windows下实现微秒级延时

最新推荐文章于 2024-10-23 19:25:53 发布

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本文介绍了两种在C/C++中实现微秒级延时的方法。一种为常规方法，通过循环对比时间差来达到延时效果；另一种为优化后的实现方式，通过直接比较计数与目标延时的乘积来简化条件判断，提高效率。

//常规

void sleep_micro_seconds(ULONG ulMicroSeconds)
{
LARGE_INTEGER varFrequency = {0}, varCounter_Start = {0}, varCounter_End = {0};
double dFrequency = 0;
LONGLONG llCount = 0;

::QueryPerformanceFrequency(&varFrequency);
dFrequency = varFrequency.QuadPart/1.0;

::QueryPerformanceCounter(&varCounter_Start);

while(true)
{
  ::QueryPerformanceCounter(&varCounter_End);
  llCount = varCounter_End.QuadPart - varCounter_Start.QuadPart;

  if((llCount/dFrequency) > (ulMicroSeconds/1000000.0) )
  {
   break;
  }
}
}

//优化

void sleep_micro_seconds(ULONG ulMicroSeconds)
{
LARGE_INTEGER varFrequency = {0}, varCounter_Start = {0}, varCounter_End = {0};
LONGLONG llCount = 0;

::QueryPerformanceFrequency(&varFrequency);
::QueryPerformanceCounter(&varCounter_Start);

while(true)
{
::QueryPerformanceCounter(&varCounter_End);

llCount = varCounter_End.QuadPart - varCounter_Start.QuadPart;

  if(1000000*llCount > ulMicroSeconds*varFrequency.QuadPart)
  {
   break;
  }
}
}

int main(int argc, char* argv[])
{

sleep_micro_seconds(40);

}