remove FrameworkFastZipWriter - interesting idea that didn't pan out
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adelikat
parent
ff029968f3
commit
de54b80447
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@ -1,283 +0,0 @@
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.IO.Compression;
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using System.Text;
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namespace BizHawk.Client.Common
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{
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/// <summary>
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/// this almost works, but it loses all of its speed advantages over FrameworkZipWriter from slow CRC calculation.
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/// </summary>
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public class FrameworkFastZipWriter : IZipWriter
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{
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private Stream _output;
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private readonly CompressionLevel _level;
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private readonly byte[] _localHeader;
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private List<byte[]> _endBlobs = new List<byte[]>();
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private readonly byte[] _fileHeaderTemplate;
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private int _numEntries;
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private bool _disposed;
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private class CRC32Stream : Stream
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{
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// Lookup table for speed.
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private static readonly uint[] Crc32Table;
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static CRC32Stream()
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{
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Crc32Table = new uint[256];
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for (uint i = 0; i < 256; ++i)
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{
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uint crc = i;
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for (int j = 8; j > 0; --j)
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{
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if ((crc & 1) == 1)
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{
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crc = (crc >> 1) ^ 0xEDB88320;
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}
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else
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{
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crc >>= 1;
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}
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}
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Crc32Table[i] = crc;
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}
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}
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private uint _crc = 0xffffffff;
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private int _count = 0;
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private Stream _baseStream;
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public int Size => _count;
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public uint Crc => ~_crc;
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public CRC32Stream(Stream baseStream)
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{
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_baseStream = baseStream;
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}
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private void CalculateByte(byte b)
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{
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_crc = (_crc >> 8) ^ Crc32Table[b ^ (_crc & 0xff)];
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}
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public override void Write(byte[] buffer, int offset, int count)
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{
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for (int i = offset; i < offset + count; i++)
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{
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CalculateByte(buffer[i]);
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}
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_count += count;
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_baseStream.Write(buffer, offset, count);
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}
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public override void WriteByte(byte value)
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{
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CalculateByte(value);
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_count++;
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_baseStream.WriteByte(value);
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}
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public override void Flush()
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{
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}
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public override long Seek(long offset, SeekOrigin origin)
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{
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throw new NotImplementedException();
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}
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public override void SetLength(long value)
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{
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throw new NotImplementedException();
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}
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public override int Read(byte[] buffer, int offset, int count)
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{
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throw new NotImplementedException();
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}
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public override bool CanRead => false;
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public override bool CanSeek => false;
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public override bool CanWrite => true;
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public override long Length => throw new NotImplementedException();
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public override long Position
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{
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get => throw new NotImplementedException();
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set => throw new NotImplementedException();
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}
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}
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/// <exception cref="NotImplementedException"><paramref name="compressionLevel"/> is <c>0</c></exception>
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public FrameworkFastZipWriter(string path, int compressionLevel)
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{
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_output = new FileStream(path, FileMode.Create, FileAccess.Write);
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if (compressionLevel == 0)
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{
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throw new NotImplementedException();
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}
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_level = compressionLevel < 5
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? CompressionLevel.Fastest
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: CompressionLevel.Optimal;
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var dt = DateTime.Now;
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var mtime = dt.Second >> 1
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| dt.Minute << 5
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| dt.Hour << 11;
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var mdate = dt.Day
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| dt.Month << 5
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| (dt.Year - 1980) << 9;
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var modifiedDate = new[]
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{
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(byte)(mtime & 0xff),
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(byte)(mtime >> 8),
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(byte)(mdate & 0xff),
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(byte)(mdate >> 8)
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};
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_localHeader = new byte[]
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{
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0x50, 0x4b, 0x03, 0x04, // signature
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0x14, 0x00, // version
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0x08, 0x00, // flags: has data descriptor
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0x08, 0x00, // method: deflate
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modifiedDate[0], modifiedDate[1], // mod time
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modifiedDate[2], modifiedDate[3], // mod date
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0x00, 0x00, 0x00, 0x00, // crc32
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0x00, 0x00, 0x00, 0x00, // compressed size
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0x00, 0x00, 0x00, 0x00, // uncompressed size
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0x00, 0x00, // filename length
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0x00, 0x00, // extra field length
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};
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_fileHeaderTemplate = new byte[]
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{
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0x50, 0x4b, 0x01, 0x02, // signature
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0x17, 0x03, // ??
