        e' = convertExpr info $ substitute info e
+        val = Call (Ident "$clog2") (Args [e'] [])
+        val' = simplifyStep val
 convertExpr info (Mux cc aa bb) =
     if before == after
-        then simplify $ Mux cc aa bb
-        else simplify $ Mux after aa bb
+        then simplifyStep $ Mux cc' aa' bb'
+        else simplifyStep $ Mux after aa' bb'
     where
-        before = substitute info cc
-        after = simplify before
-convertExpr _ (other @ Repeat{}) = traverseNestedExprs simplify other
-convertExpr _ (other @ Concat{}) = simplify other
-convertExpr _ (other @ BinOp{}) = simplify other
-convertExpr _ (other @ UniOp{}) = simplify other
-convertExpr _ other = other
+        before = substitute info cc'
+        after = convertExpr info before
+        aa' = convertExpr info aa
+        bb' = convertExpr info bb
+        cc' = convertExpr info cc
+convertExpr info (BinOp op e1 e2) =
+    simplifyStep $ BinOp op
+        (convertExpr info e1)
+        (convertExpr info e2)
+convertExpr info (UniOp op expr) =
+    simplifyStep $ UniOp op $ convertExpr info expr
+convertExpr info (Repeat expr exprs) =
+    simplifyStep $ Repeat
+        (convertExpr info expr)
+        (map (convertExpr info) exprs)
+convertExpr info (Concat exprs) =
+    simplifyStep $ Concat (map (convertExpr info) exprs)
+convertExpr info expr =
+    traverseSinglyNestedExprs (convertExpr info) expr
 
 substitute :: Info -> Expr -> Expr
 substitute info expr =
-    traverseNestedExprs substitute' $ simplify expr
+    traverseNestedExprs substitute' expr
     where
         substitute' :: Expr -> Expr
         substitute' (Ident x) =
diff --git a/src/Convert/SizeCast.hs b/src/Convert/SizeCast.hs
index 4831d16..49a7f02 100644
--- a/src/Convert/SizeCast.hs
+++ b/src/Convert/SizeCast.hs
@@ -12,6 +12,7 @@ import Control.Monad.Writer
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
 
+import Convert.ExprUtils
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
@@ -55,8 +56,8 @@ traverseModuleItemM item = traverseExprsM traverseExprM item
 traverseStmtM :: Stmt -> ST Stmt
 traverseStmtM stmt = traverseStmtExprsM traverseExprM stmt
 
-pattern ConvertedUU :: Char -> Expr
-pattern ConvertedUU ch = Number ['1', '\'', 's', 'b', ch]
+pattern ConvertedUU :: Integer -> Integer -> Expr
+pattern ConvertedUU a b = Number (Based 1 True Binary a b)
 
 traverseExprM :: Expr -> ST Expr
 traverseExprM =
@@ -64,16 +65,25 @@ traverseExprM =
     where
         convertExprM :: Expr -> ST Expr
         convertExprM (Cast (Right (Number s)) (Number n)) =
-            if elem '\'' n && s == takeWhile (/= '\'') n
-            then return $ Number n
-            else case (readNumber s, readNumber n) of
-                (Just s', Just n') ->
-                    return $ Number str
+            case n of
+                UnbasedUnsized{} -> fallback
+                Decimal (-32) True val ->
+                    num $ Decimal (fromIntegral size) False val'
                     where
-                        str = (show size) ++ "'d"  ++ (show num)
-                        size = s'
-                        num = n' `mod` (2 ^ s')
-                _ -> convertCastM (Number s) (Number n)
+                        Just size = numberToInteger s
+                        val' = val `mod` (2 ^ size)
+                Decimal size signed val ->
+                    if sizesMatch
+                        then num $ Decimal (abs size) signed val
+                        else fallback
+                Based size signed base vals knds ->
+                    if sizesMatch
+                        then num $ Based (abs size) signed base vals knds
+                        else fallback
+            where
+                sizesMatch = numberToInteger s == Just (numberBitLength n)
+                fallback = convertCastM (Number s) (Number n)
+                num = return . Number
         convertExprM (orig @ (Cast (Right DimsFn{}) _)) =
             return orig
         convertExprM (Cast (Right (Ident x)) e) = do
@@ -91,13 +101,13 @@ traverseExprM =
         convertExprM other = return other
 
         convertCastM :: Expr -> Expr -> ST Expr
-        convertCastM (s @ (Number str)) (e @ (ConvertedUU ch)) = do
-            typeMap <- get
-            case (exprSigning typeMap e, readNumber str) of
-                (Just Unspecified, Just n) -> return $ Number $
-                    show n ++ "'b" ++ take (fromIntegral n) (repeat ch)
-                (Just sg, _) -> convertCastWithSigningM s e sg
-                _ -> return $ Cast (Right s) e
+        convertCastM (RawNum n) (ConvertedUU a b) =
+            return $ Number $ Based (fromIntegral n) False Binary
+                (extend a) (extend b)
+            where
+                extend 0 = 0
+                extend 1 = (2 ^ n) - 1
+                extend _ = error "not possible"
         convertCastM s e = do
             typeMap <- get
             case exprSigning typeMap e of
@@ -117,7 +127,7 @@ castFn e sg =
     Function Automatic t fnName [decl] [Return $ Ident inp]
     where
         inp = "inp"
-        r = (simplify $ BinOp Sub e (Number "1"), Number "0")
+        r = (simplify $ BinOp Sub e (RawNum 1), RawNum 0)
         t = IntegerVector TLogic sg [r]
         fnName = castFnName e sg
         decl = Variable Input t inp [] Nil
@@ -130,7 +140,7 @@ castFnName e sg =
     where
         sizeStr = case e of
             Number n ->
-                case readNumber n of
+                case numberToInteger n of
                     Just v -> show v
                     _ -> shortHash e
             _ -> shortHash e
diff --git a/src/Convert/Stream.hs b/src/Convert/Stream.hs
index 312a31b..17024a9 100644
--- a/src/Convert/Stream.hs
+++ b/src/Convert/Stream.hs
@@ -29,8 +29,8 @@ streamerBlock chunk size asgn output input =
     , asgn output (Ident out)
     ]
     where
-        lo = Number "0"
-        hi = BinOp Sub size (Number "1")
+        lo = RawNum 0
+        hi = BinOp Sub size (RawNum 1)
         t = IntegerVector TLogic Unspecified [(hi, lo)]
         name = streamerBlockName chunk size
         inp = name ++ "_inp"
@@ -49,7 +49,7 @@ streamerBlock chunk size asgn output input =
         lhs2 = LHSRange (LHSIdent out) IndexedMinus (BinOp Sub hi base, left)
         expr2 = Range (Ident inp) IndexedPlus (base, left)
         stmt2 = Asgn AsgnOpEq Nothing lhs2 expr2
-        cmp2 = BinOp Gt left (Number "0")
+        cmp2 = BinOp Gt left (RawNum 0)
 
 streamerBlockName :: Expr -> Expr -> Identifier
 streamerBlockName chunk size =
@@ -60,11 +60,14 @@ traverseStmt (Asgn op mt lhs expr) =
     traverseAsgn (lhs, expr) (Asgn op mt)
 traverseStmt other = other
 
+zeroBit :: Expr
+zeroBit = Number $ Based 1 False Binary 0 0
+
 traverseAsgn :: (LHS, Expr) -> (LHS -> Expr -> Stmt) -> Stmt
 traverseAsgn (lhs, Stream StreamR _ exprs) constructor =
     constructor lhs expr
     where
-        expr = Concat $ exprs ++ [Repeat delta [Number "1'b0"]]
+        expr = Concat $ exprs ++ [Repeat delta [zeroBit]]
         size = DimsFn FnBits $ Right $ lhsToExpr lhs
         exprSize = DimsFn FnBits $ Right (Concat exprs)
         delta = BinOp Sub size exprSize
@@ -73,7 +76,7 @@ traverseAsgn (LHSStream StreamR _ lhss, expr) constructor =
 traverseAsgn (lhs, Stream StreamL chunk exprs) constructor = do
     streamerBlock chunk size constructor lhs expr
     where
-        expr = Concat $ Repeat delta [Number "1'b0"] : exprs
+        expr = Concat $ Repeat delta [zeroBit] : exprs
         size = DimsFn FnBits $ Right $ lhsToExpr lhs
         exprSize = DimsFn FnBits $ Right (Concat exprs)
         delta = BinOp Sub size exprSize
diff --git a/src/Convert/Struct.hs b/src/Convert/Struct.hs
index 0eb128d..3866159 100644
--- a/src/Convert/Struct.hs
+++ b/src/Convert/Struct.hs
@@ -12,6 +12,7 @@ import Data.Tuple (swap)
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
 
