怎么快速计算CPU的频率 要的是动态频率,和cpuz看到的同步,大家都看上吧

float Cxxx::GetCpuClock(void)
{
    /*
    RdTSC:
    It's the Pentium instruction "ReaD Time Stamp Counter". It measures the
    number of clock cycles that have passed since the processor was reset, as a
    64-bit number. That's what the _emit lines do.*/
#define RdTSC __asm _emit 0x0f __asm _emit 0x31

    // variables for the clock-cycles:
    __int64 cyclesStart = 0, cyclesStop = 0;
    // variables for the High-Res Preformance Counter:
    unsigned __int64 nCtr = 0, nFreq = 0, nCtrStop = 0;


    // retrieve performance-counter frequency per second:
    if(!QueryPerformanceFrequency((LARGE_INTEGER *) &nFreq)) return 0;

    // retrieve the current value of the performance counter:
    QueryPerformanceCounter((LARGE_INTEGER *) &nCtrStop);

    // add the frequency to the counter-value:
    nCtrStop += nFreq;

    _asm
    {// retrieve the clock-cycles for the start value:
        RdTSC
            mov DWORD PTR cyclesStart, eax
            mov DWORD PTR [cyclesStart + 4], edx
    }

    do{// retrieve the value of the performance counter until 1 sec has gone by:
        QueryPerformanceCounter((LARGE_INTEGER *) &nCtr);
    }while (nCtr < nCtrStop);

    _asm
    {// retrieve again the clock-cycles after 1 sec. has gone by:
        RdTSC
            mov DWORD PTR cyclesStop, eax
            mov DWORD PTR [cyclesStop + 4], edx
    }

    // stop-start is speed in Hz divided by 1,000,000 is speed in MHz
    return    ((float)cyclesStop-(float)cyclesStart) / 1000000;
}