michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=8 sts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: #include "AudioCompactor.h"
michael@0: #if defined(MOZ_MEMORY)
michael@0: # include "mozmemory.h"
michael@0: #endif
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: static size_t
michael@0: MallocGoodSize(size_t aSize)
michael@0: {
michael@0: # if defined(MOZ_MEMORY)
michael@0:   return malloc_good_size(aSize);
michael@0: # else
michael@0:   return aSize;
michael@0: # endif
michael@0: }
michael@0: 
michael@0: static size_t
michael@0: TooMuchSlop(size_t aSize, size_t aAllocSize, size_t aMaxSlop)
michael@0: {
michael@0:   // If the allocated size is less then our target size, then we
michael@0:   // are chunking.  This means it will be completely filled with
michael@0:   // zero slop.
michael@0:   size_t slop = (aAllocSize > aSize) ? (aAllocSize - aSize) : 0;
michael@0:   return slop > aMaxSlop;
michael@0: }
michael@0: 
michael@0: uint32_t
michael@0: AudioCompactor::GetChunkSamples(uint32_t aFrames, uint32_t aChannels,
michael@0:                                 size_t aMaxSlop)
michael@0: {
michael@0:   size_t size = AudioDataSize(aFrames, aChannels);
michael@0:   size_t chunkSize = MallocGoodSize(size);
michael@0: 
michael@0:   // Reduce the chunk size until we meet our slop goal or the chunk
michael@0:   // approaches an unreasonably small size.
michael@0:   while (chunkSize > 64 && TooMuchSlop(size, chunkSize, aMaxSlop)) {
michael@0:     chunkSize = MallocGoodSize(chunkSize / 2);
michael@0:   }
michael@0: 
michael@0:   // Calculate the number of samples based on expected malloc size
michael@0:   // in order to allow as many frames as possible to be packed.
michael@0:   return chunkSize / sizeof(AudioDataValue);
michael@0: }
michael@0: 
michael@0: uint32_t
michael@0: AudioCompactor::NativeCopy::operator()(AudioDataValue *aBuffer,
michael@0:                                        uint32_t aSamples)
michael@0: {
michael@0:   NS_ASSERTION(aBuffer, "cannot copy to null buffer pointer");
michael@0:   NS_ASSERTION(aSamples, "cannot copy zero values");
michael@0: 
michael@0:   size_t bufferBytes = aSamples * sizeof(AudioDataValue);
michael@0:   size_t maxBytes = std::min(bufferBytes, mSourceBytes - mNextByte);
michael@0:   uint32_t frames = maxBytes / BytesPerFrame(mChannels);
michael@0:   size_t bytes = frames * BytesPerFrame(mChannels);
michael@0: 
michael@0:   NS_ASSERTION((mNextByte + bytes) <= mSourceBytes,
michael@0:                "tried to copy beyond source buffer");
michael@0:   NS_ASSERTION(bytes <= bufferBytes, "tried to copy beyond destination buffer");
michael@0: 
michael@0:   memcpy(aBuffer, mSource + mNextByte, bytes);
michael@0: 
michael@0:   mNextByte += bytes;
michael@0:   return frames;
michael@0: }
michael@0: 
michael@0: } // namespace mozilla