+import Convert.ExprUtils
 import Convert.Scoper
 import Convert.Traverse
 import Language.SystemVerilog.AST
@@ -43,7 +44,7 @@ convertStruct' isStruct sg fields =
         then Just (unstructType, unstructFields)
         else Nothing
     where
-        zero = Number "0"
+        zero = RawNum 0
         typeRange :: Type -> Range
         typeRange t =
             case ranges of
@@ -61,13 +62,13 @@ convertStruct' isStruct sg fields =
         -- used here because SystemVerilog structs are laid out backwards
         fieldLos =
             if isStruct
-                then map simplify $ tail $ scanr (BinOp Add) (Number  "0") fieldSizes
-                else map simplify $ repeat (Number "0")
+                then map simplify $ tail $ scanr (BinOp Add) (RawNum 0) fieldSizes
+                else map simplify $ repeat (RawNum 0)
         fieldHis =
             if isStruct
                 then map simplify $ init $ scanr (BinOp Add) minusOne fieldSizes
                 else map simplify $ map (BinOp Add minusOne) fieldSizes
-        minusOne = UniOp UniSub $ Number "1"
+        minusOne = UniOp UniSub $ RawNum 1
 
         -- create the mapping structure for the unstructured fields
         keys = map snd fields
@@ -80,7 +81,7 @@ convertStruct' isStruct sg fields =
             if isStruct
                 then foldl1 (BinOp Add) fieldSizes
                 else head fieldSizes
-        packedRange = (simplify $ BinOp Sub structSize (Number "1"), zero)
+        packedRange = (simplify $ BinOp Sub structSize (RawNum 1), zero)
         unstructType = IntegerVector TLogic sg [packedRange]
 
         -- check if this struct can be packed into an integer vector; we only
@@ -208,20 +209,20 @@ convertExpr (t @ IntegerVector{}) (Concat exprs) =
         caster = Cast (Left $ dropInnerTypeRange t)
         exprs' = map caster exprs
         isUnsizedNumber :: Expr -> Bool
-        isUnsizedNumber (Number n) = not $ elem '\'' n
+        isUnsizedNumber (Number n) = not $ numberIsSized n
         isUnsizedNumber (UniOp UniSub e) = isUnsizedNumber e
         isUnsizedNumber _ = False
 convertExpr (Struct packing fields (_:rs)) (Concat exprs) =
     Concat $ map (convertExpr (Struct packing fields rs)) exprs
 convertExpr (Struct packing fields (_:rs)) (Bit e _) =
     convertExpr (Struct packing fields rs) e
-convertExpr (Struct packing fields []) (Pattern [("", Repeat (Number nStr) exprs)]) =
-    case fmap fromIntegral (readNumber nStr) of
-        Just n -> convertExpr (Struct packing fields []) $ Pattern $
-                zip (repeat "") (concat $ take n $ repeat exprs)
+convertExpr (Struct packing fields []) (Pattern [("", Repeat (Number n) exprs)]) =
+    case fmap fromIntegral (numberToInteger n) of
+        Just val -> convertExpr (Struct packing fields []) $ Pattern $
+                zip (repeat "") (concat $ replicate val exprs)
         Nothing ->
             error $ "unable to handle repeat in pattern: " ++
-                (show $ Repeat (Number nStr) exprs)
+                (show $ Repeat (Number n) exprs)
 convertExpr (struct @ (Struct _ fields [])) (Pattern itemsOrig) =
     if extraNames /= Set.empty then
         error $ "pattern " ++ show (Pattern itemsOrig) ++
@@ -332,7 +333,7 @@ convertSubExpr scopes (Dot e x) =
         (fieldType, bounds, dims) = lookupFieldInfo subExprType x
         base = fst bounds
         len = rangeSize bounds
-        undotted = if null dims || rangeSize (head dims) == Number "1"
+        undotted = if null dims || rangeSize (head dims) == RawNum 1
             then Bit e' (fst bounds)
             else Range e' IndexedMinus (base, len)
 convertSubExpr scopes (Range (Dot e x) NonIndexed rOuter) =
@@ -374,7 +375,7 @@ convertSubExpr scopes (Range (Dot e x) mode (baseO, lenO)) =
             NonIndexed   -> error "invariant violated"
         base = endianCondExpr dim baseDec baseInc
         undotted = Range e' mode (base, lenO)
-        one = Number "1"
+        one = RawNum 1
 convertSubExpr scopes (Range e mode r) =
     (dropInnerTypeRange t, Range e' mode r)
     where (t, e') = convertSubExpr scopes e
diff --git a/src/Convert/Traverse.hs b/src/Convert/Traverse.hs
index 279ef2f..4f505a9 100644
--- a/src/Convert/Traverse.hs
+++ b/src/Convert/Traverse.hs
@@ -78,6 +78,9 @@ module Convert.Traverse
 , traverseNestedExprsM
 , traverseNestedExprs
 , collectNestedExprsM
+, traverseSinglyNestedExprsM
+, traverseSinglyNestedExprs
+, collectSinglyNestedExprsM
 , traverseNestedLHSsM
 , traverseNestedLHSs
 , collectNestedLHSsM
@@ -211,8 +214,13 @@ traverseSinglyNestedStmtsM fullMapper = cs
         cs (DoWhile e stmt) = fullMapper stmt >>= return . DoWhile e
         cs (Forever   stmt) = fullMapper stmt >>= return . Forever
         cs (Foreach x vars stmt) = fullMapper stmt >>= return . Foreach x vars
-        cs (If NoCheck (Number "1") s _) = fullMapper s
-        cs (If NoCheck (Number "0") _ s) = fullMapper s
+        cs (If NoCheck (Number n) s1 s2) = do
+            s1' <- fullMapper s1
+            s2' <- fullMapper s2
+            return $ case numberToInteger n of
+                Nothing -> If NoCheck (Number n) s1' s2'
+                Just 0 -> s2'
+                Just _ -> s1'
         cs (If u e s1 s2) = do
             s1' <- fullMapper s1
             s2' <- fullMapper s2
@@ -379,8 +387,16 @@ collectStmtLHSsM = collectify traverseStmtLHSsM
 
 traverseNestedExprsM :: Monad m => MapperM m Expr -> MapperM m Expr
 traverseNestedExprsM mapper = exprMapper
+    where exprMapper = mapper >=> traverseSinglyNestedExprsM exprMapper
+
+traverseNestedExprs :: Mapper Expr -> Mapper Expr
+traverseNestedExprs = unmonad traverseNestedExprsM
+collectNestedExprsM :: Monad m => CollectorM m Expr -> CollectorM m Expr
+collectNestedExprsM = collectify traverseNestedExprsM
+
+traverseSinglyNestedExprsM :: Monad m => MapperM m Expr -> MapperM m Expr
+traverseSinglyNestedExprsM exprMapper = em
     where
-        exprMapper = mapper >=> em
         (_, _, _, typeMapper, _) = exprMapperHelpers exprMapper
         typeOrExprMapper (Left t) =
             typeMapper t >>= return . Left
@@ -393,7 +409,8 @@ traverseNestedExprsM mapper = exprMapper
             e2' <- exprMapper e2
             return $ Right (e1', e2')
         em (String s) = return $ String s
-        em (Number s) = return $ Number s
+        em (Real   s) = return $ Real   s
+        em (Number n) = return $ Number n
         em (Time   s) = return $ Time   s
         em (Ident  i) = return $ Ident  i
         em (PSIdent x y) = return $ PSIdent x y
@@ -466,6 +483,11 @@ traverseNestedExprsM mapper = exprMapper
             return $ MinTypMax e1' e2' e3'
         em (Nil) = return Nil
 
