Помощь с редактированием кода C# для получения идентификатора ЦП

Но есть ошибка, которую я не знаю как исправить...

Недопустимый элемент ref в выражении

на строке ref byte[] code;

Сам код предоставлю ниже:

using System;
using System.Text;
using System.Runtime.InteropServices;

namespace ConsoleApplication1
{
    class Program
    {
        [DllImport("user32", EntryPoint = "CallWindowProcW", CharSet = CharSet.Unicode,
       SetLastError = true, ExactSpelling = true)]
        private static extern IntPtr CallWindowProcW([In] 
byte[] bytes, IntPtr hWnd, int msg, [In, Out] byte[] wParam, IntPtr lParam);
        [return: MarshalAs(UnmanagedType.Bool)]
        [DllImport("kernel32", CharSet = CharSet.Unicode, SetLastError = true)]
        public static
            extern bool VirtualProtect([In] byte[] bytes, IntPtr size, int newProtect, out int oldProtect);
        const int PAGE_EXECUTE_READWRITE = 0x40;
        static void Main(string[] args)
        {
            string s = ProcessorId();
            Console.WriteLine("ProcessorId: " + s);
            Console.ReadLine();
        }
        private static string ProcessorId()
        {
            byte[] sn = new byte[8];
            if (!ExecuteCode(ref sn))
                return "ND";
            return string.Format("{0}{1}", BitConverter.ToUInt32(sn, 4).ToString("X8"),
           BitConverter.ToUInt32(sn, 0).ToString("X8"));
        }
        private static bool ExecuteCode(ref byte[] result)
        {
            int num;
            /* The opcodes below implement a C function with the signature: 
            * __stdcall CpuIdWindowProc(hWnd, Msg, wParam, lParam); 
            * with wParam interpreted as a pointer pointing to an 8 byte unsigned character buffer. 
            * */
            byte[] code_x86 = new byte[] { 
             0x55, /* push ebp */ 
             0x89, 0xe5, /* mov ebp, esp */ 
             0x57, /* push edi */ 
             0x8b, 0x7d, 0x10, /* mov edi, [ebp+0x10] */ 
             0x6a, 0x01, /* push 0x1 */ 
             0x58, /* pop eax */ 
             0x53, /* push ebx */ 
             0x0f, 0xa2, /* cpuid */ 
             0x89, 0x07, /* mov [edi], eax */ 
             0x89, 0x57, 0x04, /* mov [edi+0x4], edx */ 
             0x5b, /* pop ebx */ 
             0x5f, /* pop edi */ 
             0x89, 0xec, /* mov esp, ebp */ 
             0x5d, /* pop ebp */ 
             0xc2, 0x10, 0x00, /* ret 0x10 */ 
             };
            byte[] code_x64 = new byte[] { 
             0x53, /* push rbx */ 
             0x48, 0xc7, 0xc0, 0x01, 0x00, 0x00, 0x00, /* mov rax, 0x1 */ 
             0x0f, 0xa2, /* cpuid */ 
             0x41, 0x89, 0x00, /* mov [r8], eax */ 
             0x41, 0x89, 0x50, 0x04, /* mov [r8+0x4], edx */ 
             0x5b, /* pop rbx */ 
             0xc3, /* ret */ 
             };
            ref byte[] code;
            if (IsX64Process())
                code = ref code_x64;
            else
                code = ref code_x86;

            IntPtr ptr = new IntPtr(code.Length);
            if (!VirtualProtect(code, ptr, PAGE_EXECUTE_READWRITE, out num))
                Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
            ptr = new IntPtr(result.Length);
            return (CallWindowProcW(code, IntPtr.Zero, 0, result, ptr) != IntPtr.Zero);
        }
        private static bool IsX64Process()
        {
            return IntPtr.Size == 8;
        }
    }
}