Implement system menu show delay opcodes

engine/Age.Engine.Tests/SystemMenuShowDelayOpcodeTests.cs

@@ -0,0 +1,71 @@
+using Age.Engine.Model;
+using Age.Engine.Sys4;
+using Age.Engine.Vm;
+
+public class SystemMenuShowDelayOpcodeTests
+{
+    private static readonly OpcodeTable Table = OpcodeTableJson.Load(Paths.OpcodesJson);
+    private static Operand I(long value) => new(0, value);
+    private static Operand G(long address) => new(3, address);
+    private static (int, Operand[]) Exit() => (0x2, Array.Empty<Operand>());
+
+    [Fact]
+    public void System4DelayRoundTripsThroughThePairedGetter()
+    {
+        Script system4 = ScriptAssembler.Assemble(Table, "SYSTEM4.BIN",
+        [
+            (0x149, [I(1000)]),
+            (0x148, [G(0x100)]),
+            Exit(),
+        ], []);
+        var vm = new VirtualMachine(system4, Table, new RecordingHost());
+
+        Assert.Equal(0u, vm.SystemMenuShowDelayMilliseconds);
+
+        vm.Run();
+
+        Assert.Equal(1000u, vm.SystemMenuShowDelayMilliseconds);
+        Assert.Equal(1000, vm.Globals[0x100]);
+    }
+
+    [Fact]
+    public void SetterAndGetterPreserveTheCompleteNativeDword()
+    {
+        Script system4 = ScriptAssembler.Assemble(Table, "SYSTEM4.BIN",
+        [
+            (0x149, [I(0x80000001L)]),
+            (0x148, [G(0x100)]),
+            Exit(),
+        ], []);
+        var vm = new VirtualMachine(system4, Table, new RecordingHost());
+
+        vm.Run();
+
+        Assert.Equal(0x80000001u, vm.SystemMenuShowDelayMilliseconds);
+        Assert.Equal(unchecked((int)0x80000001u), vm.Globals[0x100]);
+    }
+
+    [Fact]
+    public void RootSceneReloadRestoresTheZeroDefault()
+    {
+        Script reloadedSystem4 = ScriptAssembler.Assemble(Table, "SYSTEM4.BIN",
+        [
+            (0x148, [G(0x100)]),
+            Exit(),
+        ], []);
+        Script initial = ScriptAssembler.Assemble(Table, "INITIAL",
+        [
+            (0x149, [I(1000)]),
+            (0x9, Array.Empty<Operand>()),
+        ], []);
+        var provider = new MapProvider(new Dictionary<long, Script> { [0] = reloadedSystem4 });
+        var host = new RecordingHost();
+        var vm = new VirtualMachine(initial, Table, host, provider: provider);
+
+        vm.Run();
+
+        Assert.Equal(0u, vm.SystemMenuShowDelayMilliseconds);
+        Assert.Equal(0, vm.Globals[0x100]);
+        Assert.Equal(1, host.SceneContextResets);
+    }
+}