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用VC实现CPU速度自测
 
#include <windows.h>
#include <iostream>
using namespace std;
//测试速度的子程序
float MeasureSpeed(void);
int main(void)
{
    cout << "您的CPU的运行速度是: " << MeasureSpeed() << "MHz" << endl;
    system("pause");
    return 0;
}
float MeasureSpeed()
{
unsigned long int       ticks;          //先是存放计时次数，后存放固定时间间隔值
unsigned long int       stock0, stock1; //存放两固定时刻的CPU内置时钟值，值的含意为计数
unsigned long int       cycles;         //存放内置时钟值之差，好固定时段的计数值 
unsigned long int       freq[5] = {0,0,0,0,0}; //存放频率，为了提高精度，采用了相邻的测的5个频率的平均值
unsigned long int       nums = 0;       //循环次数
unsigned long int       total = 0;      //存放频率之和
    LARGE_INTEGER       t0,t1;
    LARGE_INTEGER       countfreq;
    //返回高精度的计数频率，即每秒多少次;
    if (!QueryPerformanceFrequency( &countfreq ) )
    {
        return 0.0f;
    }
    //返回特定进程的优先级;
    DWORD priority_class = GetPriorityClass(GetCurrentProcess());
    //返回特定线程的优先级;
    int   thread_priority = GetThreadPriority(GetCurrentThread());
    //将当前进程设成实时进程;
    SetPriorityClass(GetCurrentProcess(), REALTIME_PRIORITY_CLASS);
	//设定线程优先级;
  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL);
    do
    {
        nums++;
        freq[4] = freq[3];
        freq[3] = freq[2];
        freq[2] = freq[1];
        freq[1] = freq[0];
	//返回高精度计数的值;
        QueryPerformanceCounter(&t0);
        t1.LowPart = t0.LowPart;
        t1.HighPart = t0.HighPart;
	//这句中的50和后面相同语句中的1000是一个经验值，起的作用是控制时间间隔，可以
	//调节这两个值来实现最佳时间间隔。
 while ( (unsigned long int)t1.LowPart - (unsigned long int)t0.LowPart<10)
        {
            QueryPerformanceCounter(&t1);
        }
        _asm
        {
rdtsc  //启动读取CPU的内置时钟，其返回值是个64位的整数，高32到EDX，低32到EAX里
 mov stock0, EAX //高位部份在短暂时间内是不会有变化的，故无需读出对比
	}
 t0.LowPart = t1.LowPart;        // 重置初始时刻
  t0.HighPart = t1.HighPart;
 while ((unsigned long int)t1.LowPart-(unsigned long int)t0.LowPart<1000 )
        {
            QueryPerformanceCounter(&t1);
        }
        _asm
        {
            rdtsc
            mov  stock1, EAX
	}
        cycles = stock1 - stock0;
        ticks = (unsigned long int) t1.LowPart - (unsigned long int) t0.LowPart;
        ticks = ticks * 1000000;
        ticks = ticks / countfreq.LowPart;
   if ( ticks % countfreq.LowPart > countfreq.LowPart/2 )
        {
            ticks++;            // 使数据收敛
        }
freq[0] = cycles / ticks;    // 求出频率，单位：MHz
        if ( cycles%ticks > ticks/2 )
        {
           freq[0]++;             // 使数据收敛
        }
   total = (freq[0] + freq[1] + freq[2] + freq[3] + freq[4]);
    } while ((nums < 5 ) || (nums < 100) && ( (abs(5 * freq[0] - total) < 5)
             || (abs(5 * freq[1]-total) < 5) || (abs(5 * freq[2] - total) < 5)
			 || (abs(5 * freq[3]-total) < 5) || (abs(5 * freq[4] - total) < 5)
			 ));
//条件循环，以确保循环不少于5次，在大于5次后确保达到一定的精度后退出
    if ( total/5  !=  ( total + 1 )/5 )
    {
        total ++;               // 使数据收敛
    }
    // 恢复进程及线程的优先级别;
    SetPriorityClass(GetCurrentProcess(), priority_class);
    SetThreadPriority(GetCurrentThread(), thread_priority);
    return float(total) / 5.0f;
}