Implement tiled surface edge opcode

engine/Age.Engine.Tests/TiledSurfaceEdgeOpcodeTests.cs

@@ -0,0 +1,44 @@
+using Age.Engine.Model;
+using Age.Engine.Sys4;
+using Age.Engine.Vm;
+using Xunit;
+
+public class TiledSurfaceEdgeOpcodeTests
+{
+    private static Operand I(long value) => new(0, value);
+
+    [Fact]
+    public void OpcodeRetainsSystem4EdgeWhileModeOneSurfaceUsesPortableBackend()
+    {
+        var table = OpcodeTableJson.Load(Paths.OpcodesJson);
+        var scene = ScriptAssembler.Assemble(table, "TILED-SURFACE", new List<(int, Operand[])>
+        {
+            (0x248, new[] { I(128) }),
+            (0x249, new[] { I(0x32da), I(0x3e), I(0) }),
+            (0x2, System.Array.Empty<Operand>()),
+        }, System.Array.Empty<string>());
+        var host = new RecordingHost();
+        var vm = new VirtualMachine(scene, table, host);
+
+        vm.Run();
+
+        Assert.Equal(128, vm.Gfx.TiledSurfaceEdgeLength);
+        Assert.Equal((0x32daL, 0x3e), Assert.Single(host.Textures));
+        var surface = Assert.Single(vm.Gfx.CapturePersistenceSnapshot().Surfaces);
+        Assert.Equal((0x3e, 0x32daL), (surface.Slot, surface.ResourceId));
+    }
+
+    [Fact]
+    public void SettingReplacesSignedDwordAndSurvivesSceneContextReset()
+    {
+        var gfx = new GfxState();
+        Assert.Equal(0, gfx.TiledSurfaceEdgeLength);
+
+        gfx.SetTiledSurfaceEdgeLength(-1);
+        Assert.Equal(-1, gfx.TiledSurfaceEdgeLength);
+
+        gfx.SetTiledSurfaceEdgeLength(128);
+        gfx.ResetSceneContext();
+        Assert.Equal(128, gfx.TiledSurfaceEdgeLength);
+    }
+}