How do I find the array index with its highest value with vhdl?

Question

I would like to find the array index with its highest value. Is it possible to simply use an vhdl-attribute therefore? If so, how?

TYPE x_Array IS ARRAY (0 TO 3) OF STD_LOGIC_VECTOR(2 DOWNTO 0);      
SIGNAL y : x_Array;

Example:

x_Array(0) = "000"
x_Array(1) = "011"
x_Array(2) = "111"
x_Array(3) = "101"


index <= x_Array'high;    -- is this correct or..?

Question: How can I get the index of 2 (x_Array(2) has the highest value (7)) in vhdl?

Answer 1

As written, your question doesn't make sense: a std_logic_vector needs an interpretation to even be considered as a number.

So let's assume you knew that and wrote the sensible

library ieee;
use ieee.numeric_std.all;
use ieee.std_logic_1164.all;
type x_array is array(integer range <>) of unsigned(2 downto 0);      
signal y : x_array(0 to 3);

just write the function

function maxindex(a : x_array) return integer is
  variable index : integer := 0;
  unsigned foundmax : unsigned(2 downto 0) := (others => '0');
begin
  for i in 0 to a'high loop
    if a(i) > foundmax then
      index := i;
      foundmax := a(i);
    end if;
  end loop
  return index;
end function;

And apply as necessary.