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library ieee;
use ieee.std_logic_1164.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;
signal ch : character;
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;
ch <= seq(index);
data <= to_bit(ch);
end architecture rtl;
library ieee;
use ieee.std_logic_1164.all;
entity psl_next_event_a is
end entity psl_next_event_a;
architecture psl of psl_next_event_a is
signal clk : std_logic := '0';
component sequencer is
generic (
seq : string
);
port (
clk : in std_logic;
data : out std_logic
);
end component sequencer;
signal a, b, c : std_logic;
begin
-- 012345678901234
SEQ_A : sequencer generic map ("_-______________-____") port map (clk, a);
SEQ_B : sequencer generic map ("--___--__----________") port map (clk, b);
SEQ_C : sequencer generic map ("_____-___---_____----") port map (clk, c);
-- All is sensitive to rising edge of clk
default clock is rising_edge(clk);
-- This assertion holds
assert_NEXT_EVENT_a : assert always ((a and b) -> next_event_a(c)[1 to 4](b));
process
begin
for i in 1 to 2*20 loop
wait for 1 ns;
clk <= not clk;
end loop;
wait;
end process;
end architecture psl;
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