Timer.h

/*
Copyright 2011 Matt DeVore

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// mundane constants
const int SECONDSPERMINUTE = 60;
const int HUNDREDTHSPERSECOND = 100;

class CTimer {
  friend bool operator <(const CTimer&,const CTimer&);
  friend bool operator >(const CTimer&,const CTimer&);
  friend bool operator >=(const CTimer&,const CTimer&);
  friend bool operator <=(const CTimer&,const CTimer&);

  friend CTimer operator +(const CTimer&,const CTimer&);
  friend CTimer operator -(const CTimer&,const CTimer&);

 public:
  static void Wait(double time);

  inline float SecondsPassed32() const {
    return (float)this->TicksPassed() / (float) ticks_per_second ;
  }
  inline double SecondsPassed80() const {
    return (double)this->TicksPassed() / (double)ticks_per_second;
  }
  inline int SecondsPassedInt() const {
    return (int)(this->TicksPassed() / ticks_per_second);
  }
  inline long SecondsPassedFixed() const {
    return (long)((this->TicksPassed() << 16) / ticks_per_second);
  }

  void Minutes(int& min) const;
  void MinutesSeconds(int& min,int& sec) const;
  void MinutesSecondsHundredths(int& min,int& sec,int& hundredths) const;

  void Pause();
  void Resume();
  void Restart();
  bool Paused() const;

  // returns true if there has been at least one clock tick
  //  since the last restart
  bool ElapsedTimeIsMeasurable() const;

  CTimer(const CTimer& r);
  CTimer();
  ~CTimer();

  CTimer& operator =(const CTimer&);

  // adds the time passed for r to the time passed for this
  CTimer& operator +=(const CTimer&);

  // subtracts the time passed for r from the time passed for this
  CTimer& operator -=(const CTimer&);

 private:
  // timer state constants
  enum {TS_NEVERBEENCREATED,TS_USESSUPERIORTIMER,TS_USESLAMENTABLETIMER};

  inline LONGLONG TicksPassed() const
    {return NULL == pause ? Now() - last_count : *pause - last_count;}

  static inline LONGLONG Now() {
    if (TS_USESSUPERIORTIMER == state) {
      LONGLONG now;
      QueryPerformanceCounter((LARGE_INTEGER *)&now);
      return now;
    } else {
      return GetTickCount();
    }
  }

  // equal to null if the timer is not currently paused,
  // otherwise points to the tick count of when it was paused
  LONGLONG *pause;

  LONGLONG last_count;

  static LONGLONG ticks_per_second;
  static int state;
};

bool operator <(const CTimer&,const CTimer&);
bool operator >(const CTimer&,const CTimer&);
bool operator >=(const CTimer&,const CTimer&);
bool operator <=(const CTimer&,const CTimer&);

CTimer operator +(const CTimer&,const CTimer&);
CTimer operator -(const CTimer&,const CTimer&);