/// <summary>
/// Small function that takes a Huffman tree & a TKMK00CommandWriter and writes out the tree construction information to the writer.
/// </summary>
/// <param name="node"></param>
/// <param name="writer"></param>
private static void WriteHuffmanTree(TKMK00HuffmanTreeNode node, TKMK00CommandWriter writer)
{
if (!node.IsEndNode)
{
writer.Write(1, 1);
WriteHuffmanTree(node.Left, writer);
WriteHuffmanTree(node.Right, writer);
}
else
{
writer.Write(0, 1);
writer.Write(node.Value, 5);
}
}
/// <summary>
/// Creates a Huffman-style binary tree that holds the 5-bit color data referenced in the
/// TKMK00 decoding process.
/// </summary>
private static TKMK00HuffmanTreeNode SetUpHuffmanTree(uint val, byte[] data, TKMK00CommandReader commandReader)
{
TKMK00HuffmanTreeNode newTree = new TKMK00HuffmanTreeNode();
int command = commandReader.ReadBits(1);//1 - Make new branches, 0 - End current branch
if (command != 0)
{
newTree.Value = (int)val; //Not used, but can't hurt to number it
val++;
newTree.Left = SetUpHuffmanTree(val, data, commandReader);
newTree.Right = SetUpHuffmanTree(val, data, commandReader);
return newTree;
}
//Else, return a node with a value
int value = 0;
int bitCount = 5;
do
{
command = commandReader.ReadBits(1);
value = value * 2 + command; //basically bitshifts s0 to the left and adds v0, aka it's loading 5 bytes straight from the comandReader
bitCount -= 1;
} while (bitCount > 0);
newTree.Value = value;
return newTree;
}
/// <summary>
/// Uses the existing Huffman tree and the command that is being looked for, and saves the combination of bits used to
/// reach that command in the Huffman tree into outCommands (the value) and outBits (# of bits used)
/// </summary>
private static void GetHuffmanTreeTraversalCommands(TKMK00HuffmanTreeNode node, int commandTotal, int bitCount,
int[] outCommands, int[] outBits)
{
if (node.IsEndNode)
{
outCommands[node.Value] = commandTotal;
outBits[node.Value] = bitCount;
}
else
{
bitCount++;
commandTotal <<= 1;
GetHuffmanTreeTraversalCommands(node.Left, commandTotal, bitCount, outCommands, outBits);
commandTotal++;
GetHuffmanTreeTraversalCommands(node.Right, commandTotal, bitCount, outCommands, outBits);
}
}
//Only called when creating new rgba value. Traverses the Huffman tree to return the correct value
private static int RetrieveHuffmanTreeValue(byte[] data, TKMK00HuffmanTreeNode currentNode, TKMK00CommandReader commandReader)
{
while (!currentNode.IsEndNode)/*currentNode.Value >= 0x20*/
{
int command = commandReader.ReadBits(1); // 0 - left, 1 - right
if (command == 0)
currentNode = currentNode.Left;
else
currentNode = currentNode.Right;
}
return currentNode.Value;
}
/// <summary>
/// Returns the differential code used to turn the predicted color to the actual color
/// </summary>
private static TKMK00HuffmanTreeNode ConstructTree(int[] colorCounts)
{
//Link to Huffman balancing document: https://www.siggraph.org/education/materials/HyperGraph/video/mpeg/mpegfaq/huffman_tutorial.html
List<Tuple<int, TKMK00HuffmanTreeNode>> frequenciesAndValues = new List<Tuple<int, TKMK00HuffmanTreeNode>>();
for (int i = 0; i < colorCounts.Length; i++)
{
TKMK00HuffmanTreeNode node = new TKMK00HuffmanTreeNode();
node.Value = i;
frequenciesAndValues.Add(new Tuple<int, TKMK00HuffmanTreeNode>(colorCounts[i], node));
}
while (frequenciesAndValues.Count > 1)
{
frequenciesAndValues.Sort((s1, s2) => s2.Item1.CompareTo(s1.Item1));
//Merge two into a new Huffman tree (NOTE: LEFT IS LESS THAN RIGHT)
TKMK00HuffmanTreeNode node = new TKMK00HuffmanTreeNode();
node.Left = frequenciesAndValues[frequenciesAndValues.Count - 1].Item2;
node.Right = frequenciesAndValues[frequenciesAndValues.Count - 2].Item2;
node.Value = 64; //Invalid value to denote a traversal node rather than an end node
int newCount = frequenciesAndValues[frequenciesAndValues.Count - 1].Item1 + frequenciesAndValues[frequenciesAndValues.Count - 2].Item1;
frequenciesAndValues.RemoveAt(frequenciesAndValues.Count - 1);
frequenciesAndValues.RemoveAt(frequenciesAndValues.Count - 1);
frequenciesAndValues.Add(new Tuple<int, TKMK00HuffmanTreeNode>(newCount, node));
}
return frequenciesAndValues[0].Item2;
}