+traverseSinglyNestedExprs :: Mapper Expr -> Mapper Expr
+traverseSinglyNestedExprs = unmonad traverseSinglyNestedExprsM
+collectSinglyNestedExprsM :: Monad m => CollectorM m Expr -> CollectorM m Expr
+collectSinglyNestedExprsM = collectify traverseSinglyNestedExprsM
+
 exprMapperHelpers :: Monad m => MapperM m Expr ->
     ( MapperM m Range
     , MapperM m Decl
@@ -1033,8 +1055,11 @@ traverseNestedModuleItemsM mapper = fullMapper
                 Generate subItems -> GenBlock "" subItems
                 _ -> GenModuleItem moduleItem'
         genItemMapper (GenIf _ GenNull GenNull) = return GenNull
-        genItemMapper (GenIf (Number "1") s _) = return s
-        genItemMapper (GenIf (Number "0") _ s) = return s
+        genItemMapper (GenIf (Number n) s1 s2) = do
+            case numberToInteger n of
+                Nothing -> return $ GenIf (Number n) s1 s2
+                Just 0 -> genItemMapper s2
+                Just _ -> genItemMapper s1
         genItemMapper (GenBlock "" [item]) = return item
         genItemMapper (GenBlock _ []) = return GenNull
         genItemMapper other = return other
@@ -1049,11 +1074,6 @@ traverseNestedStmts = unmonad traverseNestedStmtsM
 collectNestedStmtsM :: Monad m => CollectorM m Stmt -> CollectorM m Stmt
 collectNestedStmtsM = collectify traverseNestedStmtsM
 
-traverseNestedExprs :: Mapper Expr -> Mapper Expr
-traverseNestedExprs = unmonad traverseNestedExprsM
-collectNestedExprsM :: Monad m => CollectorM m Expr -> CollectorM m Expr
-collectNestedExprsM = collectify traverseNestedExprsM
-
 -- Traverse all the declaration scopes within a ModuleItem. Note that Functions,
 -- Tasks, Always/Initial/Final blocks are all NOT passed through ModuleItem
 -- mapper, and Decl ModuleItems are NOT passed through the Decl mapper. The
diff --git a/src/Convert/TypeOf.hs b/src/Convert/TypeOf.hs
index 2422aef..0b22d85 100644
--- a/src/Convert/TypeOf.hs
+++ b/src/Convert/TypeOf.hs
@@ -6,7 +6,6 @@
 
 module Convert.TypeOf (convert) where
 
-import Data.List (elemIndex)
 import Data.Tuple (swap)
 import qualified Data.Map.Strict as Map
 
@@ -76,8 +75,9 @@ typeof :: Expr -> Scoper Type Type
 typeof (Number n) =
     return $ IntegerVector TLogic sg [r]
     where
-        (size, sg) = parseNumber n
-        r = (Number $ show (size - 1), Number "0")
+        r = (RawNum $ size - 1, RawNum 0)
+        size = numberBitLength n
+        sg = if numberIsSigned n then Signed else Unspecified
 typeof (Call (Ident x) _) =
     typeof $ Ident x
 typeof (orig @ (Bit e _)) = do
@@ -94,8 +94,8 @@ typeof (orig @ (Range e mode r)) = do
         lo = fst r
         hi = case mode of
             NonIndexed   -> snd r
-            IndexedPlus  -> BinOp Sub (uncurry (BinOp Add) r) (Number "1")
-            IndexedMinus -> BinOp Add (uncurry (BinOp Sub) r) (Number "1")
+            IndexedPlus  -> BinOp Sub (uncurry (BinOp Add) r) (RawNum 1)
+            IndexedMinus -> BinOp Add (uncurry (BinOp Sub) r) (RawNum 1)
 typeof (orig @ (Dot e x)) = do
     t <- typeof e
     case t of
@@ -133,19 +133,6 @@ typeof (Repeat reps exprs) = return $ typeOfSize size
     where size = BinOp Mul reps (concatSize exprs)
 typeof other = lookupTypeOf other
 
--- determines the size and sign of a number literal
-parseNumber :: String -> (Integer, Signing)
-parseNumber s =
-    case elemIndex '\'' s of
-        Nothing  -> (32, Signed)
-        Just 0   -> parseNumber $ '3' : '2' : s
-        Just idx -> (size, signing)
-            where
-                Just size = readNumber $ take idx s
-                signing = case drop (idx + 1) s of
-                    's' : _ -> Signed
-                    _       -> Unsigned
-
 -- produces a type large enough to hold either expression
 largerSizeType :: Expr -> Expr -> Type
 largerSizeType a b =
@@ -158,7 +145,7 @@ largerSizeType a b =
 -- returns the total size of concatenated list of expressions
 concatSize :: [Expr] -> Expr
 concatSize exprs =
-    foldl (BinOp Add) (Number "0") $
+    foldl (BinOp Add) (RawNum 0) $
     map sizeof exprs
     where
         sizeof = DimsFn FnBits . Right
@@ -166,10 +153,10 @@ concatSize exprs =
 -- produces a generic type of the given size
 typeOfSize :: Expr -> Type
 typeOfSize size =
-    IntegerVector TLogic sg [(hi, Number "0")]
+    IntegerVector TLogic sg [(hi, RawNum 0)]
     where
         sg = Unspecified -- suitable for now
-        hi = BinOp Sub size (Number "1")
+        hi = BinOp Sub size (RawNum 1)
 
 -- combines a type with unpacked ranges
 injectRanges :: Type -> [Range] -> Type
diff --git a/src/Convert/UnbasedUnsized.hs b/src/Convert/UnbasedUnsized.hs
index 7ca1434..b27ac55 100644
--- a/src/Convert/UnbasedUnsized.hs
+++ b/src/Convert/UnbasedUnsized.hs
@@ -76,7 +76,7 @@ bindItem ports bind =
     where
         portName = lookupPort ports (bPort bind)
         size = DimsFn FnBits $ Right $ Ident portName
-        rng = (BinOp Sub size (Number "1"), Number "0")
+        rng = (BinOp Sub size (RawNum 1), RawNum 0)
         typ = Implicit Unspecified [rng]
         name = bindName bind
         expr = literalFor $ bBit bind
@@ -102,8 +102,8 @@ convertModuleItemM (Instance moduleName params instanceName [] bindings) = do
             expr'' <- traverseNestedExprsM (replaceBindingExpr port) expr'
             return (portName, expr'')
         replaceBindingExpr :: Port -> Expr -> Writer Binds Expr
-        replaceBindingExpr port (orig @ (Cast Right{} (Number num))) = do
-            let ch = last num
+        replaceBindingExpr port (orig @ (Cast Right{} (ConvertedUU a b))) = do
+            let ch = charForBit a b
             if orig == sizedLiteralFor tag ch
                 then do
                     let bind = Bind moduleName ch port
@@ -120,14 +120,24 @@ convertModuleItem =
     traverseTypes (traverseNestedTypes convertType) .
     traverseAsgns convertAsgn
 
-digits :: [Char]
-digits = ['0', '1', 'x', 'z', 'X', 'Z']
-
 literalFor :: Char -> Expr
-literalFor ch =
-    if elem ch digits
-        then Number ("1'sb" ++ [ch])
-        else error $ "unexpected unbased-unsized digit: " ++ [ch]
+literalFor 'Z' = literalFor 'z'
+literalFor 'X' = literalFor 'x'
+literalFor '0' = Number $ Based 1 True Binary 0 0
+literalFor '1' = Number $ Based 1 True Binary 1 0
+literalFor 'x' = Number $ Based 1 True Binary 0 1
+literalFor 'z' = Number $ Based 1 True Binary 1 1
+literalFor ch = error $ "unexpected unbased-unsized digit: " ++ [ch]
+
+pattern ConvertedUU :: Integer -> Integer -> Expr
+pattern ConvertedUU a b = Number (Based 1 True Binary a b)
+
+charForBit :: Integer -> Integer -> Char
+charForBit 0 0 = '0'
+charForBit 1 0 = '1'
+charForBit 0 1 = 'x'
+charForBit 1 1 = 'z'
+charForBit _ _ = error "charForBit invariant violated"
 
 sizedLiteralFor :: Expr -> Char -> Expr
 sizedLiteralFor expr ch =
@@ -206,7 +216,7 @@ convertExpr (ContextDetermined expr) (UU ch) =
 convertExpr _ other = other
 
