public void OutputAndBuildPaths(BitArrayBuilder bitBuilder, List <bool> path)
{
if (!IsLeaf)
{
bitBuilder.Append(false);
var leftPath = new List <bool>(path);
leftPath.Add(false);
Left.OutputAndBuildPaths(bitBuilder, leftPath);
var rightPath = new List <bool>(path);
rightPath.Add(true);
Right.OutputAndBuildPaths(bitBuilder, rightPath);
}
else
{
Path = path;
bitBuilder.Append(true);
bitBuilder.Append(B);
}
}
public byte[] Compress()
{
_builder.Append(HALC.ProbabilityMagicSignature);
// build huffman tree
var histogram = GetHistogram();
var nodes = histogram.Select(kvp => new Frequency(kvp.Key, kvp.Value)).OrderBy(f => f.Count).ToList();
var indexedNodes = nodes.ToDictionary(f => f.B, f => f);
while (nodes.Count() > 1)
{
var left = nodes[0];
var right = nodes[1];
var newNode = new Frequency(left, right);
nodes.Remove(left);
nodes.Remove(right);
nodes.Add(newNode);
nodes = nodes.OrderBy(f => f.Count).ToList();
}
// output tree
var bitBuilder = new BitArrayBuilder();
nodes[0].OutputAndBuildPaths(bitBuilder, new List <bool>());
_builder.Append(bitBuilder.GetBytes());
// output huffman codes for each byte
bitBuilder = new BitArrayBuilder();
foreach (var b in _data)
{
var node = indexedNodes[b];
foreach (var p in node.Path)
{
bitBuilder.Append(p);
}
}
_builder.Append(bitBuilder.GetBytes());
return(_builder.GetBytes());
}
