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
andprint_array
to simulate thefmt.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 themain
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.