added conversion for packed unions

src/Convert/Struct.hs

 {- sv2v
  - Author: Zachary Snow <zach@zachjs.com>
  -
- - Conversion for `struct packed`
+ - Conversion for `struct packed` and `union packed`
  -}
 
 module Convert.Struct (convert) where
@@ -70,10 +70,19 @@ convertDescription other = other
 
 -- write down unstructured versions of packed struct types
 collectStructM :: Type -> Writer Structs ()
-collectStructM (Struct (Packed sg) fields _) = do
+collectStructM (Struct (Packed sg) fields _) =
+    collectStructM' Struct True  sg fields
+collectStructM (Union  (Packed sg) fields _) =
+    collectStructM' Union  False sg fields
+collectStructM _ = return ()
+
+collectStructM'
+    :: (Packing -> [Field] -> [Range] -> Type)
+    -> Bool -> Signing -> [Field] -> Writer Structs ()
+collectStructM' constructor isStruct sg fields = do
     if canUnstructure
         then tell $ Map.singleton
-            (Struct (Packed sg) fields)
+            (constructor (Packed sg) fields)
             (unstructType, unstructFields)
         else return ()
     where
@@ -90,8 +99,14 @@ collectStructM (Struct (Packed sg) fields _) = do
 
         -- layout the fields into the unstructured type; note that `scanr` is
         -- used here because SystemVerilog structs are laid out backwards
-        fieldLos = map simplify $ tail $ scanr (BinOp Add) (Number  "0") fieldSizes
-        fieldHis = map simplify $ init $ scanr (BinOp Add) (Number "-1") fieldSizes
+        fieldLos =
+            if isStruct
+                then map simplify $ tail $ scanr (BinOp Add) (Number  "0") fieldSizes
+                else map simplify $ repeat (Number "0")
+        fieldHis =
+            if isStruct
+                then map simplify $ init $ scanr (BinOp Add) (Number "-1") fieldSizes
+                else map simplify $ map (BinOp Add (Number "-1")) fieldSizes
 
         -- create the mapping structure for the unstructured fields
         unstructOffsets = map simplify $ map snd fieldRanges
@@ -102,7 +117,10 @@ collectStructM (Struct (Packed sg) fields _) = do
 
         -- create the unstructured type; result type takes on the signing of the
         -- struct itself to preserve behavior of operations on the whole struct
-        structSize = foldl1 (BinOp Add) fieldSizes
+        structSize =
+            if isStruct
+                then foldl1 (BinOp Add) fieldSizes
+                else head fieldSizes
         packedRange = (simplify $ BinOp Sub structSize (Number "1"), zero)
         unstructType = IntegerVector TLogic sg [packedRange]
 
@@ -114,7 +132,6 @@ collectStructM (Struct (Packed sg) fields _) = do
         isIntVec _ = False
         canUnstructure = all isIntVec fieldTypes
 
-collectStructM _ = return ()
 
 -- convert a struct type to its unstructured equivalent
 convertType :: Structs -> Type -> Type
@@ -252,7 +269,13 @@ convertAsgn structs types (lhs, expr) =
         convertLHS (LHSDot    l x ) =
             case t of
                 InterfaceT _ _ _ -> (Implicit Unspecified [], LHSDot l' x)
-                Struct _ _ _ -> case Map.lookup structTf structs of
+                Struct p fields [] -> undot (Struct p fields) fields
+                Union  p fields [] -> undot (Union  p fields) fields
+                Implicit sg _ -> (Implicit sg [], LHSDot l' x)
+                _ -> error $ "convertLHS encountered dot for bad type: " ++ show (t, l, x)
+            where
+                (t, l') = convertLHS l
+                undot structTf fields = case Map.lookup structTf structs of
                     Nothing -> (fieldType, LHSDot l' x)
                     Just (structT, m) -> (tf [tr], LHSRange l' NonIndexed r)
                         where
@@ -261,13 +284,8 @@ convertAsgn structs types (lhs, expr) =
                             hi' = BinOp Add base $ BinOp Sub hi lo
                             lo' = base
                             tr = (simplify hi', simplify lo')
-                Implicit sg _ -> (Implicit sg [], LHSDot l' x)
-                _ -> error $ "convertLHS encountered dot for bad type: " ++ show (t, l, x)
-            where
-                (t, l') = convertLHS l
-                Struct p fields [] = t
-                structTf = Struct p fields
-                fieldType = lookupFieldType fields x
+                    where
+                        fieldType = lookupFieldType fields x
         convertLHS (LHSConcat lhss) =
             (Implicit Unspecified [], LHSConcat $ map (snd . convertLHS) lhss)
 
