...
private static GameUI GetCGameUI(Int32 construct, Int32 destruct)
    {
        // Manual implementation of __fastcall.
        // Moves the two first arguments to the registers.

        var code = new byte[16];
        var stream = new MemoryStream(code);
        var writer = new BinaryWriter(stream);

        var codePtr = Kernel32.VirtualAlloc(IntPtr.Zero, code.Length, AllocationType.Commit, MemoryProtection.ExecuteReadWrite);

        // (BA) mov edx, destruct boolean
        writer.Write((Byte)0xBA);
        writer.Write((UInt32)destruct);

        // (B9) mov ecx, construct boolean
        writer.Write((Byte)0xB9);
        writer.Write((UInt32)construct);

        // (E8) call, GetCGameUI relative offset
        writer.Write((Byte)0xE8);
        writer.Write((UInt32)((Int32)Addresses.GetCGameUI - (Int32)codePtr - (Int32)writer.BaseStream.Position - 4));

        // (C3) retn
        writer.Write((Byte)0xC3);

        Marshal.Copy(code, 0, codePtr, code.Length);

        var ui = ((EmptyGetCGameUIPrototype)Marshal.GetDelegateForFunctionPointer(codePtr, typeof(EmptyGetCGameUIPrototype)))();

        Kernel32.VirtualFree(codePtr, code.Length, 0x8000);

        return ui;
    }
...