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/* Copyright (C) Teemu Suutari */
#include "HFMNDecompressor.hpp"
#include "HuffmanDecoder.hpp"
#include "InputStream.hpp"
#include "OutputStream.hpp"
#include "common/OverflowCheck.hpp"
#include "common/Common.hpp"
namespace ancient::internal
{
bool HFMNDecompressor::detectHeaderXPK(uint32_t hdr) noexcept
{
return hdr==FourCC("HFMN");
}
std::shared_ptr<XPKDecompressor> HFMNDecompressor::create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify)
{
return std::make_shared<HFMNDecompressor>(hdr,recursionLevel,packedData,state,verify);
}
HFMNDecompressor::HFMNDecompressor(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify) :
XPKDecompressor{recursionLevel},
_packedData{packedData}
{
if (!detectHeaderXPK(hdr) || packedData.size()<4)
throw Decompressor::InvalidFormatError();
uint16_t tmp{packedData.readBE16(0)};
if (tmp&3U)
throw Decompressor::InvalidFormatError(); // header is being written in 4 byte chunks
_headerSize=tmp&0x1ffU; // the top 7 bits are flags. No definition what they are and they are ignored in decoder...
if (OverflowCheck::sum(_headerSize,4U)>packedData.size())
throw Decompressor::InvalidFormatError();
_rawSize=packedData.readBE16(_headerSize+2U);
if (!_rawSize)
throw Decompressor::InvalidFormatError();
_headerSize+=4;
}
const std::string &HFMNDecompressor::getSubName() const noexcept
{
static std::string name{"XPK-HFMN: Huffman compressor"};
return name;
}
void HFMNDecompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
{
ForwardOutputStream outputStream{rawData,0,rawData.size()};
HuffmanDecoder<uint32_t> decoder;
if (rawData.size()!=_rawSize)
throw Decompressor::DecompressionError();
{
ForwardInputStream inputStream{_packedData,2,_headerSize};
MSBBitReader<ForwardInputStream> bitReader{inputStream};
auto readBit=[&]()->uint32_t
{
return bitReader.readBits8(1);
};
uint32_t code{1};
uint32_t codeBits{1};
for (;;)
{
if (!readBit())
{
uint32_t lit=rotateBits(bitReader.readBits8(8),8);
decoder.insert(HuffmanCode{codeBits,code,lit});
while (!(code&1) && codeBits)
{
codeBits--;
code>>=1;
}
if (!codeBits) break;
code--;
} else {
code=(code<<1)+1;
codeBits++;
}
}
}
ForwardInputStream inputStream{_packedData,_headerSize,_packedData.size()};
MSBBitReader<ForwardInputStream> bitReader{inputStream};
auto readBit=[&]()->uint32_t
{
return bitReader.readBits8(1);
};
while (!outputStream.eof())
outputStream.writeByte(decoder.decode(readBit));
}
}
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