Made verify_sync and expected_out_enable more simple and robust.

libraries/base/dp/tb/vhdl/tb_dp_bsn_sync_scheduler.vhd

@@ -40,9 +40,9 @@
 --
 -- Development steps:
 --  . Step    1 ~1 day work (idea started earlier, so requirements were clear),
---    steps 2,5 ~1.5 days work (fixing details and verifying all features),
---    steps 3,4 ~0.5 day work,
---    total ~3 days work spent in ~ 1 week.
+--    steps 2,5 ~2 days work (fixing details and verifying all features),
+--    steps 3,4 ~1 day work,
+--    total ~4 days work spent in ~ 1 week.
 -- 1a Draft design description of dp_bsn_sync_scheduler
 --  b Initial implementation that compiles
 -- 2a Initial tb using u_stimuli to generate in_sosi and using p_stimuli
@@ -130,7 +130,7 @@ ARCHITECTURE tb OF tb_dp_bsn_sync_scheduler IS
   SIGNAL ctrl_enable_evt       : STD_LOGIC := '0';
   SIGNAL ctrl_interval_size    : NATURAL := g_nof_samples_per_output_sync;
   SIGNAL ctrl_start_bsn        : STD_LOGIC_VECTOR(c_bsn_w-1 DOWNTO 0) := (OTHERS=>'0');
-  SIGNAL mon_input_current_bsn : STD_LOGIC_VECTOR(c_bsn_w-1 DOWNTO 0);
+  SIGNAL mon_current_input_bsn : STD_LOGIC_VECTOR(c_bsn_w-1 DOWNTO 0);
   SIGNAL mon_input_bsn_at_sync : STD_LOGIC_VECTOR(c_bsn_w-1 DOWNTO 0);
   SIGNAL mon_output_enable     : STD_LOGIC;
   SIGNAL mon_output_sync_bsn   : STD_LOGIC_VECTOR(c_bsn_w-1 DOWNTO 0);
@@ -161,7 +161,6 @@ ARCHITECTURE tb OF tb_dp_bsn_sync_scheduler IS
   SIGNAL verifying_sync_equal  : STD_LOGIC := '0';
 
   SIGNAL prev_out_enable       : STD_LOGIC := '0';
-  SIGNAL pending_out_enable    : STD_LOGIC := '0';
   SIGNAL pending_out_disable   : STD_LOGIC := '0';
   SIGNAL expected_out_enable   : STD_LOGIC := '0';
   SIGNAL expecting_out_start   : STD_LOGIC := '0';
@@ -358,56 +357,39 @@ BEGIN
     END IF;
   END PROCESS;
 
-  p_expected_out_enable : PROCESS(ctrl_enable, ctrl_enable_evt, in_sosi, ctrl_start_bsn, out_enable, pending_out_enable, pending_out_disable, hold_out_eop)
-  BEGIN
   -- Determine expected out_enable
-    IF ctrl_enable = '1' THEN
-      -- Detect output enable event
+  p_expected_out_enable : PROCESS(ctrl_enable, ctrl_enable_evt, in_sosi, ctrl_start_bsn, out_enable, pending_out_disable, hold_out_eop)
+  BEGIN
+    -- Expect output disable after ctrl_enable_evt
     IF ctrl_enable_evt = '1' THEN
-        -- Determine whether the output enable event is scheduled in the future
-        IF UNSIGNED(in_sosi.bsn) < UNSIGNED(ctrl_start_bsn) THEN
-          pending_out_enable <= '1';
-
-          -- Detect output re-enable event, to plan output disable before re-enable
-          IF out_enable = '1' THEN
-            IF hold_out_eop = '1' THEN
+       IF out_enable = '0' THEN
+         -- Output is already disabled
          expected_out_enable <= '0';
        ELSE
-              pending_out_disable <= '1';
-            END IF;
-          END IF;
-        END IF;  -- else ignore output enable event in the past
+         -- Output is enabled, so this is a re-enable event.
+         IF hold_out_eop = '1' THEN
+           expected_out_enable <= '0';  -- end of block, so output can disable immediately
+         ELSE
+           pending_out_disable <= '1';  -- plan output disable before re-enable
          END IF;
-
-      -- Enable expected_out_enable at start BSN (and at in_sosi.sop)
-      IF pending_out_enable = '1' THEN
-        IF UNSIGNED(in_sosi.bsn) >= UNSIGNED(ctrl_start_bsn) THEN
-          expected_out_enable <= '1';
-          pending_out_enable <= '0';
        END IF;
     END IF;
-    ELSE
-      -- Immediately remove any pending output enable
-      pending_out_enable <= '0';
 
