/*
 * License Information
 * 
 * Copyright (C) 2010 Jeroen Frijters
 * 
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * This code may only be studied and used for experimental purposes.
 * 
 */
using System;
using System.Threading;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Reflection;

static class __Hack__DoNotUse
{
    /* --- IMPORTANT NOTICE ---
     * 
     * This code is NOT SAFE to use in production.
     * 
     * Patching instructions like this is not "thread" safe.
     * 
     */
    static __Hack__DoNotUse()
    {
        byte[] code = {
            0x53,                           // push        ebx
            0x90,                           // nop
            0x8B, 0x5C, 0x24, 0x04,         // mov         ebx,dword ptr [esp+4]
            0xB8, 0x0F, 0xAE, 0xF0, 0xB0,   // mov         eax,B0F0AE0Fh
            0xF0, 0x87, 0x43, 0xFB,         // lock xchg   eax,dword ptr [ebx-5]
            0x5B,                           // pop         ebx
            0xC3                            // ret
        };
        if (IntPtr.Size == 8)
        {
            code[1] = 0x48;                 // rex.w
            code[5] = 0x08;                 // mov         rbx,qword ptr [esp+8]
        }
        RuntimeMethodHandle method = ((ThreadStart)MemoryBarrier).Method.MethodHandle;
        RuntimeHelpers.PrepareMethod(method);
        IntPtr p = method.GetFunctionPointer();
        Marshal.Copy(code, 0, p, code.Length);
    }

    [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)]
    public static void MemoryBarrier()
    {
        // reserve some space to overwrite
        MemoryBarrier();
        MemoryBarrier();
        MemoryBarrier();
        MemoryBarrier();
        MemoryBarrier();
        MemoryBarrier();
        MemoryBarrier();
        MemoryBarrier();
    }
}

class Program
{
    static volatile int foo;

    static void Main(string[] args)
    {
        for (; ; )
        {
            Stopwatch sw = Stopwatch.StartNew();
            for (int i = 0; i < 100000000; i++)
            {
                foo = 0;
                __Hack__DoNotUse.MemoryBarrier();
                //Thread.MemoryBarrier();
            }
            sw.Stop();
            Console.WriteLine(sw.ElapsedMilliseconds);
        }
    }
}