Revert "This CL is to reduce the complexity of current FIFO structure."

third_party/WebKit/Source/platform/audio/AudioFIFO.cpp

Index: third_party/WebKit/Source/platform/audio/AudioFIFO.cpp
diff --git a/third_party/WebKit/Source/platform/audio/AudioFIFO.cpp b/third_party/WebKit/Source/platform/audio/AudioFIFO.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c35ce14df01364152229796decdc565d2558150e
--- /dev/null
+++ b/third_party/WebKit/Source/platform/audio/AudioFIFO.cpp
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2012 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 "platform/audio/AudioFIFO.h"
+
+namespace blink {
+
+AudioFIFO::AudioFIFO(unsigned numberOfChannels, size_t fifoLength)
+    : m_fifoAudioBus(AudioBus::create(numberOfChannels, fifoLength)),
+      m_fifoLength(fifoLength),
+      m_framesInFifo(0),
+      m_readIndex(0),
+      m_writeIndex(0) {}
+
+void AudioFIFO::consume(AudioBus* destination, size_t framesToConsume) {
+  bool isGood = destination && (framesToConsume <= m_fifoLength) &&
+                (framesToConsume <= m_framesInFifo) &&
+                (destination->length() >= framesToConsume);
+  ASSERT(isGood);
+  if (!isGood)
+    return;
+
+  // Copy the requested number of samples to the destination.
+
+  size_t part1Length;
+  size_t part2Length;
+  findWrapLengths(m_readIndex, framesToConsume, part1Length, part2Length);
+
+  size_t numberOfChannels = m_fifoAudioBus->numberOfChannels();
+
+  for (size_t channelIndex = 0; channelIndex < numberOfChannels;
+       ++channelIndex) {
+    float* destinationData = destination->channel(channelIndex)->mutableData();
+    const float* sourceData = m_fifoAudioBus->channel(channelIndex)->data();
+
+    bool isCopyGood = ((m_readIndex < m_fifoLength) &&
+                       (m_readIndex + part1Length) <= m_fifoLength &&
+                       (part1Length <= destination->length()) &&
+                       (part1Length + part2Length) <= destination->length());
+    ASSERT(isCopyGood);
+    if (!isCopyGood)
+      return;
+
+    memcpy(destinationData, sourceData + m_readIndex,
+           part1Length * sizeof(*sourceData));
+    // Handle wrap around of the FIFO, if needed.
+    if (part2Length)
+      memcpy(destinationData + part1Length, sourceData,
+             part2Length * sizeof(*sourceData));
+  }
+  m_readIndex = updateIndex(m_readIndex, framesToConsume);
+  ASSERT(m_framesInFifo >= framesToConsume);
+  m_framesInFifo -= framesToConsume;
+}
+
+void AudioFIFO::push(const AudioBus* sourceBus) {
+  // Copy the sourceBus into the FIFO buffer.
+
+  bool isGood =
+      sourceBus && (m_framesInFifo + sourceBus->length() <= m_fifoLength);
+  if (!isGood)
+    return;
+
+  size_t sourceLength = sourceBus->length();
+  size_t part1Length;
+  size_t part2Length;
+  findWrapLengths(m_writeIndex, sourceLength, part1Length, part2Length);
+
+  size_t numberOfChannels = m_fifoAudioBus->numberOfChannels();
+
+  for (size_t channelIndex = 0; channelIndex < numberOfChannels;
+       ++channelIndex) {
+    float* destination = m_fifoAudioBus->channel(channelIndex)->mutableData();
+    const float* source = sourceBus->channel(channelIndex)->data();
+
+    bool isCopyGood = ((m_writeIndex < m_fifoLength) &&
+                       (m_writeIndex + part1Length) <= m_fifoLength &&
+                       part2Length < m_fifoLength &&
+                       part1Length + part2Length <= sourceLength);
+    ASSERT(isCopyGood);
+    if (!isCopyGood)
+      return;
+
+    memcpy(destination + m_writeIndex, source,
+           part1Length * sizeof(*destination));
+
+    // Handle wrap around of the FIFO, if needed.
+    if (part2Length)
+      memcpy(destination, source + part1Length,
+             part2Length * sizeof(*destination));
+  }
+
+  m_framesInFifo += sourceLength;
+  ASSERT(m_framesInFifo <= m_fifoLength);
+  m_writeIndex = updateIndex(m_writeIndex, sourceLength);
+}
+
+void AudioFIFO::findWrapLengths(size_t index,
+                                size_t size,
+                                size_t& part1Length,
+                                size_t& part2Length) {
+  SECURITY_DCHECK(index < m_fifoLength && size <= m_fifoLength);
+  if (index < m_fifoLength && size <= m_fifoLength) {
+    if (index + size > m_fifoLength) {
+      // Need to wrap. Figure out the length of each piece.
+      part1Length = m_fifoLength - index;
+      part2Length = size - part1Length;
+    } else {
+      // No wrap needed.
+      part1Length = size;
+      part2Length = 0;
+    }
+  } else {
+    // Invalid values for index or size. Set the part lengths to zero so nothing
+    // is copied.
+    part1Length = 0;
+    part2Length = 0;
+  }
+}
+
+}  // namespace blink