jeanlemotan
151 lines
3.6 KiB
C++
151 lines
3.6 KiB
C++
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#include "fs/BufferedSource.h"
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#include <algorithm>
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namespace fs
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{
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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BufferedSource<SourceType>::BufferedSource(SourceType source, size_t bufferSize)
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: m_source(std::move(source))
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{
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if (bufferSize < 8)
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bufferSize = 8;
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m_buffer.reserve(bufferSize);
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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tl::optional<Error> BufferedSource<SourceType>::getLastError() const
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{
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tl::optional<Error> error = m_optLastError;
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m_optLastError = tl::nullopt;
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return error;
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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size_t BufferedSource<SourceType>::read(tl::span<uint8_t> data)
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{
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if (data.empty() || m_endOfSource)
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return 0;
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auto bufferPtr = data.data();
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size_t totalSize = 0;
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size_t pendingSize = data.size();
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while (pendingSize)
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{
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if (m_buffer.empty() || m_bufferOffset >= m_buffer.size())
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{
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m_buffer.resize_uninitialized(m_buffer.capacity());
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m_bufferStartOffset = m_source.tell();
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m_bufferOffset = 0;
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const size_t readSize = m_source.read(m_buffer);
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m_buffer.resize_uninitialized(readSize);
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if (readSize == 0)
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{
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m_optLastError = m_source.getLastError();
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m_endOfSource = !m_optLastError.has_value(); //no error? then EOS
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return totalSize;
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}
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}
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TL_ASSERT(m_buffer.size());
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TL_ASSERT(m_buffer.size() > m_bufferOffset);
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const size_t frameSize = tl::min(m_buffer.size() - m_bufferOffset, pendingSize);
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TL_ASSERT(frameSize);
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memcpy(bufferPtr, m_buffer.data() + m_bufferOffset, frameSize);
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bufferPtr += frameSize;
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TL_ASSERT(data.size() >= frameSize);
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pendingSize -= frameSize;
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totalSize += frameSize;
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TL_ASSERT(totalSize <= data.size());
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m_bufferOffset += frameSize;
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}
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m_endOfSource = tell() >= getSize();
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return totalSize;
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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void BufferedSource<SourceType>::seekBeg(uint64_t offset)
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{
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offset = tl::min(offset, m_source.getSize());
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if (offset < m_bufferStartOffset || offset >= m_bufferStartOffset + m_buffer.size())
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{
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m_source.seekBeg(offset);
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m_optLastError = m_source.getLastError();
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m_buffer.clear();
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m_bufferOffset = 0;
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m_bufferStartOffset = m_source.tell();
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}
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else
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m_bufferOffset = offset - m_bufferStartOffset;
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m_endOfSource = tell() >= getSize();
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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void BufferedSource<SourceType>::seekRel(int64_t offset)
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{
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if (!offset)
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return;
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if (offset != 0)
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{
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int64_t newOffset = tell();
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newOffset += offset;
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newOffset = tl::max<int64_t>(newOffset, 0);
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seekBeg(static_cast<uint64_t>(tl::min<int64_t>(newOffset, getSize())));
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}
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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uint64_t BufferedSource<SourceType>::tell() const
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{
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return m_bufferStartOffset + m_bufferOffset;
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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uint64_t BufferedSource<SourceType>::getSize() const
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{
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return m_source.getSize();
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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bool BufferedSource<SourceType>::isEOS() const
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{
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return m_endOfSource;
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}
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//////////////////////////////////////////////////////////////////////////
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template< typename SourceType>
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size_t BufferedSource<SourceType>::getPreferredBufferSize() const
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{
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return m_buffer.size();
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}
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}
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