85 lines
2.2 KiB
C++
85 lines
2.2 KiB
C++
/* Copyright (C) Teemu Suutari */
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#include "HUFFDecompressor.hpp"
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#include "HuffmanDecoder.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 HUFFDecompressor::detectHeaderXPK(uint32_t hdr) noexcept
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{
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return hdr==FourCC("HUFF");
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}
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std::shared_ptr<XPKDecompressor> HUFFDecompressor::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<HUFFDecompressor>(hdr,recursionLevel,packedData,state,verify);
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}
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HUFFDecompressor::HUFFDecompressor(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) || packedData.size()<6)
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throw Decompressor::InvalidFormatError();
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// version: only 0 is defined
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uint16_t ver=packedData.readBE16(0);
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if (ver) throw Decompressor::InvalidFormatError();
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// password: we do not support it...
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uint32_t pwd=packedData.readBE32(2);
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if (pwd!=0xabadcafe) throw Decompressor::InvalidFormatError();
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}
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HUFFDecompressor::~HUFFDecompressor()
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{
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// nothing needed
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}
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const std::string &HUFFDecompressor::getSubName() const noexcept
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{
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static std::string name="XPK-HUFF: Huffman compressor";
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return name;
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}
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void HUFFDecompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
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{
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ForwardInputStream inputStream(_packedData,6,_packedData.size());
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MSBBitReader<ForwardInputStream> bitReader(inputStream);
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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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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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HuffmanDecoder<uint32_t> decoder;
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for (uint32_t i=0;i<256;i++)
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{
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uint8_t codeBits=readByte()+1;
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if (!codeBits) continue;
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if (codeBits>32) throw Decompressor::DecompressionError();
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uint32_t code=0;
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int32_t shift=-codeBits;
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for (uint32_t j=0;j<codeBits;j+=8)
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{
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code=(code<<8)|readByte();
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shift+=8;
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}
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code=(code>>shift)&((1<<codeBits)-1);
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decoder.insert(HuffmanCode<uint32_t>{codeBits,code,i});
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}
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while (!outputStream.eof())
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outputStream.writeByte(decoder.decode(readBit));
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}
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}
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