75 lines
1.9 KiB
C++
75 lines
1.9 KiB
C++
/* Copyright (C) Teemu Suutari */
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#include "LZW2Decompressor.hpp"
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#include "InputStream.hpp"
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#include "OutputStream.hpp"
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#include "common/Common.hpp"
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namespace ancient::internal
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{
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bool LZW2Decompressor::detectHeaderXPK(uint32_t hdr) noexcept
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{
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return hdr==FourCC("LZW2") || hdr==FourCC("LZW3");
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}
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std::shared_ptr<XPKDecompressor> LZW2Decompressor::create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify)
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{
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return std::make_shared<LZW2Decompressor>(hdr,recursionLevel,packedData,state,verify);
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}
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LZW2Decompressor::LZW2Decompressor(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify) :
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XPKDecompressor(recursionLevel),
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_packedData(packedData)
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{
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if (!detectHeaderXPK(hdr)) throw Decompressor::InvalidFormatError();
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_ver=(hdr==FourCC("LZW2"))?2:3;
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}
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LZW2Decompressor::~LZW2Decompressor()
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{
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// nothing needed
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}
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const std::string &LZW2Decompressor::getSubName() const noexcept
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{
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static std::string name2="XPK-LZW2: LZW2 CyberYAFA compressor";
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static std::string name3="XPK-LZW3: LZW3 CyberYAFA compressor";
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return (_ver==2)?name2:name3;
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}
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void LZW2Decompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
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{
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ForwardInputStream inputStream(_packedData,0,_packedData.size());
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LSBBitReader<ForwardInputStream> bitReader(inputStream);
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auto readBit=[&]()->uint32_t
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{
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return bitReader.readBitsBE32(1);
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};
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auto readByte=[&]()->uint8_t
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{
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return inputStream.readByte();
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};
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ForwardOutputStream outputStream(rawData,0,rawData.size());
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while (!outputStream.eof())
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{
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if (!readBit())
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{
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outputStream.writeByte(readByte());
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} else {
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uint32_t distance=uint32_t(readByte())<<8;
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distance|=uint32_t(readByte());
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if (!distance) throw Decompressor::DecompressionError();
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distance=65536-distance;
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uint32_t count=uint32_t(readByte())+4;
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outputStream.copy(distance,count);
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}
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}
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}
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}
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