update Verilator-related files to compile on version 4.228

- Starting from Verilator version 4.210, the model class is an interface
object. For reaching Verilog variables internal to a module this means that we
need to include an extra header in cpp files that reference them (#include
"Vj1a___024root.h"). And they're now part of a rootp class which is a member of
the model class; we need to add an extra level of indirection. So
'top->v__DOT__ram_prog[i] = v;' becomes 'top->rootp->v__DOT__ram_prog[i] =
v;'. See https://verilator.org/guide/latest/connecting.html for more words.

- I don't know when these were introduced, but Verilator has become more strict
about allowing assignments to wires. So 'insn' has become a reg as we assign to
it inside a procedural block. And the 'wire uart0_(wr|rd) = ..' wire
declarations on line 60/61 were duplicates of the module port declarations.

j1a/verilator/j1a.v

@@ -19,7 +19,7 @@ module j1a(input wire clk,
   /* verilator lint_off UNUSED */
   wire [12:0] code_addr;
   /* verilator lint_on UNUSED */
-  wire [15:0] insn;
+  reg [15:0] insn;
 
   reg [15:0] ram_prog[0:4095] /* verilator public_flat */;
   always @(posedge clk) begin
@@ -57,8 +57,8 @@ module j1a(input wire clk,
 
   // ######   UART   ##########################################
 
-  wire uart0_wr = io_wr_ & io_addr_[12];
-  wire uart0_rd = io_rd_ & io_addr_[12];
+  assign uart0_wr = io_wr_ & io_addr_[12];
+  assign uart0_rd = io_rd_ & io_addr_[12];
   assign uart_w = dout_[7:0];
 
   // always @(posedge clk) begin

j1a/verilator/sim_main.cpp

@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include "Vj1a.h"
+#include "Vj1a___024root.h"
 #include "verilated_vcd_c.h"
 
 int main(int argc, char **argv)
@@ -20,7 +21,7 @@ int main(int argc, char **argv)
         fprintf(stderr, "invalid hex value at line %d\n", i + 1);
         exit(1);
       }
-      top->v__DOT__ram_prog[i] = v;
+      top->rootp->v__DOT__ram_prog[i] = v;
     }
 
     top->resetq = 0;

j1a/verilator/vsim.cpp

@@ -1,5 +1,6 @@
 #include <assert.h>
 #include "Vj1a.h"
+#include "Vj1a___024root.h"
 #include "verilated.h"
 #define VCD 0
 #if VCD
@@ -60,7 +61,7 @@ Vj1a_init(v3 *self, PyObject *args, PyObject *kwds)
       fprintf(stderr, "invalid hex value at line %d\n", i + 1);
       exit(1);
     }
-    self->dut->v__DOT__ram_prog[i] = v;
+    self->dut->rootp->v__DOT__ram_prog[i] = v;
   }
   memset(self->rdepth, 0, sizeof(self->rdepth));
   memset(self->ddepth, 0, sizeof(self->ddepth));
@@ -126,11 +127,11 @@ static void cycle(v3* v)
   dut->clk = 1;
   dut->eval();
 
-  int pc = 4095 & dut->v__DOT___j1__DOT__pc;
-  if (dut->v__DOT___j1__DOT__dstack__DOT__depth > v->ddepth[pc])
-    v->ddepth[pc] = dut->v__DOT___j1__DOT__dstack__DOT__depth;
-  if (dut->v__DOT___j1__DOT__rstack__DOT__depth > v->rdepth[pc])
-    v->rdepth[pc] = dut->v__DOT___j1__DOT__rstack__DOT__depth;
+  int pc = 4095 & dut->rootp->v__DOT___j1__DOT__pc;
+  if (dut->rootp->v__DOT___j1__DOT__dstack__DOT__depth > v->ddepth[pc])
+    v->ddepth[pc] = dut->rootp->v__DOT___j1__DOT__dstack__DOT__depth;
+  if (dut->rootp->v__DOT___j1__DOT__rstack__DOT__depth > v->rdepth[pc])
+    v->rdepth[pc] = dut->rootp->v__DOT___j1__DOT__rstack__DOT__depth;
 }
 
 PyObject *v3_read(PyObject *_, PyObject *args)