private static Dictionary <int, Dictionary <int, byte> > BuildOptmizedTable(HuffmanDecodingData huffmanData)
{
var returned = new Dictionary <int, Dictionary <int, byte> >();
foreach (var entry in huffmanData.Table)
{
if (!returned.ContainsKey(entry.Value.NbBits))
{
returned.Add(entry.Value.NbBits, new Dictionary <int, byte>());
}
returned[entry.Value.NbBits].Add(entry.Value.EncodedValue, entry.Key);
}
return(returned);
}
private static void WriteCompressedFiles
(
string outputFile,
string outputTableFile,
byte[] bytes,
Dictionary <byte, HuffmanTableEntry> huffmanBinaryTable
)
{
int toWrite = 0;
int nbBits = 0;
int nbBitsTotal = 0;
FileStream fs = File.Create(outputFile);
foreach (var b in bytes)
{
var entry = huffmanBinaryTable[b];
toWrite = toWrite << entry.NbBits;
toWrite = toWrite + entry.EncodedValue;
nbBits += entry.NbBits;
nbBitsTotal += entry.NbBits;
if (nbBits >= NB_BITS_PACKED)
{
var copy = toWrite;
int deltaShift = nbBits - NB_BITS_PACKED;
BigInteger shiftBack = copy >> deltaShift;
var bytesToWrite = shiftBack.ToByteArray();
fs.Write(bytesToWrite, 0, 1);
int mask = 0;
for (int i = 0; i < deltaShift; i++)
{
mask = mask << 1;
mask = mask + 1;
}
toWrite = toWrite & mask;
nbBits = nbBits - NB_BITS_PACKED;
}
}
if (nbBits > 0)
{
var shift = NB_BITS_PACKED - nbBits;
toWrite = toWrite << shift;
var bytesToWrite = (new BigInteger(toWrite)).ToByteArray();
fs.Write(bytesToWrite, 0, 1);
}
fs.Flush();
fs.Close();
HuffmanDecodingData data = new HuffmanDecodingData()
{
NbElements = bytes.Length,
Table = huffmanBinaryTable
};
var jsonString = JsonConvert.SerializeObject(data, Formatting.Indented);
File.WriteAllText(outputTableFile, jsonString);
}