webrtc/system_wrappers/source/clock.cc

/*
 *  Copyright (c) 2013 The WebRTC 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 in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "webrtc/system_wrappers/interface/clock.h"

#if defined(_WIN32)
// Windows needs to be included before mmsystem.h
#include <Windows.h>
#include <WinSock.h>
#include <MMSystem.h>
#elif ((defined WEBRTC_LINUX) || (defined WEBRTC_MAC))
#include <sys/time.h>
#include <time.h>
#endif

#include "webrtc/system_wrappers/interface/tick_util.h"

namespace webrtc {

const double kNtpFracPerMs = 4.294967296E6;

int64_t Clock::NtpToMs(uint32_t ntp_secs, uint32_t ntp_frac) {
  const double ntp_frac_ms = static_cast<double>(ntp_frac) / kNtpFracPerMs;
  return 1000 * static_cast<int64_t>(ntp_secs) +
      static_cast<int64_t>(ntp_frac_ms + 0.5);
}

class RealTimeClock : public Clock {
  // Return a timestamp in milliseconds relative to some arbitrary source; the
  // source is fixed for this clock.
  virtual int64_t TimeInMilliseconds() OVERRIDE {
    return TickTime::MillisecondTimestamp();
  }

  // Return a timestamp in microseconds relative to some arbitrary source; the
  // source is fixed for this clock.
  virtual int64_t TimeInMicroseconds() OVERRIDE {
    return TickTime::MicrosecondTimestamp();
  }

  // Retrieve an NTP absolute timestamp in seconds and fractions of a second.
  virtual void CurrentNtp(uint32_t& seconds, uint32_t& fractions) OVERRIDE {
    timeval tv = CurrentTimeVal();
    double microseconds_in_seconds;
    Adjust(tv, &seconds, &microseconds_in_seconds);
    fractions = static_cast<uint32_t>(
        microseconds_in_seconds * kMagicNtpFractionalUnit + 0.5);
  }

  // Retrieve an NTP absolute timestamp in milliseconds.
  virtual int64_t CurrentNtpInMilliseconds() OVERRIDE {
    timeval tv = CurrentTimeVal();
    uint32_t seconds;
    double microseconds_in_seconds;
    Adjust(tv, &seconds, &microseconds_in_seconds);
    return 1000 * static_cast<int64_t>(seconds) +
        static_cast<int64_t>(1000.0 * microseconds_in_seconds + 0.5);
  }

 protected:
  virtual timeval CurrentTimeVal() const = 0;

  static void Adjust(const timeval& tv, uint32_t* adjusted_s,
                     double* adjusted_us_in_s) {
    *adjusted_s = tv.tv_sec + kNtpJan1970;
    *adjusted_us_in_s = tv.tv_usec / 1e6;

    if (*adjusted_us_in_s >= 1) {
      *adjusted_us_in_s -= 1;
      ++*adjusted_s;
    } else if (*adjusted_us_in_s < -1) {
      *adjusted_us_in_s += 1;
      --*adjusted_s;
    }
  }
};

#if defined(_WIN32)
class WindowsRealTimeClock : public RealTimeClock {
 public:
  WindowsRealTimeClock() {}

  virtual ~WindowsRealTimeClock() {}

 protected:
  virtual timeval CurrentTimeVal() const OVERRIDE {
    const uint64_t FILETIME_1970 = 0x019db1ded53e8000;

    FILETIME StartTime;
    uint64_t Time;
    struct timeval tv;

    GetSystemTimeAsFileTime(&StartTime);

    Time = (((uint64_t) StartTime.dwHighDateTime) << 32) +
           (uint64_t) StartTime.dwLowDateTime;

    // Convert the hecto-nano second time to tv format.
    Time -= FILETIME_1970;

    tv.tv_sec = (uint32_t)(Time / (uint64_t)10000000);
    tv.tv_usec = (uint32_t)((Time % (uint64_t)10000000) / 10);
    return tv;
  }
};

#elif ((defined WEBRTC_LINUX) || (defined WEBRTC_MAC))
class UnixRealTimeClock : public RealTimeClock {
 public:
  UnixRealTimeClock() {}

  virtual ~UnixRealTimeClock() {}

 protected:
  virtual timeval CurrentTimeVal() const OVERRIDE {
    struct timeval tv;
    struct timezone tz;
    tz.tz_minuteswest = 0;
    tz.tz_dsttime = 0;
    gettimeofday(&tv, &tz);
    return tv;
  }
};
#endif

Clock* Clock::GetRealTimeClock() {
#if defined(_WIN32)
  static WindowsRealTimeClock clock;
  return &clock;
#elif defined(WEBRTC_LINUX) || defined(WEBRTC_MAC)
  static UnixRealTimeClock clock;
  return &clock;
#else
  return NULL;
#endif
}

SimulatedClock::SimulatedClock(int64_t initial_time_us)
    : time_us_(initial_time_us) {}

int64_t SimulatedClock::TimeInMilliseconds() {
  return (time_us_ + 500) / 1000;
}

int64_t SimulatedClock::TimeInMicroseconds() {
  return time_us_;
}

void SimulatedClock::CurrentNtp(uint32_t& seconds, uint32_t& fractions) {
  seconds = (TimeInMilliseconds() / 1000) + kNtpJan1970;
  fractions = (uint32_t)((TimeInMilliseconds() % 1000) *
      kMagicNtpFractionalUnit / 1000);
}

int64_t SimulatedClock::CurrentNtpInMilliseconds() {
  return TimeInMilliseconds() + 1000 * static_cast<int64_t>(kNtpJan1970);
}

void SimulatedClock::AdvanceTimeMilliseconds(int64_t milliseconds) {
  AdvanceTimeMicroseconds(1000 * milliseconds);
}

void SimulatedClock::AdvanceTimeMicroseconds(int64_t microseconds) {
  time_us_ += microseconds;
}

};  // namespace webrtc