internal int DecodeScalar(DataPacket packet)
{
int bits = (int)packet.TryPeekU64Bits(PrefixBitLength, out int bitCnt);
if (bitCnt == 0)
{
return(-1);
}
// try to get the value from the prefix list...
HuffmanNode node = PrefixList[bits];
if (node != null)
{
packet.SkipBits(node.Length);
return(node.Value);
}
// nope, not possible... run the tree
bits = (int)packet.TryPeekU64Bits(MaxBits, out _);
node = PrefixOverflowTree;
do
{
if (node.Bits == (bits & node.Mask))
{
packet.SkipBits(node.Length);
return(node.Value);
}
} while ((node = node.Next) != null);
return(-1);
}
public static void Return(HuffmanNode node)
{
if (node == null)
{
return;
}
if (node.IsInUse)
{
node.IsInUse = false;
lock (_mutex)
{
Return(node.Next);
node.Next = null;
if (_pool.Count < MAX_NODES)
{
_pool.Push(node);
}
}
}
}
protected virtual void Dispose(bool disposing)
{
if (!_disposed)
{
if (disposing)
{
HuffmanPool.Return(PrefixOverflowTree);
PrefixOverflowTree = null;
for (int i = 0; i < PrefixList.Length; i++)
{
HuffmanPool.Return(PrefixList[i]);
}
Array.Clear(PrefixList, 0, PrefixList.Length);
PrefixList = null;
Lengths = null;
LookupTable = null;
}
_disposed = true;
}
}
static internal HuffmanNode[] BuildPrefixedLinkedList(
Span <int> values, Span <int> lengthList, Span <int> codeList,
out int tableBits, out HuffmanNode firstOverflowNode)
{
var list = new HuffmanNode[lengthList.Length];
int maxLen = 0;
for (int i = 0; i < lengthList.Length; i++)
{
int nodeLength = lengthList[i] <= 0 ? 99999 : lengthList[i];
int mask = (1 << lengthList[i]) - 1;
list[i] = HuffmanPool.Rent(values[i], nodeLength, codeList[i], mask);
if (lengthList[i] > 0 && maxLen < lengthList[i])
{
maxLen = lengthList[i];
}
}
tableBits = maxLen > MAX_TABLE_BITS ? MAX_TABLE_BITS : maxLen;
var prefixList = new HuffmanNode[1 << tableBits];
Array.Sort(list, 0, lengthList.Length);
firstOverflowNode = null;
for (int i = 0; i < lengthList.Length && list[i].Length < 99999; i++)
{
if (firstOverflowNode == null)
{
HuffmanNode node = list[i];
node.IsLinked = true;
if (node.Length > tableBits)
{
firstOverflowNode = node;
}
else
{
int maxVal = 1 << (tableBits - node.Length);
for (int j = 0; j < maxVal; j++)
{
int idx = (j << node.Length) | node.Bits;
prefixList[idx] = node;
}
}
}
else
{
list[i - 1].Next = list[i];
list[i].IsLinked = true;
}
}
foreach (var node in list)
{
if (node != null && !node.IsLinked)
{
HuffmanPool.Return(node);
}
}
return(prefixList);
}
