From 235a3dcfca5e1d2fd96e07af9117d8950bff7068 Mon Sep 17 00:00:00 2001
From: David Harris <David_Harris@hmc.edu>
Date: Wed, 24 Apr 2024 08:44:37 -0700
Subject: [PATCH] ROM preload compatible with Verilator lint, sim, and Design
 Compiler

---
 src/generic/mem/rom1p1r.sv | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/generic/mem/rom1p1r.sv b/src/generic/mem/rom1p1r.sv
index dc8ef74a9..e17b8af60 100644
--- a/src/generic/mem/rom1p1r.sv
+++ b/src/generic/mem/rom1p1r.sv
@@ -33,12 +33,6 @@ module rom1p1r #(parameter ADDR_WIDTH = 8, DATA_WIDTH = 32, PRELOAD_ENABLED = 0)
    output logic [DATA_WIDTH-1:0] dout
 );
 
-`ifdef VERILATOR
-    import "DPI-C" function string getenvval(input string env_name);
-    string       WALLY_DIR = getenvval("WALLY"); 
-`else
-    string       WALLY_DIR = "$WALLY";
-`endif
 
    // Core Memory
    bit [DATA_WIDTH-1:0]    ROM [(2**ADDR_WIDTH)-1:0];
@@ -53,10 +47,21 @@ module rom1p1r #(parameter ADDR_WIDTH = 8, DATA_WIDTH = 32, PRELOAD_ENABLED = 0)
 
   end else begin */
 
+  `ifdef VERILATOR
+    import "DPI-C" function string getenvval(input string env_name);
+  `endif
+  
   initial 
     if (PRELOAD_ENABLED) begin
-      if (DATA_WIDTH == 64) $readmemh({WALLY_DIR,"/fpga/src/boot.mem"}, ROM, 0);  // load boot ROM for FPGA
-      else begin // put something in the ROM so it is not optimized away
+      if (DATA_WIDTH == 64) begin
+        `ifdef VERILATOR
+            // because Verilator doesn't automatically accept $WALLY from shell
+            string       WALLY_DIR = getenvval("WALLY"); 
+            $readmemh({WALLY_DIR,"/fpga/src/boot.mem"}, ROM, 0);  // load boot ROM for FPGA
+        `else
+            $readmemh({"$WALLY/fpga/src/boot.mem"}, ROM, 0);  // load boot ROM for FPGA
+        `endif
+      end else begin // put something in the ROM so it is not optimized away
         ROM[0] = 'h00002197;
       end
     end