From 3992da60278ff8494f5edc79c22d449afbca496f Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Tue, 24 Feb 2026 04:17:42 -0500
Subject: [PATCH] Tests: Add t_assign_func

---
 test_regress/t/t_assign_func.py | 18 ++++++
 test_regress/t/t_assign_func.v  | 99 +++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100755 test_regress/t/t_assign_func.py
 create mode 100644 test_regress/t/t_assign_func.v

diff --git a/test_regress/t/t_assign_func.py b/test_regress/t/t_assign_func.py
new file mode 100755
index 000000000..8a938befd
--- /dev/null
+++ b/test_regress/t/t_assign_func.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: 2026 Wilson Snyder
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile()
+
+test.execute()
+
+test.passes()
diff --git a/test_regress/t/t_assign_func.v b/test_regress/t/t_assign_func.v
new file mode 100644
index 000000000..0664d3745
--- /dev/null
+++ b/test_regress/t/t_assign_func.v
@@ -0,0 +1,99 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
+// SPDX-License-Identifier: CC0-1.0
+
+module t (
+    input clk
+);
+
+  int cyc;
+  reg [63:0] crc;
+  reg [63:0] sum;
+
+  // Take CRC data and apply to testblock inputs
+  wire [9:0] a0 = crc[9:0];
+  wire [9:0] a1 = crc[19:10];
+  wire [9:0] b1 = crc[39:30];
+  wire asel = crc[62];
+  wire bsel = crc[63];
+
+  /*AUTOWIRE*/
+  // Beginning of automatic wires (for undeclared instantiated-module outputs)
+  wire [9:0] aq;  // From test of Test.v
+  wire [9:0] bq;  // From test of Test.v
+  // End of automatics
+
+  Test test (  /*AUTOINST*/
+      // Outputs
+      .aq(aq[9:0]),
+      .bq(bq[9:0]),
+      // Inputs
+      .a0(a0[9:0]),
+      .a1(a1[9:0]),
+      .b1(b1[9:0]),
+      .asel(asel),
+      .bsel(bsel)
+  );
+
+  // Aggregate outputs into a single result vector
+  wire [63:0] result = {44'h0, aq, bq};
+
+  // Test loop
+  always @(posedge clk) begin
+`ifdef TEST_VERBOSE
+    $write("[%0t] cyc==%0d crc=%x result=%x\n", $time, cyc, crc, result);
+`endif
+    cyc <= cyc + 1;
+    crc <= {crc[62:0], crc[63] ^ crc[2] ^ crc[0]};
+    sum <= result ^ {sum[62:0], sum[63] ^ sum[2] ^ sum[0]};
+    if (cyc == 0) begin
+      // Setup
+      crc <= 64'h5aef0c8d_d70a4497;
+      sum <= '0;
+    end
+    else if (cyc < 10) begin
+      sum <= '0;
+    end
+    else if (cyc < 90) begin
+    end
+    else if (cyc == 99) begin
+      $write("[%0t] cyc==%0d crc=%x sum=%x\n", $time, cyc, crc, sum);
+      if (crc !== 64'hc77bb9b3784ea091) $stop;
+      // What checksum will we end up with (above print should match)
+      `define EXPECTED_SUM 64'h2c5e6c5e285efafa
+      if (sum !== `EXPECTED_SUM) $stop;
+      $write("*-* All Finished *-*\n");
+      $finish;
+    end
+  end
+
+endmodule
+
+module Test (
+    input [9:0] a0,
+    input [9:0] a1,
+    input [9:0] b1,
+    input asel,
+    input bsel,
+    output wire [9:0] aq,
+    output wire [9:0] bq
+);
+
+  assign aq = MUX10_2(a0, a1, asel);
+  assign bq = MUX10_2(aq, b1, bsel);
+
+  function [9:0] MUX10_2;  // Legacy code - not function automatic
+    input [9:0] i0;
+    input [9:0] i1;
+    input [0:0] sel;
+    /*static*/ logic [9:0] result;  // Note this is not automatic
+    case (sel)
+      1'b0: result = i0;
+      default: result = i1;
+    endcase
+    MUX10_2 = result;
+  endfunction
+
+endmodule