From 655a08f12e2104cc459eb22902fab3630c71d0f2 Mon Sep 17 00:00:00 2001
From: "Wesley W. Terpstra" <wesley@sifive.com>
Date: Thu, 7 Sep 2017 13:29:59 -0700
Subject: [PATCH] config: support default values for Field[T] keys

---
 src/main/scala/config/Config.scala | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/main/scala/config/Config.scala b/src/main/scala/config/Config.scala
index 457dd184..0f4db18e 100644
--- a/src/main/scala/config/Config.scala
+++ b/src/main/scala/config/Config.scala
@@ -2,7 +2,11 @@
 
 package freechips.rocketchip.config
 
-abstract class Field[T]
+abstract class Field[T] private (val default: Option[T])
+{
+  def this() = this(None)
+  def this(x: T) = this(Some(x))
+}
 
 abstract class View {
   final def apply[T](pname: Field[T]): T = apply(pname, this)
@@ -42,7 +46,7 @@ class Config(p: Parameters) extends Parameters {
 // Internal implementation:
 
 private class TerminalView extends View {
-  def find[T](pname: Field[T], site: View): Option[T] = None
+  def find[T](pname: Field[T], site: View): Option[T] = pname.default
 }
 
 private class ChainView(head: Parameters, tail: View) extends View {