[SharePlay] Report inactive share-play state

Co-authored-by: Sekai <140012992+SekaixX@users.noreply.github.com>

src/SharpEmu.Libs/Share/SharePlayExports.cs

@@ -0,0 +1,34 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using SharpEmu.HLE;
+
+namespace SharpEmu.Libs.Share;
+
+public static class SharePlayExports
+{
+    private static int _controllerProhibited;
+
+    [SysAbiExport(
+        Nid = "FzQS6DREDfk",
+        ExportName = "sceSharePlayProhibitController",
+        Target = Generation.Gen5,
+        LibraryName = "libSceSharePlay")]
+    public static int SharePlayProhibitController(CpuContext ctx)
+    {
+        var prohibited = ctx[CpuRegister.Rdi];
+        if (prohibited > 1)
+        {
+            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
+        }
+
+        Volatile.Write(ref _controllerProhibited, unchecked((int)prohibited));
+        return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK);
+    }
+
+    public static void ResetRuntimeState() => Volatile.Write(ref _controllerProhibited, 0);
+
+    internal static bool IsControllerProhibited => Volatile.Read(ref _controllerProhibited) != 0;
+
+    internal static void ResetForTests() => ResetRuntimeState();
+}