Merge branch 'main-return' into 'rv64'

main: return 0 only when hitting good trap

See merge request projectn/nemu!7

src/main.c

 int init_monitor(int, char *[]);
 void ui_mainloop(int);
+int goodtrap(void);
 
 int main(int argc, char *argv[]) {
   /* Initialize the monitor. */
@@ -8,5 +9,5 @@ int main(int argc, char *argv[]) {
   /* Receive commands from user. */
   ui_mainloop(is_batch_mode);
 
-  return 0;
+  return !goodtrap();
 }

src/monitor/cpu-exec.c

@@ -14,6 +14,10 @@
 
 NEMUState nemu_state = {.state = NEMU_STOP};
 
+int goodtrap(void) {
+  return (nemu_state.state == NEMU_END && nemu_state.halt_ret == 0);
+}
+
 void interpret_rtl_exit(int state, vaddr_t halt_pc, uint32_t halt_ret) {
   nemu_state = (NEMUState) { .state = state, .halt_pc = halt_pc, .halt_ret = halt_ret };
 }