1 files changed, 51 insertions, 17 deletions

diff --git a/simulator.c b/simulator.c
index 1507f22..92c07b5 100644
--- a/simulator.c
+++ b/simulator.c
@@ -9,6 +9,7 @@
  * for more details.
  */
 
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
@@ -23,10 +24,40 @@
 static bool simulator_running;
 static struct nios2 *this_cpu = NULL;
 
-static void sigint_handler(int sig __unused)
+static void simulator_pause(void)
 {
-	info("SIGINT caught\n");
-	simulator_running = false;
+	do {
+		char input;
+
+		info("\n=== Simulator paused ===\n\n"
+		     "Please choose an option:\n"
+		     "  d  enter debug mode\n"
+		     "  r  resume simulator\n"
+		     "  q  quit simulator\n"
+		     "> ");
+
+		input = tolower(getchar());
+		do {} while (getchar() != '\n');
+		switch (input) {
+		case 'd':
+			dbg("Entering debug mode\n");
+			return;
+		case 'r':
+			return;
+		case 'q':
+			simulator_running = false;
+			return;
+		default:
+			continue;
+		}
+	} while (true);
+}
+
+static void sigint_handler(int sig)
+{
+	signal(sig, SIG_IGN);
+	simulator_pause();
+	signal(SIGINT, sigint_handler);
 }
 
 static void sigsegv_handler(int sig __unused)
@@ -58,28 +89,36 @@ void simulator_run(struct nios2 *cpu)
 	memory_dump(cpu->mem, cpu->pc, 32);
 
 	simulator_running = true;
-	while (simulator_running) {
+	while (true) {
 		instr = nios2_fetch_instr(cpu);
 
 		ret = nios2_execute_instr(cpu, instr);
-
-		if (ret == PC_INC_NORMAL)
+		switch (ret) {
+		case PC_INC_NORMAL:
 			nios2_cpu_inc_pc(cpu);
-		else if (ret == PC_INC_BY_INSTR)
-			;
-		else if (IS_EXCEPTION(ret)) {
+			break;
+		case PC_INC_BY_INSTR:
+			/* do nothing */
+			break;
+		case INSTR_BREAK:
+			simulator_pause();
+			break;
+		case INSTR_EXCEPTION:
 			dbg("Exception\n");
-			nios2_exception(cpu, EXCEPTION_CAUSE(ret));
-		} else if (ret == INSTR_UNIMPL) {
+			nios2_handle_exception(cpu);
+		case INSTR_UNIMPL:
 			simulator_running = false;
 			break;
-		} else {
+		default:
 			err("Invalid instruction 0x%08x at PC 0x%08x\n", instr, cpu->pc);
 			nios2_dump_registers(cpu);
 			simulator_running = false;
 			break;
 		}
 
+		if (!simulator_running)
+			break;
+
 		nios2_simulate(cpu);
 		device_simulate_all();
 	}
@@ -90,11 +129,6 @@ void simulator_run(struct nios2 *cpu)
 #if 0
 static int32_t simulator_mode = SIM_MODE;
 
-static void set_init_pc(struct NIOS_CPU * cpu, uint32_t pc)
-{
-	cpu->pc = pc;
-}
-
 static void quit_debug_mode(struct NIOS_CPU * cpu)
 {
 	simulator_mode = SIM_MODE;