public byte[] Compress(byte[] arg)
{
var result = new LZNT1_Buffer();
var chunks = new List <LZNT1_Chunk>();
int index = 0;
while (index < arg.Length)
{
int length = Math.Min(arg.Length - index, 4096);
var chunk = CompressChunk(arg.Skip(index).Take(length).ToArray());
chunks.Add(chunk);
index += length;
}
result.Chunk = chunks.ToArray();
var buffer = new LittleEndianByteBuffer();
int offset = 0;
result.Marshal(buffer, ref offset);
return(buffer.GetBytes());
}
/// <summary>
/// Decode LZ77 symbols to data.
/// </summary>
/// <param name="symbols">LZ77 symbols to be decoded.</param>
/// <returns>The data after decoded.</returns>
public byte[] Decode(List <LZ77Symbol> symbols)
{
var buffer = new LittleEndianByteBuffer();
int offset = 0;
Verify(symbols);
foreach (var symbol in symbols)
{
symbol.Decode(buffer, ref offset);
}
return(buffer.GetBytes());
}
/// <summary>
/// Encode LZ77 symbols.
/// </summary>
/// <param name="symbols">LZ77 symbols to be encoded.</param>
/// <returns>Byte array containing encoded result.</returns>
public byte[] Encode(List <LZ77Symbol> symbols)
{
long Flags = 0;
int FlagCount = 0;
int FlagOutputPosition = 0;
int OutputPosition = 4;
int LastLengthHalfByte = 0;
var buffer = new LittleEndianByteBuffer();
foreach (var symbol in symbols)
{
if (symbol is LZ77Literal)
{
var literal = symbol as LZ77Literal;
buffer.WriteBytes(OutputPosition, literal.Literal, 1);
OutputPosition += 1;
Flags <<= 1;
FlagCount += 1;
}
else if (symbol is LZ77Match)
{
var match = symbol as LZ77Match;
int MatchLength = match.Length;
int MatchOffset = match.Distance;
MatchLength -= 3;
MatchOffset -= 1;
MatchOffset <<= 3;
if (MatchLength < 7)
{
MatchOffset += (int)MatchLength;
buffer.WriteBytes(OutputPosition, MatchOffset, 2);
OutputPosition += 2;
}
else
{
MatchOffset |= 7;
buffer.WriteBytes(OutputPosition, MatchOffset, 2);
OutputPosition += 2;
MatchLength -= 7;
bool EncodeExtraLen;
if (LastLengthHalfByte == 0)
{
LastLengthHalfByte = OutputPosition;
if (MatchLength < 15)
{
buffer.WriteBytes(OutputPosition, MatchLength, 1);
OutputPosition += 1;
EncodeExtraLen = false;
}
else
{
buffer.WriteBytes(OutputPosition, 15, 1);
OutputPosition++;
EncodeExtraLen = true;
}
}
else
{
if (MatchLength < 15)
{
byte LastLength = buffer[LastLengthHalfByte];
LastLength |= (byte)(MatchLength << 4);
buffer.WriteBytes(LastLengthHalfByte, LastLength, 1);
LastLengthHalfByte = 0;
EncodeExtraLen = false;
}
else
{
byte LastLength = buffer[LastLengthHalfByte];
LastLength |= 15 << 4;
buffer.WriteBytes(LastLengthHalfByte, LastLength, 1);
LastLengthHalfByte = 0;
EncodeExtraLen = true;
}
}
if (EncodeExtraLen)
{
MatchLength -= 15;
if (MatchLength < 255)
{
buffer.WriteBytes(OutputPosition, MatchLength, 1);
OutputPosition += 1;
}
else
{
buffer.WriteBytes(OutputPosition, 255, 1);
OutputPosition += 1;
MatchLength += 7 + 15;
if (MatchLength < (1 << 16))
{
buffer.WriteBytes(OutputPosition, MatchLength, 2);
OutputPosition += 2;
}
else
{
buffer.WriteBytes(OutputPosition, 0, 2);
OutputPosition += 2;
buffer.WriteBytes(OutputPosition, MatchLength, 4);
OutputPosition += 4;
}
}
}
}
Flags = (Flags << 1) | 1;
FlagCount += 1;
}
else if (symbol is LZ77EOF)
{
// Do nothing to EOF.
}
else
{
throw new XcaException("Unreachable code!");
}
if (FlagCount == 32)
{
buffer.WriteBytes(FlagOutputPosition, (int)Flags, 4);
FlagCount = 0;
FlagOutputPosition = OutputPosition;
OutputPosition += 4;
}
}
Flags <<= (32 - FlagCount);
Flags |= (((long)1 << (32 - FlagCount)) - 1);
buffer.WriteBytes(FlagOutputPosition, (int)Flags, 4);
return(buffer.GetBytes());
}