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

/*
 * 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;
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 */

#include "platform/audio/ReverbAccumulationBuffer.h"
#include "platform/audio/VectorMath.h"

namespace blink {

using namespace VectorMath;

ReverbAccumulationBuffer::ReverbAccumulationBuffer(size_t length)
    : m_buffer(length), m_readIndex(0), m_readTimeFrame(0) {}

void ReverbAccumulationBuffer::readAndClear(float* destination,
                                            size_t numberOfFrames) {
  size_t bufferLength = m_buffer.size();
  bool isCopySafe =
      m_readIndex <= bufferLength && numberOfFrames <= bufferLength;

  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.data();
  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::updateReadIndex(int* readIndex,
                                               size_t numberOfFrames) const {
  // Update caller's readIndex
  *readIndex = (*readIndex + numberOfFrames) % m_buffer.size();
}

int ReverbAccumulationBuffer::accumulate(float* source,
                                         size_t numberOfFrames,
                                         int* readIndex,
                                         size_t delayFrames) {
  size_t bufferLength = m_buffer.size();

  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.data();

  bool isSafe = writeIndex <= bufferLength &&
                numberOfFrames1 + writeIndex <= bufferLength &&
                numberOfFrames2 <= bufferLength;
  ASSERT(isSafe);
  if (!isSafe)
    return 0;

  vadd(source, 1, destination + writeIndex, 1, destination + writeIndex, 1,
       numberOfFrames1);

  // Handle wrap-around if necessary
  if (numberOfFrames2 > 0)
    vadd(source + numberOfFrames1, 1, destination, 1, destination, 1,
         numberOfFrames2);

  return writeIndex;
}

void ReverbAccumulationBuffer::reset() {
  m_buffer.zero();
  m_readIndex = 0;
  m_readTimeFrame = 0;
}

}  // namespace blink