Merge pull request #179 from SpiceSharp/fix_gnd

Wrong handling of "GND" in subcircuits

Author: marcin-golebiowski

src/SpiceSharpParser.IntegrationTests/Components/SubcircuitTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using Xunit;
 
 namespace SpiceSharpParser.IntegrationTests.Components
@@ -455,5 +456,48 @@ public void SubcircuitWithWrongEnding()
             var model = parser.ParseNetlist(text);
             Assert.True(model.ValidationResult.HasError);
         }
+
+        [Fact]
+        public void When_GND_Port_Used_In_Behavioral_Source_With_Tran()
+        {
+            // Regression test: SUBCKT with GND port name + behavioral source
+            // must work in .TRAN, not just .OP. Previously, Generate() bypassed
+            // the pin map for "GND", creating a floating node instead of mapping
+            // to the external ground node "0".
+            var model = GetSpiceSharpModel(
+                "Subcircuit GND Port TRAN Test",
+                "V1 IN 0 4.0",
+                "X1 0 IN OUT test_subckt",
+                ".SUBCKT test_subckt GND INPUT OUTPUT",
+                "R1 INPUT mid 5k",
+                "R2 mid GND 5k",
+                "B1 OUTPUT GND V={0.5 * V(INPUT,GND)}",
+                ".ENDS test_subckt",
+                ".TRAN 1u 100u",
+                ".SAVE V(OUT)",
+                ".END");
+
+            var simulations = model.Simulations;
+            Assert.Single(simulations);
+
+            var tran = simulations[0];
+            double lastValue = double.NaN;
+
+            tran.EventExportData += (sender, e) =>
+            {
+                var exports = model.Exports.Where(ex => ex.Simulation == tran).ToList();
+                foreach (var export in exports)
+                {
+                    lastValue = export.Extract();
+                }
+            };
+
+            var codes = tran.Run(model.Circuit, -1);
+            codes = tran.InvokeEvents(codes);
+            codes.ToArray();
+
+            // B1 = 0.5 * V(IN,0) = 0.5 * 4.0 = 2.0V
+            Assert.InRange(lastValue, 1.9, 2.1);
+        }
     }
 }

src/SpiceSharpParser/ModelReaders/Netlist/Spice/Context/Names/SubcircuitNodeNameGenerator.cs

@@ -108,6 +108,17 @@ public string Generate(string nodeName)
                 throw new ArgumentNullException(nameof(nodeName));
             }
 
+            // Pin map takes priority — subcircuit port mapping must override
+            // the GND alias below, otherwise a port named "GND" mapped to
+            // external "0" would create a floating node instead of connecting
+            // to the real ground.
+            var pinIdentifier = nodeName;
+
+            if (_pinMap.ContainsKey(pinIdentifier))
+            {
+                return _pinMap[pinIdentifier];
+            }
+
             if (nodeName.ToUpper() == "GND")
             {
                 return nodeName;
@@ -118,16 +129,7 @@ public string Generate(string nodeName)
                 return nodeName;
             }
 
-            var pinIdentifier = nodeName;
-
-            if (_pinMap.ContainsKey(pinIdentifier))
-            {
-                return _pinMap[pinIdentifier];
-            }
-            else
-            {
-                return $"{SubCircuitFullName}{Separator}{nodeName}";
-            }
+            return $"{SubCircuitFullName}{Separator}{nodeName}";
         }
 
         /// <summary>

src/SpiceSharpParser/SpiceSharpParser.csproj

@@ -22,7 +22,7 @@
     <StartupObject />
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <LangVersion>latest</LangVersion>
-    <Version>3.2.11</Version>
+    <Version>3.2.12</Version>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Debug|AnyCPU'">