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/* Copyright (C) Teemu Suutari */
#include "LZW2Decompressor.hpp"
#include "InputStream.hpp"
#include "OutputStream.hpp"
#include "common/Common.hpp"
namespace ancient::internal
{
bool LZW2Decompressor::detectHeaderXPK(uint32_t hdr) noexcept
{
return hdr==FourCC("LZW2") || hdr==FourCC("LZW3");
}
std::shared_ptr<XPKDecompressor> LZW2Decompressor::create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify)
{
return std::make_shared<LZW2Decompressor>(hdr,recursionLevel,packedData,state,verify);
}
LZW2Decompressor::LZW2Decompressor(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify) :
XPKDecompressor{recursionLevel},
_packedData{packedData}
{
if (!detectHeaderXPK(hdr))
throw Decompressor::InvalidFormatError();
_ver=(hdr==FourCC("LZW2"))?2:3;
}
const std::string &LZW2Decompressor::getSubName() const noexcept
{
static std::string name2{"XPK-LZW2: LZW2 CyberYAFA compressor"};
static std::string name3{"XPK-LZW3: LZW3 CyberYAFA compressor"};
return (_ver==2)?name2:name3;
}
void LZW2Decompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
{
ForwardInputStream inputStream{_packedData,0,_packedData.size()};
LSBBitReader<ForwardInputStream> bitReader{inputStream};
auto readBit=[&]()->uint32_t
{
return bitReader.readBitsBE32(1);
};
auto readByte=[&]()->uint8_t
{
return inputStream.readByte();
};
ForwardOutputStream outputStream{rawData,0,rawData.size()};
while (!outputStream.eof())
{
if (!readBit())
{
outputStream.writeByte(readByte());
} else {
uint32_t distance{uint32_t(readByte())<<8};
distance|=uint32_t(readByte());
if (!distance)
throw Decompressor::DecompressionError();
distance=65536-distance;
uint32_t count{uint32_t(readByte())+4};
outputStream.copy(distance,count);
}
}
}
}
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