/**
* Reads the next symbol from input. The symbol is encoded using the
* huffman tree.
* @param input the input source.
* @return the next symbol, or -1 if not enough input is available.
*/
public int getSymbol(StreamManipulator input)
{
int lookahead, symbol;
if ((lookahead = input.peekBits(9)) >= 0)
{
if ((symbol = tree[lookahead]) >= 0)
{
input.dropBits(symbol & 15);
return symbol >> 4;
}
int subtree = -(symbol >> 4);
int bitlen = symbol & 15;
if ((lookahead = input.peekBits(bitlen)) >= 0)
{
symbol = tree[subtree | (lookahead >> 9)];
input.dropBits(symbol & 15);
return symbol >> 4;
}
else
{
int bits = input.getAvailableBits();
lookahead = input.peekBits(bits);
symbol = tree[subtree | (lookahead >> 9)];
if ((symbol & 15) <= bits)
{
input.dropBits(symbol & 15);
return symbol >> 4;
}
else
return -1;
}
}
else
{
int bits = input.getAvailableBits();
lookahead = input.peekBits(bits);
symbol = tree[lookahead];
if (symbol >= 0 && (symbol & 15) <= bits)
{
input.dropBits(symbol & 15);
return symbol >> 4;
}
else
return -1;
}
}
