89 lines
2.7 KiB
C#
89 lines
2.7 KiB
C#
using NLog;
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using System;
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using System.IO;
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namespace Resources
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{
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public class Compression
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{
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private static readonly Logger Logger = LogManager.GetCurrentClassLogger();
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class Header
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{
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public const int Size = 9;
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public byte[] Buffer;
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public byte Flags => Buffer[0];
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public uint CompressedLength => BitConverter.ToUInt32(Buffer, 1);
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public uint DecompressedLength => BitConverter.ToUInt32(Buffer, 5);
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public bool IsCompressed => (Flags & 1) > 0;
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public int LengthSize => (Flags & 2) > 0 ? 4 : 1;
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public static Header Read(BinaryReader reader)
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{
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var buffer = new byte[Size];
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reader.Read(buffer, 0, buffer.Length);
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return new Header { Buffer = buffer };
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}
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}
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private readonly Stream _stream;
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private readonly BinaryReader _reader;
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private readonly long _streamSize;
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public Compression(Stream stream)
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{
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_stream = stream;
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_reader = new BinaryReader(stream);
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_streamSize = stream.Length;
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}
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public Stream Decompress()
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{
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var output = new MemoryStream();
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var buffer = new byte[5120];
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var offset = (uint)0;
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while (true)
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{
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var header = Header.Read(_reader);
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if (header.DecompressedLength == 4096)
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{
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Logger.Debug("Compression block header read at offset 0x{0:X}", offset);
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Logger.Debug("Flags 0x{0:X}, Compressed {1}, Decompressed {2}, LengthSize {3}",
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header.Flags, header.CompressedLength, header.DecompressedLength, header.LengthSize);
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_reader.Read(buffer, 0, (int)header.CompressedLength - 9);
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offset += header.CompressedLength;
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if (header.IsCompressed)
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{
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// Here should be decompression
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}
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else
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output.Write(buffer, 0, (int)header.CompressedLength);
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}
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else
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{
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var latestBlock = _streamSize - offset;
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Logger.Debug("Latest block read at offset 0x{0:X}, size: {1}", offset, latestBlock);
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_reader.Read(buffer, 0, (int)(latestBlock - Header.Size));
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output.Write(header.Buffer, 0, Header.Size);
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output.Write(buffer, 0, (int)(latestBlock - Header.Size));
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break;
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}
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}
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output.Seek(0, SeekOrigin.Begin);
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return output;
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}
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}
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}
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