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/* Copyright (C) Teemu Suutari */
#include "HUFFDecompressor.hpp"
#include "HuffmanDecoder.hpp"
#include "InputStream.hpp"
#include "OutputStream.hpp"
#include "common/Common.hpp"
namespace ancient::internal
{
bool HUFFDecompressor::detectHeaderXPK(uint32_t hdr) noexcept
{
return hdr==FourCC("HUFF");
}
std::shared_ptr<XPKDecompressor> HUFFDecompressor::create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify)
{
return std::make_shared<HUFFDecompressor>(hdr,recursionLevel,packedData,state,verify);
}
HUFFDecompressor::HUFFDecompressor(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()<6)
throw Decompressor::InvalidFormatError();
// version: only 0 is defined
uint16_t ver{packedData.readBE16(0)};
if (ver)
throw Decompressor::InvalidFormatError();
// password: we do not support it...
uint32_t pwd{packedData.readBE32(2)};
if (pwd!=0xabadcafe)
throw Decompressor::InvalidFormatError();
}
const std::string &HUFFDecompressor::getSubName() const noexcept
{
static std::string name{"XPK-HUFF: Huffman compressor"};
return name;
}
void HUFFDecompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
{
ForwardInputStream inputStream{_packedData,6,_packedData.size()};
MSBBitReader<ForwardInputStream> bitReader{inputStream};
auto readBit=[&]()->uint32_t
{
return bitReader.readBits8(1);
};
auto readByte=[&]()->uint8_t
{
return inputStream.readByte();
};
ForwardOutputStream outputStream{rawData,0,rawData.size()};
HuffmanDecoder<uint8_t> decoder;
for (uint32_t i=0;i<256;i++)
{
uint8_t codeBits{uint8_t(readByte()+1)};
if (!codeBits) continue;
if (codeBits>32)
throw Decompressor::DecompressionError();
uint32_t code{0};
int32_t shift{-codeBits};
for (uint32_t j=0;j<codeBits;j+=8)
{
code=(code<<8)|readByte();
shift+=8;
}
code=(code>>shift)&((1<<codeBits)-1);
decoder.insert(HuffmanCode{codeBits,code,uint8_t(i)});
}
while (!outputStream.eof())
outputStream.writeByte(decoder.decode(readBit));
}
}
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