public static byte[] Decode(byte[] encodedData, Dictionary <BitsWithLength, byte> decodeTable, long bitsCount)
{
var result = new List <byte>();
var sample = new BitsWithLength {
Bits = 0, BitsCount = 0
};
for (var byteNum = 0; byteNum < encodedData.Length; byteNum++)
{
var b = encodedData[byteNum];
for (var bitNum = 0; bitNum < 8 && byteNum * 8 + bitNum < bitsCount; bitNum++)
{
sample.Bits = (sample.Bits << 1) + ((b & (1 << (8 - bitNum - 1))) != 0 ? 1 : 0);
sample.BitsCount++;
if (!decodeTable.TryGetValue(sample, out var decodedByte))
{
continue;
}
result.Add(decodedByte);
sample.BitsCount = 0;
sample.Bits = 0;
}
}
return(result.ToArray());
}
public void Add(BitsWithLength bitsWithLength)
{
var bitsCount = bitsWithLength.BitsCount;
var bits = bitsWithLength.Bits;
int neededBits = 8 - unfinishedBits.BitsCount;
while (bitsCount >= neededBits)
{
bitsCount -= neededBits;
buffer.Add((byte) ((unfinishedBits.Bits << neededBits) + (bits >> bitsCount)));
bits = bits & ((1 << bitsCount) - 1);
unfinishedBits.Bits = 0;
unfinishedBits.BitsCount = 0;
neededBits = 8;
}
unfinishedBits.BitsCount += bitsCount;
unfinishedBits.Bits = (unfinishedBits.Bits << bitsCount) + bits;
}
public static byte[] Encode(List <byte> data, out Dictionary <BitsWithLength, byte> decodeTable,
out long bitsCount)
{
var frequences = CalcFrequences(data);
var root = BuildHuffmanTree(frequences);
var encodeTable = new BitsWithLength[byte.MaxValue + 1];
FillEncodeTable(root, encodeTable);
var bitsBuffer = new BitsBuffer();
foreach (var b in data)
{
bitsBuffer.Add(encodeTable[b]);
}
decodeTable = CreateDecodeTable(encodeTable);
return(bitsBuffer.ToArray(out bitsCount));
}