1 files changed, 102 insertions, 0 deletions
diff --git a/third_party/libwebrtc/system_wrappers/source/clock.cc b/third_party/libwebrtc/system_wrappers/source/clock.cc
new file mode 100644
index 0000000000..f7460b831c
--- /dev/null
+++ b/third_party/libwebrtc/system_wrappers/source/clock.cc
@@ -0,0 +1,102 @@
+/*
+ *  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 "system_wrappers/include/clock.h"
+
+#include "rtc_base/time_utils.h"
+
+namespace webrtc {
+namespace {
+
+int64_t NtpOffsetUsCalledOnce() {
+  constexpr int64_t kNtpJan1970Sec = 2208988800;
+  int64_t clock_time = rtc::TimeMicros();
+  int64_t utc_time = rtc::TimeUTCMicros();
+  return utc_time - clock_time + kNtpJan1970Sec * rtc::kNumMicrosecsPerSec;
+}
+
+NtpTime TimeMicrosToNtp(int64_t time_us) {
+  static int64_t ntp_offset_us = NtpOffsetUsCalledOnce();
+
+  int64_t time_ntp_us = time_us + ntp_offset_us;
+  RTC_DCHECK_GE(time_ntp_us, 0);  // Time before year 1900 is unsupported.
+
+  // Convert seconds to uint32 through uint64 for a well-defined cast.
+  // A wrap around, which will happen in 2036, is expected for NTP time.
+  uint32_t ntp_seconds =
+      static_cast<uint64_t>(time_ntp_us / rtc::kNumMicrosecsPerSec);
+
+  // Scale fractions of the second to NTP resolution.
+  constexpr int64_t kNtpFractionsInSecond = 1LL << 32;
+  int64_t us_fractions = time_ntp_us % rtc::kNumMicrosecsPerSec;
+  uint32_t ntp_fractions =
+      us_fractions * kNtpFractionsInSecond / rtc::kNumMicrosecsPerSec;
+
+  return NtpTime(ntp_seconds, ntp_fractions);
+}
+
+}  // namespace
+
+class RealTimeClock : public Clock {
+ public:
+  RealTimeClock() = default;
+
+  Timestamp CurrentTime() override {
+    return Timestamp::Micros(rtc::TimeMicros());
+  }
+
+  NtpTime ConvertTimestampToNtpTime(Timestamp timestamp) override {
+    return TimeMicrosToNtp(timestamp.us());
+  }
+};
+
+Clock* Clock::GetRealTimeClockRaw() {
+  static Clock* const clock = new RealTimeClock();
+  return clock;
+}
+
+SimulatedClock::SimulatedClock(int64_t initial_time_us)
+    : time_us_(initial_time_us) {}
+
+SimulatedClock::SimulatedClock(Timestamp initial_time)
+    : SimulatedClock(initial_time.us()) {}
+
+SimulatedClock::~SimulatedClock() {}
+
+Timestamp SimulatedClock::CurrentTime() {
+  return Timestamp::Micros(time_us_.load(std::memory_order_relaxed));
+}
+
+NtpTime SimulatedClock::ConvertTimestampToNtpTime(Timestamp timestamp) {
+  int64_t now_us = timestamp.us();
+  uint32_t seconds = (now_us / 1'000'000) + kNtpJan1970;
+  uint32_t fractions = static_cast<uint32_t>(
+      (now_us % 1'000'000) * kMagicNtpFractionalUnit / 1'000'000);
+  return NtpTime(seconds, fractions);
+}
+
+void SimulatedClock::AdvanceTimeMilliseconds(int64_t milliseconds) {
+  AdvanceTime(TimeDelta::Millis(milliseconds));
+}
+
+void SimulatedClock::AdvanceTimeMicroseconds(int64_t microseconds) {
+  AdvanceTime(TimeDelta::Micros(microseconds));
+}
+
+// TODO(bugs.webrtc.org(12102): It's desirable to let a single thread own
+// advancement of the clock. We could then replace this read-modify-write
+// operation with just a thread checker. But currently, that breaks a couple of
+// tests, in particular, RepeatingTaskTest.ClockIntegration and
+// CallStatsTest.LastProcessedRtt.
+void SimulatedClock::AdvanceTime(TimeDelta delta) {
+  time_us_.fetch_add(delta.us(), std::memory_order_relaxed);
+}
+
+}  // namespace webrtc