From db6a727485153cbb92989be2f5d67e059e0878ad Mon Sep 17 00:00:00 2001
From: Jack Koenig
Date: Fri, 7 Apr 2017 16:42:34 -0700
Subject: Change Enum to emit minimum widths of 1 (#574)

Fixes #554---
 src/main/scala/chisel3/util/Enum.scala    |  2 +-
 src/test/scala/chiselTests/EnumSpec.scala | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 src/test/scala/chiselTests/EnumSpec.scala

(limited to 'src')

diff --git a/src/main/scala/chisel3/util/Enum.scala b/src/main/scala/chisel3/util/Enum.scala
index a3e39047..6ed0d422 100644
--- a/src/main/scala/chisel3/util/Enum.scala
+++ b/src/main/scala/chisel3/util/Enum.scala
@@ -10,7 +10,7 @@ import chisel3._
 trait Enum {
   /** Returns a sequence of Bits subtypes with values from 0 until n. Helper method. */
   protected def createValues(n: Int): Seq[UInt] =
-    (0 until n).map(_.U(log2Ceil(n).W))
+    (0 until n).map(_.U((1 max log2Ceil(n)).W))
 
   /** Returns n unique UInt values, use with unpacking to specify an enumeration.
     *
diff --git a/src/test/scala/chiselTests/EnumSpec.scala b/src/test/scala/chiselTests/EnumSpec.scala
new file mode 100644
index 00000000..37bbe2ff
--- /dev/null
+++ b/src/test/scala/chiselTests/EnumSpec.scala
@@ -0,0 +1,19 @@
+// See LICENSE for license details.
+
+package chiselTests
+
+import chisel3._
+import chisel3.util.Enum
+import chisel3.testers.BasicTester
+
+class EnumSpec extends ChiselFlatSpec {
+
+  "1-entry Enums" should "work" in {
+    assertTesterPasses(new BasicTester {
+      val onlyState :: Nil = Enum(1)
+      val wire = Wire(init = onlyState)
+      chisel3.assert(wire === onlyState)
+      stop()
+    })
+  }
+}
-- 
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