VCDiffResult DecodeCopy(int size, byte mode, ByteBuffer addresses)
{
long here = window.SourceLength + decodedOnly;
long decoded = addressCache.DecodeAddress(here, mode, addresses);
switch ((VCDiffResult)decoded)
{
case VCDiffResult.ERRROR:
return(VCDiffResult.ERRROR);
case VCDiffResult.EOD:
return(VCDiffResult.EOD);
default:
if (decoded < 0 || decoded > here)
{
return(VCDiffResult.ERRROR);
}
break;
}
if (decoded + size <= window.SourceLength)
{
dict.Position = decoded;
byte[] rbytes = dict.ReadBytes(size);
sout.writeBytes(rbytes);
targetData.AddRange(rbytes);
decodedOnly += size;
return(VCDiffResult.SUCCESS);
}
///will come back to this once
///target data reading is implemented
/*if(decoded < window.SourceLength)
* {
* long partial = window.SourceLength - decoded;
* dict.Position = decoded;
* sout.writeBytes(dict.ReadBytes((int)partial));
* bytesWritten += partial;
* size -= (int)partial;
* }
*
* decoded -= window.SourceLength;
*
* while(size > (bytesDecoded - decoded))
* {
* long partial = bytesDecoded - decoded;
* target.Position = decoded;
* sout.writeBytes(target.ReadBytes((int)partial));
* decoded += partial;
* size -= (int)partial;
* bytesWritten += partial;
* }
*
* target.Position = decoded;
* sout.writeBytes(target.ReadBytes(size));*/
return(VCDiffResult.ERRROR);
}
/// <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.Error);
}
VCDiffResult result = VCDiffResult.Succes;
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);
}
public void Output(ByteStreamWriter sout)
{
int lengthOfDelta = CalculateLengthOfTheDeltaEncoding();
int windowSize = lengthOfDelta +
1 +
VarIntBE.CalcInt32Length((int)dictionarySize) +
VarIntBE.CalcInt32Length(0);
VarIntBE.CalcInt32Length(lengthOfDelta);
//Google's Checksum Implementation Support
if (hasChecksum)
{
sout.writeByte((byte)VCDiffWindowFlags.VCDSOURCE | (byte)VCDiffWindowFlags.VCDCHECKSUM); //win indicator
}
else
{
sout.writeByte((byte)VCDiffWindowFlags.VCDSOURCE); //win indicator
}
VarIntBE.AppendInt32((int)dictionarySize, sout); //dictionary size
VarIntBE.AppendInt32(0, sout); //dictionary start position 0 is default aka encompass the whole dictionary
VarIntBE.AppendInt32(lengthOfDelta, sout); //length of delta
//begin of delta encoding
Int64 sizeBeforeDelta = sout.Position;
VarIntBE.AppendInt32((int)targetLength, sout); //final target length after decoding
sout.writeByte(0x00); //uncompressed
// [Here is where a secondary compressor would be used
// if the encoder and decoder supported that feature.]
//non interleaved then it is separata areas for each type
if (!interleaved)
{
VarIntBE.AppendInt32(dataForAddAndRun.Count, sout); //length of add/run
VarIntBE.AppendInt32(instructionAndSizes.Count, sout); //length of instructions and sizes
VarIntBE.AppendInt32(addressForCopy.Count, sout); //length of addresses for copys
//Google Checksum Support
if (hasChecksum)
{
VarIntBE.AppendInt64(checksum, sout);
}
sout.writeBytes(dataForAddAndRun.ToArray()); //data section for adds and runs
sout.writeBytes(instructionAndSizes.ToArray()); //data for instructions and sizes
sout.writeBytes(addressForCopy.ToArray()); //data for addresses section copys
}
else
{
//interleaved everything is woven in and out in one block
VarIntBE.AppendInt32(0, sout); //length of add/run
VarIntBE.AppendInt32(instructionAndSizes.Count, sout); //length of instructions and sizes + other data for interleaved
VarIntBE.AppendInt32(0, sout); //length of addresses for copys
//Google Checksum Support
if (hasChecksum)
{
VarIntBE.AppendInt64(checksum, sout);
}
sout.writeBytes(instructionAndSizes.ToArray()); //data for instructions and sizes, in interleaved it is everything
}
//end of delta encoding
Int64 sizeAfterDelta = sout.Position;
if (lengthOfDelta != sizeAfterDelta - sizeBeforeDelta)
{
Console.WriteLine("Delta output length does not match");
}
dataForAddAndRun.Clear();
instructionAndSizes.Clear();
addressForCopy.Clear();
if (targetLength == 0)
{
Console.WriteLine("Empty target window");
}
addrCache = new AddressCache();
}