 pattern UU :: Char -> Expr
-pattern UU ch = Number ['\'', ch]
+pattern UU ch = Number (UnbasedUnsized ch)
 
 convertType :: Type -> Type
 convertType (TypeOf e) = TypeOf $ convertExpr SelfDetermined e
diff --git a/src/Convert/Wildcard.hs b/src/Convert/Wildcard.hs
index a50f416..318a1bc 100644
--- a/src/Convert/Wildcard.hs
+++ b/src/Convert/Wildcard.hs
@@ -34,7 +34,7 @@ import qualified Data.Map.Strict as Map
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
-type Patterns = Map.Map Identifier String
+type Patterns = Map.Map Identifier Number
 
 convert :: [AST] -> [AST]
 convert = map $ traverseDescriptions convertDescription
@@ -64,10 +64,7 @@ traverseExprM = traverseNestedExprsM $ stately convertExpr
 
 isPlainPattern :: Patterns -> Expr -> Bool
 isPlainPattern _ (Number n) =
-    not $ any isWildcardChar n
-    where
-        isWildcardChar :: Char -> Bool
-        isWildcardChar = flip elem "xzXZ?"
+    numberToInteger n /= Nothing
 isPlainPattern patterns (Ident x) =
     case Map.lookup x patterns of
         Nothing -> False
@@ -81,7 +78,7 @@ convertExpr patterns (BinOp WEq l r) =
         else
             BinOp BitAnd couldMatch $
             BinOp BitOr  noExtraXZs $
-            Number "1'bx"
+            Number (Based 1 False Binary 0 1)
     where
         lxl = BinOp BitXor l l
         rxr = BinOp BitXor r r
diff --git a/src/Language/SystemVerilog/AST.hs b/src/Language/SystemVerilog/AST.hs
index ee22105..4d93f85 100644
--- a/src/Language/SystemVerilog/AST.hs
+++ b/src/Language/SystemVerilog/AST.hs
@@ -22,6 +22,7 @@ module Language.SystemVerilog.AST
     , module GenItem
     , module LHS
     , module ModuleItem
+    , module Number
     , module Op
     , module Stmt
     , module Type
@@ -40,6 +41,7 @@ import Language.SystemVerilog.AST.Expr as Expr
 import Language.SystemVerilog.AST.GenItem as GenItem
 import Language.SystemVerilog.AST.LHS as LHS
 import Language.SystemVerilog.AST.ModuleItem as ModuleItem
+import Language.SystemVerilog.AST.Number as Number
 import Language.SystemVerilog.AST.Op as Op
 import Language.SystemVerilog.AST.Stmt as Stmt
 import Language.SystemVerilog.AST.Type as Type
diff --git a/src/Language/SystemVerilog/AST/Expr.hs b/src/Language/SystemVerilog/AST/Expr.hs
index 32e88da..b811532 100644
--- a/src/Language/SystemVerilog/AST/Expr.hs
+++ b/src/Language/SystemVerilog/AST/Expr.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE PatternSynonyms #-}
 {- sv2v
  - Author: Zachary Snow <zach@zachjs.com>
  - Initial Verilog AST Author: Tom Hawkins <tomahawkins@gmail.com>
@@ -17,23 +18,15 @@ module Language.SystemVerilog.AST.Expr
     , showAssignment
     , showRanges
     , showExprOrRange
-    , simplify
-    , rangeSize
-    , rangeSizeHiLo
-    , endianCondExpr
-    , endianCondRange
-    , dimensionsSize
-    , readNumber
     , ParamBinding
     , showParams
+    , pattern RawNum
     ) where
 
-import Data.Bits (shiftL, shiftR)
 import Data.List (intercalate)
-import Numeric (readHex)
 import Text.Printf (printf)
-import Text.Read (readMaybe)
 
+import Language.SystemVerilog.AST.Number (Number(..))
 import Language.SystemVerilog.AST.Op
 import Language.SystemVerilog.AST.ShowHelp
 import {-# SOURCE #-} Language.SystemVerilog.AST.Type
@@ -43,9 +36,13 @@ type Range = (Expr, Expr)
 type TypeOrExpr = Either Type Expr
 type ExprOrRange = Either Expr Range
 
+pattern RawNum :: Integer -> Expr
+pattern RawNum n = Number (Decimal (-32) True n)
+
 data Expr
     = String  String
-    | Number  String
+    | Real    String
+    | Number  Number
     | Time    String
     | Ident   Identifier
     | PSIdent Identifier Identifier
@@ -71,9 +68,10 @@ data Expr
 
 instance Show Expr where
     show (Nil          ) = ""
-    show (Number  str  ) = str
     show (Time    str  ) = str
     show (Ident   str  ) = str
+    show (Real    str  ) = str
+    show (Number  n    ) = show n
     show (PSIdent x y  ) = printf "%s::%s" x y
     show (CSIdent x p y) = printf "%s#%s::%s" x (showParams p) y
     show (String  str  ) = printf "\"%s\"" str
@@ -193,24 +191,6 @@ showExprOrRange :: ExprOrRange -> String
 showExprOrRange (Left  x) = show x
 showExprOrRange (Right x) = show x
 
-clog2Help :: Integer -> Integer -> Integer
-clog2Help p n = if p >= n then 0 else 1 + clog2Help (p*2) n
-clog2 :: Integer -> Integer
-clog2 n = if n < 2 then 0 else clog2Help 1 n
-
-readNumber :: String -> Maybe Integer
-readNumber ('3' : '2' : '\'' : 'd' : rest) = readMaybe rest
-readNumber (            '\'' : 'd' : rest) = readMaybe rest
-readNumber ('3' : '2' : '\'' : 'h' : rest) =
-    case readHex rest of
-        [(v, _)] -> Just v
-        _ -> Nothing
-readNumber ('\'' : 'h' : rest) =
-    case readHex rest of
-        [(v, _)] -> Just v
-        _ -> Nothing
-readNumber n = readMaybe n
-
 showUniOpPrec :: Expr -> ShowS
 showUniOpPrec (e @ UniOp{}) = (showParen True . shows) e
 showUniOpPrec (e @ BinOp{}) = (showParen True . shows) e
@@ -220,154 +200,6 @@ showBinOpPrec :: Expr -> ShowS
 showBinOpPrec (e @ BinOp{}) = (showParen True . shows) e
 showBinOpPrec e = shows 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 (UniOp LogNot (BinOp Eq a b)) = BinOp Ne a b
-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 [Number n] []))) =
-    case readNumber n of
-        Nothing -> orig
-        Just x -> toLiteral $ 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 Sub (BinOp Add e (Number n1)) (Number n2)) =
-    simplify $ BinOp Add e (BinOp Sub (Number n1) (Number n2))
-simplify (BinOp Add (Number n1) (BinOp Add (Number n2) e)) =
-    simplify $ BinOp Add (BinOp Add (Number n1) (Number n2)) e
-simplify (BinOp Ge (BinOp Sub e (Number "1")) (Number "0")) =
-    simplify $ BinOp Ge e (Number "1")
-simplify (BinOp Add e1 (UniOp UniSub e2)) =
-    simplify $ BinOp Sub e1 e2
-simplify (BinOp Add (UniOp UniSub e2) e1) =
-    simplify $ BinOp Sub e1 e2
-simplify (BinOp Add (BinOp Sub (Number n1) e) (Number n2)) =
-    case (readNumber n1, readNumber n2) of
-        (Just x, Just y) ->
-            simplify $ BinOp Sub (toLiteral (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, readNumber b) of
-                (Add, Just x, Just y) -> toLiteral (x + y)
-                (Sub, Just x, Just y) -> toLiteral (x - y)
-                (Mul, Just x, Just y) -> toLiteral (x * y)
-                (Div, Just _, Just 0) -> Number "x"
-                (Div, Just x, Just y) -> toLiteral (x `quot` y)
-                (Mod, Just x, Just y) -> toLiteral (x `rem` y)
-                (Pow, Just x, Just y) -> toLiteral (x ^ 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
-                (ShiftAL, Just x, Just y) -> toLiteral $ shiftL x (toInt y)
-                (ShiftAR, Just x, Just y) -> toLiteral $ shiftR x (toInt y)
-                (ShiftL , Just x, Just y) -> toLiteral $ shiftL x (toInt y)
-                (ShiftR , Just x, Just y) ->
-                    if x < 0 && y > 0
-                        then BinOp ShiftR (Number a) (Number b)
-                        else toLiteral $ shiftR x (toInt y)
-                _ -> BinOp op e1' e2'
-            where
-                toInt :: Integer -> Int
-                toInt = fromIntegral
-        (Add, BinOp Add e (Number a), Number b) ->
-            case (readNumber a, readNumber b) of
-                (Just x, Just y) -> BinOp Add e $ toLiteral (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
-
-toLiteral :: Integer -> Expr
-toLiteral n =
-    if n >= 4294967296
-        then Number $ show (bits n) ++ "'d" ++ show n
-        else Number $ show n
-
-bits :: Integer -> Integer
-bits 0 = 0
-bits n = 1 + bits (quot n 2)
-
-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
-
 type ParamBinding = (Identifier, TypeOrExpr)
 
