From 2ccfc6cca33db308748978315667f97d849a2fbf Mon Sep 17 00:00:00 2001
From: Ethan Sifferman <ethan@sifferman.dev>
Date: Mon, 2 Feb 2026 14:59:36 -0800
Subject: [PATCH] added t_timing_nba_whole_partial

---
 test_regress/t/t_timing_nba_whole_partial.py | 18 ++++++++
 test_regress/t/t_timing_nba_whole_partial.v  | 48 ++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 test_regress/t/t_timing_nba_whole_partial.py
 create mode 100644 test_regress/t/t_timing_nba_whole_partial.v

diff --git a/test_regress/t/t_timing_nba_whole_partial.py b/test_regress/t/t_timing_nba_whole_partial.py
new file mode 100644
index 000000000..7da1fcea5
--- /dev/null
+++ b/test_regress/t/t_timing_nba_whole_partial.py
@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of either the GNU Lesser General Public License Version 3
+# or the Perl Artistic License Version 2.0.
+# SPDX-FileCopyrightText: 2024 Wilson Snyder
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+
+test.compile(verilator_flags2=["--binary", "--assert"])
+
+test.execute()
+
+test.passes()
diff --git a/test_regress/t/t_timing_nba_whole_partial.v b/test_regress/t/t_timing_nba_whole_partial.v
new file mode 100644
index 000000000..4257f5807
--- /dev/null
+++ b/test_regress/t/t_timing_nba_whole_partial.v
@@ -0,0 +1,48 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 Ethan Sifferman
+// SPDX-License-Identifier: CC0-1.0
+
+// Test that mixing whole-variable and partial NBAs with suspend points between
+// them produces E_UNSUPPORTED error (not yet correctly supported)
+//
+// The "last NBA wins" semantics are not correctly implemented when there are
+// suspend points between NBAs to the same variable with mixed whole/partial updates.
+
+module t;
+
+  int delay = 0; always #1 delay = int'($time) / 4;
+  task automatic do_delay;
+    if (delay > 0) #(delay);
+  endtask
+
+  // Test: whole then partial with suspend between
+  logic [7:0] a = 0;
+  always begin
+    a <= 8'hff;
+    do_delay();
+    a[3:0] <= 4'h0; // Last NBA should win
+    #1;
+    // Expected: a = 8'hf0, Receives a = 8'h00
+    assert (a == 8'hf0) else $fatal(0, "received %0h", a);
+  end
+
+  // Test: partial then whole with suspend between
+  logic [7:0] b = 0;
+  always begin
+    b[3:0] <= 4'h0;
+    do_delay();
+    b <= 8'hff; // Last NBA should win
+    #1;
+    // Expected: b = 8'hff, Receives b = 8'h00
+    assert (b == 8'hff) else $fatal(0, "received %0h", b);
+  end
+
+  initial begin
+    #20;
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+
+endmodule