xbmc/cores/RetroPlayer/playback/GameLoop.cpp

   1 /*
   2  *  Copyright (C) 2016-2018 Team Kodi
   3  *  This file is part of Kodi - https://kodi.tv
   4  *
   5  *  SPDX-License-Identifier: GPL-2.0-or-later
   6  *  See LICENSES/README.md for more information.
   7  */
   8
   9 #include "GameLoop.h"
  10
  11 #include <chrono>
  12 #include <cmath>
  13
  14 using namespace KODI;
  15 using namespace RETRO;
  16 using namespace std::chrono_literals;
  17
  18 #define DEFAULT_FPS 60 // In case fps is 0 (shouldn't happen)
  19 #define FOREVER_MS (7 * 24 * 60 * 60 * 1000) // 1 week is large enough
  20
  21 CGameLoop::CGameLoop(IGameLoopCallback* callback, double fps)
  22   : CThread("GameLoop"), m_callback(callback), m_fps(fps ? fps : DEFAULT_FPS), m_speedFactor(0.0)
  23 {
  24 }
  25
  26 CGameLoop::~CGameLoop()
  27 {
  28   Stop();
  29 }
  30
  31 void CGameLoop::Start()
  32 {
  33   Create();
  34 }
  35
  36 void CGameLoop::Stop()
  37 {
  38   StopThread(false);
  39   m_sleepEvent.Set();
  40   StopThread(true);
  41 }
  42
  43 void CGameLoop::SetSpeed(double speedFactor)
  44 {
  45   m_speedFactor = speedFactor;
  46
  47   m_sleepEvent.Set();
  48 }
  49
  50 void CGameLoop::PauseAsync()
  51 {
  52   SetSpeed(0.0);
  53 }
  54
  55 void CGameLoop::Process(void)
  56 {
  57   while (!m_bStop)
  58   {
  59     if (m_speedFactor == 0.0)
  60     {
  61       m_lastFrameMs = 0.0;
  62       m_sleepEvent.Wait(5000ms);
  63     }
  64     else
  65     {
  66       if (m_speedFactor > 0.0)
  67         m_callback->FrameEvent();
  68       else if (m_speedFactor < 0.0)
  69         m_callback->RewindEvent();
  70
  71       if (m_lastFrameMs > 0.0)
  72       {
  73         m_lastFrameMs += FrameTimeMs();
  74         m_adjustTime = m_lastFrameMs - NowMs();
  75       }
  76       else
  77       {
  78         m_lastFrameMs = NowMs();
  79         m_adjustTime = 0.0;
  80       }
  81
  82       // Calculate sleep time
  83       double sleepTimeMs = SleepTimeMs();
  84
  85       // Sleep at least 1 ms to avoid sleeping forever
  86       while (sleepTimeMs > 1.0)
  87       {
  88         m_sleepEvent.Wait(std::chrono::milliseconds(static_cast<unsigned int>(sleepTimeMs)));
  89
  90         if (m_bStop)
  91           break;
  92
  93         // Speed may have changed, update sleep time
  94         sleepTimeMs = SleepTimeMs();
  95       }
  96     }
  97   }
  98 }
  99
 100 double CGameLoop::FrameTimeMs() const
 101 {
 102   if (m_speedFactor != 0.0)
 103     return 1000.0 / m_fps / std::abs(m_speedFactor);
 104   else
 105     return 1000.0 / m_fps / 1.0;
 106 }
 107
 108 double CGameLoop::SleepTimeMs() const
 109 {
 110   // Calculate next frame time
 111   const double nextFrameMs = m_lastFrameMs + FrameTimeMs();
 112
 113   // Calculate sleep time
 114   double sleepTimeMs = (nextFrameMs - NowMs()) + m_adjustTime;
 115
 116   // Reset adjust time
 117   m_adjustTime = 0.0;
 118
 119   // Positive or zero
 120   sleepTimeMs = (sleepTimeMs >= 0.0 ? sleepTimeMs : 0.0);
 121
 122   return sleepTimeMs;
 123 }
 124
 125 double CGameLoop::NowMs() const
 126 {
 127   return std::chrono::duration<double, std::milli>(
 128              std::chrono::steady_clock::now().time_since_epoch())
 129       .count();
 130 }