public static List <FileBlock> ComputeDelta(System.IO.Stream input, long inputSize, ChunkedChecksum chunks, out long deltaSize, Action <long, long> progress = null)
{
List <FileBlock> deltas = new List <FileBlock>();
if (inputSize < chunks.ChunkSize)
{
deltas.Add(new FileBlock()
{
Base = false, Offset = 0, Length = inputSize
});
deltaSize = 1 + 8 + inputSize;
return(deltas);
}
List <Chunk> sortedChunks = chunks.Chunks.OrderBy(x => new Tuple <uint, long>(x.Adler32, x.Offset)).ToList();
Dictionary <uint, int> adlerToIndex = new Dictionary <uint, int>();
for (int i = 0; i < sortedChunks.Count; i++)
{
adlerToIndex[sortedChunks[i].Adler32] = i;
}
BufferedView view = new BufferedView(input, 4 * 1024 * 1024);
CircularBuffer circularBuffer = new CircularBuffer(chunks.ChunkSize);
long readHead = 0;
long processHead = 0;
uint checksum = 0;
FileBlock lastMatch = null;
System.Security.Cryptography.SHA1 sha1 = null;
if (chunks.HashType == HashMode.SHA1)
{
sha1 = System.Security.Cryptography.SHA1.Create();
}
while (processHead != inputSize)
{
// first run through
if (readHead == processHead)
{
for (int i = 0; i < chunks.ChunkSize; i++)
{
circularBuffer.AddByte(view.Next());
}
readHead = chunks.ChunkSize;
checksum = FastHash(circularBuffer.ToArray(chunks.ChunkSize), chunks.ChunkSize);
}
int remainder = (int)(readHead - processHead);
if (progress != null)
{
progress(inputSize, processHead);
}
int possibleChunkLookup;
Chunk match = null;
if (adlerToIndex.TryGetValue(checksum, out possibleChunkLookup))
{
byte[] data = circularBuffer.ToArray(chunks.ChunkSize > remainder ? remainder : chunks.ChunkSize);
byte[] realHash = null;
if (sha1 != null)
{
realHash = sha1.ComputeHash(data, 0, data.Length);
}
else
{
realHash = (new Utilities.Murmur3()).ComputeHash(data);
}
while (true)
{
Chunk inspectedChunk = sortedChunks[possibleChunkLookup];
if (inspectedChunk.Adler32 != checksum)
{
break;
}
if (inspectedChunk.Length == remainder &&
System.Collections.StructuralComparisons.StructuralEqualityComparer.Equals(realHash, inspectedChunk.Hash))
{
match = inspectedChunk;
break;
}
possibleChunkLookup--;
}
}
if (match != null)
{
if (lastMatch == null || (lastMatch.Base == false || lastMatch.End != match.Offset))
{
lastMatch = new FileBlock()
{
Base = true, Length = 0, Offset = match.Offset
};
deltas.Add(lastMatch);
}
lastMatch.Length += match.Length;
}
else
{
if (lastMatch == null || lastMatch.Base == true)
{
lastMatch = new FileBlock()
{
Base = false, Length = 0, Offset = processHead
};
deltas.Add(lastMatch);
}
lastMatch.Length++;
}
// eat next byte
int bytesToEat = 1;
if (match != null)
{
bytesToEat = match.Length;
}
while (bytesToEat-- != 0)
{
remainder = (int)(readHead - processHead);
if (readHead < inputSize)
{
byte add = view.Next();
byte remove = circularBuffer.AddByte(add);
checksum = RotateHash(checksum, add, remove, remainder);
readHead++;
}
else if (bytesToEat == 0)
{
checksum = FastHash(circularBuffer.ToArray(remainder - 1), remainder - 1);
}
processHead++;
}
}
deltaSize = 0;
foreach (var x in deltas)
{
deltaSize++;
if (x.Base == false)
{
deltaSize += 8;
deltaSize += x.Length;
}
else
{
deltaSize += 8;
deltaSize += 8;
}
}
return(deltas);
}
