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/**********************************************************************
Audacity: A Digital Audio Editor
BufferedStreamReader.cpp
Dmitry Vedenko
**********************************************************************/
#include "BufferedStreamReader.h"
#include <algorithm>
#include <memory>
#include <cstring>
BufferedStreamReader::BufferedStreamReader(size_t bufferSize)
: mBufferSize(std::max(bufferSize, RequiredAlignment))
{
mBufferData.resize(mBufferSize + RequiredAlignment);
auto ptr = static_cast<void*>(mBufferData.data());
auto space = mBufferData.size();
std::align(RequiredAlignment, mBufferSize, ptr, space);
mBufferStart = static_cast<uint8_t*>(ptr);
}
size_t BufferedStreamReader::Read(void* buffer, size_t maxBytes)
{
size_t bytesWritten = 0;
while (maxBytes > 0)
{
if (mCurrentBytes == mCurrentIndex)
{
if (!HandleUnderflow())
return bytesWritten;
}
const size_t availableBytes = mCurrentBytes - mCurrentIndex;
const size_t bytesToRead = std::min(maxBytes, availableBytes);
std::memcpy(static_cast<uint8_t*>(buffer) + bytesWritten, mBufferStart + mCurrentIndex, bytesToRead);
maxBytes -= bytesToRead;
bytesWritten += bytesToRead;
mCurrentIndex += bytesToRead;
}
return bytesWritten;
}
bool BufferedStreamReader::Eof() const
{
return mCurrentBytes == mCurrentIndex && !HasMoreData();
}
int BufferedStreamReader::GetC()
{
uint8_t value = 0;
if (ReadValue(value))
return value;
return -1;
}
bool BufferedStreamReader::HandleUnderflow()
{
if (!HasMoreData())
return false;
mCurrentBytes = ReadData(mBufferStart, mBufferSize);
mCurrentIndex = 0;
return true;
}
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