mirror of
https://github.com/borgesdan/xn65
synced 2024-12-29 21:54:47 +01:00
89 lines
3.7 KiB
C++
89 lines
3.7 KiB
C++
#ifndef XNA_CONTENT_LZX_DECODERSTREAM_HPP
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#define XNA_CONTENT_LZX_DECODERSTREAM_HPP
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#include "decoder.hpp"
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namespace xna {
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class LzxDecoderStream : public Stream {
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public:
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LzxDecoderStream(sptr<Stream>& input, Int decompressedSize, Int compressedSize) {
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dec = New<LzxDecoder>(16);
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Decompress(input, decompressedSize, compressedSize);
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}
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private:
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void Decompress(sptr<Stream>& stream, Int decompressedSize, Int compressedSize) {
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//thanks to ShinAli (https://bitbucket.org/alisci01/xnbdecompressor)
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// default window size for XNB encoded files is 64Kb (need 16 bits to represent it)
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decompressedStream = New<MemoryStream>(decompressedSize);
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auto startPos = stream->Position();
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auto pos = startPos;
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while (pos - startPos < compressedSize)
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{
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// the compressed stream is seperated into blocks that will decompress
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// into 32Kb or some other size if specified.
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// normal, 32Kb output blocks will have a short indicating the size
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// of the block before the block starts
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// blocks that have a defined output will be preceded by a byte of value
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// 0xFF (255), then a short indicating the output size and another
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// for the block size
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// all shorts for these cases are encoded in big endian order
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Int hi = stream->ReadByte();
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Int lo = stream->ReadByte();
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Int block_size = (hi << 8) | lo;
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Int frame_size = 0x8000; // frame size is 32Kb by default
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// does this block define a frame size?
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if (hi == 0xFF) {
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hi = lo;
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lo = static_cast<Byte>(stream->ReadByte());
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frame_size = (hi << 8) | lo;
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hi = static_cast<Byte>(stream->ReadByte());
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lo = static_cast<Byte>(stream->ReadByte());
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block_size = (hi << 8) | lo;
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pos += 5;
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}
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else
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pos += 2;
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// either says there is nothing to decode
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if (block_size == 0 || frame_size == 0)
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break;
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auto decompressed = reinterpret_pointer_cast<Stream>(decompressedStream);
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dec->Decompress(stream, block_size, decompressed, frame_size);
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pos += block_size;
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// reset the position of the input just incase the bit buffer
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// read in some unused bytes
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stream->Seek(pos, SeekOrigin::Begin);
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}
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if (decompressedStream->Position() != decompressedSize)
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{
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return;
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}
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decompressedStream->Seek(0, SeekOrigin::Begin);
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}
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private:
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sptr<LzxDecoder> dec = nullptr;
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sptr<MemoryStream>decompressedStream = nullptr;
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// Inherited via Stream
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Int Length() override;
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Long Position() override;
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void Close() override;
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Long Seek(Long offset, SeekOrigin const& origin, xna_error_nullarg) override;
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Int Read(Byte* buffer, Int bufferLength, Int offset, Int count, xna_error_nullarg) override;
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Int Read(std::vector<Byte>& buffer, Int offset, Int count, xna_error_nullarg) override;
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Int ReadByte(xna_error_nullarg) override;
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void Write(Byte const* buffer, Int bufferLength, Int offset, Int count, xna_error_nullarg) override;
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void Write(std::vector<Byte> const& buffer, Int offset, Int count, xna_error_nullarg) override;
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void WriteByte(Byte value, xna_error_nullarg) override;
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virtual constexpr bool IsClosed() override { return false; }
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};
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}
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#endif |