kc3-lang/angle/util/osx/OSXTimer.cpp

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• Hash : 479918de
  Author :
  Date : 2018-10-22T11:53:51
  

  Get absolute time from timers
  
  Independent of start()/stop()/getElapsedTime() functionality,
  getAbsoluteTime() is added to return the time regardless of whether the
  timer is running.
  
  Bug: angleproject:2908
  Change-Id: I056aeb6eddfba8757a139934c1cf68e00e860de6
  Reviewed-on: https://chromium-review.googlesource.com/c/1296952
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  

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• util/osx/OSXTimer.cpp

• //
  // Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // OSXTimer.cpp: Implementation of a high precision timer class on OSX
  
  #include "osx/OSXTimer.h"
  
  #include <CoreServices/CoreServices.h>
  #include <mach/mach.h>
  #include <mach/mach_time.h>
  
  OSXTimer::OSXTimer()
      : mRunning(false),
      mSecondCoeff(0)
  {
  }
  
  double OSXTimer::getSecondCoeff()
  {
      // If this is the first time we've run, get the timebase.
      if (mSecondCoeff == 0.0)
      {
          mach_timebase_info_data_t timebaseInfo;
          mach_timebase_info(&timebaseInfo);
  
          mSecondCoeff = timebaseInfo.numer * (1.0 / 1000000000) / timebaseInfo.denom;
      }
  
      return mSecondCoeff;
  }
  
  void OSXTimer::start()
  {
      mStartTime = mach_absolute_time();
      // Cache secondCoeff
      getSecondCoeff();
      mRunning = true;
  }
  
  void OSXTimer::stop()
  {
      mStopTime = mach_absolute_time();
      mRunning = false;
  }
  
  double OSXTimer::getElapsedTime() const
  {
      if (mRunning)
      {
          return mSecondCoeff * (mach_absolute_time() - mStartTime);
      }
      else
      {
          return mSecondCoeff * (mStopTime - mStartTime);
      }
  }
  
  double OSXTimer::getAbsoluteTime()
  {
      return getSecondCoeff() * mach_absolute_time();
  }
  
  Timer *CreateTimer()
  {
      return new OSXTimer();
  }
  

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