 showParams :: [ParamBinding] -> String
diff --git a/src/Language/SystemVerilog/AST/Number.hs b/src/Language/SystemVerilog/AST/Number.hs
new file mode 100644
index 0000000..eb9cec5
--- /dev/null
+++ b/src/Language/SystemVerilog/AST/Number.hs
@@ -0,0 +1,298 @@
+{- sv2v
+ - Author: Zachary Snow <zach@zachjs.com>
+ -
+ - SystemVerilog number literals
+ -}
+
+module Language.SystemVerilog.AST.Number
+    ( Number (..)
+    , Base (..)
+    , parseNumber
+    , numberBitLength
+    , numberIsSigned
+    , numberIsSized
+    , numberToInteger
+    ) where
+
+import Data.Char (digitToInt, intToDigit, toLower)
+import Data.List (elemIndex)
+import Text.Read (readMaybe)
+
+-- normalize the number first, making everything lowercase and removing
+-- visual niceties like spaces and underscores
+parseNumber :: String -> Number
+parseNumber = parseNumber' . map toLower . filter (not . isPad)
+    where isPad ch = ch == '_' || ch == ' '
+
+parseNumber' :: String -> Number
+parseNumber' ['\'', ch] = UnbasedUnsized ch
+parseNumber' str =
+    -- simple decimal number
+    if maybeIdx == Nothing then
+        let n = readDecimal str
+        in Decimal (negate $ decimalSize True n) True n
+    -- non-decimal based integral number
+    else if maybeBase /= Nothing then
+        let (values, kinds) = parseBasedDigits (baseSize base) digitsExtended
+        in Based size signed base values kinds
+    -- decimal X or Z literal
+    else if numDigits == 1 && elem leadDigit xzDigits then
+        let (vals, knds) = parseBasedDigits 2 $ replicate (abs size) leadDigit
+        in Based size signed Binary vals knds
+    -- explicitly-based decimal number
+    else
+        let num = readDecimal digits
+        in if rawSize == 0
+            then Decimal (negate $ decimalSize signed num) signed num
+            else Decimal size signed num
+    where
+        -- pull out the components of the literals
+        maybeIdx = elemIndex '\'' str
+        Just idx = maybeIdx
+        signBasedAndDigits = drop (idx + 1) str
+        (signed, baseAndDigits) = takeSign signBasedAndDigits
+        (maybeBase, digits) = takeBase baseAndDigits
+
+        -- high-order X or Z is extended up to the size of the literal
+        leadDigit = head digits
+        numDigits = length digits
+        digitsExtended =
+            if elem leadDigit xzDigits
+                then replicate (sizeDigits - numDigits) leadDigit ++ digits
+                else digits
+
+        -- determine the number of digits needed based on the size
+        sizeDigits = ((abs size) `div` bitsPerDigit) + sizeExtraDigit
+        sizeExtraDigit =
+            if (abs size) `mod` bitsPerDigit == 0
+                then 0
+                else 1
+
+        -- determine the explicit size of the literal in bites
+        Just base = maybeBase
+        rawSize =
+            if idx == 0
+                then 0
+                else readDecimal $ take idx str
+        size =
+            if rawSize /= 0 then
+                rawSize
+            else if maybeBase /= Nothing then
+                negate $ max 32 (bitsPerDigit * numDigits)
+            else
+                -32
+        bitsPerDigit = bits $ baseSize base - 1
+
+-- read a simple unsigned decimal number
+readDecimal :: Read a => String -> a
+readDecimal str =
+    case readMaybe str of
+        Nothing -> error $ "could not parse decimal " ++ show str
+        Just n -> n
+
+-- returns the number of bits necessary to represent a number; it gives an extra
+-- bit for signed numbers so that the literal doesn't sign extend unnecessarily
+decimalSize :: Bool -> Integer -> Int
+decimalSize True = max 32 . fromIntegral . bits . (* 2)
+decimalSize False = max 32 . fromIntegral . bits
+
+-- remove the leading sign specified, if it is present
+takeSign :: String -> (Bool, String)
+takeSign ('s' : rest) = (True, rest)
+takeSign rest = (False, rest)
+
+-- pop the leading base specified from a based coda
+takeBase :: String -> (Maybe Base, String)
+takeBase ('d' : rest) = (Nothing, rest)
+takeBase ('b' : rest) = (Just Binary, rest)
+takeBase ('o' : rest) = (Just Octal, rest)
+takeBase ('h' : rest) = (Just Hex, rest)
+takeBase rest = error $ "cannot parse based coda " ++ show rest
+
+-- convert the digits of a based number to its corresponding value and kind bits
+parseBasedDigits :: Integer -> String -> (Integer, Integer)
+parseBasedDigits base str =
+    (values, kinds)
+    where
+        values = parseDigits parseValueDigit str
+        kinds = parseDigits parseKindDigit str
+
+        parseDigits :: (Char -> Integer) -> String -> Integer
+        parseDigits f = foldl sumStep 0 . map f
+        sumStep :: Integer -> Integer -> Integer
+        sumStep total digit = total * base + digit
+
+        parseValueDigit :: Char -> Integer
+        parseValueDigit x =
+            if elem x xDigits then
+                0
+            else if elem x zDigits then
+                base - 1
+            else
+                fromIntegral $ digitToInt x
+
+        parseKindDigit :: Char -> Integer
+        parseKindDigit x =
+            if elem x xzDigits
+                then base - 1
+                else 0
+
+xDigits :: [Char]
+xDigits = ['x']
+zDigits :: [Char]
+zDigits = ['z', '?']
+xzDigits :: [Char]
+xzDigits = xDigits ++ zDigits
+
+data Base
+    = Binary
+    | Octal
+    | Hex
+    deriving (Eq, Ord)
+
+instance Show Base where
+    show Binary = "b"
+    show Octal  = "o"
+    show Hex    = "h"
+
+data Number
+    = UnbasedUnsized Char
+    | Decimal Int Bool Integer
+    | Based   Int Bool Base Integer Integer
+    deriving (Eq, Ord)
+
+baseSize :: Integral a => Base -> a
+baseSize Binary = 2
+baseSize Octal  = 8
+baseSize Hex    = 16
+
+-- get the number of bits in a number
+numberBitLength :: Number -> Integer
+numberBitLength UnbasedUnsized{} = 32
+numberBitLength (Decimal size _ _) = fromIntegral $ abs size
+numberBitLength (Based size _ _ _ _) = fromIntegral $ abs size
+
+-- get whether or not a number is signed
+numberIsSized :: Number -> Bool
+numberIsSized UnbasedUnsized{} = False
+numberIsSized (Decimal size _ _) = size > 0
+numberIsSized (Based size _ _ _ _) = size > 0
+
+-- get whether or not a number is signed
+numberIsSigned :: Number -> Bool
+numberIsSigned UnbasedUnsized{} = False
+numberIsSigned (Decimal _ signed _) = signed
+numberIsSigned (Based _ signed _ _ _) = signed
+
+-- get the integer value of a number, provided it has not X or Z bits
+numberToInteger :: Number -> Maybe Integer
+numberToInteger (UnbasedUnsized '1') = Just 1
+numberToInteger (UnbasedUnsized '0') = Just 0
+numberToInteger UnbasedUnsized{} = Nothing
+numberToInteger (Decimal _ _ num) = Just num
+numberToInteger (Based _ _ _ num 0) = Just num
+numberToInteger Based{} = Nothing
+
+-- return the number of bits in a number (i.e. ilog2)
+bits :: Integral a => a -> a
+bits 0 = 0
+bits n = 1 + bits (quot n 2)
+
+-- number to string conversion
+instance Show Number where
+    show (UnbasedUnsized ch) =
+        if elem ch "01xzXZ"
+            then ['\'', ch]
+            else error $ "illegal unbased-unsized char: " ++ show ch
+    show (Decimal (-32) True value) =
+        if value < 0
+            then error $ "illegal decimal: " ++ show value
+            else show value
+    show (Decimal size signed value) =
+        if size == 0
+            then error $ "illegal decimal literal: "
+                ++ show (size, signed, value)
+            else sizeStr ++ '\'' : signedStr ++ 'd' : valueStr
+        where
+            sizeStr = if size > 0 then show size else ""
+            signedStr = if signed then "s" else ""
+            valueStr = show value
+    show (Based size signed base value kinds) =
+        if size == 0 || value < 0 || kinds < 0
+            then error $ "illegal based literal: "
+                ++ show (size, signed, base, value, kinds)
+            else sizeStr ++ '\'' : signedStr ++ baseCh : valueStr
+        where
+            sizeStr = if size > 0 then show size else ""
+            signedStr = if signed then "s" else ""
+            [baseCh] = show base
+            valueStr = showBasedDigits (baseSize base) size value kinds
+
+showBasedDigits :: Int -> Int -> Integer -> Integer -> String
+showBasedDigits base size values kinds =
+    if numDigits > sizeDigits then
+        error $ "invalid based literal digits: "
+            ++ show (base, size, values, kinds, numDigits, sizeDigits)
+    else if size < -32 then
+        padList '0' sizeDigits digits
+    else if leadingXZ && size < 0 then
+        removeExtraPadding digits
+    else if leadingXZ then
+        padList '0' sizeDigits digits
+    else
+        digits
+    where
+        valChunks = chunk (fromIntegral base) values
+        kndChunks = chunk (fromIntegral base) kinds
+        numDigits = max (length valChunks) (length kndChunks)
+
+        digits = zipWith combineChunks
+            (padList 0 numDigits valChunks)
+            (padList 0 numDigits kndChunks)
+        leadingXZ = elem (head digits) xzDigits
+
+        removeExtraPadding :: String -> String
+        removeExtraPadding ('x' : 'x' : chs) = removeExtraPadding ('x' : chs)
+        removeExtraPadding ('z' : 'z' : chs) = removeExtraPadding ('z' : chs)
+        removeExtraPadding chs = chs
+
+        -- determine the number of digits needed based on the explicit size
+        sizeDigits = ((abs size) `div` bitsPerDigit) + sizeExtraDigit
+        sizeExtraDigit =
+            if (abs size) `mod` bitsPerDigit == 0
+                then 0
+                else 1
+        bitsPerDigit = bits $ base - 1
+
+        -- combine a value and kind digit into their corresponding character
+        combineChunks :: Int -> Int -> Char
+        combineChunks value kind =
+            if kind == 0 then
+                intToDigit value
+            else if kind /= base - 1 then
+                invalid
+            else if value == 0 then
+                'x'
+            else if value == base - 1 then
+                'z'
+            else
+                invalid
+            where
+                invalid = error $ "based bits inconsistent: "
+                    ++ show (base, values, kinds, value, kind)
+
+-- pad the left side of a list with `padding` to be at least `size` elements
+padList :: a -> Int -> [a] -> [a]
+padList padding size values =
+    replicate (size - length values) padding ++ values
+
+-- split an integer into chunks of `base` bits
+chunk :: Integer -> Integer -> [Int]
+chunk base n0 =
+    reverse $ chunkStep (quotRem n0 base)
+    where
+        chunkStep (n, d) =
+            case n of
+                0 -> [d']
+                _ -> d' : chunkStep (quotRem n base)
+            where d' = fromIntegral d
diff --git a/src/Language/SystemVerilog/AST/Type.hs b/src/Language/SystemVerilog/AST/Type.hs
index cb26853..f1fea7e 100644
--- a/src/Language/SystemVerilog/AST/Type.hs
+++ b/src/Language/SystemVerilog/AST/Type.hs
@@ -112,10 +112,10 @@ typeRanges (UnpackedType t rs) = (UnpackedType t, rs)
 
