Add example for next_event operator

src/psl_next_event.vhd

@@ -0,0 +1,48 @@
+library ieee;
+  use ieee.std_logic_1164.all;
+
+use work.pkg.all;
+
+
+entity psl_next_event is
+  port (
+    clk : in std_logic
+  );
+end entity psl_next_event;
+
+
+architecture psl of psl_next_event is
+
+  signal a, b, c : std_logic;
+  signal d, e, f : 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);
+
+  --                              012345678901234
+  SEQ_D : sequencer generic map ("_-______-_-____") port map (clk, d);
+  SEQ_E : sequencer generic map ("____-_-_--_-__-") port map (clk, e);
+  SEQ_F : sequencer generic map ("____-___-__-___") port map (clk, f);
+
+
+  -- All is sensitive to rising edge of clk
+  default clock is rising_edge(clk);
+
+  -- This assertion holds
+  NEXT_EVENT_0_a : assert always (a -> next_event(b)(c));
+
+  -- This assertion holds
+  NEXT_EVENT_1_a : assert always (d -> next_event(e)(f));
+
+  -- This assertion holds
+  NEXT_EVENT_2_a : assert always (a -> next next_event(b)(c));
+
+  -- This assertion doesn't hold at cycle 9
+  NEXT_EVENT_3_a : assert always (d -> next next_event(e)(f));
+
+
+end architecture psl;