nixpkgs/pkgs/development/compilers/ghdl/simple-tb.vhd

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library ieee;
use IEEE.STD_LOGIC_1164.all;
use ieee.numeric_std.all;
library STD;
use STD.textio.all;
entity tb is
end tb;
architecture beh of tb is
component simple
port (
CLK, RESET : in std_ulogic;
DATA_OUT : out std_ulogic_vector(7 downto 0);
DONE_OUT : out std_ulogic
);
end component;
signal data : std_ulogic_vector(7 downto 0) := "00100000";
signal clk : std_ulogic;
signal RESET : std_ulogic := '0';
signal done : std_ulogic := '0';
signal cyclecount : integer := 0;
constant cycle_time_c : time := 200 ms;
constant maxcycles : integer := 100;
begin
simple1 : simple
port map (
CLK => clk,
RESET => RESET,
DATA_OUT => data,
DONE_OUT => done
);
clk_process : process
begin
clk <= '0';
wait for cycle_time_c/2;
clk <= '1';
wait for cycle_time_c/2;
end process;
count_process : process(CLK)
begin
if (CLK'event and CLK ='1') then
if (RESET = '1') then
cyclecount <= 0;
else
cyclecount <= cyclecount + 1;
end if;
end if;
end process;
test : process
begin
RESET <= '1';
wait until (clk'event and clk='1');
wait until (clk'event and clk='1');
RESET <= '0';
wait until (clk'event and clk='1');
for cyclecnt in 1 to maxcycles loop
exit when done = '1';
wait until (clk'event and clk='1');
report integer'image(to_integer(unsigned(data)));
end loop;
wait until (clk'event and clk='1');
report "All tests passed." severity NOTE;
wait;
end process;
end beh;