Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : #include "AudioCompactor.h"
       7             : #if defined(MOZ_MEMORY)
       8             : # include "mozmemory.h"
       9             : #endif
      10             : 
      11             : namespace mozilla {
      12             : 
      13             : static size_t
      14           0 : MallocGoodSize(size_t aSize)
      15             : {
      16             : # if defined(MOZ_MEMORY)
      17           0 :   return malloc_good_size(aSize);
      18             : # else
      19             :   return aSize;
      20             : # endif
      21             : }
      22             : 
      23             : static size_t
      24           0 : TooMuchSlop(size_t aSize, size_t aAllocSize, size_t aMaxSlop)
      25             : {
      26             :   // If the allocated size is less then our target size, then we
      27             :   // are chunking.  This means it will be completely filled with
      28             :   // zero slop.
      29           0 :   size_t slop = (aAllocSize > aSize) ? (aAllocSize - aSize) : 0;
      30           0 :   return slop > aMaxSlop;
      31             : }
      32             : 
      33             : uint32_t
      34           0 : AudioCompactor::GetChunkSamples(uint32_t aFrames, uint32_t aChannels,
      35             :                                 size_t aMaxSlop)
      36             : {
      37           0 :   size_t size = AudioDataSize(aFrames, aChannels);
      38           0 :   size_t chunkSize = MallocGoodSize(size);
      39             : 
      40             :   // Reduce the chunk size until we meet our slop goal or the chunk
      41             :   // approaches an unreasonably small size.
      42           0 :   while (chunkSize > 64 && TooMuchSlop(size, chunkSize, aMaxSlop)) {
      43           0 :     chunkSize = MallocGoodSize(chunkSize / 2);
      44             :   }
      45             : 
      46             :   // Calculate the number of samples based on expected malloc size
      47             :   // in order to allow as many frames as possible to be packed.
      48           0 :   return chunkSize / sizeof(AudioDataValue);
      49             : }
      50             : 
      51             : uint32_t
      52           0 : AudioCompactor::NativeCopy::operator()(AudioDataValue *aBuffer,
      53             :                                        uint32_t aSamples)
      54             : {
      55           0 :   NS_ASSERTION(aBuffer, "cannot copy to null buffer pointer");
      56           0 :   NS_ASSERTION(aSamples, "cannot copy zero values");
      57             : 
      58           0 :   size_t bufferBytes = aSamples * sizeof(AudioDataValue);
      59           0 :   size_t maxBytes = std::min(bufferBytes, mSourceBytes - mNextByte);
      60           0 :   uint32_t frames = maxBytes / BytesPerFrame(mChannels);
      61           0 :   size_t bytes = frames * BytesPerFrame(mChannels);
      62             : 
      63           0 :   NS_ASSERTION((mNextByte + bytes) <= mSourceBytes,
      64             :                "tried to copy beyond source buffer");
      65           0 :   NS_ASSERTION(bytes <= bufferBytes, "tried to copy beyond destination buffer");
      66             : 
      67           0 :   memcpy(aBuffer, mSource + mNextByte, bytes);
      68             : 
      69           0 :   mNextByte += bytes;
      70           0 :   return frames;
      71             : }
      72             : 
      73             : } // namespace mozilla