Add support for equality checking with don't-cares in LogicValue (#294)

intel · Mar 7, 2023 · 7813e4c · 7813e4c
1 parent 023fc58
commit 7813e4c
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diff --git a/lib/src/values/logic_value.dart b/lib/src/values/logic_value.dart
@@ -928,6 +928,41 @@ abstract class LogicValue {
     ].swizzle();
   }
 
+  /// Checks if `this` is equal to [other], except ignoring bits of
+  /// which are not valid.
+  ///
+  /// Returns `true` if each bit of `this` which [isValid] is equal
+  /// to each bit of [other] which [isValid].
+  ///
+  /// For example:
+  /// ```dart
+  /// // Returns false
+  /// LogicValue.ofString('1010xz').equalsWithDontCare(
+  ///   LogicValue.ofString('10111x'));
+  ///
+  /// // Returns true
+  /// LogicValue.ofString('10x111').equalsWithDontCare(
+  ///   LogicValue.ofString('10111x'));
+  ///
+  /// // Returns false
+  /// LogicValue.ofString('10x1z1').equalsWithDontCare(
+  ///   LogicValue.ofString('10101x'));
+  /// ```
+  bool equalsWithDontCare(LogicValue other) {
+    if (width == other.width) {
+      for (var i = 0; i < width; i++) {
+        if (!this[i].isValid || !other[i].isValid) {
+          continue;
+        } else if (this[i] != other[i]) {
+          return false;
+        }
+      }
+      return true;
+    } else {
+      return false;
+    }
+  }
+
   /// Returns new [LogicValue] replicated [multiplier] times. An exception will
   /// be thrown in case the multiplier is <1
   LogicValue replicate(int multiplier) {

diff --git a/test/logic_value_test.dart b/test/logic_value_test.dart
@@ -428,6 +428,32 @@ void main() {
     });
   });
   group('comparison operations', () {
+    test('equalsWithDontCare', () {
+      expect(
+          // == not equal
+          LogicValue.ofString('1010xz')
+              .equalsWithDontCare(LogicValue.ofString('10111x')),
+          equals(false));
+      expect(
+          // == equal
+          LogicValue.ofString('1010xz')
+              .equalsWithDontCare(LogicValue.ofString('101z1x')),
+          equals(true));
+      expect(
+          // == not equal
+          LogicValue.ofString('10x1z1')
+              .equalsWithDontCare(LogicValue.ofString('10101x')),
+          equals(false));
+      expect(
+          //
+          LogicValue.ofString('10x1z1')
+              .equalsWithDontCare(LogicValue.ofString('10101x')),
+          equals(false));
+      expect(
+          LogicValue.ofString('10x1z1')
+              .equalsWithDontCare(LogicValue.ofString('101x11')),
+          equals(true));
+    });
     test('equality', () {
       expect(
           // == equal
@@ -740,7 +766,6 @@ void main() {
           equals(LogicValue.ofBigInt(BigInt.from(3), 512)));
     });
   });
-
   group('FilledLogicValue', () {
     test('overrides', () {
       expect(