 nullRange :: Type -> ([Range] -> Type)
 nullRange t [] = t
-nullRange t [(Number "0", Number "0")] = t
+nullRange t [(RawNum 0, RawNum 0)] = t
 nullRange (IntegerAtom TInteger sg) rs =
     -- integer arrays are allowed in SystemVerilog but not in Verilog
-    IntegerVector TBit sg (rs ++ [(Number "31", Number "0")])
+    IntegerVector TBit sg (rs ++ [(RawNum 31, RawNum 0)])
 nullRange t rs1 =
     if t == t'
         then error $ "non-vector type " ++ show t ++
@@ -136,9 +136,9 @@ elaborateIntegerAtom other = other
 -- size; if not unspecified, the first signing overrides the second
 baseIntType :: Signing -> Signing -> Int -> Type
 baseIntType sgOverride sgBase size =
-    IntegerVector TReg sg [(Number hi, Number "0")]
+    IntegerVector TReg sg [(RawNum hi, RawNum 0)]
     where
-        hi = show (size - 1)
+        hi = fromIntegral $ size - 1
         sg = if sgOverride /= Unspecified
                 then sgOverride
                 else sgBase
diff --git a/src/Language/SystemVerilog/Parser/Lex.x b/src/Language/SystemVerilog/Parser/Lex.x
index a45bb7d..528ab00 100644
--- a/src/Language/SystemVerilog/Parser/Lex.x
+++ b/src/Language/SystemVerilog/Parser/Lex.x
@@ -74,9 +74,6 @@ import Language.SystemVerilog.Parser.Tokens
     | @binaryNumber
     | @hexNumber
     | @unbasedUnsizedLiteral
-@number
-    = @integralNumber
-    | @realNumber
 
 -- Strings
 
@@ -366,7 +363,8 @@ tokens :-
     @escapedIdentifier { tok Id_escaped }
     @systemIdentifier  { tok Id_system  }
 
-    @number            { tok Lit_number }
+    @realNumber        { tok Lit_real }
+    @integralNumber    { tok Lit_number }
     @string            { tok Lit_string }
     @time              { tok Lit_time }
 
diff --git a/src/Language/SystemVerilog/Parser/Parse.y b/src/Language/SystemVerilog/Parser/Parse.y
index 19fbfe7..ab51ef6 100644
--- a/src/Language/SystemVerilog/Parser/Parse.y
+++ b/src/Language/SystemVerilog/Parser/Parse.y
@@ -295,6 +295,7 @@ import Language.SystemVerilog.Parser.Tokens
 simpleIdentifier   { Token Id_simple       _ _ }
 escapedIdentifier  { Token Id_escaped      _ _ }
 systemIdentifier   { Token Id_system       _ _ }
+real               { Token Lit_real        _ _ }
 number             { Token Lit_number      _ _ }
 string             { Token Lit_string      _ _ }
 time               { Token Lit_time        _ _ }
@@ -630,10 +631,10 @@ DeclToken :: { DeclToken }
   | ExplicitLifetime                   {% posInject \p -> DTLifetime p $1 }
   | "const" PartialType                {% posInject \p -> DTType     p $2 }
   | "{" StreamOp StreamSize Concat "}" {% posInject \p -> DTStream   p $2 $3           (map toLHS $4) }
-  | "{" StreamOp            Concat "}" {% posInject \p -> DTStream   p $2 (Number "1") (map toLHS $3) }
+  | "{" StreamOp            Concat "}" {% posInject \p -> DTStream   p $2 (RawNum 1) (map toLHS $3) }
   | opt("var") "type" "(" Expr ")"     {% posInject \p -> DTType     p (\Unspecified -> \[] -> TypeOf $4) }
   | "<=" opt(DelayOrEvent) Expr        {% posInject \p -> DTAsgn     p AsgnOpNonBlocking $2 $3 }
-  | IncOrDecOperator                   {% posInject \p -> DTAsgn     p (AsgnOp $1) Nothing (Number "1") }
+  | IncOrDecOperator                   {% posInject \p -> DTAsgn     p (AsgnOp $1) Nothing (RawNum 1) }
   | Identifier               "::" Identifier {% posInject \p -> DTPSIdent p $1    $3 }
   | Identifier ParamBindings "::" Identifier {% posInject \p -> DTCSIdent p $1 $2 $4 }
 DeclTokenAsgn :: { DeclToken }
@@ -905,7 +906,7 @@ DimensionsNonEmpty :: { [Range] }
   | DimensionsNonEmpty Dimension { $1 ++ [$2] }
 Dimension :: { Range }
   : Range        { $1 }
-  | "[" Expr "]" { (Number "0", BinOp Sub $2 (Number "1")) }
+  | "[" Expr "]" { (RawNum 0, BinOp Sub $2 (RawNum 1)) }
 
