/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* 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 "AudioCompactor.h"

#if defined(MOZ_MEMORY)

# include "mozmemory.h"

#endif

namespace mozilla {

static size_t

MallocGoodSize(size_t aSize)

{

# if defined(MOZ_MEMORY)

  return malloc_good_size(aSize);

# else

  return aSize;

# endif

}

static size_t

TooMuchSlop(size_t aSize, size_t aAllocSize, size_t aMaxSlop)

{

  // If the allocated size is less then our target size, then we

  // are chunking.  This means it will be completely filled with

  // zero slop.

  size_t slop = (aAllocSize > aSize) ? (aAllocSize - aSize) : 0;

  return slop > aMaxSlop;

}

uint32_t

AudioCompactor::GetChunkSamples(uint32_t aFrames, uint32_t aChannels,

                                size_t aMaxSlop)

{

  size_t size = AudioDataSize(aFrames, aChannels);

  size_t chunkSize = MallocGoodSize(size);

  // Reduce the chunk size until we meet our slop goal or the chunk

  // approaches an unreasonably small size.

  while (chunkSize > 64 && TooMuchSlop(size, chunkSize, aMaxSlop)) {

    chunkSize = MallocGoodSize(chunkSize / 2);

  }

  // Calculate the number of samples based on expected malloc size

  // in order to allow as many frames as possible to be packed.

  return chunkSize / sizeof(AudioDataValue);

}

uint32_t

AudioCompactor::NativeCopy::operator()(AudioDataValue *aBuffer,

                                       uint32_t aSamples)

{

  NS_ASSERTION(aBuffer, "cannot copy to null buffer pointer");

  NS_ASSERTION(aSamples, "cannot copy zero values");

  size_t bufferBytes = aSamples * sizeof(AudioDataValue);

  size_t maxBytes = std::min(bufferBytes, mSourceBytes - mNextByte);

  uint32_t frames = maxBytes / BytesPerFrame(mChannels);

  size_t bytes = frames * BytesPerFrame(mChannels);

  NS_ASSERTION((mNextByte + bytes) <= mSourceBytes,

               "tried to copy beyond source buffer");

  NS_ASSERTION(bytes <= bufferBytes, "tried to copy beyond destination buffer");

  memcpy(aBuffer, mSource + mNextByte, bytes);

  mNextByte += bytes;

  return frames;

}

} // namespace mozilla