improve ALU and fix revealed emulator bug

rocket/src/main/scala/util.scala

@@ -15,12 +15,23 @@ object FillInterleaved
   def apply(n: Int, in: Bits) =
   {
     var out = Fill(n, in(0))
-    for (i <- 1 until in.width)
+    for (i <- 1 until in.getWidth)
       out = Cat(Fill(n, in(i)), out)
     out
   }
 }
 
+object Reverse
+{
+  def apply(in: Bits) =
+  {
+    var out = in(in.getWidth-1)
+    for (i <- 1 until in.getWidth)
+      out = Cat(in(in.getWidth-i-1), out)
+    out
+  }
+}
+
 class Mux1H(n: Int, w: Int) extends Component
 {
   val io = new Bundle {