109 lines
3.2 KiB
C++
Vendored
109 lines
3.2 KiB
C++
Vendored
/* Copyright (C) Teemu Suutari */
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#include "LHLBDecompressor.hpp"
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#include "InputStream.hpp"
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#include "OutputStream.hpp"
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#include "DynamicHuffmanDecoder.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 LHLBDecompressor::detectHeaderXPK(uint32_t hdr) noexcept
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{
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return hdr==FourCC("LHLB");
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}
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std::shared_ptr<XPKDecompressor> LHLBDecompressor::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<LHLBDecompressor>(hdr,recursionLevel,packedData,state,verify);
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}
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LHLBDecompressor::LHLBDecompressor(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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LHLBDecompressor::~LHLBDecompressor()
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{
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// nothing needed
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}
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const std::string &LHLBDecompressor::getSubName() const noexcept
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{
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static std::string name="XPK-LHLB: LZRW-compressor";
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return name;
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}
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void LHLBDecompressor::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 readBits=[&](uint32_t count)->uint32_t
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{
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return bitReader.readBits8(count);
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};
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auto readBit=[&]()->uint32_t
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{
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return bitReader.readBits8(1);
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};
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ForwardOutputStream outputStream(rawData,0,rawData.size());
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// Same logic as in Choloks pascal implementation
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// Differences to LH1:
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// - LHLB does not halve probabilities at 32k
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// - 314 vs. 317 sized huffman entry
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// - no end code
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// - different distance/count logic
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DynamicHuffmanDecoder<317> decoder;
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while (!outputStream.eof())
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{
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uint32_t code=decoder.decode(readBit);
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if (code==316) break;
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if (decoder.getMaxFrequency()<0x8000U) decoder.update(code);
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if (code<256)
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{
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outputStream.writeByte(code);
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} else {
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static const uint8_t distanceHighBits[256]={
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5,
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6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7,
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8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
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10,10,10,10,10,10,10,10, 11,11,11,11,11,11,11,11,
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12,12,12,12,13,13,13,13, 14,14,14,14,15,15,15,15,
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16,16,16,16,17,17,17,17, 18,18,18,18,19,19,19,19,
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20,20,20,20,21,21,21,21, 22,22,22,22,23,23,23,23,
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24,24,25,25,26,26,27,27, 28,28,29,29,30,30,31,31,
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32,32,33,33,34,34,35,35, 36,36,37,37,38,38,39,39,
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40,40,41,41,42,42,43,43, 44,44,45,45,46,46,47,47,
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48,49,50,51,52,53,54,55, 56,57,58,59,60,61,62,63};
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static const uint8_t distanceBits[16]={1,1,2,2,2,3,3,3,3,4,4,4,5,5,5,6};
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uint32_t tmp=readBits(8);
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uint32_t distance=uint32_t(distanceHighBits[tmp])<<6;
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uint32_t bits=distanceBits[tmp>>4];
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tmp=(tmp<<bits)|readBits(bits);
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distance|=tmp&63;
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uint32_t count=code-255;
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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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