@@ -330,17 +348,18 @@ convertAsgn structs types (lhs, expr) =
                 Just t -> (t, Ident x)
         convertSubExpr (Dot e x) =
             case subExprType of
-                Struct _ _ _ ->
-                    if Map.notMember structTf structs
-                        then (fieldType, Dot e' x)
-                        else (fieldType, Range  e' NonIndexed r)
+                Struct p fields [] -> undot (Struct p fields) fields
+                Union  p fields [] -> undot (Union  p fields) fields
                 _ -> (Implicit Unspecified [], Dot e' x)
             where
                 (subExprType, e') = convertSubExpr e
-                Struct p fields [] = subExprType
-                structTf = Struct p fields
-                fieldType = lookupFieldType fields x
-                r = lookupUnstructRange structTf x
+                undot structTf fields =
+                    if Map.notMember structTf structs
+                        then (fieldType, Dot e' x)
+                        else (fieldType, Range  e' NonIndexed r)
+                    where
+                        fieldType = lookupFieldType fields x
+                        r = lookupUnstructRange structTf x
         convertSubExpr (Range eOuter NonIndexed (rOuter @ (hiO, loO))) =
             -- VCS doesn't allow ranges to be cascaded, so we need to combine
             -- nested Ranges into a single range. My understanding of the

src/Language/SystemVerilog/AST/Type.hs

@@ -8,6 +8,7 @@
 
 module Language.SystemVerilog.AST.Type
     ( Identifier
+    , Field
     , Type    (..)
     , Signing (..)
     , Packing (..)

test/basic/union.sv

+typedef union packed {
+  logic [4:0] x;
+  logic [4:0] y;
+} A;
+
+typedef union packed {
+  logic [4:0] x;
+  logic [0:4] y;
+} B;
+
+typedef union packed {
+  logic [4:0] x;
+  logic [1:5] y;
+} C;
+
+typedef union packed {
+  logic [4:0] x;
+  struct packed {
+    logic [2:0] a;
+    logic [1:0] b;
+  } y;
+  struct packed {
+    logic [1:0] a;
+    logic [0:2] b;
+  } z;
+} D;
+
+module wrap;
+
+    A a;
+    B b;
+    C c;
+    D d;
+
+    initial begin
+
+        $monitor($time, " %b %b", a.x, a.y);
+        a.x = 5'b01101; #10;
+        a.y = 5'b11101; #10;
+
+        $monitor($time, " %b %b", b.x, b.y);
+        b.x = 5'b01101; #10;
+        b.y = 5'b11101; #10;
+
+        $monitor($time, " %b %b", c.x, c.y);
+        c.x = 5'b01101; #10;
+        c.y = 5'b11101; #10;
+
+        $monitor($time, " %b %b {%b %b} %b {%b %b}", d.x, d.y, d.y.a, d.y.b,
+            d.z, d.z.a, d.z.b);
+        d.x = 5'b01101; #10;
+        d.y = '{ a: 3'b110, b: 2'b01 }; #10;
+        d.z = '{ b: 3'b110, a: 2'b01 }; #10;
+        d.y.a = 3'b010; #10;
+        d.y.b = 2'b10; #10;
+        d.z.a = 2'b11; #10;
+        d.z.b = 3'b101; #10;
+
+    end
+
+endmodule

test/basic/union.v

+module wrap;
+
+    initial begin
+
+        // This was generated by running the original through VCS.
+
+        $display("                   0 01101 01101");
+        $display("                  10 11101 11101");
+
+        $display("                  20 01101 01101");
+        $display("                  30 11101 11101");
+
+        $display("                  40 01101 01101");
+        $display("                  50 11101 11101");
+
+        $display("                  60 01101 01101 {011 01} 01101 {01 101}");
+        $display("                  70 11001 11001 {110 01} 11001 {11 001}");
+        $display("                  80 01110 01110 {011 10} 01110 {01 110}");
+        $display("                  90 01010 01010 {010 10} 01010 {01 010}");
+        $display("                 110 11010 11010 {110 10} 11010 {11 010}");
+        $display("                 120 11101 11101 {111 01} 11101 {11 101}");
+
+        #130;
+
+    end
+
+endmodule

test/basic/union_tb.v

+module top;
+    wrap wrap();
+endmodule