private static void writeHuffmanTreeToStream(Stream fileStream)
{
BitBuffer bitBuffer = new BitBuffer(1, fileStream);
fileStream.WriteByte((byte)frequencyTable.TableSize);
for (int i = 0; i < frequencyTable.MaxTableSize; i++)
{
if (frequencyTable.Hits[i] != 0)
{
fileStream.WriteByte((byte)i);
fileStream.WriteByte((byte)frequencyTable.Codewords[i].Length);
}
}
for (int i = 0; i < frequencyTable.MaxTableSize; i++)
{
if (frequencyTable.Hits[i] != 0)
{
bitBuffer.AddToBuffer(frequencyTable.Codewords[i]);
}
}
bitBuffer.Flush();
}
public static void EncodeStream(Stream inStream, Stream outStream)
{
int i = 0; // counter
int newFreq;
// the list of all Huffman Tree nodes
List<TreeNode<int, byte>> huffmanTree = new List<TreeNode<int, byte>>();
// the root of Huffman Tree
TreeNode<int, byte> huffmanTreeRoot = new TreeNode<int, byte>(0, 0);
frequencyTable = new FrequencyTable();
/*frequencyTable = new FrequencyEntry[256 ];
for (i = 0; i < frequencyTable.Length; ++i)
frequencyTable[i] = new FrequencyEntry();*/
calculateFrequency(inStream);
i = 0;
// construct a forest
for (i = 0; i < frequencyTable.MaxTableSize; i++)
{
if (frequencyTable.Hits[i] != 0)
// add a new node to Huffman Tree, where character hits is the key
// and the character itself is the value
huffmanTree.Add(new TreeNode<int, byte>(frequencyTable.Hits[i], (byte)i));
}
// link the nodes
while (huffmanTree.Count > 1)
{
huffmanTree.Sort(compareTreeNodes);
newFreq = huffmanTree[0].Key + huffmanTree[1].Key;
TreeNode<int, byte> node = new TreeNode<int, byte>(newFreq, 0);
node.Left = huffmanTree[0];
node.Right = huffmanTree[1];
node.Left.Parent = node;
node.Right.Parent = node;
huffmanTree.RemoveAt(0);
huffmanTree.RemoveAt(0);
huffmanTree.Add(node);
huffmanTreeRoot = node;
}
//calculate codewords
traverseTree(huffmanTreeRoot, "");
//wrtie table
writeHuffmanTreeToStream(outStream);
//
outStream.WriteByte((byte)(inStream.Length % 256));
//wrtie encoded stream
//string buffer = "", bits = "";
//string pooledBuffer = "";
BitBuffer bitBuffer = new BitBuffer(1, outStream);
int nextChar = 0;
inStream.Seek(0, SeekOrigin.Begin);
nextChar = inStream.ReadByte();
while (nextChar != -1)
{
bitBuffer.AddToBuffer(frequencyTable.Codewords[nextChar]);
//pooledBuffer += frequencyTable.Codewords[nextChar];
/*if (buffer.Length >= 8)
{
bits = buffer.Substring(0, 8);
buffer = buffer.Substring(8);
outStream.WriteByte(encodeBitString(bits));
}*/
nextChar = inStream.ReadByte();
}
bitBuffer.Flush();
//if (buffer.Length > 0)
// outStream.WriteByte(encodeBitString(buffer));
}