/// <summary>
/// This method returns an uncompressed version of the given compressed byte array
/// </summary>
/// <param name="inputBlob">the byte array to be decompressed</param>
/// <param name="decompressedLength">the known length of the decompressed byte array</param>
/// <param name="compressionCode">a generation number that indicates what compression technique to use</param>
/// <returns>the decompressed byte array</returns>
public static unsafe Byte[] DecompressBlob(Byte[] inputBlob, int decompressedLength,
int compressionCode)
{
if (compressionCode == 1)
{
// the byte array of the output blob
Byte[] decompressedBlob = new Byte[decompressedLength];
// Decompress using LZFX algorithm.
// This method will throw an exception if the decompressed data does not
// exactly fit into the allocated array size.
LZFX.Decompress(inputBlob, decompressedBlob);
return(decompressedBlob);
}
if (compressionCode == 2)
{
// the byte array of the output blob
Byte[] decompressedBlob = new Byte[decompressedLength];
// Decompress using LZFX algorithm.
// This method will throw an exception if the decompressed data does not
// exactly fit into the allocated array size.
LZ4.Decompress(inputBlob, decompressedBlob);
return(decompressedBlob);
}
else
{ // return without doing any compression
return(inputBlob);
}
}
/// <summary>
/// This returns a compressed version of the given byte array
/// </summary>
/// <param name="uncompressedBlob">the uncompressed byte array</param>
/// <param name="compressionCode">a generation number that indicates what compression technique to use</param>
/// <returns>the compressed byte array</returns>
public static unsafe Byte[] CompressBlob(Byte[] uncompressedBlob, int compressionCode)
{
if (compressionCode == 1)
{
Byte[] compressedBlob;
// the byte-array length of the input blob
int inputLength = uncompressedBlob.Length;
// The byte array that will be created by the compression.
// Note that some incompressible BLOBs will actually be made larger by LZFX
// compression. We have observed about 1% increase over the original BLOB,
// so the factor of 1.05 is expected to be safe. We add 16 since the factor
// of 1.05 is insufficient when the BLOB is very small.
compressedBlob = new Byte[(int)(inputLength * 1.05) + 16];
// Compress using LZFX algorithm.
// This method resizes the compressed byte array for us.
LZFX.Compress(uncompressedBlob, ref compressedBlob);
return(compressedBlob);
}
if (compressionCode == 2)
{
Byte[] compressedBlob;
// the byte-array length of the input blob
int inputLength = uncompressedBlob.Length;
// The byte array that will be created by the compression.
// Note that some incompressible BLOBs might actually be made larger by LZ4
// compression. The GetMaxSize method calls a function built into LZ4 which
// returns the maximum possible size of the output array. LZ4 documentation suggests
// that speed is optimized by allocating this max size.
compressedBlob = new Byte[(int)LZ4.GetMaxSize(inputLength)];
// Compress using LZ4 algorithm.
// This method resizes the compressed byte array for us.
LZ4.Compress(uncompressedBlob, ref compressedBlob, 4);
return(compressedBlob);
}
else
{ // return without doing any compression
return(uncompressedBlob);
}
}
