Simple extract bits from vector

[Charlie84]

Hi, i can't imagine, how to implement simple bit extractor.

-- pseudocode
signal input : std_logic_vector(63 downto 0);
signal output : std_logic_vector(63 downto 0);
type bit_index is range 63 downto 0;
signal min : bit_index;
signal max : bit_index;

-- min and max indexes determine, which bits I want to extract from input to output
-- e.g.
output(63 downto 0) <= input(max downto min);

Thank you very much for any reply!