1 files changed, 114 insertions, 0 deletions
diff --git a/dom/media/webaudio/blink/ReverbAccumulationBuffer.cpp b/dom/media/webaudio/blink/ReverbAccumulationBuffer.cpp
new file mode 100644
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+++ b/dom/media/webaudio/blink/ReverbAccumulationBuffer.cpp
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+/*
+ * Copyright (C) 2010 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ *     its contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "ReverbAccumulationBuffer.h"
+#include "AudioNodeEngine.h"
+#include "mozilla/PodOperations.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+namespace WebCore {
+
+ReverbAccumulationBuffer::ReverbAccumulationBuffer()
+    : m_readIndex(0), m_readTimeFrame(0) {}
+
+bool ReverbAccumulationBuffer::allocate(size_t length) {
+  if (!m_buffer.SetLength(length, fallible)) {
+    return false;
+  }
+  PodZero(m_buffer.Elements(), length);
+  return true;
+}
+
+void ReverbAccumulationBuffer::readAndClear(float* destination,
+                                            size_t numberOfFrames) {
+  size_t bufferLength = m_buffer.Length();
+  bool isCopySafe =
+      m_readIndex <= bufferLength && numberOfFrames <= bufferLength;
+
+  MOZ_ASSERT(isCopySafe);
+  if (!isCopySafe) return;
+
+  size_t framesAvailable = bufferLength - m_readIndex;
+  size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);
+  size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;
+
+  float* source = m_buffer.Elements();
+  memcpy(destination, source + m_readIndex, sizeof(float) * numberOfFrames1);
+  memset(source + m_readIndex, 0, sizeof(float) * numberOfFrames1);
+
+  // Handle wrap-around if necessary
+  if (numberOfFrames2 > 0) {
+    memcpy(destination + numberOfFrames1, source,
+           sizeof(float) * numberOfFrames2);
+    memset(source, 0, sizeof(float) * numberOfFrames2);
+  }
+
+  m_readIndex = (m_readIndex + numberOfFrames) % bufferLength;
+  m_readTimeFrame += numberOfFrames;
+}
+
+void ReverbAccumulationBuffer::accumulate(const float* source,
+                                          size_t numberOfFrames,
+                                          size_t* readIndex,
+                                          size_t delayFrames) {
+  size_t bufferLength = m_buffer.Length();
+
+  size_t writeIndex = (*readIndex + delayFrames) % bufferLength;
+
+  // Update caller's readIndex
+  *readIndex = (*readIndex + numberOfFrames) % bufferLength;
+
+  size_t framesAvailable = bufferLength - writeIndex;
+  size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);
+  size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;
+
+  float* destination = m_buffer.Elements();
+
+  bool isSafe = writeIndex <= bufferLength &&
+                numberOfFrames1 + writeIndex <= bufferLength &&
+                numberOfFrames2 <= bufferLength;
+  MOZ_ASSERT(isSafe);
+  if (!isSafe) return;
+
+  AudioBufferAddWithScale(source, 1.0f, destination + writeIndex,
+                          numberOfFrames1);
+  if (numberOfFrames2 > 0) {
+    AudioBufferAddWithScale(source + numberOfFrames1, 1.0f, destination,
+                            numberOfFrames2);
+  }
+}
+
+void ReverbAccumulationBuffer::reset() {
+  PodZero(m_buffer.Elements(), m_buffer.Length());
+  m_readIndex = 0;
+  m_readTimeFrame = 0;
+}
+
+}  // namespace WebCore