92 lines
2.6 KiB
C++
92 lines
2.6 KiB
C++
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/* Copyright (C) Teemu Suutari */
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#include "HFMNDecompressor.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/OverflowCheck.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 HFMNDecompressor::detectHeaderXPK(uint32_t hdr) noexcept
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{
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return hdr==FourCC("HFMN");
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}
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std::shared_ptr<XPKDecompressor> HFMNDecompressor::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<HFMNDecompressor>(hdr,recursionLevel,packedData,state,verify);
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}
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HFMNDecompressor::HFMNDecompressor(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()<4)
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throw Decompressor::InvalidFormatError();
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uint16_t tmp=packedData.readBE16(0);
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if (tmp&3U) throw Decompressor::InvalidFormatError(); // header is being written in 4 byte chunks
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_headerSize=tmp&0x1ffU; // the top 7 bits are flags. No definition what they are and they are ignored in decoder...
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if (OverflowCheck::sum(_headerSize,4U)>packedData.size()) throw Decompressor::InvalidFormatError();
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_rawSize=packedData.readBE16(_headerSize+2U);
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if (!_rawSize) throw Decompressor::InvalidFormatError();
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_headerSize+=4;
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}
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HFMNDecompressor::~HFMNDecompressor()
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{
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// nothing needed
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}
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const std::string &HFMNDecompressor::getSubName() const noexcept
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{
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static std::string name="XPK-HFMN: Huffman compressor";
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return name;
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}
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void HFMNDecompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
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{
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if (rawData.size()!=_rawSize) throw Decompressor::DecompressionError();
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ForwardInputStream inputStream(_packedData,2,_headerSize);
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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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ForwardOutputStream outputStream(rawData,0,rawData.size());
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HuffmanDecoder<uint32_t> decoder;
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uint32_t code=1;
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uint32_t codeBits=1;
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for (;;)
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{
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if (!readBit())
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{
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uint32_t lit=0;
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for (uint32_t i=0;i<8;i++) lit|=readBit()<<i;
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decoder.insert(HuffmanCode<uint32_t>{codeBits,code,lit});
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while (!(code&1) && codeBits)
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{
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codeBits--;
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code>>=1;
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}
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if (!codeBits) break;
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code--;
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} else {
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code=(code<<1)+1;
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codeBits++;
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}
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}
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inputStream=ForwardInputStream(_packedData,_headerSize,_packedData.size());
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bitReader.reset();
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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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