【Windows API】QueryPerformanceFrequencyで高精度時間差を取得

LARGE_INTEGER	SystemFrequency, StartTime, StopTime;
double          dbDuration;

QueryPerformanceFrequency(&SystemFrequency);
QueryPerformanceCounter(&StartTime);

//          

QueryPerformanceCounter(&StopTime );
dbDuration = (double)(StopTime.QuadPart - StartTime.QuadPart) / (double)SystemFrequency.QuadPart;