internal List <byte> Decode(UnaryModel model)
{
var byteLength = 256;
var alphabet = new Dictionary <int, byte>(byteLength);
var currentWeight = 0;
foreach (var frequency in model.Frequencies.OrderByDescending(f => f.Value))
{
alphabet[currentWeight] = frequency.Key;
currentWeight++;
}
var encodedBits = new BitArray(model.Bytes.ToArray());
var decodedBytes = new List <byte>();
var oneCount = 0;
for (int i = 0; i < encodedBits.Count; i++)
{
if (encodedBits[i])
{
oneCount++;
}
else
{
decodedBytes.Add(alphabet[oneCount]);
oneCount = 0;
}
}
return(decodedBytes);
}
internal UnaryModel Encode(List <byte> bytes)
{
_bytes = bytes;
var byteLength = 256;
byte initialValue = 0;
var frequencies = Enumerable
.Range(0, byteLength)
.Select(i => new Frequency
{
Key = initialValue++,
Value = 0
})
.ToList();
foreach (var element in _bytes)
{
frequencies[element].Value++;
}
frequencies = frequencies.OrderByDescending(f => f.Value).ToList();
var alphabet = new Dictionary <byte, BitArray>(byteLength);
var currentWeight = 1;
for (int i = 0; i < byteLength; i++)
{
var frequency = frequencies[i];
if (frequency.Value != 0)
{
var value = new BitArray(currentWeight, true);
value[value.Count - 1] = false;
alphabet[frequency.Key] = value;
currentWeight++;
}
}
var lengthBytes = 0;
foreach (var symbol in alphabet)
{
lengthBytes += frequencies.First(f => f.Key == symbol.Key).Value *symbol.Value.Count;
}
lengthBytes = (lengthBytes - 1) / 8 + 1;
var lengthBits = lengthBytes * 8;
var encodedBools = new bool[lengthBits];
var currentPosition = 0;
foreach (var element in _bytes)
{
alphabet[element].CopyTo(encodedBools, currentPosition);
currentPosition += alphabet[element].Length;
}
for (int i = currentPosition; i < lengthBits; i++)
{
encodedBools[i] = true;
}
var encodedBits = new BitArray(encodedBools);
var encodedBytes = new byte[lengthBytes];
encodedBits.CopyTo(encodedBytes, 0);
var frequenciesDictionary = new Dictionary <byte, int>();
for (int i = 0; i < byteLength; i++)
{
if (frequencies[i].Value != 0)
{
frequenciesDictionary[frequencies[i].Key] = frequencies[i].Value;
}
}
var encodedBytesList = new List <byte>(encodedBytes);
var model = new UnaryModel(frequenciesDictionary, encodedBytesList);
return(model);
}