 DeclAsgns :: { [(Identifier, Expr, [Range])] }
   : DeclAsgn               { [$1] }
@@ -928,8 +929,8 @@ LHS :: { LHS }
   | LHS "[" Expr "]"   { LHSBit    $1 $3 }
   | LHS "." Identifier { LHSDot    $1 $3 }
   | LHSConcat          { LHSConcat $1    }
-  | "{" StreamOp StreamSize Concat "}" { LHSStream $2 $3           (map toLHS $4) }
-  | "{" StreamOp            Concat "}" { LHSStream $2 (Number "1") (map toLHS $3) }
+  | "{" StreamOp StreamSize Concat "}" { LHSStream $2 $3         (map toLHS $4) }
+  | "{" StreamOp            Concat "}" { LHSStream $2 (RawNum 1) (map toLHS $3) }
 
 LHSConcat :: { [LHS] }
   : "{" LHSs "}" { $2 }
@@ -972,8 +973,8 @@ StmtAsgn :: { Stmt }
   : LHS "="  opt(DelayOrEvent) Expr ";" { Asgn AsgnOpEq $3 $1 $4 }
   | LHS "<=" opt(DelayOrEvent) Expr ";" { Asgn AsgnOpNonBlocking $3 $1 $4 }
   | LHS AsgnBinOp              Expr ";" { Asgn $2  Nothing $1 $3 }
-  | LHS IncOrDecOperator ";" { Asgn (AsgnOp $2) Nothing $1 (Number "1") }
-  | IncOrDecOperator LHS ";" { Asgn (AsgnOp $1) Nothing $2 (Number "1") }
+  | LHS IncOrDecOperator ";" { Asgn (AsgnOp $2) Nothing $1 (RawNum 1) }
+  | IncOrDecOperator LHS ";" { Asgn (AsgnOp $1) Nothing $2 (RawNum 1) }
   | LHS          ";" { Subroutine (lhsToExpr $1) (Args [] []) }
   | LHS CallArgs ";" { Subroutine (lhsToExpr $1) $2 }
 StmtNonAsgn :: { Stmt }
@@ -1021,7 +1022,7 @@ ForInit :: { Either [Decl] [(LHS, Expr)] }
   | DeclTokens(";") { parseDTsAsDeclsOrAsgns $1 }
 
 ForCond :: { Expr }
-  :      ";" { Number "1" }
+  :      ";" { RawNum 1 }
   | Expr ";" { $1 }
 
 ForStep :: { [(LHS, AsgnOp, Expr)] }
@@ -1032,8 +1033,8 @@ ForStepNonEmpty :: { [(LHS, AsgnOp, Expr)] }
   | ForStepNonEmpty "," ForStepAssignment { $1 ++ [$3] }
 ForStepAssignment :: { (LHS, AsgnOp, Expr) }
   : LHS AsgnOp Expr { ($1, $2, $3) }
-  | IncOrDecOperator LHS { ($2, AsgnOp $1, Number "1") }
-  | LHS IncOrDecOperator { ($1, AsgnOp $2, Number "1") }
+  | IncOrDecOperator LHS { ($2, AsgnOp $1, RawNum 1) }
+  | LHS IncOrDecOperator { ($1, AsgnOp $2, RawNum 1) }
 
 IdxVars :: { [Identifier] }
   : "[" IdxVarsInside "]" { $2 }
@@ -1122,8 +1123,11 @@ InsideCase :: { ([ExprOrRange], Stmt) }
   : OpenRangeList ":"  Stmt { ($1, $3) }
   | "default" opt(":") Stmt { ([], $3) }
 
-Number :: { String }
-  : number    { tokenString $1 }
+Real :: { String }
+  : real { tokenString $1 }
+
+Number :: { Number }
+  : number { parseNumber $ tokenString $1 }
 
 String :: { String }
   : string { tail $ init $ tokenString $1 }
@@ -1169,11 +1173,12 @@ ValueRange :: { ExprOrRange }
 Expr :: { Expr }
   : "(" Expr ")"                { $2 }
   | String                      { String $1 }
+  | Real                        { Real   $1 }
   | Number                      { Number $1 }
   | Time                        { Time   $1 }
   | Expr CallArgs               { Call $1 $2 }
   | DimsFn "(" TypeOrExpr ")"   { DimsFn $1 $3 }
-  | DimFn  "(" TypeOrExpr ")"   { DimFn  $1 $3 (Number "1") }
+  | DimFn  "(" TypeOrExpr ")"   { DimFn  $1 $3 (RawNum 1) }
   | DimFn  "(" TypeOrExpr "," Expr ")" { DimFn $1 $3 $5 }
   | Expr PartSelect             { Range $1 (fst $2) (snd $2) }
   | Expr "[" Expr "]"           { Bit   $1 $3 }
@@ -1184,8 +1189,8 @@ Expr :: { Expr }
   | "'" "{" PatternItems "}"    { Pattern $3 }
   | CastingType "'" "(" Expr ")" { Cast (Left  $1) $4 }
   | Expr        "'" "(" Expr ")" { Cast (Right $1) $4 }
-  | "{" StreamOp StreamSize Concat "}" { Stream $2 $3           $4 }
-  | "{" StreamOp            Concat "}" { Stream $2 (Number "1") $3 }
+  | "{" StreamOp StreamSize Concat "}" { Stream $2 $3         $4 }
+  | "{" StreamOp            Concat "}" { Stream $2 (RawNum 1) $3 }
   | Expr "inside" "{" OpenRangeList "}" { Inside $1 $4 }
   | "(" Expr ":" Expr ":" Expr ")" { MinTypMax $2 $4 $6 }
   | Identifier %prec REDUCE_OP {- defer -}   { Ident         $1 }
@@ -1302,8 +1307,8 @@ GenvarInitialization :: { Expr -> (Identifier, AsgnOp, Expr) -> GenItem -> GenIt
 
 GenvarIteration :: { (Identifier, AsgnOp, Expr) }
   : Identifier AsgnOp Expr { ($1, $2, $3) }
-  | IncOrDecOperator Identifier { ($2, AsgnOp $1, Number "1") }
-  | Identifier IncOrDecOperator { ($1, AsgnOp $2, Number "1") }
+  | IncOrDecOperator Identifier { ($2, AsgnOp $1, RawNum 1) }
+  | Identifier IncOrDecOperator { ($1, AsgnOp $2, RawNum 1) }
 
 AsgnOp :: { AsgnOp }
   : "=" { AsgnOpEq }
diff --git a/src/Language/SystemVerilog/Parser/ParseDecl.hs b/src/Language/SystemVerilog/Parser/ParseDecl.hs
index cb60e52..23be5ea 100644
--- a/src/Language/SystemVerilog/Parser/ParseDecl.hs
+++ b/src/Language/SystemVerilog/Parser/ParseDecl.hs
@@ -183,7 +183,7 @@ parseDTsAsIntantiations (DTIdent _ name : tokens) =
                 follow = if null toks' then [] else step (tail toks')
                 asRange :: DeclToken -> Range
                 asRange (DTRange _ (NonIndexed, s)) = s
-                asRange (DTBit _ s) = (Number "0", BinOp Sub s (Number "1"))
+                asRange (DTBit _ s) = (RawNum 0, BinOp Sub s (RawNum 1))
                 asRange _ = failure
                 failure = error $ "unrecognized instantiation of " ++ name
                             ++ ": " ++ show inst
@@ -439,14 +439,14 @@ takeRanges (token : tokens) =
         _                         -> ([]            , token : tokens)
     where
         (rs, rest) = takeRanges tokens
-        asRange s = (Number "0", BinOp Sub s (Number "1"))
+        asRange s = (RawNum 0, BinOp Sub s (RawNum 1))
         autoDim :: [a] -> ([Range], [DeclToken])
         autoDim l =
             ((lo, hi) : rs, rest)
             where
                 n = length l
-                lo = Number "0"
-                hi = Number $ show (n - 1)
+                lo = RawNum 0
+                hi = RawNum $ fromIntegral $ n - 1
 
