1 files changed, 44 insertions, 0 deletions
diff --git a/src/test/scala/ChiselTests/Counter.scala b/src/test/scala/ChiselTests/Counter.scala
new file mode 100644
index 00000000..cab61c53
--- /dev/null
+++ b/src/test/scala/ChiselTests/Counter.scala
@@ -0,0 +1,44 @@
+package ChiselTests
+import Chisel._
+
+object Counter {
+  def wrapAround(n: UInt, max: UInt) = 
+    Mux(n > max, UInt(0), n)
+  def apply(max: UInt, en: Bool, amt: UInt): UInt = {
+    val x = Reg(init=UInt(0, max.getWidth))
+    when (en) { x := wrapAround(x +% amt, max) }
+    x
+  }
+}
+
+class Counter extends Module {
+  val io = new Bundle {
+    val inc = Bool(INPUT)
+    val amt = UInt(INPUT,  4)
+    val tot = UInt(OUTPUT, 8)
+  }
+  io.tot := Counter(UInt(255), io.inc, io.amt)
+}
+
+class CounterTester(c: Counter) extends Tester(c) {
+  val maxInt  = 16
+  var curCnt  = 0
+
+  def intWrapAround(n: Int, max: Int) = 
+    if(n > max) 0 else n
+
+  // let it spin for a bit
+  for (i <- 0 until 5) {
+    step(1)
+  }
+
+  for (i <- 0 until 10) {
+    val inc = rnd.nextBoolean()
+    val amt = rnd.nextInt(maxInt)
+    poke(c.io.inc, if (inc) 1 else 0)
+    poke(c.io.amt, amt)
+    step(1)
+    curCnt = if(inc) intWrapAround(curCnt + amt, 255) else curCnt
+    expect(c.io.tot, curCnt)
+  }
+}