Do not assign default value for g_reset in common_fifo_sc. To avoid clutter in...

Do not assign default value for g_reset in common_fifo_sc. To avoid clutter in report when using e.g.: grep -rl 'g_reset ' libraries.

Closes L2SDP-1005

libraries/base/common/src/vhdl/common_areset.vhd

@@ -79,29 +79,41 @@ begin
   -- 2009
   -- Capture asynchronous reset assertion, to also support i_rst when there is
   -- no clk.
-  u_async : entity work.common_async
-  generic map (
-    g_rst_level => c_out_rst_level,
-    g_delay_len => g_delay_len
-  )
-  port map (
-    rst  => i_rst,
-    clk  => clk,
-    din  => c_out_rst_level_n,
-    dout => o_rst
-  );
+  without_pipe : if g_tree_len = 0 generate
+    u_async : entity work.common_async
+    generic map (
+      g_rst_level => c_out_rst_level,
+      g_delay_len => g_delay_len
+    )
+    port map (
+      rst  => i_rst,
+      clk  => clk,
+      din  => c_out_rst_level_n,
+      dout => out_rst
+    );
+  end generate;
 
   -- 2024
   -- Pass on synchronized reset with sufficient g_tree_len to ease timing
   -- closure by FF duplication in out_rst tree. Keep rst = '0' to break
   -- combinatorial path with in_rst to ease timing closure in the reset tree
-  -- network. Use g_tree_len = 0 for wire out_rst <= o_rst, so no reset tree
-  -- as in 2009.
-  no_pipe : if g_tree_len = 0 generate
-    out_rst <= o_rst;  -- wires
-  end generate;
+  -- network. Use g_tree_len = 0 for no clocked reset tree as in 2009.
+  -- Instantiate u_async again to keep 2009 and 2024 completely independent.
+  -- To avoid delta-cycle differences due to e.g. out_rst <= o_rst when
+  -- g_tree_len = 0, that could lead to different results in a simulation tb.
+  with_pipe : if g_tree_len > 0 generate
+    u_async : entity work.common_async
+    generic map (
+      g_rst_level => c_out_rst_level,
+      g_delay_len => g_delay_len
+    )
+    port map (
+      rst  => i_rst,
+      clk  => clk,
+      din  => c_out_rst_level_n,
+      dout => o_rst
+    );
 
-  gen_pipe : if g_tree_len > 0 generate
     u_pipe : entity work.common_async
     generic map (
       g_rst_level => c_out_rst_level,