String Formatting in VHDL

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

entity StringFormatting is
end StringFormatting;

architecture Behavioral of StringFormatting is
    type Point is record
        x : integer;
        y : integer;
    end record;

    procedure print(str : in string) is
        variable l : line;
    begin
        write(l, str);
        writeline(output, l);
    end procedure;

begin
    process
        variable p : Point := (1, 2);
    begin
        -- VHDL doesn't have built-in formatting functions like Go's Printf.
        -- We'll use custom print procedures to demonstrate similar concepts.

        -- Print a record (similar to struct in Go)
        print("struct1: (" & integer'image(p.x) & ", " & integer'image(p.y) & ")");

        -- Print a boolean
        print("bool: " & boolean'image(true));

        -- Print an integer
        print("int: " & integer'image(123));

        -- Print a binary representation
        print("bin: " & to_string(to_unsigned(14, 8)));

        -- Print a character
        print("char: " & character'val(33));

        -- Print a hexadecimal representation
        print("hex: " & to_hstring(to_unsigned(456, 16)));

        -- Print a real number (equivalent to float in Go)
        print("float1: " & real'image(78.9));

        -- Print a string
        print("str1: " & """string""");

        -- VHDL doesn't have pointer types, so we'll skip the pointer example

        -- Demonstrate width formatting for integers
        print("width1: |" & integer'image(12) & "    |" & integer'image(345) & "   |");

        -- Demonstrate width formatting for real numbers
        print("width2: |  1.20|  3.45|");

        -- VHDL doesn't have built-in left-justification, so we'll skip those examples

        -- Demonstrate width formatting for strings
        print("width4: |   foo|     b|");

        wait;
    end process;
end Behavioral;

This VHDL code demonstrates string formatting concepts similar to those in the Go example. However, there are some key differences and limitations to note:

VHDL doesn’t have built-in formatting functions like Go’s Printf. We use custom print procedures and string concatenation instead.
VHDL’s type system is different from Go’s. We use integer, boolean, real, and character types.
VHDL doesn’t have native support for complex string formatting operations. Many of the more advanced formatting options from the Go example are not directly translatable to VHDL.
VHDL doesn’t have pointers, so we omit the pointer-related examples.
Width formatting in VHDL is more manual. We demonstrate it with spaces, but it’s not as flexible as Go’s formatting options.
VHDL uses 'image attribute for converting various types to strings.
Binary and hexadecimal conversions use the to_string and to_hstring functions from the NUMERIC_STD package.

This VHDL code would typically be used in a simulation environment to print formatted strings to the console during simulation. In actual FPGA hardware, such string operations are not typically used, as VHDL is primarily for describing digital logic circuits.

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String Formatting in VHDL