Examples of using PSL for functional and formal verification of VHDL with GHDL (and SymbiYosys)
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vunit issue_vunit (issue(psl)) {
-- VHDL declaration seem to be working
signal a_delayed : std_logic := '0';
signal prev_valid : boolean := false;
-- Other VHDL code not
-- results in parser errors
-- during synthesis
-- EDIT: works since fix of ghdl issue #1366
process is
begin
wait until rising_edge(clk);
a_delayed <= a;
prev_valid <= true;
end process;
-- All is sensitive to rising edge of clk
default clock is rising_edge(clk);
-- This assertion holds
CHECK_0_a : assert always (a -> b);
-- You can't do anything with the declared signal
-- Can be synthesized with GHDL, however
-- results in error in ghdl-yosys-plugin:
-- ERROR: Assert `n.id != 0' failed in src/ghdl.cc:172
-- EDIT: works since fix of ghdl issue #1366
CHECK_1_a : assert always prev_valid -> a_delayed = prev(a);
}
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity sequencer is
generic (
seq : string
);
port (
clk : in std_logic;
data : out std_logic
);
end entity sequencer;
architecture rtl of sequencer is
signal index : natural := seq'low;
function to_bit (a : in character) return std_logic is
variable ret : std_logic;
begin
case a is
when '0' | '_' => ret := '0';
when '1' | '-' => ret := '1';
when others => ret := 'X';
end case;
return ret;
end function to_bit;
begin
process (clk) is
begin
if rising_edge(clk) then
if (index < seq'high) then
index <= index + 1;
end if;
end if;
end process;
data <= to_bit(seq(index));
end architecture rtl;
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity issue is
port (
clk : in std_logic
);
end entity issue;
architecture psl of issue is
component sequencer is
generic (
seq : string
);
port (
clk : in std_logic;
data : out std_logic
);
end component sequencer;
signal a, b : std_logic;
begin
-- 0123456789
SEQ_A : sequencer generic map ("__-__-____") port map (clk, a);
SEQ_B : sequencer generic map ("__-__-____") port map (clk, b);
end architecture psl;