code: public static int raise_2( int x ) {
  		int y;
  		y = eval_table( exp_2_table, x & IBXM.FP_MASK ) << IBXM.FP_SHIFT;
  		return y >> IBXM.FP_SHIFT - ( x >> IBXM.FP_SHIFT );
  	}
docs: /*
  Raise 2 to the power x (fixed point).
  A fixed point value is returned.