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/* Copyright (C) Teemu Suutari */
#include <cstring>
#include <algorithm>
#include "OutputStream.hpp"
// for exceptions
#include "Decompressor.hpp"
#include "common/Common.hpp"
#include "common/OverflowCheck.hpp"
namespace ancient::internal
{
ForwardOutputStream::ForwardOutputStream(Buffer &buffer,size_t startOffset,size_t endOffset) :
_bufPtr(buffer.data()),
_startOffset(startOffset),
_currentOffset(startOffset),
_endOffset(endOffset)
{
if (_startOffset>_endOffset || _currentOffset>buffer.size() || _endOffset>buffer.size()) throw Decompressor::DecompressionError();
}
ForwardOutputStream::~ForwardOutputStream()
{
// nothing needed
}
void ForwardOutputStream::writeByte(uint8_t value)
{
if (_currentOffset>=_endOffset) throw Decompressor::DecompressionError();
_bufPtr[_currentOffset++]=value;
}
uint8_t ForwardOutputStream::copy(size_t distance,size_t count)
{
if (!distance || OverflowCheck::sum(_startOffset,distance)>_currentOffset || OverflowCheck::sum(_currentOffset,count)>_endOffset) throw Decompressor::DecompressionError();
uint8_t ret=0;
for (size_t i=0;i<count;i++,_currentOffset++)
ret=_bufPtr[_currentOffset]=_bufPtr[_currentOffset-distance];
return ret;
}
uint8_t ForwardOutputStream::copy(size_t distance,size_t count,const Buffer &prevBuffer)
{
if (!distance || OverflowCheck::sum(_currentOffset,count)>_endOffset) throw Decompressor::DecompressionError();
size_t prevCount=0;
uint8_t ret=0;
if (OverflowCheck::sum(_startOffset,distance)>_currentOffset)
{
size_t prevSize=prevBuffer.size();
if (_startOffset+distance>_currentOffset+prevSize) throw Decompressor::DecompressionError();
size_t prevDist=_startOffset+distance-_currentOffset;
prevCount=std::min(count,prevDist);
const uint8_t *prev=&prevBuffer[prevSize-prevDist];
for (size_t i=0;i<prevCount;i++,_currentOffset++)
ret=_bufPtr[_currentOffset]=prev[i];
}
for (size_t i=prevCount;i<count;i++,_currentOffset++)
ret=_bufPtr[_currentOffset]=_bufPtr[_currentOffset-distance];
return ret;
}
uint8_t ForwardOutputStream::copy(size_t distance,size_t count,uint8_t defaultChar)
{
if (!distance || OverflowCheck::sum(_currentOffset,count)>_endOffset) throw Decompressor::DecompressionError();
size_t prevCount=0;
uint8_t ret=0;
if (OverflowCheck::sum(_startOffset,distance)>_currentOffset)
{
prevCount=std::min(count,_startOffset+distance-_currentOffset);
for (size_t i=0;i<prevCount;i++,_currentOffset++)
ret=_bufPtr[_currentOffset]=defaultChar;
}
for (size_t i=prevCount;i<count;i++,_currentOffset++)
ret=_bufPtr[_currentOffset]=_bufPtr[_currentOffset-distance];
return ret;
}
const uint8_t *ForwardOutputStream::history(size_t distance) const
{
if (distance>_currentOffset) throw Decompressor::DecompressionError();
return &_bufPtr[_currentOffset-distance];
}
void ForwardOutputStream::produce(const uint8_t *src,size_t bytes)
{
if (OverflowCheck::sum(_currentOffset,bytes)>_endOffset) throw Decompressor::DecompressionError();
std::memcpy(&_bufPtr[_currentOffset],src,bytes);
_currentOffset+=bytes;
}
BackwardOutputStream::BackwardOutputStream(Buffer &buffer,size_t startOffset,size_t endOffset) :
_bufPtr(buffer.data()),
_startOffset(startOffset),
_currentOffset(endOffset),
_endOffset(endOffset)
{
if (_startOffset>_endOffset || _currentOffset>buffer.size() || _endOffset>buffer.size()) throw Decompressor::DecompressionError();
}
BackwardOutputStream::~BackwardOutputStream()
{
// nothing needed
}
void BackwardOutputStream::writeByte(uint8_t value)
{
if (_currentOffset<=_startOffset) throw Decompressor::DecompressionError();
_bufPtr[--_currentOffset]=value;
}
uint8_t BackwardOutputStream::copy(size_t distance,size_t count)
{
if (!distance || OverflowCheck::sum(_startOffset,count)>_currentOffset || OverflowCheck::sum(_currentOffset,distance)>_endOffset) throw Decompressor::DecompressionError();
uint8_t ret=0;
for (size_t i=0;i<count;i++,--_currentOffset)
ret=_bufPtr[_currentOffset-1]=_bufPtr[_currentOffset+distance-1];
return ret;
}
}
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