1 files changed, 76 insertions, 0 deletions
diff --git a/media/base/clock.cc b/media/base/clock.cc
new file mode 100644
index 0000000..aa0dbfb
--- /dev/null
+++ b/media/base/clock.cc
@@ -0,0 +1,76 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/base/clock.h"
+
+#include "base/logging.h"
+#include "media/base/buffers.h"
+
+namespace media {
+
+Clock::Clock(TimeProvider* time_provider)
+    : time_provider_(time_provider),
+      playing_(false),
+      playback_rate_(1.0f) {
+}
+
+Clock::~Clock() {}
+
+base::TimeDelta Clock::Play() {
+  DCHECK(!playing_);
+  reference_ = GetTimeFromProvider();
+  playing_ = true;
+  return media_time_;
+}
+
+base::TimeDelta Clock::Pause() {
+  DCHECK(playing_);
+  // Save our new accumulated amount of media time.
+  media_time_ = Elapsed();
+  playing_ = false;
+  return media_time_;
+}
+
+void Clock::SetTime(const base::TimeDelta& time) {
+  if (time == kNoTimestamp) {
+    NOTREACHED();
+    return;
+  }
+  if (playing_) {
+    reference_ = GetTimeFromProvider();
+  }
+  media_time_ = time;
+}
+
+void Clock::SetPlaybackRate(float playback_rate) {
+  if (playing_) {
+    base::Time time = GetTimeFromProvider();
+    media_time_ = ElapsedViaProvidedTime(time);
+    reference_ = time;
+  }
+  playback_rate_ = playback_rate;
+}
+
+base::TimeDelta Clock::Elapsed() const {
+  if (!playing_) {
+    return media_time_;
+  }
+  return ElapsedViaProvidedTime(GetTimeFromProvider());
+}
+
+base::TimeDelta Clock::ElapsedViaProvidedTime(const base::Time& time) const {
+  // TODO(scherkus): floating point badness scaling time by playback rate.
+  int64 now_us = (time - reference_).InMicroseconds();
+  now_us = static_cast<int64>(now_us * playback_rate_);
+  return media_time_ + base::TimeDelta::FromMicroseconds(now_us);
+}
+
+base::Time Clock::GetTimeFromProvider() const {
+  if (time_provider_) {
+    return time_provider_();
+  }
+  return base::Time();
+}
+
+}  // namespace media