Add utilities for UInt and SInt literals (#815)

Also minor cleanup to literal construction in Visitor

1 files changed, 17 insertions, 28 deletions

diff --git a/src/main/scala/firrtl/Visitor.scala b/src/main/scala/firrtl/Visitor.scala
index c45d7f56..64249c11 100644
--- a/src/main/scala/firrtl/Visitor.scala
+++ b/src/main/scala/firrtl/Visitor.scala
@@ -284,9 +284,6 @@ class Visitor(infoMode: InfoMode) extends FIRRTLBaseVisitor[FirrtlNode] {
     }
   }
 
-  // TODO
-  // - Add mux
-  // - Add validif
   private def visitExp[FirrtlNode](ctx: FIRRTLParser.ExpContext): Expression = {
     val ctx_exp = ctx.exp.asScala
     if (ctx.getChildCount == 1)
@@ -294,32 +291,24 @@ class Visitor(infoMode: InfoMode) extends FIRRTLBaseVisitor[FirrtlNode] {
     else
       ctx.getChild(0).getText match {
         case "UInt" =>
-          // This could be better
-          val (width, value) =
-            if (ctx.getChildCount > 4)
-              (IntWidth(string2BigInt(ctx.intLit(0).getText)), string2BigInt(ctx.intLit(1).getText))
-            else {
-              val bigint = string2BigInt(ctx.intLit(0).getText)
-              (IntWidth(BigInt(scala.math.max(bigint.bitLength, 1))), bigint)
-            }
-          UIntLiteral(value, width)
+          if (ctx.getChildCount > 4) {
+            val width = IntWidth(string2BigInt(ctx.intLit(0).getText))
+            val value = string2BigInt(ctx.intLit(1).getText)
+            UIntLiteral(value, width)
+          } else {
+            val value = string2BigInt(ctx.intLit(0).getText)
+            UIntLiteral(value)
+          }
         case "SInt" =>
-          val (width, value) =
-            if (ctx.getChildCount > 4) {
-              val width = string2BigInt(ctx.intLit(0).getText)
-              val value = string2BigInt(ctx.intLit(1).getText)
-              (IntWidth(width), value)
-            } else {
-              val str = ctx.intLit(0).getText
-              val value = string2BigInt(str)
-              // To calculate bitwidth of negative number,
-              //  1) negate number and subtract one to get the maximum positive value.
-              //  2) get bitwidth of max positive number
-              //  3) add one to account for the signed representation
-              val width = if (value < 0) (value.abs - BigInt(1)).bitLength + 1 else value.bitLength + 1
-              (IntWidth(BigInt(width)), value)
-            }
-          SIntLiteral(value, width)
+          if (ctx.getChildCount > 4) {
+            val width = string2BigInt(ctx.intLit(0).getText)
+            val value = string2BigInt(ctx.intLit(1).getText)
+            SIntLiteral(value, IntWidth(width))
+          } else {
+            val str = ctx.intLit(0).getText
+            val value = string2BigInt(str)
+            SIntLiteral(value)
+          }
         case "validif(" => ValidIf(visitExp(ctx_exp(0)), visitExp(ctx_exp(1)), UnknownType)
         case "mux(" => Mux(visitExp(ctx_exp(0)), visitExp(ctx_exp(1)), visitExp(ctx_exp(2)), UnknownType)
         case _ =>