indexing - Creating a vector with other vector`s index as elements in VHDL -

i have std_logic_vector 1 input: v1 = "10001010" , want create vector one: v2 = x"00000731", x"7", x"3", , x"1" represent index of first vector (v1) value '1'.

v1(1) = '1', v1(2) = '0', v1(3) = '1', etc.

please me coding examples can create v2.

something like:

variable base : natural := 0; .... v2 <= (others => '0'); in v1'right v1'left loop   if v1(i) = '1'     v2(base+3 downto base) = to_unsigned(i,4);     base := base + 4;   end if; end for;