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