114 lines
2.7 KiB
C++
114 lines
2.7 KiB
C++
/* Copyright (C) Teemu Suutari */
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#include "InputStream.hpp"
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// for exceptions
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#include "Decompressor.hpp"
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#include "common/OverflowCheck.hpp"
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namespace ancient::internal
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{
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ForwardInputStream::ForwardInputStream(const Buffer &buffer,size_t startOffset,size_t endOffset,bool allowOverrun) :
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_bufPtr(buffer.data()),
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_currentOffset(startOffset),
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_endOffset(endOffset),
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_allowOverrun(allowOverrun)
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{
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if (_currentOffset>_endOffset || _currentOffset>buffer.size() || _endOffset>buffer.size()) throw Decompressor::DecompressionError();
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}
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ForwardInputStream::~ForwardInputStream()
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{
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// nothing needed
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}
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uint8_t ForwardInputStream::readByte()
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{
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if (_currentOffset>=_endOffset)
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{
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if (_allowOverrun)
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{
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_currentOffset++;
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return 0;
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}
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throw Decompressor::DecompressionError();
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}
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uint8_t ret=_bufPtr[_currentOffset++];
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if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
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return ret;
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}
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const uint8_t *ForwardInputStream::consume(size_t bytes,uint8_t *buffer)
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{
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if (OverflowCheck::sum(_currentOffset,bytes)>_endOffset)
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{
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if (_allowOverrun && buffer)
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{
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for (size_t i=0;i<bytes;i++)
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{
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buffer[i]=(_currentOffset<_endOffset)?_bufPtr[_currentOffset]:0;
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_currentOffset++;
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}
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return buffer;
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}
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throw Decompressor::DecompressionError();
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}
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const uint8_t *ret=&_bufPtr[_currentOffset];
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_currentOffset+=bytes;
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if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
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return ret;
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}
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BackwardInputStream::BackwardInputStream(const Buffer &buffer,size_t startOffset,size_t endOffset,bool allowOverrun) :
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_bufPtr(buffer.data()),
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_currentOffset(endOffset),
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_endOffset(startOffset),
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_allowOverrun(allowOverrun)
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{
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if (_currentOffset<_endOffset || _currentOffset>buffer.size() || _endOffset>buffer.size()) throw Decompressor::DecompressionError();
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}
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BackwardInputStream::~BackwardInputStream()
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{
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// nothing needed
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}
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uint8_t BackwardInputStream::readByte()
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{
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if (_currentOffset<=_endOffset)
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{
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if (_allowOverrun)
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{
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--_currentOffset;
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return 0;
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}
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throw Decompressor::DecompressionError();
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}
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uint8_t ret=_bufPtr[--_currentOffset];
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if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
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return ret;
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}
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const uint8_t *BackwardInputStream::consume(size_t bytes,uint8_t *buffer)
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{
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if (_currentOffset<OverflowCheck::sum(_endOffset,bytes))
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{
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if (_allowOverrun && buffer)
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{
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for (size_t i=bytes;i;i--)
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{
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buffer[i-1]=(_currentOffset>_endOffset)?_bufPtr[_currentOffset-1]:0;
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--_currentOffset;
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}
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return buffer;
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}
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throw Decompressor::DecompressionError();
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}
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_currentOffset-=bytes;
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if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
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return &_bufPtr[_currentOffset];
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}
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}
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