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