git.sesse.net Git - casparcg/blob - common/utility/timer.h

   1 /*\r
   2 * copyright (c) 2010 Sveriges Television AB <info@casparcg.com>\r
   3 *\r
   4 *  This file is part of CasparCG.\r
   5 *\r
   6 *    CasparCG is free software: you can redistribute it and/or modify\r
   7 *    it under the terms of the GNU General Public License as published by\r
   8 *    the Free Software Foundation, either version 3 of the License, or\r
   9 *    (at your option) any later version.\r
  10 *\r
  11 *    CasparCG is distributed in the hope that it will be useful,\r
  12 *    but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  13 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  14 *    GNU General Public License for more details.\r
  15 \r
  16 *    You should have received a copy of the GNU General Public License\r
  17 *    along with CasparCG.  If not, see <http://www.gnu.org/licenses/>.\r
  18 *\r
  19 */\r
  20 #pragma once\r
  21 \r
  22 #include <windows.h>\r
  23 \r
  24 namespace caspar {\r
  25         \r
  26 class high_prec_timer\r
  27 {\r
  28 public:\r
  29         high_prec_timer()\r
  30         {\r
  31                 QueryPerformanceFrequency(&freq_);\r
  32                 QueryPerformanceCounter(&time_);\r
  33         }\r
  34 \r
  35         // Author: Ryan M. Geiss\r
  36         // http://www.geisswerks.com/ryan/FAQS/timing.html\r
  37         void tick(double interval)\r
  38         {       \r
  39                 LARGE_INTEGER t;\r
  40                 QueryPerformanceCounter(&t);\r
  41 \r
  42                 if (time_.QuadPart != 0)\r
  43                 {\r
  44                         __int64 ticks_to_wait = static_cast<int>(static_cast<double>(freq_.QuadPart) * interval);\r
  45                         __int64 done = 0;\r
  46                         do\r
  47                         {\r
  48                                 QueryPerformanceCounter(&t);\r
  49                                 \r
  50                                 __int64 ticks_passed = static_cast<__int64>(t.QuadPart) - static_cast<__int64>(time_.QuadPart);\r
  51                                 __int64 ticks_left = ticks_to_wait - ticks_passed;\r
  52 \r
  53                                 if (t.QuadPart < time_.QuadPart)    // time wrap\r
  54                                         done = 1;\r
  55                                 if (ticks_passed >= ticks_to_wait)\r
  56                                         done = 1;\r
  57                                 \r
  58                                 if (!done)\r
  59                                 {\r
  60                                         // if > 0.002s left, do Sleep(1), which will actually sleep some \r
  61                                         //   steady amount, probably 1-2 ms,\r
  62                                         //   and do so in a nice way (cpu meter drops; laptop battery spared).\r
  63                                         // otherwise, do a few Sleep(0)'s, which just give up the timeslice,\r
  64                                         //   but don't really save cpu or battery, but do pass a tiny\r
  65                                         //   amount of time.\r
  66                                         if (ticks_left > static_cast<__int64>((freq_.QuadPart*2)/1000))\r
  67                                                 Sleep(1);\r
  68                                         else                        \r
  69                                                 for (int i = 0; i < 10; ++i) \r
  70                                                         Sleep(0);  // causes thread to give up its timeslice\r
  71                                 }\r
  72                         }\r
  73                         while (!done);            \r
  74                 }\r
  75 \r
  76                 time_ = t;\r
  77         }               \r
  78 private:        \r
  79         LARGE_INTEGER freq_;\r
  80         LARGE_INTEGER time_;\r
  81 };\r
  82 \r
  83 \r
  84 }