I've been working on my homework assignment where we had to create a parity bit generator circuit that for an 8 bit sequence outputs a 9 bit sequence where the new is the parity bit (it get set to 1 if there is an odd number of bits that are 1 in the sequence). This is the code for it:
library ieee;
use ieee.std_logic_1164.all;
entity top is
port(
idata:in bit_vector(7 downto 0);
odata:out bit_vector(8 downto 0)
);
end top;
architecture parity_gen of top is
signal temp : bit_vector(5 downto 0);
begin
temp(0)<=idata(0) xor idata(1);
temp(1)<=temp(0) xor idata(2);
temp(2)<=temp(1) xor idata(3);
temp(3)<=temp(2) xor idata(4);
temp(4)<=temp(3) xor idata(5);
temp(5)<=temp(4) xor idata(6);
odata(0)<= temp(5) xor idata(7);
odata(1)<=idata(0);
odata(2)<=idata(1);
odata(3)<=idata(2);
odata(4)<=idata(3);
odata(5)<=idata(4);
odata(6)<=idata(5);
odata(7)<=idata(6);
odata(8)<=idata(7);
end parity_gen;
Now I also created a testbench program for it that looks like this:
library ieee;
use ieee.std_logic_1164.all;
entity top_tb is end top_tb;
architecture behavior of top_tb is
component top is
port(
idata:in bit_vector(7 downto 0);
odata:out bit_vector(8 downto 0)
);
end component;
signal input : bit_vector(7 downto 0);
signal output : bit_vector(8 downto 0);
begin
uut: top port map (
idata(7 downto 0) => input(7 downto 0),
odata(8 downto 0) => output(8 downto 0)
);
stim_proc: process
begin
input <= "10100101"; wait for 10 ns; assert output = "101001010" report "test failed";
report "Top testbench finished";
wait;
end process;
end;
Is there a way to test this component for a longer input sequence, lets say 24 bits and what actual changes would I have to make in the code to achieve that?
Input : [ 1 0 1 0 0 1 0 1 1 1 0 0 0 1 1 1 1 0 1 0 1 1 0 0 ]
Output: [ 1 0 1 0 0 1 0 1 0 1 1 0 0 0 1 1 1 1 1 0 1 0 1 1 0 0 0]
I basically want to do something like this:
input <= "101001011100011110101100"; wait for 10 ns; assert output = "101001010110001111101011000" report "test failed";
You can create a forloop and just iterate over elements of an array of inputs while checking a similarly sized array of outputs
type t_in_array is array 0 to num_of_inputs of std_logic_vector(7 downto 0);
signal s_input_arr : t_in_array := ("10100101", ...);
type t_out_array is array 0 to num_of_inputs of std_logic_vector(8 downto 0);
signal s_exp_out_arr: t_out_array := ("101001010", ...);
stim_proc: process
begin
for i in 0 to num_of_inputs
input <= s_input_arr(i);
wait for 10 ns;
assert output = s_exp_out_arr(i)
report "failed";
end loop;
wait;
end process stim_proc;
Wrote that on the fly without testing FYI.