/// <summary>
/// This method creates the windows and finds longest match from lookahead in history. If one
/// longer than 2 is found, then a PointerByte is returned indicating where the match is relative
/// to the current index.
/// </summary>
/// <returns> EncodedLZByte that is either a pointer to match or raw data. </returns>
public EncodedLZByte Slide()
{
if (AtEnd())
{
return(null);
}
var history = LoadHistory(_historyLength);
var lookAhead = LoadLookAhead(_lookAheadLength);
MatchPointer match;
try {
match = findLongestMatch(history, lookAhead);
}
catch (Exception exception) {
// If the loading went bad
if (exception is DllNotFoundException ||
exception is MarshalDirectiveException)
{
// Change to using the C# implementation
findLongestMatch = FindMatchingBytes.FindLongestMatch;
match = findLongestMatch(history, lookAhead);
}
else
{
throw;
}
}
EncodedLZByte r;
if (match.Length != 0)
{
r = new PointerByte(history.Length - match.Index - 1, match.Length - 1);
_currentIndex += match.Length;
}
else
{
r = new RawByte(lookAhead[0]);
_currentIndex++;
}
return(r);
}
public SlidingWindow(byte[] bytes)
{
_bytes = bytes;
findLongestMatch = CFindMatchingBytes.FindLongestMatch;
}
