Fix bug in LogicStructure previousValue (#565)

intel · Feb 20, 2025 · a260cca · a260cca
1 parent f31c3a5
commit a260cca
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Showing 2 changed files with 31 additions and 2 deletions.
diff --git a/lib/src/signals/logic_structure.dart b/lib/src/signals/logic_structure.dart
@@ -328,8 +328,12 @@ class LogicStructure implements Logic {
       elements.map((e) => e.value).toList(growable: false).rswizzle();
 
   @override
-  LogicValue? get previousValue =>
-      elements.map((e) => e.value).toList(growable: false).rswizzle();
+  LogicValue? get previousValue => elements.any((e) => e.previousValue == null)
+      ? null
+      : elements
+          .map((e) => e.previousValue!)
+          .toList(growable: false)
+          .rswizzle();
 
   @override
   late final int width = elements.map((e) => e.width).sum;

diff --git a/test/logic_structure_test.dart b/test/logic_structure_test.dart
@@ -261,4 +261,29 @@ void main() {
       SimCompare.checkIverilogVector(mod, vectors);
     });
   });
+
+  test('logicstructure value and previous value', () async {
+    final s = MyStruct();
+
+    final val1 = LogicValue.ofInt(1, 2);
+    final val2 = LogicValue.ofInt(2, 2);
+
+    s.put(val1);
+
+    expect(s.value, val1);
+    expect(s.previousValue, isNull);
+
+    var checkRan = false;
+
+    Simulator.registerAction(10, () {
+      s.put(val2);
+      expect(s.value, val2);
+      expect(s.previousValue, val1);
+      checkRan = true;
+    });
+
+    await Simulator.run();
+
+    expect(checkRan, isTrue);
+  });
 }