1 files changed, 45 insertions, 0 deletions
diff --git a/third_party/libwebrtc/test/drifting_clock.cc b/third_party/libwebrtc/test/drifting_clock.cc
new file mode 100644
index 0000000000..47c8e56916
--- /dev/null
+++ b/third_party/libwebrtc/test/drifting_clock.cc
@@ -0,0 +1,45 @@
+/*
+ *  Copyright (c) 2016 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 "test/drifting_clock.h"
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+namespace test {
+constexpr float DriftingClock::kNoDrift;
+
+DriftingClock::DriftingClock(Clock* clock, float speed)
+    : clock_(clock), drift_(speed - 1.0f), start_time_(clock_->CurrentTime()) {
+  RTC_CHECK(clock);
+  RTC_CHECK_GT(speed, 0.0f);
+}
+
+TimeDelta DriftingClock::Drift() const {
+  auto now = clock_->CurrentTime();
+  RTC_DCHECK_GE(now, start_time_);
+  return (now - start_time_) * drift_;
+}
+
+Timestamp DriftingClock::Drift(Timestamp timestamp) const {
+  return timestamp + Drift() / 1000.;
+}
+
+NtpTime DriftingClock::Drift(NtpTime ntp_time) const {
+  // NTP precision is 1/2^32 seconds, i.e. 2^32 ntp fractions = 1 second.
+  const double kNtpFracPerMicroSecond = 4294.967296;  // = 2^32 / 10^6
+
+  uint64_t total_fractions = static_cast<uint64_t>(ntp_time);
+  total_fractions += Drift().us() * kNtpFracPerMicroSecond;
+  return NtpTime(total_fractions);
+}
+
+}  // namespace test
+}  // namespace webrtc