If anybody cares, here's the QPC counter overload I've been using. It has the same functionality as the timer class. I could do a similar one using gettimeofday on Linux if somebody is interested. class usecTimer : public timer{ #ifdef WIN32 public: usecTimer() { QueryPerformanceFrequency(&_pc_freq); _start_time = HFClock(); } // postcondition: elapsed()==0 void restart() { _start_time = HFClock(); } // post: elapsed()==0 double elapsed() // return elapsed time in seconds { return HFClock() - _start_time; } double elapsed_max() const // return estimated maximum value for elapsed() { return double((std::numeric_limits<LONGLONG>::max)()) / double(_pc_freq.QuadPart); } double elapsed_min() const // return minimum value for elapsed() { return (1.0 / double(_pc_freq.QuadPart)); } private: LARGE_INTEGER _pc_freq, _now_tic; double _start_time; double HFClock(void) { assert(_pc_freq.QuadPart != 0); // Query current clock tick QueryPerformanceCounter(&_now_tic); return double(_now_tic.QuadPart) / double(_pc_freq.QuadPart); } #endif };
Because of the long discussion about QueryPerformanceCounter that didn't came to a real conclusion, I decided to implement two additionnal timers:
- boost::qpc_timer, which use QueryPerformanceCounter() for its resolution. - boost::tgt_timer, which use timeGetTime() for its resolution.
As using those timers would make no sense on another platform than windows, those are not defined by default. One must #define BOOST_QPC_TIMER to get boost::qpc_timer and must #define BOOST_TGT_TIMER to get boost::tgt_timer.
Trying to do those defines on another platform than windows results in an #error.