93 lines
2.1 KiB
C++
93 lines
2.1 KiB
C++
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/* Copyright (C) Teemu Suutari */
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#include "TPWMDecompressor.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 TPWMDecompressor::detectHeader(uint32_t hdr) noexcept
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{
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return hdr==FourCC("TPWM");
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}
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std::shared_ptr<Decompressor> TPWMDecompressor::create(const Buffer &packedData,bool exactSizeKnown,bool verify)
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{
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return std::make_shared<TPWMDecompressor>(packedData,verify);
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}
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TPWMDecompressor::TPWMDecompressor(const Buffer &packedData,bool verify) :
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_packedData(packedData)
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{
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uint32_t hdr=packedData.readBE32(0);
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if (!detectHeader(hdr) || packedData.size()<12) throw InvalidFormatError();
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_rawSize=packedData.readBE32(4);
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if (!_rawSize || _rawSize>getMaxRawSize())
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throw InvalidFormatError();
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}
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TPWMDecompressor::~TPWMDecompressor()
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{
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// nothing needed
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}
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const std::string &TPWMDecompressor::getName() const noexcept
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{
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static std::string name="TPWM: Turbo Packer";
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return name;
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}
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size_t TPWMDecompressor::getPackedSize() const noexcept
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{
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// No packed size in the stream :(
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// After decompression, we can tell how many bytes were actually used
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return _decompressedPackedSize;
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}
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size_t TPWMDecompressor::getRawSize() const noexcept
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{
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return _rawSize;
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}
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void TPWMDecompressor::decompressImpl(Buffer &rawData,bool verify)
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{
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if (rawData.size()<_rawSize) throw DecompressionError();
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ForwardInputStream inputStream(_packedData,8,_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,_rawSize);
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while (!outputStream.eof())
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{
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if (readBit())
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{
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uint8_t byte1=readByte();
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uint8_t byte2=readByte();
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uint32_t distance=(uint32_t(byte1&0xf0)<<4)|byte2;
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uint32_t count=uint32_t(byte1&0xf)+3;
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count=std::min(count,uint32_t(_rawSize-outputStream.getOffset()));
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outputStream.copy(distance,count);
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} else {
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outputStream.writeByte(readByte());
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}
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}
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_decompressedPackedSize=inputStream.getOffset();
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}
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}
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