 -- Matching `AsgnOpEq` and `AsgnOpNonBlocking` here allows tripLookahead to work
 -- both for standard declarations and in `parseDTsAsDeclOrStmt`, where we're
diff --git a/src/Language/SystemVerilog/Parser/Tokens.hs b/src/Language/SystemVerilog/Parser/Tokens.hs
index 20d3f45..ebc6877 100644
--- a/src/Language/SystemVerilog/Parser/Tokens.hs
+++ b/src/Language/SystemVerilog/Parser/Tokens.hs
@@ -302,6 +302,7 @@ data TokenName
     | Id_simple
     | Id_escaped
     | Id_system
+    | Lit_real
     | Lit_number
     | Lit_string
     | Lit_time
diff --git a/sv2v.cabal b/sv2v.cabal
index 62e1074..e0df76e 100644
--- a/sv2v.cabal
+++ b/sv2v.cabal
@@ -43,6 +43,7 @@ executable sv2v
     Language.SystemVerilog.AST.GenItem
     Language.SystemVerilog.AST.LHS
     Language.SystemVerilog.AST.ModuleItem
+    Language.SystemVerilog.AST.Number
     Language.SystemVerilog.AST.Op
     Language.SystemVerilog.AST.ShowHelp
     Language.SystemVerilog.AST.Stmt
@@ -64,6 +65,7 @@ executable sv2v
     Convert.DuplicateGenvar
     Convert.EmptyArgs
     Convert.Enum
+    Convert.ExprUtils
     Convert.ForDecl
     Convert.Foreach
     Convert.FuncRet
diff --git a/test/basic/dimensions.sv b/test/basic/dimensions.sv
index ef9af85..50e0b61 100644
--- a/test/basic/dimensions.sv
+++ b/test/basic/dimensions.sv
@@ -25,6 +25,14 @@ module top;
         $display($size(Ram[0]));
         $display($bits(foo));
 
+        $display("args %b", $size(RamPair, 1));
+        $display("args %b", $size(RamPair, 1'b1));
+        $display("args %b", $size(RamPair, '1));
+        $display("args %b", $size(RamPair, 'o1));
+        $display("args %b", $size(RamPair, 1'h1));
+        $display("args %b", $size(RamPair, 1'd1));
+        $display("args %b", $size(RamPair, 1'dx));
+
         `EXHAUST(Ram);
         `EXHAUST(Ram[0+:2]);
         `EXHAUST(Ram[1+:2]);
diff --git a/test/basic/dimensions.v b/test/basic/dimensions.v
index d77c1cd..f9d38f8 100644
--- a/test/basic/dimensions.v
+++ b/test/basic/dimensions.v
@@ -5,6 +5,14 @@ module top;
         $display(16);
         $display(3);
 
+        $display("args %b", 2);
+        $display("args %b", 2);
+        $display("args %b", 2);
+        $display("args %b", 2);
+        $display("args %b", 2);
+        $display("args %b", 2);
+        $display("args %b", 1'bx);
+
         $display(10, 10, 16);
         $display(0, 0, 16);
         $display(9, 9, 1);
diff --git a/test/basic/div.sv b/test/basic/div.sv
new file mode 100644
index 0000000..e8eca02
--- /dev/null
+++ b/test/basic/div.sv
@@ -0,0 +1,8 @@
+module top;
+    localparam X = 1 / 0;
+    localparam Y = 'dx;
+    localparam Z = 40'dx____;
+    initial $display("%b", X);
+    initial $display("%b", Y);
+    initial $display("%b", Z);
+endmodule
diff --git a/test/basic/div.v b/test/basic/div.v
new file mode 100644
index 0000000..40d6d89
--- /dev/null
+++ b/test/basic/div.v
@@ -0,0 +1 @@
+`include "div.sv"
diff --git a/test/lex/number.sv b/test/lex/number.sv
new file mode 100644
index 0000000..fb8a3a8
--- /dev/null
+++ b/test/lex/number.sv
@@ -0,0 +1,41 @@
+`define TEST(N) \
+    $display(`"N -> %0d %b`", N, N); \
+    $display(`"$bits(N) -> %0d`", $bits(N));
+
+module top;
+    initial begin
+        `TEST(0) `TEST(1) `TEST(2)
+        `TEST(-0) `TEST(-1) `TEST(-2)
+        `TEST('d0) `TEST('d1) `TEST('d2)
+        `TEST('sd0) `TEST('sd1) `TEST('sd2)
+        `TEST('b0) `TEST('b1) `TEST('b10)
+        `TEST('sd0) `TEST('sd1) `TEST('sd2)
+        `TEST(1'sox) `TEST(2'sox) `TEST(3'sox) `TEST(7'sox) `TEST(8'sox) `TEST(9'sox) `TEST(9'soxx) `TEST(10'soxx)
+        `TEST(1'soz) `TEST(2'soz) `TEST(3'soz) `TEST(7'soz) `TEST(8'soz) `TEST(9'soz) `TEST(9'sozz) `TEST(10'sozz)
+        `TEST(1'SOZ) `TEST(2'SOZ) `TEST(3'SOZ) `TEST(7'SOZ) `TEST(8'SOZ) `TEST(9'SOZ) `TEST(9'SOZZ) `TEST(10'SOZZ)
+
+        `TEST(1234_5678) `TEST('h1234_5678) `TEST('o1234_5677) `TEST('b0101_1100)
+        `TEST('d4294967295) `TEST('d4294967296) `TEST('d4294967297) `TEST('d4294967298) `TEST('d4294967299)
+        `TEST('d004294967295) `TEST('d004294967296) `TEST('d004294967297) `TEST('d004294967298) `TEST('d004294967299)
+
+        `TEST(4294967295) `TEST(4294967296) `TEST(4294967297) `TEST(4294967298) `TEST(4294967299)
+        `TEST(-4294967295) `TEST(-4294967297) `TEST(-4294967298) `TEST(-4294967299)
+        `TEST(-8589934593) `TEST(8589934592) `TEST(8589934593)
+        // iverlog does weird things with these: `TEST(-4294967296) `TEST(-8589934592)
+
+        `TEST(659) `TEST('h 837FF) `TEST('o7460)
+        `TEST(4'b1001) `TEST(5 'D 3) `TEST(3'b01x) `TEST(12'hx) `TEST(16'hz)
+        `TEST(-8 'd 6) `TEST(4 'shf) `TEST(-4 'sd15) `TEST(16'sd?)
+
+        `TEST('bx) `TEST('bz) `TEST('bzx) `TEST('bxz)
+        `TEST(3'bx) `TEST(3'b1x) `TEST(3'bx1) `TEST('b1x) `TEST('bx1) `TEST(3'b0x1) `TEST(3'b0z1)
+        `TEST('hf & 10'hf) `TEST(7'hf & 10'hf)
+
+        `TEST('b01xz01xz01xz01xz01xz01xz01xz01xz01xz) `TEST('b101xz01xz01xz01xz01xz01xz01xz01xz01xz)
+        `TEST(36'b01xz01xz01xz01xz01xz01xz01xz01xz01xz) `TEST(37'b01xz01xz01xz01xz01xz01xz01xz01xz01xz)
+        `TEST(36'sb01xz01xz01xz01xz01xz01xz01xz01xz01xz) `TEST(37'sb01xz01xz01xz01xz01xz01xz01xz01xz01xz)
+        `TEST('h01xz01xz) `TEST('h101xz01xz)
+        `TEST(36'h01xz01xz) `TEST(37'h01xz01xz)
+        `TEST(36'hb01xz01xz) `TEST(37'hb01xz01xz)
+    end
+endmodule
diff --git a/test/lex/number.v b/test/lex/number.v
new file mode 100644
index 0000000..2dc2720
--- /dev/null
+++ b/test/lex/number.v
@@ -0,0 +1 @@
+`include "number.sv"