git.sesse.net Git - casparcg/blob - common/os/linux/prec_timer.cpp

   1 /*
   2 * Copyright (c) 2011 Sveriges Television AB <info@casparcg.com>
   3 *
   4 * This file is part of CasparCG (www.casparcg.com).
   5 *
   6 * CasparCG is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * CasparCG is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with CasparCG. If not, see <http://www.gnu.org/licenses/>.
  18 *
  19 * Author: Robert Nagy, ronag89@gmail.com
  20 */
  21
  22 #include "../../stdafx.h"
  23
  24 #include "../../prec_timer.h"
  25
  26 #include <boost/thread.hpp>
  27 #include <boost/chrono/system_clocks.hpp>
  28
  29 #include <time.h>
  30
  31 #include <cmath>
  32
  33 using namespace boost::chrono;
  34
  35 namespace caspar {
  36
  37 prec_timer::prec_timer()
  38         : time_(0)
  39 {
  40 }
  41
  42 void prec_timer::tick_millis(int64_t ticks_to_wait)
  43 {
  44         ticks_to_wait *= 1000000;
  45         auto t = duration_cast<nanoseconds>(high_resolution_clock::now().time_since_epoch()).count();
  46
  47         if (time_ != 0)
  48         {
  49                 bool done = 0;
  50                 do
  51                 {
  52                         auto ticks_passed = t - time_;
  53                         auto ticks_left = ticks_to_wait - ticks_passed;
  54
  55                         if (t < time_)    // time wrap
  56                                 done = 1;
  57                         if (ticks_passed >= ticks_to_wait)
  58                                 done = 1;
  59
  60                         if (!done)
  61                         {
  62                                 timespec spec;
  63
  64                                 if (ticks_left > 2000000)
  65                                 {
  66                                         spec.tv_sec = ticks_left / 1000000000;
  67                                         spec.tv_nsec = 1000000;
  68                                 }
  69                                 else
  70                                 {
  71                                         spec.tv_sec = 0;
  72                                         spec.tv_nsec = ticks_left / 100;
  73                                 }
  74
  75                                 nanosleep(&spec, nullptr);
  76                         }
  77
  78                         t = duration_cast<nanoseconds>(high_resolution_clock::now().time_since_epoch()).count();
  79                 } while (!done);
  80         }
  81
  82         time_ = t;
  83 }
  84
  85 }