1 files changed, 156 insertions, 0 deletions
diff --git a/dom/media/webaudio/GainNode.cpp b/dom/media/webaudio/GainNode.cpp
new file mode 100644
index 000000000..46ac99763
--- /dev/null
+++ b/dom/media/webaudio/GainNode.cpp
@@ -0,0 +1,156 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GainNode.h"
+#include "mozilla/dom/GainNodeBinding.h"
+#include "AlignmentUtils.h"
+#include "AudioNodeEngine.h"
+#include "AudioNodeStream.h"
+#include "AudioDestinationNode.h"
+#include "WebAudioUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(GainNode, AudioNode,
+                                   mGain)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(GainNode)
+NS_INTERFACE_MAP_END_INHERITING(AudioNode)
+
+NS_IMPL_ADDREF_INHERITED(GainNode, AudioNode)
+NS_IMPL_RELEASE_INHERITED(GainNode, AudioNode)
+
+class GainNodeEngine final : public AudioNodeEngine
+{
+public:
+  GainNodeEngine(AudioNode* aNode, AudioDestinationNode* aDestination)
+    : AudioNodeEngine(aNode)
+    , mDestination(aDestination->Stream())
+    // Keep the default value in sync with the default value in GainNode::GainNode.
+    , mGain(1.f)
+  {
+  }
+
+  enum Parameters {
+    GAIN
+  };
+  void RecvTimelineEvent(uint32_t aIndex,
+                         AudioTimelineEvent& aEvent) override
+  {
+    MOZ_ASSERT(mDestination);
+    WebAudioUtils::ConvertAudioTimelineEventToTicks(aEvent,
+                                                    mDestination);
+
+    switch (aIndex) {
+    case GAIN:
+      mGain.InsertEvent<int64_t>(aEvent);
+      break;
+    default:
+      NS_ERROR("Bad GainNodeEngine TimelineParameter");
+    }
+  }
+
+  void ProcessBlock(AudioNodeStream* aStream,
+                    GraphTime aFrom,
+                    const AudioBlock& aInput,
+                    AudioBlock* aOutput,
+                    bool* aFinished) override
+  {
+    if (aInput.IsNull()) {
+      // If input is silent, so is the output
+      aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
+    } else if (mGain.HasSimpleValue()) {
+      // Optimize the case where we only have a single value set as the volume
+      float gain = mGain.GetValue();
+      if (gain == 0.0f) {
+        aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
+      } else {
+        *aOutput = aInput;
+        aOutput->mVolume *= gain;
+      }
+    } else {
+      // First, compute a vector of gains for each track tick based on the
+      // timeline at hand, and then for each channel, multiply the values
+      // in the buffer with the gain vector.
+      aOutput->AllocateChannels(aInput.ChannelCount());
+
+      // Compute the gain values for the duration of the input AudioChunk
+      StreamTime tick = mDestination->GraphTimeToStreamTime(aFrom);
+      float computedGain[WEBAUDIO_BLOCK_SIZE + 4];
+      float* alignedComputedGain = ALIGNED16(computedGain);
+      ASSERT_ALIGNED16(alignedComputedGain);
+      mGain.GetValuesAtTime(tick, alignedComputedGain, WEBAUDIO_BLOCK_SIZE);
+
+      for (size_t counter = 0; counter < WEBAUDIO_BLOCK_SIZE; ++counter) {
+        alignedComputedGain[counter] *= aInput.mVolume;
+      }
+
+      // Apply the gain to the output buffer
+      for (size_t channel = 0; channel < aOutput->ChannelCount(); ++channel) {
+        const float* inputBuffer = static_cast<const float*> (aInput.mChannelData[channel]);
+        float* buffer = aOutput->ChannelFloatsForWrite(channel);
+        AudioBlockCopyChannelWithScale(inputBuffer, alignedComputedGain, buffer);
+      }
+    }
+  }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
+  {
+    // Not owned:
+    // - mDestination (probably)
+    // - mGain - Internal ref owned by AudioNode
+    return AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  AudioNodeStream* mDestination;
+  AudioParamTimeline mGain;
+};
+
+GainNode::GainNode(AudioContext* aContext)
+  : AudioNode(aContext,
+              2,
+              ChannelCountMode::Max,
+              ChannelInterpretation::Speakers)
+  , mGain(new AudioParam(this, GainNodeEngine::GAIN, 1.0f, "gain"))
+{
+  GainNodeEngine* engine = new GainNodeEngine(this, aContext->Destination());
+  mStream = AudioNodeStream::Create(aContext, engine,
+                                    AudioNodeStream::NO_STREAM_FLAGS,
+                                    aContext->Graph());
+}
+
+GainNode::~GainNode()
+{
+}
+
+size_t
+GainNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  size_t amount = AudioNode::SizeOfExcludingThis(aMallocSizeOf);
+  amount += mGain->SizeOfIncludingThis(aMallocSizeOf);
+  return amount;
+}
+
+size_t
+GainNode::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+JSObject*
+GainNode::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GainNodeBinding::Wrap(aCx, this, aGivenProto);
+}
+
+} // namespace dom
+} // namespace mozilla