public static void Decompress(FileInfo inputFile)
{
Stopwatch stopwacth = new Stopwatch();
stopwacth.Start();
Console.WriteLine("Starting decompression...");
DecompressionInfo di = new DecompressionInfo();
HuffmanNode root = null;
HuffmanNode iteratedNode = null;
byte[] fileBytes = null;
int bytesOfDataToSkip = 0;
using (FileStream stream = new FileStream(inputFile.FullName, FileMode.Open))
{
using (BinaryReader reader = new BinaryReader(stream))
{
di.SizeInBytes = reader.ReadInt32();
di.DecompressionInfoString = Encoding.UTF8.GetString(reader.ReadBytes(di.SizeInBytes));
di.OrderLevel = reader.ReadInt16();
fileBytes = reader.ReadBytes((int)(reader.BaseStream.Length - reader.BaseStream.Position));
reader.Close();
}
}
List <bool> decodedTextBits = new List <bool>();
BitArray bitmap = new BitArray(fileBytes);
BitArray encodedTextBits = new BitArray(bitmap.Length - di.OrderLevel * 8);
BitArray firstSymbols = new BitArray(di.OrderLevel * 8);
// copy first symbols to know starting context and what's left to encoded text array
int index = 0;
for (int p = 0; p < di.OrderLevel * 8; p++)
{
firstSymbols[index] = bitmap[p];
index++;
}
index = 0;
byte[] firstSymbolBytes = new byte[firstSymbols.Length / 8];
firstSymbols.CopyTo(firstSymbolBytes, 0);
string firstSymbolsString = Encoding.ASCII.GetString(firstSymbolBytes);
for (int h = di.OrderLevel * 8; h < bitmap.Length; h++)
{
encodedTextBits[index] = bitmap[h];
index++;
}
Dictionary <string, HuffmanNode> decompressionTrees = ConstructDecompressionTree(di.DecompressionInfoString);
int i = 0;
string currentContext = firstSymbolsString;
string decodedText = currentContext;
HuffmanNode treeByContext = decompressionTrees[currentContext];
iteratedNode = treeByContext;
for (int l = 0; l < encodedTextBits.Length; l++)
{
if (iteratedNode.Left == null && iteratedNode.Right == null)
{
decodedText += iteratedNode.Character;
currentContext = decodedText.Substring(decodedText.Length - di.OrderLevel, di.OrderLevel);
// decoded one symbol, return tree node to root
iteratedNode = decompressionTrees[currentContext];
continue;
}
else
{
if (encodedTextBits[l] == true)
{
iteratedNode = iteratedNode.Right;
}
else
{
iteratedNode = iteratedNode.Left;
}
}
l++;
}
/*BitArray tempTextBitsArray = new BitArray(decodedTextBits.ToArray());
* byte[] bytesToWrite = new byte[tempTextBitsArray.Length / 8 + (tempTextBitsArray.Length % 8 == 0 ? 0 : 1)];
* tempTextBitsArray.CopyTo(bytesToWrite, 0);
* decodedText = Encoding.ASCII.GetString(bytesToWrite);*/
string outputFile = $"dec_{inputFile.Name.Substring(0, inputFile.Name.Length - 5)}";
outputFile = Path.Combine(inputFile.DirectoryName, outputFile);
File.WriteAllText(outputFile, decodedText);
stopwacth.Stop();
Console.WriteLine($"Decompression finished in: {stopwacth.ElapsedMilliseconds}");
Console.WriteLine("Ending decompression...\n");
}
public static void Compress(Dictionary <string, Dictionary <char, string> > huffmanCodes,
Dictionary <string, Dictionary <char, int> > contextFrequencies, int orderLevel, string originalText, string outputFile)
{
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
Console.WriteLine("\nStarting compression...");
DecompressionInfo decInfo = ConstructDecompressionInfoObject(contextFrequencies, (short)orderLevel);
if (File.Exists(outputFile))
{
File.Delete(outputFile);
}
var encodedText = "";
var firstSymbols = new BitArray(System.Text.ASCIIEncoding.ASCII.GetBytes(originalText.Substring(0, orderLevel)));
foreach (bool bit in firstSymbols)
{
encodedText += (bit == true) ? "1" : "0";
}
int contextPosition = 0;
for (int i = orderLevel; i < originalText.Length; i++)
{
var currentSymbol = originalText[i];
var currentContext = originalText.Substring(contextPosition, orderLevel);
encodedText += huffmanCodes[currentContext][currentSymbol];
contextPosition++;
}
BitArray textBits = new BitArray(encodedText.Length);
for (int i = 0; i < encodedText.Length; i++)
{
textBits[i] = (encodedText[i].Equals('1')) ? true : false;
}
byte[] bytesToWrite = new byte[textBits.Length / 8 + (textBits.Length % 8 == 0 ? 0 : 1)];
textBits.CopyTo(bytesToWrite, 0);
using (FileStream stream = new FileStream(outputFile, FileMode.OpenOrCreate))
{
using (BinaryWriter writer = new BinaryWriter(stream))
{
writer.Write(decInfo.SizeInBytes);
writer.Write(decInfo.DecompressionInfoString.ToCharArray(), 0, decInfo.DecompressionInfoString.Length);
writer.Write(decInfo.OrderLevel);
writer.Write(bytesToWrite);
writer.Close();
}
}
stopwatch.Stop();
Console.WriteLine("Compression finished in: {0}", stopwatch.ElapsedMilliseconds);
Console.WriteLine("Ending compression...");
}
