QueryPerformanceTimer

Whenever I try to use a high resolution timer,

I have written source codes down everytime.

This post is to save it. Back up. :)

#include windows.h

class QueryPerformanceTimer
{
public:
QueryPerformanceTimer() : timer_frequency_(0)
{
 init();
}
virtual ~QueryPerformanceTimer() {;}

void init()
{
 if (QueryPerformanceFrequency(&frequency_))
 {
  //printf("High:%d, Quad:%d, Low:%d\n", frequency_.HighPart, frequency_.QuadPart, frequency_.LowPart);
  timer_frequency_ = (double)((long double)(frequency_.HighPart >> 32) + frequency_.LowPart);
 }
 else
  printf("QueryPerformanceFrequency returned FAIL\n");
}

void start()
{
 if (timer_frequency_ == 0)
  return;

 QueryPerformanceCounter(&initial_);
}

void stop()
{
 if (timer_frequency_ == 0)
  return;

 QueryPerformanceCounter(&counter_);
}

double elapsed()
{
 if (timer_frequency_ == 0)
  return 0;

 double elapsed = (double)((long double)(counter_.QuadPart - initial_.QuadPart) / (long double)frequency_.QuadPart);
 return elapsed;
}

bool is_valid()
{
 return timer_frequency_ != 0;
}

double timer_frequency()
{
 return timer_frequency_;
}

private:
LARGE_INTEGER initial_;
LARGE_INTEGER frequency_;
LARGE_INTEGER counter_;

double timer_frequency_;
};

This code is very weak against exceptions. But it's okay if you use it simply.

Copy & Paste!!!