Counting the position of ones in a binary vector

And simulated. 466 LC, 80 registers, 105 MHz in a Cyclone II EP2C5F256C6.

library ieee;
	use ieee.std_logic_1164.all;
	use IEEE.numeric_std.all;
	
	
	
entity bitpos is
	port (
		Clk		:	in	std_logic ;
		data_in		:	in	std_logic_vector(15 downto 0) ;
		data_out	:	out	std_logic_vector(63 downto 0) 
		);
	end bitpos ;
		
architecture a of bitpos is
	signal	ld	:	std_logic_vector(15 downto 0) ;
begin
	process(clk)
		variable j 	: natural ;
		variable lq	: std_logic_vector(63 downto 0) ;
	begin
		if rising_edge(Clk ) then
			ld <= data_in ;
			j := 0 ;
			lq := (others => '0') ;
			for i in 0 to 15 loop
				if ld(i) = '1' then
				lq(j*4+3 downto j*4) := std_logic_vector(to_unsigned(i,4));
				j := j + 1 ;
				end if;
			end loop;
			data_out <= lq ;
		end if ;
	end process;
end a ;