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/**********************************************************************
Audacity: A Digital Audio Editor
MemoryStream.cpp
Dmitry Vedenko
**********************************************************************/
#include "MemoryStream.h"
#include <algorithm>
void MemoryStream::Clear()
{
mChunks = {};
mLinearData = {};
mDataSize = 0;
}
void MemoryStream::AppendByte(char data)
{
AppendData(&data, 1);
}
void MemoryStream::AppendData(const void* data, const size_t length)
{
if (mChunks.empty())
mChunks.emplace_back();
StreamChunk dataView = { data, length };
while (mChunks.back().Append(dataView) > 0)
mChunks.emplace_back();
mDataSize += length;
}
const void* MemoryStream::GetData() const
{
if (!mChunks.empty())
{
const size_t desiredSize = GetSize();
mLinearData.reserve(desiredSize);
for (const Chunk& chunk : mChunks)
{
auto begin = chunk.Data.begin();
auto end = begin + chunk.BytesUsed;
mLinearData.insert(mLinearData.end(), begin, end);
}
mChunks = {};
}
return mLinearData.data();
}
const size_t MemoryStream::GetSize() const noexcept
{
return mDataSize;
}
size_t MemoryStream::Chunk::Append(StreamChunk& dataView)
{
const size_t dataSize = dataView.second;
const size_t bytesToWrite = std::min(ChunkSize - BytesUsed, dataSize);
const size_t bytesLeft = dataSize - bytesToWrite;
const uint8_t* beginData = static_cast<const uint8_t*>(dataView.first);
const uint8_t* endData = beginData + bytesToWrite;
// Some extreme micro optimization for MSVC (at least)
// std::copy will generate a call to memmove in any case
// which will be slower than just writing the byte
if (bytesToWrite == 1)
{
Data[BytesUsed] = *beginData;
}
else
{
// There is a chance for unaligned access, so we do no handle
// types as int32_t separately. Unaligned access is slow on x86
// and fails horribly on ARM
std::copy(beginData, endData, Data.begin() + BytesUsed);
}
dataView.first = endData;
dataView.second = bytesLeft;
BytesUsed += bytesToWrite;
return bytesLeft;
}
bool MemoryStream::IsEmpty() const noexcept
{
return mDataSize == 0;
}
MemoryStream::Iterator MemoryStream::begin() const
{
return Iterator(this, true);
}
MemoryStream::Iterator MemoryStream::end() const
{
return Iterator(this, false);
}
MemoryStream::Iterator::Iterator(const MemoryStream* stream, bool isBegin)
: mStream(stream)
, mListIterator(isBegin ? mStream->mChunks.cbegin() : mStream->mChunks.cend())
, mShowLinearPart(isBegin && mStream->mLinearData.size() > 0)
{
}
MemoryStream::Iterator& MemoryStream::Iterator::operator++()
{
if (mShowLinearPart)
mShowLinearPart = false;
else
++mListIterator;
return *this;
}
MemoryStream::Iterator MemoryStream::Iterator::operator++(int)
{
Iterator result { *this };
this->operator++();
return result;
}
MemoryStream::StreamChunk MemoryStream::Iterator::operator*() const
{
if (mShowLinearPart)
return { mStream->mLinearData.data(), mStream->mLinearData.size() };
return { mListIterator->Data.data(), mListIterator->BytesUsed };
}
MemoryStream::StreamChunk MemoryStream::Iterator::operator->() const
{
return this->operator*();
}
bool MemoryStream::Iterator::operator!=(const Iterator& rhs) const noexcept
{
return !(*this == rhs);
}
bool MemoryStream::Iterator::operator==(const Iterator& rhs) const noexcept
{
return mStream == rhs.mStream && mListIterator == rhs.mListIterator &&
mShowLinearPart == rhs.mShowLinearPart;
}
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