/// <summary>
/// Adds <paramref name="vlc"/> to this table and recursively creates
/// new tables when needed.
/// </summary>
/// <param name="vlc">the VLC to add</param>
public void AddVlc(Vlc vlc)
{
int n = Length - vlc.Length;
if (n >= 0)
{
uint c = (vlc.Code << n) - Code;
// Insert code into this table
for (int i = 0; i < (1 << n); i++)
{
_lut[c + i] = vlc;
}
}
else
{
uint c = (vlc.Code >> (-n)) - Code;
VlcLut table = _lut[c] as VlcLut;
// Follow chain of LUTs
if (table == null)
{
_lut[c] = table = new VlcLut(Code + c, Length, Bits);
}
table.AddVlc(vlc);
}
}
/// <summary>
/// Creates a VLC-table for the bit codes in <param name="data"/>.
/// The <paramref name="data"/> is a list of bitcode and value pairs.
/// Bitcode is encoded as a <c>string</c>, e.g. <c>"0010"</c>,
/// and value is expected to be of type <typeparamref name="T"/>.
/// </summary>
/// <param name="data">array of bitcode, value pairs</param>
/// <param name="defaultValue">the value returned for a value not found in the VLC-table</param>
public VlcTable(object[,] data, T defaultValue)
{
if (data == null)
{
throw new ArgumentNullException("data");
}
_defaultValue = defaultValue;
_values = new Dictionary <Vlc, T>();
_lut = new VlcLut(0, 0, GetMaxBits(data));
// Add the codes to the table
for (int i = 0; i < data.GetLength(0); i++)
{
string bitcode = data[i, 0] as string;
if (bitcode == null || !(data[i, 1] is T))
{
throw new ArgumentException(string.Format("Invalid data at index {0}", i), "data");
}
Vlc vlc = new Vlc(Convert.ToUInt32(bitcode, 2), bitcode.Length);
_values[vlc] = (T)data[i, 1];
_lut.AddVlc(vlc);
}
}
/// <summary>
/// Retrieves the VLC code correspondig to a bit <paramref name="code"/>.
/// </summary>
/// <param name="code">the code of length <c>Bits</c></param>
/// <returns>the VLC code, null if </c>code<c> is not in this table</returns>
public Vlc GetVlc(uint code)
{
Vlc vlc = _lut[(code >> (_bits - Length)) - Code];
VlcLut table = (vlc as VlcLut);
return((table == null) ? vlc : table.GetVlc(code));
}