Sorting By Functions in VHDL

In VHDL, we don’t have built-in sorting functions or dynamic data structures like slices. However, we can implement custom sorting algorithms using arrays and custom types. Here’s an example of how we might implement custom sorting in VHDL.

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity sorting_example is
end sorting_example;

architecture Behavioral of sorting_example is
    type string_array is array (natural range <>) of string(1 to 10);
    type person is record
        name : string(1 to 10);
        age : integer;
    end record;
    type person_array is array (natural range <>) of person;
    
    function sort_by_length(arr : string_array) return string_array is
        variable temp : string(1 to 10);
        variable result : string_array(arr'range) := arr;
    begin
        for i in result'range loop
            for j in i + 1 to result'high loop
                if result(i)'length > result(j)'length then
                    temp := result(i);
                    result(i) := result(j);
                    result(j) := temp;
                end if;
            end loop;
        end loop;
        return result;
    end function;
    
    function sort_by_age(arr : person_array) return person_array is
        variable temp : person;
        variable result : person_array(arr'range) := arr;
    begin
        for i in result'range loop
            for j in i + 1 to result'high loop
                if result(i).age > result(j).age then
                    temp := result(i);
                    result(i) := result(j);
                    result(j) := temp;
                end if;
            end loop;
        end loop;
        return result;
    end function;
    
    constant fruits : string_array(0 to 2) := ("peach     ", "banana    ", "kiwi      ");
    constant people : person_array(0 to 2) := (
        ("Jax       ", 37),
        ("TJ        ", 25),
        ("Alex      ", 72)
    );
begin
    process
        variable sorted_fruits : string_array(fruits'range);
        variable sorted_people : person_array(people'range);
    begin
        sorted_fruits := sort_by_length(fruits);
        sorted_people := sort_by_age(people);
        
        -- Print results (this would typically be done in a testbench)
        report "Sorted fruits: " & sorted_fruits(0) & ", " & sorted_fruits(1) & ", " & sorted_fruits(2);
        report "Sorted people: " & sorted_people(0).name & " (age " & integer'image(sorted_people(0).age) & "), " &
                                  sorted_people(1).name & " (age " & integer'image(sorted_people(1).age) & "), " &
                                  sorted_people(2).name & " (age " & integer'image(sorted_people(2).age) & ")";
        wait;
    end process;
end Behavioral;

In this VHDL example, we’ve implemented custom sorting functions for both strings (by length) and a custom person type (by age). Here’s a breakdown of the code:

We define custom types for arrays of strings and persons.
The sort_by_length function implements a simple bubble sort algorithm to sort strings by their length.
The sort_by_age function similarly sorts an array of person records by their age.
In the main process, we create arrays of fruits and people, sort them using our custom functions, and then report the results.

Note that VHDL is typically used for hardware description, so this example is more academic in nature. In real VHDL applications, you would typically implement sorting in hardware using more efficient algorithms suitable for parallel processing.

To “run” this VHDL code, you would typically simulate it in a VHDL simulator. The simulation would show the reported sorted results:

Sorted fruits: kiwi      , peach     , banana    
Sorted people: TJ         (age 25), Jax        (age 37), Alex       (age 72)

This example demonstrates how we can implement custom sorting logic in VHDL, even though the language doesn’t have built-in sorting functions like some high-level programming languages.

Sorting in VHDL

Panic in VHDL

Learn X By Example

Title here

Sorting By Functions in VHDL