// Starting at the current position, looks for pairs of locations in the _baselineData & _secondaryData that are byte-wise equivalent.
// These are candidiates for where the difference ends.
private Dictionary <int, List <int> > FindPotentialRealignments()
{
byte[] baselineReplayBuffer = _baselineData.ReadBytes(DifferenceCheckWindowSize, out int baselineBytesRead);
Span <byte> baselineSpan = baselineReplayBuffer;
// setup the baseline lookups
Dictionary <string, IList <int> > baselinePositionals = new Dictionary <string, IList <int> >(StringComparer.Ordinal);
for (int start = 0; start < baselineBytesRead - PositionalSize; start++)
{
Span <byte> slice = baselineSpan.Slice(start, PositionalSize);
string sliceString = Encoding.Default.GetString(slice.ToArray());
if (!baselinePositionals.TryGetValue(sliceString, out IList <int> positions))
{
positions = new List <int>();
baselinePositionals[sliceString] = positions;
}
positions.Add(start);
}
byte[] secondaryReplayBuffer = _secondaryData.ReadBytes(DifferenceCheckWindowSize, out int checkBytesRead);
Span <byte> secondarySpan = secondaryReplayBuffer;
// start looking for "sames" in the check buffer
Dictionary <int, List <int> > checkStartToBaselineStartMatches = new Dictionary <int, List <int> >();
int finalCheckSliceStart = Math.Min(baselineBytesRead, checkBytesRead) - PositionalSize;
for (int start = 0; start < finalCheckSliceStart; start++)
{
Span <byte> slice = secondarySpan.Slice(start, PositionalSize);
string sliceString = Encoding.Default.GetString(slice.ToArray());
if (baselinePositionals.TryGetValue(sliceString, out IList <int> baselineMatchPositions))
{
if (!checkStartToBaselineStartMatches.TryGetValue(start, out List <int> baselineStartPositions))
{
baselineStartPositions = new List <int>();
checkStartToBaselineStartMatches[start] = baselineStartPositions;
}
baselineStartPositions.AddRange(baselineMatchPositions);
}
}
_baselineData.SetupReplayBytes(baselineReplayBuffer);
_secondaryData.SetupReplayBytes(secondaryReplayBuffer);
return(checkStartToBaselineStartMatches);
}
