public static byte[] Compress(Stream instream, bool precedingSize = false, bool blockIndep = true, bool blockChecksum = false, bool contentSize = false, bool contentChecksum = true, bool dictID = false, BlockMaxSize blockMaxSize = BlockMaxSize.MB1)
{
var ms = new MemoryStream();
using (var br = new BinaryReaderX(ms, true))
using (var bw = new BinaryWriterX(ms, true))
{
if (precedingSize)
{
bw.Write((uint)instream.Length);
}
#region Write LZ4 Frame header
//Magic
bw.Write(0x184D2204);
//FLG Byte
byte flg = 0x40;
if (blockIndep)
{
flg |= 0x20;
}
if (blockChecksum)
{
flg |= 0x10;
}
if (contentSize)
{
flg |= 0x08;
}
if (contentChecksum)
{
flg |= 0x04;
}
if (dictID)
{
flg |= 0x01;
}
bw.Write(flg);
//BD Byte
byte bd = (byte)((byte)blockMaxSize << 4);
bw.Write(bd);
//Content Size
if (contentSize)
{
bw.Write((long)instream.Length);
}
//Dictionary - STUB since Dictionary usage isn't understood in LZ4
if (dictID)
{
bw.Write(0);
}
//XXHash32
br.BaseStream.Position = 4;
var fieldDesc = br.ReadBytes((int)br.BaseStream.Length - 4);
byte hc = (byte)((XXH32.Create(fieldDesc) >> 8) & 0xFF);
bw.Write(hc);
#endregion
//Write Block Data
var comp = LZ4Codec.Encode(new BinaryReaderX(instream, true).ReadAllBytes(), 0, (int)instream.Length);
bw.Write(comp.Length);
bw.Write(comp);
if (blockChecksum)
{
bw.Write(XXH32.Create(comp));
}
//End Mark
bw.Write(0);
//Content checksum
if (contentChecksum)
{
bw.Write(XXH32.Create(new BinaryReaderX(instream, true).ReadAllBytes()));
}
}
return(ms.ToArray());
}
public static byte[] Decompress(Stream instream, bool precedingSize = false)
{
var ms = new MemoryStream();
using (var bw = new BinaryWriterX(ms, true))
using (var br2 = new BinaryReaderX(ms, true))
using (var br = new BinaryReaderX(instream, true))
{
uint decompressedSize = 0;
if (precedingSize)
{
decompressedSize = br.ReadUInt32();
}
var magic = br.ReadUInt32();
if (magic != 0x184D2204)
{
throw new Exception("LZ4 magic isn't valid.");
}
var flg = br.ReadByte();
if ((flg >> 6) != 1)
{
throw new Exception($"Unsupported Version {flg >> 6}.");
}
bool blockIndep = ((flg >> 5) & 1) == 1;
bool blockChecksum = ((flg >> 4) & 1) == 1;
bool contentSize = ((flg >> 3) & 1) == 1;
bool contentChecksum = ((flg >> 2) & 1) == 1;
bool dictID = (flg & 1) == 1;
var bd = br.ReadByte();
BlockMaxSize blockMaxSize = (BlockMaxSize)((bd >> 4) & 0x7);
if (contentSize)
{
br.ReadUInt64();
}
if (dictID)
{
br.ReadInt32();
}
var headerLength = 3 + ((contentSize) ? 8 : 0) + ((dictID) ? 4 : 0);
br.BaseStream.Position -= headerLength - 1;
var header = br.ReadBytes(headerLength - 1);
var hc = br.ReadByte();
if (((XXH32.Create(header) >> 8) & 0xFF) != hc)
{
throw new Exception("Header Checksum is invalid.");
}
//Blocks
while (br.BaseStream.Position < br.BaseStream.Length - ((contentChecksum) ? 4 : 0))
{
var blockSize = br.ReadInt32();
while (blockSize != 0)
{
var compData = br.ReadBytes(blockSize);
var decomp = DecompressBlock(compData);
if (blockChecksum)
{
var check = br.ReadUInt32();
if (check != XXH32.Create(compData))
{
throw new Exception("One block checksum was invalid.");
}
}
bw.Write(decomp);
blockSize = br.ReadInt32();
}
}
if (contentChecksum)
{
br2.BaseStream.Position = 0;
if (br.ReadUInt32() != XXH32.Create(br2.ReadAllBytes()))
{
throw new Exception("Decompressed data is corrupted.");
}
}
if (precedingSize && decompressedSize != br2.BaseStream.Length)
{
throw new Exception("Preceding decompressed size doesn't match.");
}
}
return(ms.ToArray());
}
