/// <summary>
/// Encodes the file
/// </summary>
/// <param name="interleaved">Set this to true to enable SDHC interleaved vcdiff google format</param>
/// <param name="checksum">Set this to true to add checksum for encoded data windows</param>
/// <returns></returns>
public VCDiffResult Encode(bool interleaved = false, bool checksum = false)
{
if (newData.Length == 0 || oldData.Length == 0)
{
return(VCDiffResult.ERRROR);
}
VCDiffResult result = VCDiffResult.SUCCESS;
oldData.Position = 0;
newData.Position = 0;
//file header
//write magic bytes
if (!interleaved && !checksum)
{
sout.writeBytes(MagicBytes);
}
else
{
sout.writeBytes(MagicBytesExtended);
}
//buffer the whole olddata (dictionary)
//otherwise it will be a slow process
//even Google's version reads in the entire dictionary file to memory
//it is just faster that way because of having to move the memory pointer around
//to find all the hash comparisons and stuff.
//It is much slower trying to random access read from file with FileStream class
//however the newData is read in chunks and processed for memory efficiency and speed
oldData.BufferAll();
//read in all the dictionary it is the only thing that needs to be
BlockHash dictionary = new BlockHash(oldData, 0, hasher);
dictionary.AddAllBlocks();
oldData.Position = 0;
ChunkEncoder chunker = new ChunkEncoder(dictionary, oldData, hasher, interleaved, checksum);
while (newData.CanRead)
{
using (ByteBuffer ntarget = new ByteBuffer(newData.ReadBytes(bufferSize)))
{
chunker.EncodeChunk(ntarget, sout);
}
//just in case
System.GC.Collect();
}
return(result);
}
/// <summary>
/// Calculate and write a diff for the file.
/// </summary>
/// <param name="interleaved">Whether to output in SDCH interleaved diff format.</param>
/// <param name="checksumFormat">
/// Whether to include Adler32 checksums for encoded data windows. If interleaved is true, <see cref="ChecksumFormat.Xdelta3"/>
/// is not supported.
/// </param>
/// <returns>
/// <see cref="VCDiffResult.SUCCESS"/> if successful, <see cref="VCDiffResult.ERROR"/> if the sourceStream or target are zero-length.</returns>
/// <exception cref="ArgumentException">If interleaved is true, and <see cref="ChecksumFormat.Xdelta3"/> is chosen.</exception>
public VCDiffResult Encode(bool interleaved = false,
ChecksumFormat checksumFormat = ChecksumFormat.None)
{
if (oldData == null)
{
this.oldData = new ByteBuffer(sourceStream);
}
if (interleaved && checksumFormat == ChecksumFormat.Xdelta3)
{
throw new ArgumentException("Interleaved diffs can not have an xdelta3 checksum!");
}
if (targetData.Length == 0 || oldData.Length == 0)
{
return(VCDiffResult.ERROR);
}
VCDiffResult result = VCDiffResult.SUCCESS;
oldData.Position = 0;
targetData.Position = 0;
// file header
// write magic bytes
if (!interleaved && checksumFormat != ChecksumFormat.SDCH)
{
outputStream.Write(MagicBytes);
}
else
{
outputStream.Write(MagicBytesExtended);
}
//read in all the dictionary it is the only thing that needs to be
BlockHash dictionary = new BlockHash(oldData, 0, hasher, blockSize);
dictionary.AddAllBlocks();
oldData.Position = 0;
ChunkEncoder chunker = new ChunkEncoder(dictionary, oldData, hasher, checksumFormat, interleaved, chunkSize);
while (targetData.CanRead)
{
using ByteBuffer ntarget = new ByteBuffer(targetData.ReadBytesAsBuf(bufferSize));
chunker.EncodeChunk(ntarget, outputStream);
}
return(result);
}
