3 files changed, 54 insertions, 17 deletions
diff --git a/src/main/scala/Chisel/CoreUtil.scala b/src/main/scala/Chisel/CoreUtil.scala
index 41266cae..aaca404b 100644
--- a/src/main/scala/Chisel/CoreUtil.scala
+++ b/src/main/scala/Chisel/CoreUtil.scala
@@ -7,21 +7,52 @@ import internal.Builder.pushCommand
 import firrtl._
 
 object assert {
+  /** Checks for a condition to be valid in the circuit at all times. If the
+    * condition evaluates to false, the circuit simulation stops with an error.
+    *
+    * Does not fire when in reset (defined as the encapsulating Module's
+    * reset). If your definition of reset is not the encapsulating Module's
+    * reset, you will need to gate this externally.
+    *
+    * May be called outside of a Module (like defined in a function), so
+    * functions using assert make the standard Module assumptions (single clock
+    * and single reset).
+    *
+    * @param cond condition, assertion fires (simulation fails) when false
+    * @param message optional message to print when the assertion fires
+    */
   def apply(cond: Bool, message: String="") {
-    when(!cond) {
-      if (message.isEmpty()) {
-        printf(s"Assertion failed: (TODO: code / lineno)")
-      } else {
-        printf(s"Assertion failed: (TODO: code / lineno): $message")
+    when (!Builder.dynamicContext.currentModule.get.reset) {
+      when(!cond) {
+        if (message.isEmpty()) {
+          printf(s"Assertion failed: (TODO: code / lineno)")
+        } else {
+          printf(s"Assertion failed: (TODO: code / lineno): $message")
+        }
+        pushCommand(Stop(Node(Builder.dynamicContext.currentModule.get.clock), 1))
       }
-      pushCommand(Stop(Node(Builder.dynamicContext.currentModule.get.clock), 1))
     }
   }
 }
 
 object printf {
+  /** Prints a message in simulation.
+    *
+    * Does not fire when in reset (defined as the encapsulating Module's
+    * reset). If your definition of reset is not the encapsulating Module's
+    * reset, you will need to gate this externally.
+    *
+    * May be called outside of a Module (like defined in a function), so
+    * functions using printf make the standard Module assumptions (single clock
+    * and single reset).
+    *
+    * @param fmt printf format string
+    * @param data format string varargs containing data to print
+    */
   def apply(fmt: String, data: Bits*) {
-    pushCommand(Printf(Node(Builder.dynamicContext.currentModule.get.clock),
-        fmt, data.map(Node(_))))
+    when (!Builder.dynamicContext.currentModule.get.reset) {
+      pushCommand(Printf(Node(Builder.dynamicContext.currentModule.get.clock),
+          fmt, data.map((d: Bits) => d.ref)))
+    }
   }
 }
diff --git a/src/main/scala/Chisel/testers/BasicTester.scala b/src/main/scala/Chisel/testers/BasicTester.scala
index fecbe2a9..1079727c 100644
--- a/src/main/scala/Chisel/testers/BasicTester.scala
+++ b/src/main/scala/Chisel/testers/BasicTester.scala
@@ -8,18 +8,20 @@ import internal.Builder.pushCommand
 import firrtl._
 
 class BasicTester extends Module {
-  val io = new Bundle {
-    val done = Bool()
-    val error = UInt(width = 4)
-  }
-  io.done := Bool(false)
-  io.error := UInt(0)
+  // The testbench has no IOs, rather it should communicate using printf, assert, and stop.
+  val io = new Bundle()
 
   def popCount(n: Long): Int = n.toBinaryString.count(_=='1')
 
-  /** Ends the test, reporting success.
+  /** Ends the test reporting success.
+    *
+    * Does not fire when in reset (defined as the encapsulating Module's
+    * reset). If your definition of reset is not the encapsulating Module's
+    * reset, you will need to gate this externally.
     */
   def stop() {
-    pushCommand(Stop(Node(clock), 0))
+    when (!reset) {
+      pushCommand(Stop(Node(clock), 0))
+    }
   }
 }
diff --git a/src/main/scala/Chisel/util/Counter.scala b/src/main/scala/Chisel/util/Counter.scala
index e4a8e95b..356cedc8 100644
--- a/src/main/scala/Chisel/util/Counter.scala
+++ b/src/main/scala/Chisel/util/Counter.scala
@@ -3,10 +3,14 @@
 package Chisel
 
 /** A counter module
-  * @param n The maximum value of the counter, does not have to be power of 2
+  * @param n number of counts before the counter resets (or one more than the
+  * maximum output value of the counter), need not be a power of two
   */
 class Counter(val n: Int) {
   val value = if (n == 1) UInt(0) else Reg(init=UInt(0, log2Up(n)))
+  /** Increment the counter this cycle. Returns whether the counter is at its
+    * maximum (and will wrap around on the next inc() call).
+    */
   def inc(): Bool = {
     if (n == 1) {
       Bool(true)