/// <summary> /// Reads the next symbol from input. The symbol is encoded using the /// huffman tree. /// </summary> /// <param name="input"> /// input the input source. /// </param> /// <returns> /// the next symbol, or -1 if not enough input is available. /// </returns> 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); } } }