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0x14, 0x00, // version
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0x08, 0x00, // flags: has data descriptor
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0x08, 0x00, // method: deflate
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modifiedDate[0], modifiedDate[1], // mod time
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modifiedDate[2], modifiedDate[3], // mod date
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0x00, 0x00, 0x00, 0x00, // crc32
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0x00, 0x00, 0x00, 0x00, // compressed size
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0x00, 0x00, 0x00, 0x00, // uncompressed size
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0x00, 0x00, // filename length
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0x00, 0x00, // extra field length
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0x00, 0x00, // file comment length
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0x00, 0x00, // disk #,
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0x00, 0x00, // internal attributes
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0x00, 0x00, 0x00, 0x00, // external attributes
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0x00, 0x00, 0x00, 0x00, // local header offset
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};
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}
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public void Dispose()
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{
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if (!_disposed)
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{
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WriteFooter();
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_output.Dispose();
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_output = null;
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_disposed = true;
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}
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}
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public void WriteItem(string name, Action<Stream> callback)
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{
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var nameb = Encoding.ASCII.GetBytes(name);
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_localHeader[26] = (byte)nameb.Length;
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_localHeader[27] = (byte)(nameb.Length >> 8);
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var localHeaderOffset = (int)_output.Position;
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_output.Write(_localHeader, 0, _localHeader.Length);
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_output.Write(nameb, 0, nameb.Length);
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var fileStart = (int)_output.Position;
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var s2 = new DeflateStream(_output, _level, true);
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var s3 = new CRC32Stream(s2);
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callback(s3);
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s2.Flush();
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var fileEnd = (int)_output.Position;
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var crc = s3.Crc;
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var compressedSize = fileEnd - fileStart;
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var uncompressedSize = s3.Size;
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var descriptor = new[]
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{
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(byte)crc,
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(byte)(crc >> 8),
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(byte)(crc >> 16),
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(byte)(crc >> 24),
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(byte)compressedSize,
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(byte)(compressedSize >> 8),
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(byte)(compressedSize >> 16),
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(byte)(compressedSize >> 24),
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(byte)uncompressedSize,
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(byte)(uncompressedSize >> 8),
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(byte)(uncompressedSize >> 16),
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(byte)(uncompressedSize >> 24)
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};
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_output.Write(descriptor, 0, descriptor.Length);
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var fileHeader = (byte[])_fileHeaderTemplate.Clone();
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fileHeader[28] = (byte)nameb.Length;
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fileHeader[29] = (byte)(nameb.Length >> 8);
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Array.Copy(descriptor, 0, fileHeader, 16, 12);
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fileHeader[42] = (byte)localHeaderOffset;
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fileHeader[43] = (byte)(localHeaderOffset >> 8);
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fileHeader[44] = (byte)(localHeaderOffset >> 16);
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fileHeader[45] = (byte)(localHeaderOffset >> 24);
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_endBlobs.Add(fileHeader);
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_endBlobs.Add(nameb);
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_numEntries++;
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}
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private void WriteFooter()
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{
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var centralHeaderOffset = (int)_output.Position;
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foreach (var blob in _endBlobs)
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_output.Write(blob, 0, blob.Length);
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var centralHeaderEnd = (int)_output.Position;
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var centralHeaderSize = centralHeaderEnd - centralHeaderOffset;
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var footer = new byte[]
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{
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0x50, 0x4b, 0x05, 0x06, // signature
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0x00, 0x00, // disk number
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0x00, 0x00, // central record disk number
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(byte)_numEntries, (byte)(_numEntries >> 8), // number of entries on disk
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(byte)_numEntries, (byte)(_numEntries >> 8), // number of entries total
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(byte)centralHeaderSize,
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(byte)(centralHeaderSize >> 8),
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(byte)(centralHeaderSize >> 16),
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(byte)(centralHeaderSize >> 24), // central directory size
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(byte)centralHeaderOffset,
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(byte)(centralHeaderOffset >> 8),
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(byte)(centralHeaderOffset >> 16),
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(byte)(centralHeaderOffset >> 24), // central directory offset
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0x07, 0x00, // comment length
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0x42, 0x69, 0x7a, 0x48, 0x61, 0x77, 0x6b // comment
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};
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_output.Write(footer, 0, footer.Length);
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}
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}
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}
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