CV_INLINE  int  cvRound( double value )
{
#if defined WIN32 && defined _MSC_VER
    int t;
    __asm
    {
        fld value;
        fistp t;
    }
    return t;
#elif __GNUC__ > 3
    return (int)lrint( value );
#else
    double temp = value + 6755399441055744.0;
    return (int)*((uint64*)&temp);
#endif
}

这个函数是在intel的图像函数库OPENCV中看到的，功能是对double型的数取与它最接近的数，函数评价是On some architectures the functions work much faster than the standard cast operations in C. 那位大虾能帮忙分析一下它的函数体啊。