public LZW(IEncoder encoder)
{
this.encoder = encoder;
this.root = new LZWNode(0, 0);
this.buffer = new Stack <byte>();
allNodes = new Dictionary <long, LZWNode>();
for (int i = 0; i <= 255; i++)
{
LZWNode child = new LZWNode((byte)i, i);
root.AddChild(child);
allNodes[i] = child;
}
currentNode = this.root;
}
private void DecodeNewValue()
{
Stack <byte> traceBuffer = new Stack <byte>();
valueToDecode = encoder.Decode();
if (!allNodes.ContainsKey(valueToDecode))
{
LZWNode backTraceNode = currentNode;
while (backTraceNode.parent != root)
{
backTraceNode = backTraceNode.parent;
}
LZWNode child = new LZWNode(backTraceNode.value, valueToDecode);
currentNode.AddChild(child);
currentNode.AddUsage();
currentNode = child;
allNodes[valueToDecode] = child;
}
LZWNode traceNode = allNodes[valueToDecode];
byte lastValue = traceNode.value;
byte firstValue = 0;
while (traceNode.parent != null)
{
buffer.Push(traceNode.value);
traceBuffer.Push(traceNode.value);
firstValue = traceNode.value;
traceNode = traceNode.parent;
}
if (!currentNode.ContainsValue(firstValue))
{
LZWNode child = new LZWNode(firstValue, nextNodeValue);
currentNode.AddChild(child);
allNodes[nextNodeValue] = child;
currentNode = allNodes[valueToDecode];
IncreaseNextNodeValue();
}
else
{
currentNode = currentNode.GetChild(firstValue);
}
encoder.AddValue(nextNodeValue);
if (buffer.Count() > maxBufferLength)
{
maxBufferLength = buffer.Count();
maxBufferNode = allNodes[valueToDecode];
}
}
public void Encode(byte value)
{
if (currentNode.ContainsValue(value))
{
currentNode = currentNode.GetChild(value);
}
else
{
LZWNode child = new LZWNode(value, nextNodeValue);
currentNode.AddChild(child);
allNodes[nextNodeValue] = child;
encoder.Encode(currentNode.identifier);
currentNode.AddUsage();
encoder.AddValue(nextNodeValue);
IncreaseNextNodeValue();
currentNode = root.GetChild(value);
}
}
public void AddChild(LZWNode child)
{
child.parent = this;
this.children[child.value] = child;
}