MFC 中怎么实现微秒级的延时 沉沉_

转自百度文库：

void DelayUs(int uDelay)
{

    LARGE_INTEGER litmp;
    LONGLONG QPart1,QPart2;

    double dfMinus,dfFreq,dfTim;
    
    /*
        Pointer to a variable that the function sets, in counts per second, to the current performance-counter frequency. 
        If the installed hardware does not support a high-resolution performance counter, 
        the value passed back through this pointer can be zero. 

    */
    QueryPerformanceFrequency(&litmp);

    dfFreq = (double)litmp.QuadPart;

    /*
        Pointer to a variable that the function sets, in counts, to the current performance-counter value. 
    */
    QueryPerformanceCounter(&litmp);

    QPart1 = litmp.QuadPart;
    do
    {
           QueryPerformanceCounter(&litmp);
        QPart2 = litmp.QuadPart;
        dfMinus = (double)(QPart2-QPart1);
        dfTim = dfMinus/dfFreq;
     }while(dfTim<0.000001 * uDelay);
}

如果你看懂了上述函数，还可以用它里面的部分代码来测试很多函数的执行时间。

当然，这个函数还是有点隐患，如果在一个延时期间，定时器溢出，那么这个值就有可能不准，需要你小心处理。

如：if (dfMinus < 0)

　　　　break;

这个假设硬件定时器是以增加的方式计数的。