Url Parsing in VHDL

Here’s the translation of the Go URL parsing example to VHDL:

URLs provide a uniform way to locate resources. Here’s how to parse URLs in VHDL.

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

entity URL_Parser is
end URL_Parser;

architecture Behavioral of URL_Parser is
    type String is array (positive range <>) of character;
    
    function Parse_URL(url : String) return String is
        variable scheme, user, host, path, query, fragment : String(1 to 100);
        variable scheme_end, user_end, host_end, path_end, query_end : integer;
    begin
        -- Find scheme
        scheme_end := 1;
        while scheme_end <= url'length and url(scheme_end) /= ':' loop
            scheme_end := scheme_end + 1;
        end loop;
        scheme(1 to scheme_end-1) := url(1 to scheme_end-1);
        
        -- Find user info
        user_end := scheme_end + 3; -- Skip "://"
        while user_end <= url'length and url(user_end) /= '@' loop
            user_end := user_end + 1;
        end loop;
        user(1 to user_end-scheme_end-3) := url(scheme_end+3 to user_end-1);
        
        -- Find host
        host_end := user_end + 1;
        while host_end <= url'length and url(host_end) /= '/' loop
            host_end := host_end + 1;
        end loop;
        host(1 to host_end-user_end-1) := url(user_end+1 to host_end-1);
        
        -- Find path
        path_end := host_end;
        while path_end <= url'length and url(path_end) /= '?' loop
            path_end := path_end + 1;
        end loop;
        path(1 to path_end-host_end) := url(host_end to path_end-1);
        
        -- Find query
        query_end := path_end + 1;
        while query_end <= url'length and url(query_end) /= '#' loop
            query_end := query_end + 1;
        end loop;
        query(1 to query_end-path_end-1) := url(path_end+1 to query_end-1);
        
        -- Find fragment
        fragment(1 to url'length-query_end) := url(query_end+1 to url'length);
        
        return scheme & user & host & path & query & fragment;
    end function;

begin
    process
        variable url : String(1 to 100) := "postgres://user:pass@host.com:5432/path?k=v#f";
        variable parsed_url : String(1 to 100);
    begin
        parsed_url := Parse_URL(url);
        
        -- Print parsed URL components (this would be implemented differently in actual VHDL)
        report "Scheme: " & parsed_url(1 to 8);
        report "User: " & parsed_url(9 to 17);
        report "Host: " & parsed_url(18 to 30);
        report "Path: " & parsed_url(31 to 35);
        report "Query: " & parsed_url(36 to 39);
        report "Fragment: " & parsed_url(40 to 40);
        
        wait;
    end process;
end Behavioral;

This VHDL code demonstrates a basic URL parsing functionality. It defines a Parse_URL function that takes a URL string as input and returns the parsed components. The main process then uses this function to parse an example URL.

Please note that VHDL is primarily used for hardware description and synthesis, not for general-purpose programming like Go. As such, many high-level concepts from Go (like built-in URL parsing libraries) don’t have direct equivalents in VHDL. This example provides a basic implementation of URL parsing using VHDL’s string manipulation capabilities.

In a real VHDL design, you would typically implement this kind of functionality as part of a larger digital system, possibly using state machines and more complex data structures. The report statements used here for output are primarily for simulation purposes and wouldn’t be synthesized into hardware.

To use this code, you would need to simulate it using a VHDL simulator. The output would show the parsed components of the URL in the simulator’s console or waveform viewer.

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Url Parsing in VHDL