/// <summary>
/// Initializes static members of the <see cref="Deflate" /> class.
/// </summary>
static Deflate()
{
var llcodelens = new int[288];
Arrays.Fill(llcodelens, 0, 144, 8);
Arrays.Fill(llcodelens, 144, 256, 9);
Arrays.Fill(llcodelens, 256, 280, 7);
Arrays.Fill(llcodelens, 280, 288, 8);
FixedLiteralLengthCode = new CanonicalCode(llcodelens).ToCodeTree();
var distcodelens = new int[32];
Arrays.Fill(distcodelens, 0, 32, 5);
FixedDistanceCode = new CanonicalCode(distcodelens).ToCodeTree();
}
/// <summary>
/// Initializes static members of the <see cref="Deflate" /> class.
/// </summary>
static Deflate()
{
var llcodelens = new int[288];
Arrays.Fill(llcodelens, 0, 144, 8);
Arrays.Fill(llcodelens, 144, 256, 9);
Arrays.Fill(llcodelens, 256, 280, 7);
Arrays.Fill(llcodelens, 280, 288, 8);
FixedLiteralLengthCode = new CanonicalCode(llcodelens).ToCodeTree();
var distcodelens = new int[32];
Arrays.Fill(distcodelens, 0, 32, 5);
FixedDistanceCode = new CanonicalCode(distcodelens).ToCodeTree();
}
/// <summary>
/// Decompresses a Huffman block.
/// </summary>
/// <param name="litLenCode">The litLen code.</param>
/// <param name="distCode">The distance code.</param>
private void DecompressHuffmanBlock(CodeTree litLenCode, CodeTree distCode)
{
if (litLenCode == null)
{
throw new InvalidOperationException();
}
while (true)
{
var sym = this.DecodeSymbol(litLenCode);
if (sym == 256)
{
// End of block
break;
}
if (sym < 256)
{
// Literal byte
this.output.Write((byte)sym);
this.dictionary.Append(sym);
}
else
{
// Length and distance for copying
var len = this.DecodeRunLength(sym);
if (distCode == null)
{
throw new FormatException("Length symbol encountered with empty distance code");
}
var distSym = this.DecodeSymbol(distCode);
var dist = this.DecodeDistance(distSym);
this.dictionary.Copy(dist, len, this.output);
}
}
}
/// <summary>
/// Decodes the specified symbol.
/// </summary>
/// <param name="code">The code.</param>
/// <returns>The <see cref="int" />.</returns>
private int DecodeSymbol(CodeTree code)
{
var currentNode = code.Root;
while (true)
{
var temp = this.input.ReadNoEof();
Node nextNode;
if (temp == 0)
{
nextNode = currentNode.LeftChild;
}
else if (temp == 1)
{
nextNode = currentNode.RightChild;
}
else
{
throw new Exception();
}
if (nextNode is Leaf)
{
return(((Leaf)nextNode).Symbol);
}
if (nextNode is InternalNode)
{
currentNode = (InternalNode)nextNode;
}
else
{
throw new InvalidOperationException();
}
}
}
/// <summary>
/// Decodes the specified symbol.
/// </summary>
/// <param name="code">The code.</param>
/// <returns>The <see cref="int" />.</returns>
private int DecodeSymbol(CodeTree code)
{
var currentNode = code.Root;
while (true)
{
var temp = this.input.ReadNoEof();
Node nextNode;
if (temp == 0)
{
nextNode = currentNode.LeftChild;
}
else if (temp == 1)
{
nextNode = currentNode.RightChild;
}
else
{
throw new Exception();
}
if (nextNode is Leaf)
{
return ((Leaf)nextNode).Symbol;
}
if (nextNode is InternalNode)
{
currentNode = (InternalNode)nextNode;
}
else
{
throw new InvalidOperationException();
}
}
}
/// <summary>
/// Decompresses a Huffman block.
/// </summary>
/// <param name="litLenCode">The litLen code.</param>
/// <param name="distCode">The distance code.</param>
private void DecompressHuffmanBlock(CodeTree litLenCode, CodeTree distCode)
{
if (litLenCode == null)
{
throw new InvalidOperationException();
}
while (true)
{
var sym = this.DecodeSymbol(litLenCode);
if (sym == 256)
{
// End of block
break;
}
if (sym < 256)
{
// Literal byte
this.output.Write((byte)sym);
this.dictionary.Append(sym);
}
else
{
// Length and distance for copying
var len = this.DecodeRunLength(sym);
if (distCode == null)
{
throw new FormatException("Length symbol encountered with empty distance code");
}
var distSym = this.DecodeSymbol(distCode);
var dist = this.DecodeDistance(distSym);
this.dictionary.Copy(dist, len, this.output);
}
}
}
/// <summary>
/// Initializes a new instance of the <see cref="CanonicalCode" /> class based on the given code tree.
/// </summary>
/// <param name="tree">The tree.</param>
/// <param name="symbolLimit">The symbol limit.</param>
public CanonicalCode(CodeTree tree, int symbolLimit)
{
this.codeLengths = new int[symbolLimit];
this.BuildCodeLengths(tree.Root, 0);
}
/// <summary>
/// Initializes a new instance of the <see cref="CanonicalCode" /> class based on the given code tree.
/// </summary>
/// <param name="tree">The tree.</param>
/// <param name="symbolLimit">The symbol limit.</param>
public CanonicalCode(CodeTree tree, int symbolLimit)
{
this.codeLengths = new int[symbolLimit];
this.BuildCodeLengths(tree.Root, 0);
}
