Type declarations

I am trying to use the following function defined in the ieee_proposed library

-- to_signed (float) function to_signed ( arg : UNRESOLVED_float; -- floating point input constant size : NATURAL; -- length of output constant check_error : BOOLEAN := float_check_error; -- check for errors constant round_style : round_type := float_round_style) -- rounding option return SIGNED is

I want to test this function. I have given inputs to entity as below

float_in : in std_logic_vector(31 downto 0); signed_out : out std_logic_vector(63 DOWNTO 0);

I want to try

signed_out