97 lines
2.2 KiB
C++
97 lines
2.2 KiB
C++
/* Copyright (C) Teemu Suutari */
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#include "TDCSDecompressor.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 TDCSDecompressor::detectHeaderXPK(uint32_t hdr) noexcept
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{
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return hdr==FourCC("TDCS");
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}
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std::shared_ptr<XPKDecompressor> TDCSDecompressor::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<TDCSDecompressor>(hdr,recursionLevel,packedData,state,verify);
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}
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TDCSDecompressor::TDCSDecompressor(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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}
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TDCSDecompressor::~TDCSDecompressor()
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{
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// nothing needed
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}
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const std::string &TDCSDecompressor::getSubName() const noexcept
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{
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static std::string name="XPK-TDCS: LZ77-compressor";
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return name;
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}
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void TDCSDecompressor::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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MSBBitReader<ForwardInputStream> bitReader(inputStream);
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auto read2Bits=[&]()->uint32_t
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{
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return bitReader.readBitsBE32(2);
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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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uint32_t distance=0;
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uint32_t count=0;
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uint32_t tmp;
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switch (read2Bits())
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{
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case 0:
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outputStream.writeByte(readByte());
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break;
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case 1:
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tmp=uint32_t(readByte())<<8;
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tmp|=uint32_t(readByte());
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count=(tmp&3)+3;
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distance=((tmp>>2)^0x3fff)+1;
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break;
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case 2:
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tmp=uint32_t(readByte())<<8;
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tmp|=uint32_t(readByte());
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count=(tmp&0xf)+3;
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distance=((tmp>>4)^0xfff)+1;
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break;
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case 3:
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distance=uint32_t(readByte())<<8;
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distance|=uint32_t(readByte());
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count=uint32_t(readByte())+3;
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if (!distance) throw Decompressor::DecompressionError();
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distance=(distance^0xffff)+1;
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break;
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default:
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throw Decompressor::DecompressionError();
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}
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if (count && distance)
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outputStream.copy(distance,count);
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}
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}
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}
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