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