[rocketemu] add quit functionality to terminate simulation

rocketemu/dpi/dpi_pre_link.cc

@@ -8,18 +8,27 @@ class VTestBench;
 VerilatedContext *contextp;
 VTestBench *topp;
 
+bool quit;
+
+void quit_c() {
+  quit = true;
+}
+
 int verilator_main_c(int argc, char **argv) {
   // Setup context, defaults, and parse command line
   Verilated::debug(0);
   contextp = new VerilatedContext();
   contextp->fatalOnError(false);
   contextp->commandArgs(argc, argv);
 
+  // Set quit flag, true means quit
+  quit = false;
+
   // Construct the Verilated model, from Vtop.h generated from Verilating
   topp = new VTestBench(contextp);
 
   // Simulate until $finish
-  while (!contextp->gotFinish()) {
+  while (!contextp->gotFinish() && !quit) {
     // Evaluate model
     topp->eval();
     // Advance time

rocketemu/dpi/dpi_pre_link.h

@@ -13,6 +13,8 @@ extern "C" {
 
 int verilator_main_c(int argc, char **argv);
 
+void quit_c();
+
 #ifdef VM_TRACE
 void dump_wave_c(char *path);
 #endif

rocketemu/driver/src/dpi.rs

@@ -178,6 +178,8 @@ unsafe extern "C" fn cosim_watchdog_rs(target: *mut (), reason: *mut c_char) {
 extern "C" {
   fn verilator_main_c(argc: c_int, argv: *mut *mut c_char) -> c_int;
 
+  fn quit_c();
+
   #[cfg(feature = "trace")]
   fn dump_wave_c(path: *const c_char);
 
@@ -190,6 +192,12 @@ pub(crate) fn get_t() -> u64 {
   unsafe { get_t_c() / 20 }
 }
 
+pub(crate) fn quit() {
+  unsafe {
+    quit_c();
+  }
+}
+
 pub(crate) fn verilator_main() {
   let mut c_args_ptr: Vec<*mut c_char> = std::env::args()
     .collect::<Vec<String>>()

rocketemu/driver/src/sim.rs

@@ -1,6 +1,7 @@
 #[cfg(feature = "trace")]
 use crate::dpi::dump_wave;
 use crate::dpi::get_t;
+use crate::dpi::quit;
 
 use clap::{arg, Parser};
 use std::collections::HashMap;
@@ -23,6 +24,8 @@ pub(crate) struct AxiReadPayload {
   pub(crate) data: Vec<u8>,
 }
 
+const EXIT_POS: u32 = 0x4000_0000;
+
 #[derive(Parser, Debug)]
 #[command(author, version, about, long_about = None)]
 pub struct SimulationArgs {
@@ -265,6 +268,12 @@ impl Simulator {
       get_t()
     );
 
+    if addr == EXIT_POS {
+      info!("exit with code: {:x?}", data);
+      quit();
+      return;
+    }
+
     self.write_mem(addr, self.dlen / 8, strobe, data);
   }