1 files changed, 33 insertions, 0 deletions
diff --git a/src/main/scala/firrtl/constraint/IsPow.scala b/src/main/scala/firrtl/constraint/IsPow.scala
new file mode 100644
index 00000000..54a06bf8
--- /dev/null
+++ b/src/main/scala/firrtl/constraint/IsPow.scala
@@ -0,0 +1,33 @@
+// See LICENSE for license details.
+
+package firrtl.constraint
+
+object IsPow {
+  def apply(child: Constraint): Constraint = new IsPow(child, 0).reduce()
+}
+
+// Dummy arg is to get around weird Scala issue that can't differentiate between a
+//   private constructor and public apply that share the same arguments
+case class IsPow private (child: Constraint, dummyArg: Int) extends Constraint {
+  override def reduce(): Constraint = child match {
+    case k: IsKnown => k.pow
+    // 2^(a + b) -> 2^a * 2^b
+    case x: IsAdd => IsMul(x.children.map { b => IsPow(b)})
+    case x: IsMul => this
+    case x: IsNeg => this
+    case x: IsPow => this
+    // 2^(max(a, b)) -> max(2^a, 2^b) since two is always positive, so a, b control magnitude
+    case x: IsMax => IsMax(x.children.map {b => IsPow(b)})
+    case x: IsMin => IsMin(x.children.map {b => IsPow(b)})
+    case x: IsVar => this
+    case _ => this
+  }
+
+  val children = Vector(child)
+
+  override def map(f: Constraint=>Constraint): Constraint = IsPow(f(child))
+
+  override def serialize: String = "(2^" + child.serialize + ")"
+}
+
+