use system functions for signedness casts

src/Convert.hs

@@ -31,6 +31,7 @@ import qualified Convert.NestPI
 import qualified Convert.Package
 import qualified Convert.ParamType
 import qualified Convert.RemoveComments
+import qualified Convert.SignCast
 import qualified Convert.Simplify
 import qualified Convert.SizeCast
 import qualified Convert.StarPort
@@ -72,6 +73,7 @@ phases excludes =
     , Convert.Unique.convert
     , Convert.UnpackedArray.convert
     , Convert.Unsigned.convert
+    , Convert.SignCast.convert
     , Convert.Package.convert
     , Convert.Enum.convert
     , Convert.NestPI.convert

src/Convert/SignCast.hs

+{- sv2v
+ - Author: Zachary Snow <zach@zachjs.com>
+ -
+ - Conversion for `signed` and `unsigned` type casts.
+ -
+ - SystemVerilog has `signed'(foo)` and `unsigned'(foo)` as syntactic sugar for
+ - the `$signed` and `$unsigned` system functions present in Verilog-2005. This
+ - conversion elaborates these casts.
+ -}
+
+module Convert.SignCast (convert) where
+
+import Convert.Traverse
+import Language.SystemVerilog.AST
+
+convert :: [AST] -> [AST]
+convert =
+    map $
+    traverseDescriptions $
+    traverseModuleItems $
+    traverseExprs $
+    traverseNestedExprs convertExpr
+
+convertExpr :: Expr -> Expr
+convertExpr (Cast (Left (Implicit Signed [])) e) =
+    Call (Ident "$signed") (Args [Just e] [])
+convertExpr (Cast (Left (Implicit Unsigned [])) e) =
+    Call (Ident "$unsigned") (Args [Just e] [])
+convertExpr other = other

sv2v.cabal

@@ -77,6 +77,7 @@ executable sv2v
     Convert.Package
     Convert.ParamType
     Convert.RemoveComments
+    Convert.SignCast
     Convert.Simplify
     Convert.SizeCast
     Convert.StarPort

test/basic/sign_cast.sv

+module top;
+    initial begin
+        $display(signed'(4294967295));
+        $display(unsigned'(4294967295));
+        $display(signed'(-1));
+        $display(unsigned'(-1));
+    end
+endmodule

test/basic/sign_cast.v

+module top;
+    initial begin
+        $display($signed(4294967295));
+        $display($unsigned(4294967295));
+        $display($signed(-1));
+        $display($unsigned(-1));
+    end
+endmodule