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本帖最后由 20011010wo 于 2016-8-22 22:25 编辑
点击停止后将会计算从上一次点击开始所用的时间,如果没有点击开始……则时间近似为窗口显示的时间 + 校准所用时间(500ms)
32位静态编译
Timer.exe
(454.5 KB, 下载次数: 765)
原理:利用某些设备主板上的晶振,开始后将会连续5次校准多核CPU采用QueryPerformanceCounter的问题 QueryPerformanceCounter的运行情况是依赖于CPU的,当CPU是多核时,在某一线程内调用QueryPerformanceCounter,线程会切换于不同的核心之间,这时候QueryPerformanceCounter返回值是不确定的。
多核CPU使用QueryPerformanceCounter 当需要在某一进程中获取时间,需要将该线程绑定在某一固定的核心上,这样获取的高精度计时器才是可靠的。通过SetThreadAffinityMask可以实现这一目的
如:SetThreadAffinityMask(GetCurrentThread(),0x00000001);//绑定当前线程到CPU 1号核心
附赠高精度时间类(C++)
- class HighAccuracyTimer:private Noncopyable
- {
- public:
- HighAccuracyTimer()
- {
- succeed = QueryPerformanceFrequency(&freq);
- oldMask = SetThreadAffinityMask(GetCurrentThread(), 0x00000001);
- QueryPerformanceCounter(&begin);
- }
- ~HighAccuracyTimer()
- {
- SetThreadAffinityMask(GetCurrentThread(), oldMask);
- }
- void Start()
- {
- QueryPerformanceCounter(&begin);
- }
- void End()
- {
- QueryPerformanceCounter(&end);
- }
- __int64 Correct()
- {
- QueryPerformanceCounter(&correct_begin);
- QueryPerformanceCounter(&correct_end);
- correct = correct_end.QuadPart - correct_begin.QuadPart;
- return correct;
- }
- unsigned __int64 Count()
- {
- return (__int64)(end.QuadPart - begin.QuadPart);
- }
- unsigned __int64 Frequency()
- {
- return freq.QuadPart;
- }
- long double Seconds()
- {
- return (end.QuadPart - begin.QuadPart - correct) / ((long double)freq.QuadPart);
- }
- long double MillSeconds()
- {
- return (end.QuadPart - begin.QuadPart - correct) / ((long double)freq.QuadPart) * 1000.0L;
- }
- long double MicroSeconds()
- {
- return (end.QuadPart - begin.QuadPart - correct) / ((long double)freq.QuadPart) * 1000000.0L;
- }
- BOOL succeed;
- private:
- LARGE_INTEGER freq;
- LARGE_INTEGER begin, end, correct_begin, correct_end;
- ULONG_PTR oldMask;
- __int64 correct = 0LL;
- };
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