-      -- Detect output disable event, to plan output disable
-      IF ctrl_enable_evt = '1' THEN
+    IF pending_out_disable <= '1' THEN
       IF hold_out_eop = '1' THEN
-          expected_out_enable <= '0';
-        ELSE
-          pending_out_disable <= '1';
-        END IF;
+        expected_out_enable <= '0';  -- end of block, so output can disable
+        pending_out_disable <= '0';
       END IF;
     END IF;
 
-    -- Expected out_enable disabled between block boundaries
-    IF pending_out_disable = '1' AND hold_out_eop = '1' THEN
-      expected_out_enable <= '0';
-      pending_out_disable <= '0';
+    -- Expect output enable at start BSN
+    IF ctrl_enable = '1' THEN
+      IF UNSIGNED(in_sosi.bsn) >= UNSIGNED(ctrl_start_bsn) THEN
+        expected_out_enable <= '1';
+      END IF;
     END IF;
   END PROCESS;
 
-
   p_verify_out_enable : PROCESS(clk)
   BEGIN
     -- Use registered values to compare, to avoid combinatorial differences
@@ -470,7 +452,7 @@ BEGIN
         REPORT "Unexpected out_start" SEVERITY ERROR;
       END IF;
 
-      -- Check when out_enable goes high whether out_start is missed
+      -- Check that out_start is active when out_enable goes high
       IF out_start = '0' AND out_enable = '1' AND prev_out_enable = '0' THEN
         REPORT "Missed out_start" SEVERITY ERROR;
       END IF;
@@ -509,20 +491,7 @@ BEGIN
   -----------------------------------------------------------------------------
   -- . Verify out_sosi.sync interval
   -----------------------------------------------------------------------------
-  p_verify_sync : PROCESS(clk)
-  BEGIN
-    IF rising_edge(clk) THEN
-      IF ctrl_enable = '1' AND ctrl_enable_evt = '1' THEN
-        verify_sync <= '0';  -- request for new sync interval
-      ELSIF out_start = '1' THEN
-        verify_sync <= '1';  -- new sync interval has started;
-      END IF;
-
-      IF recover_from_in_lost = '1' THEN
-        verify_sync <= '0';  -- after long input lost, first output_sync may get lost during catch up
-      END IF;
-    END IF;
-  END PROCESS;
+  verify_sync <= NOT recover_from_in_lost;
 
   proc_dp_verify_sync(TO_UINT(ctrl_start_bsn),
                               ctrl_interval_size,
@@ -553,8 +522,8 @@ BEGIN
     IF rising_edge(clk) THEN
       IF recover_from_in_lost = '0' THEN
         IF out_sop_dly = '1' THEN
-          v_bsn_min := TO_UINT(mon_input_current_bsn) - 1;
-          v_bsn_max := TO_UINT(mon_input_current_bsn) + c_output_nof_blocks_min + 1;
+          v_bsn_min := TO_UINT(mon_current_input_bsn) - 1;
+          v_bsn_max := TO_UINT(mon_current_input_bsn) + c_output_nof_blocks_min + 1;
 
           ASSERT TO_UINT(mon_output_sync_bsn) >= v_bsn_min
             REPORT "Wrong: mon_output_sync_bsn is behind (" & int_to_str(TO_UINT(mon_output_sync_bsn)) & " < " & int_to_str(v_bsn_min) & ")"  SEVERITY ERROR;
@@ -562,7 +531,7 @@ BEGIN
             REPORT "Wrong: mon_output_sync_bsn is too far ahead (" & int_to_str(TO_UINT(mon_output_sync_bsn)) & " > " & int_to_str(v_bsn_max) & ")" SEVERITY ERROR;
 
           --Debug report used to investigate v_bsn_min and v_bsn_max assert conditions
-          --REPORT int_to_str(TO_UINT(mon_output_sync_bsn)) & " : " & int_to_str(TO_UINT(mon_input_current_bsn)) SEVERITY NOTE;
+          --REPORT int_to_str(TO_UINT(mon_output_sync_bsn)) & " : " & int_to_str(TO_UINT(mon_current_input_bsn)) SEVERITY NOTE;
         END IF;
       END IF;
     END IF;
@@ -588,7 +557,7 @@ BEGIN
     ctrl_enable_evt       => ctrl_enable_evt,
     ctrl_interval_size    => ctrl_interval_size,
     ctrl_start_bsn        => ctrl_start_bsn,
-    mon_input_current_bsn => mon_input_current_bsn,
+    mon_current_input_bsn => mon_current_input_bsn,
     mon_input_bsn_at_sync => mon_input_bsn_at_sync,
     mon_output_enable     => mon_output_enable,
     mon_output_sync_bsn   => mon_output_sync_bsn,