Slices in VHDL

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

entity SliceExample is
end SliceExample;

architecture Behavioral of SliceExample is
    type string_array is array (natural range <>) of string(1 to 10);
    
    procedure print(s: string) is
    begin
        report s severity note;
    end procedure;
    
    procedure print_array(arr: string_array) is
        variable temp: string(1 to 100);
    begin
        temp := "[";
        for i in arr'range loop
            temp := temp & arr(i);
            if i /= arr'high then
                temp := temp & ", ";
            end if;
        end loop;
        temp := temp & "]";
        print(temp);
    end procedure;
    
begin
    process
        variable s: string_array(0 to 2);
        variable c: string_array(0 to 2);
        variable t: string_array(0 to 2);
    begin
        -- In VHDL, arrays are fixed-size, so we'll simulate slices using fixed-size arrays
        
        -- Initialize an empty array
        print("uninit: ");
        print_array(s);
        
        -- Set values in the array
        s(0) := "a         ";
        s(1) := "b         ";
        s(2) := "c         ";
        print("set: ");
        print_array(s);
        
        -- Get a value from the array
        print("get: " & s(2));
        
        -- Print the length of the array
        print("len: " & integer'image(s'length));
        
        -- Copy the array
        c := s;
        print("cpy: ");
        print_array(c);
        
        -- Declare and initialize an array in one line
        t := ("g         ", "h         ", "i         ");
        print("dcl: ");
        print_array(t);
        
        -- Multi-dimensional arrays
        print("2d: ");
        for i in 0 to 2 loop
            for j in 0 to i loop
                print(integer'image(i) & integer'image(j));
            end loop;
        end loop;
        
        wait;
    end process;
end Behavioral;

This VHDL code demonstrates concepts similar to slices in Go, although VHDL doesn’t have dynamic slices. Instead, we use fixed-size arrays and procedures to simulate some of the slice operations.

Key points:

We define a custom type string_array to represent an array of strings.
We create procedures print and print_array to simulate the fmt.Println functionality.
Arrays in VHDL are fixed-size, so we can’t dynamically append elements or create slices of varying sizes.
We demonstrate array initialization, setting and getting values, copying arrays, and working with multi-dimensional arrays.
The process block is used to execute sequential statements, similar to the main function in Go.
VHDL doesn’t have built-in string manipulation functions, so we manually concatenate strings for printing.
We use a fixed-size string of 10 characters for each array element, padding with spaces as necessary.

This VHDL code provides a similar structure to the Go example, demonstrating array operations that are analogous to slice operations in Go, within the constraints of VHDL’s type system and language features.

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Slices in VHDL