// function:
// Searches sortedArray[first]..sortedArray[last] for key.
// returns: index of the matching element if it finds key,
// otherwise -(index where it could be inserted)-1.
// parameters:
// sortedArray in array of sorted (ascending) values.
// first, last in lower and upper subscript bounds
// key in value to search for.
// returns:
// index of key, or -insertion_position -1 if key is not
// in the array. This value can easily be
// transformed into the position to insert it.
public bool Search(ChunkChecksum key, out long start)
{
start = -1;
if (ChunkCount == 0) return false;
int idx = Array.BinarySearch(Chunks, key);
if (idx >= 0) {
start = idx;
return true;
} else {
return false;
}
}
public void CalculateChecksum(byte[] data, long start, long size, ChunkChecksum K)
{
unsafe {
fixed (byte *p = &data[start]) {
var i = (UInt64*)p;
K.V = i[0];
}
}
//K.Adler32 = 0;
K.Adler32 = Adler32.Check(1, data, start, size);
}
SameBlock FindBlock(ChunkedFile sourceTree, long targetFileStartOffset)
{
if (mTargetSize - targetFileStartOffset < BlockSize) return null;
long preDataSize = targetFileStartOffset - mTargetCDataBaseOffset;
// rea the current data part in to memory
ChunkChecksum checksum = new ChunkChecksum();
sourceTree.CalculateChecksum(mTargetCData, preDataSize, BlockSize, checksum);
long foundIndex;
if (sourceTree.Search(checksum, out foundIndex)) {
// we found something
SameBlock bestMatch = new SameBlock();
bestMatch.SourceOffset = sourceTree.Chunks[foundIndex].Offset;
bestMatch.TargetOffset = targetFileStartOffset;
bestMatch.Size = 0; // default to 0. because they can all be mismatches as well
// inreae match size if possible, also check if it is a match at all
long matchCount = 0;
while ((sourceTree.Chunks[foundIndex].Checksum == checksum) &&
((MaximumMatches == 0) || (matchCount < MaximumMatches)))
{
// check if this one is better than the current match
SameBlock match = new SameBlock();
match.SourceOffset = sourceTree.Chunks[foundIndex].Offset;
match.TargetOffset = targetFileStartOffset;
match.Size = 0; // default to 0. could be a mismatch with the same key
ImproveSameBlockMatch(match, bestMatch.Size);
if (match.Size > bestMatch.Size) {
bestMatch = match;
}
foundIndex++;
matchCount++;
}
// TODO: Emit debugging information here if in verbose mode.
if (bestMatch.Size == 0) {
return null;
} else {
return bestMatch;
}
} else {
return null;
}
}