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SystemClock.h
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SystemClock.h
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/*
* Copyright (C) 2005-2011 Team XBMC
* http://www.xbmc.org
*
* This Program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This Program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with XBMC; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
* http://www.gnu.org/copyleft/gpl.html
*
*/
#pragma once
#include <limits>
namespace XbmcThreads
{
/**
* This function returns the system clock's number of milliseconds but with
* an arbitrary reference point. It handles the wrapping of any underlying
* system clock by setting a starting point at the first call. It should
* only be used for measuring time durations.
*
* Of course, on windows it just calls timeGetTime, so you're on your own.
*/
unsigned int SystemClockMillis();
/**
* DO NOT compare the results from SystemClockMillis() to an expected end time
* that was calculated by adding a number of milliseconds to some start time.
* The reason is becuse the SystemClockMillis could wrap. Instead use this
* class which uses differences (which are safe accross a wrap).
*/
class EndTime
{
unsigned int startTime;
unsigned int totalWaitTime;
public:
inline EndTime() : startTime(0), totalWaitTime(0) {}
inline EndTime(unsigned int millisecondsIntoTheFuture) : startTime(SystemClockMillis()), totalWaitTime(millisecondsIntoTheFuture) {}
inline void Set(unsigned int millisecondsIntoTheFuture) { startTime = SystemClockMillis(); totalWaitTime = millisecondsIntoTheFuture; }
inline bool IsTimePast() { return totalWaitTime == 0 ? true : (SystemClockMillis() - startTime) >= totalWaitTime; }
inline unsigned int MillisLeft()
{
unsigned int timeWaitedAlready = (SystemClockMillis() - startTime);
return (timeWaitedAlready >= totalWaitTime) ? 0 : (totalWaitTime - timeWaitedAlready);
}
inline void SetExpired() { totalWaitTime = 0; }
inline void SetInfinite() { totalWaitTime = std::numeric_limits<unsigned int>::max(); }
};
}