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// 7Zip helper code by Peter Bromberg
// http://www.eggheadcafe.com/tutorials/aspnet/064b41e4-60bc-4d35-9136-368603bcc27a/7zip-lzma-inmemory-com.aspx
using System;
using System.IO;
namespace Tango.Transport.Compression
{
public static class SevenZipHelper
{
static int dictionary = 1 << 23;
// static Int32 posStateBits = 2;
// static Int32 litContextBits = 3; // for normal files
// UInt32 litContextBits = 0; // for 32-bit data
// static Int32 litPosBits = 0;
// UInt32 litPosBits = 2; // for 32-bit data
// static Int32 algorithm = 2;
// static Int32 numFastBytes = 128;
static bool eos = false;
static CoderPropID[] propIDs =
{
CoderPropID.DictionarySize,
CoderPropID.PosStateBits,
CoderPropID.LitContextBits,
CoderPropID.LitPosBits,
CoderPropID.Algorithm,
CoderPropID.NumFastBytes,
CoderPropID.MatchFinder,
CoderPropID.EndMarker
};
// these are the default properties, keeping it simple for now:
static object[] properties =
{
(Int32)(dictionary),
(Int32)(2),
(Int32)(3),
(Int32)(0),
(Int32)(2),
(Int32)(128),
"bt4",
eos
};
public static byte[] Compress(byte[] inputBytes)
{
MemoryStream inStream = new MemoryStream(inputBytes);
MemoryStream outStream = new MemoryStream();
LZMA.Encoder encoder = new LZMA.Encoder();
encoder.SetCoderProperties(propIDs, properties);
encoder.WriteCoderProperties(outStream);
long fileSize = inStream.Length;
for (int i = 0; i < 8; i++)
outStream.WriteByte((Byte)(fileSize >> (8 * i)));
encoder.Code(inStream, outStream, -1, -1, null);
return outStream.ToArray();
}
public static byte[] Decompress(byte[] inputBytes)
{
MemoryStream newInStream = new MemoryStream(inputBytes);
LZMA.Decoder decoder = new LZMA.Decoder();
newInStream.Seek(0, 0);
MemoryStream newOutStream = new MemoryStream();
byte[] properties2 = new byte[5];
if (newInStream.Read(properties2, 0, 5) != 5)
throw (new Exception("input .lzma is too short"));
long outSize = 0;
for (int i = 0; i < 8; i++)
{
int v = newInStream.ReadByte();
if (v < 0)
throw (new Exception("Can't Read 1"));
outSize |= ((long)(byte)v) << (8 * i);
}
decoder.SetDecoderProperties(properties2);
long compressedSize = newInStream.Length - newInStream.Position;
decoder.Code(newInStream, newOutStream, compressedSize, outSize, null);
byte[] b = newOutStream.ToArray();
return b;
}
}
}
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