Updated example to ROHD APIs in a better way (#52)

example/counter.dart

@@ -32,14 +32,9 @@ class CounterInterface extends Interface<CounterDirection> {
   }
 }
 
-/// A simple counter which increments once per [clk] edge whenever
-/// [en] is high, and [reset]s to 0, with output [val].
+/// A simple counter which increments once per `clk` edge whenever
+/// `en` is high, and `reset`s to 0, with output `val`.
 class Counter extends Module {
-  Logic get clk => input('clk');
-  Logic get en => input('en');
-  Logic get reset => input('reset');
-  Logic get val => output('val');
-
   late final CounterInterface intf;
 
   Counter(CounterInterface intf) : super(name: 'counter') {
@@ -54,14 +49,10 @@ class Counter extends Module {
   void _buildLogic() {
     final nextVal = Logic(name: 'nextVal', width: intf.width);
 
-    nextVal <= val + 1;
+    nextVal <= intf.val + 1;
 
-    Sequential(clk, [
-      If(reset, then: [
-        val < 0
-      ], orElse: [
-        If(en, then: [val < nextVal])
-      ])
+    Sequential(intf.clk, reset: intf.reset, [
+      If(intf.en, then: [intf.val < nextVal])
     ]);
   }
 }

example/main.dart

@@ -32,7 +32,7 @@ Future<void> main({Level loggerLevel = Level.FINER}) async {
   Simulator.setMaxSimTime(300);
 
   // Create and start the test!
-  final test = CounterTest(tb.counter);
+  final test = CounterTest(tb.intf);
   await test.start();
 }
 
@@ -44,10 +44,10 @@ class TopTB {
   // A constant value for the width to use in this testbench
   static const int width = 8;
 
-  TopTB() {
-    // Build an instance of the interface for the Counter
-    final intf = CounterInterface();
+  // Build an instance of the interface for the Counter
+  final CounterInterface intf = CounterInterface();
 
+  TopTB() {
     // Connect a generated clock to the interface
     intf.clk <= SimpleClockGenerator(10).clk;
 
@@ -58,25 +58,25 @@ class TopTB {
 
 /// A simple test that brings the [Counter] out of reset and wiggles the enable.
 class CounterTest extends Test {
-  /// The [Counter] device under test.
-  final Counter dut;
+  /// The [CounterInterface] to the [Counter] device under test (DUT).
+  final CounterInterface intf;
 
-  /// The test environment for [dut].
+  /// The test environment for the DUT.
   late final CounterEnv env;
 
   /// A private, local pointer to the test environment's [Sequencer].
   late final CounterSequencer _counterSequencer;
 
-  CounterTest(this.dut, {String name = 'counterTest'}) : super(name) {
-    env = CounterEnv(dut.intf, this);
+  CounterTest(this.intf, {String name = 'counterTest'}) : super(name) {
+    env = CounterEnv(intf, this);
     _counterSequencer = env.agent.sequencer;
   }
 
   // A "time consuming" method, similar to `task` in SystemVerilog, which
   // waits for a given number of cycles before completing.
   Future<void> waitNegedges(int numCycles) async {
     for (var i = 0; i < numCycles; i++) {
-      await dut.clk.nextNegedge;
+      await intf.clk.nextNegedge;
     }
   }
 
@@ -92,20 +92,20 @@ class CounterTest extends Test {
 
     // Add some simple reset behavior at specified timestamps
     Simulator.registerAction(1, () {
-      dut.intf.reset.put(0);
+      intf.reset.put(0);
     });
     Simulator.registerAction(3, () {
-      dut.intf.reset.put(1);
+      intf.reset.put(1);
     });
     Simulator.registerAction(35, () {
-      dut.intf.reset.put(0);
+      intf.reset.put(0);
     });
 
     // Add an individual SequenceItem to set enable to 0 at the start
     _counterSequencer.add(CounterSeqItem(false));
 
     // Wait for the next negative edge of reset
-    await dut.intf.reset.nextNegedge;
+    await intf.reset.nextNegedge;
 
     // Wait 3 more cycles
     await waitNegedges(3);
@@ -267,9 +267,13 @@ class CounterValueMonitor extends Monitor<LogicValue> {
   Future<void> run(Phase phase) async {
     unawaited(super.run(phase));
 
+    // wait for reset before monitoring
+    await intf.reset.nextNegedge;
+
     // Every positive edge of the clock
     intf.clk.posedge.listen((event) {
       // Send out an event with the value of the counter
+      // Use `value` to look at the value after the positive edge
       add(intf.val.value);
     });
   }
@@ -288,13 +292,14 @@ class CounterEnableMonitor extends Monitor<CounterSeqItem> {
   Future<void> run(Phase phase) async {
     unawaited(super.run(phase));
 
+    // wait for reset before monitoring
+    await intf.reset.nextNegedge;
+
     // Every positive edge of the clock
     intf.clk.posedge.listen((event) {
       // If the enable bit on the interface is 1
-      if (intf.en.value == LogicValue.one) {
-        // Send out an event with `true` out of this Monitor
-        add(CounterSeqItem(true));
-      }
+      // Use `previousValue` to look at the enable sampled as a flop would
+      add(CounterSeqItem(intf.en.previousValue == LogicValue.one));
     });
   }
 }
@@ -323,41 +328,39 @@ class CounterScoreboard extends Component {
   /// The most recent value recieved on [valueStream].
   int? _seenValue;
 
-  /// The value seen last time from [valueStream].
-  int _lastSeenValue = 0;
+  int? _previousValue;
 
   @override
   Future<void> run(Phase phase) async {
     unawaited(super.run(phase));
 
-    intf.reset.posedge.listen((event) {
-      _lastSeenValue = 0;
-    });
-
-    await intf.reset.nextNegedge;
-
     // record if we've seen an enable this cycle
     enableStream.listen((event) {
       _sawEnable = event;
     });
 
     // record the value we saw this cycle
     valueStream.listen((event) {
+      _previousValue = _seenValue;
       _seenValue = event.toInt();
     });
 
-    // check values on negative edge
+    // check values on negative edge, since both monitors are on posedge
     intf.clk.negedge.listen((event) {
-      if (_sawEnable) {
-        int expected;
+      // by default, we expect the same value
+      var expected = _previousValue;
 
+      // if there was an enable, we expect it to increment
+      if (_sawEnable && _previousValue != null) {
         // handle counter overflow
-        if (_lastSeenValue == (1 << intf.width) - 1) {
+        if (_seenValue == (1 << intf.width) - 1) {
           expected = 0;
         } else {
-          expected = _lastSeenValue + 1;
+          expected = _previousValue! + 1;
         }
+      }
 
+      if (expected != null) {
         final matchesExpectations = _seenValue == expected;
 
         if (!matchesExpectations) {
@@ -366,8 +369,6 @@ class CounterScoreboard extends Component {
           logger.finest('Counter value matches expectations with $_seenValue');
         }
       }
-      _sawEnable = false;
-      _lastSeenValue = _seenValue ?? 0;
     });
   }
 }

pubspec.yaml

@@ -7,13 +7,13 @@ issue_tracker: https://github.com/intel/rohd-vf/issues
 documentation: https://intel.github.io/rohd-vf/rohd_vf/rohd_vf-library.html
 
 environment:
-  sdk: '>=2.18.0 <3.0.0'
+  sdk: '>=2.18.0 <4.0.0'
 
 dependencies:
   async: ^2.11.0
   logging: ^1.0.1
   meta: ^1.3.0
-  rohd: ^0.4.0
+  rohd: ^0.5.0
 
 dev_dependencies:
   test: ^1.17.3