bricks/_common/micropython: Use SystemAbort for forced exit.

This is a much cleaner approach.

Also restore local nlr buffers instead of a global one used to previously implement the system abort.

Author: laurensvalk

bricks/_common/micropython.c

@@ -32,23 +32,11 @@
 #include "py/stackctrl.h"
 #include "py/stream.h"
 
-// Outermost nlr buffer.
-nlr_buf_t nlr_main;
-
 // Implementation for MICROPY_EVENT_POLL_HOOK
 void pb_event_poll_hook(void) {
-    while (pbio_do_one_event()) {
-    }
 
-    // On forced exit, pop back to outer nlr buffer so the exception will
-    // always be raised and the application program exits cleanly. We also need
-    // MP_STATE_THREAD(mp_pending_exception) to be the system exit exception
-    // but we don't check it because it is set along with pyexec_system_exit.
-    if (pyexec_system_exit == PYEXEC_FORCED_EXIT) {
-        while (MP_STATE_MAIN_THREAD(nlr_top) != &nlr_main) {
-            nlr_pop();
-        }
-        pyexec_system_exit = 0;
+    // Drive pbio event loop.
+    while (pbio_do_one_event()) {
     }
 
     mp_handle_pending(true);
@@ -68,7 +56,7 @@ void pbsys_main_stop_program(bool force_stop) {
     static mp_obj_exception_t system_exit;
 
     // Schedule SystemExit exception.
-    system_exit.base.type = &mp_type_SystemExit;
+    system_exit.base.type = force_stop ? &mp_type_SystemAbort : &mp_type_SystemExit;
     system_exit.traceback_alloc = 0;
     system_exit.traceback_len = 0;
     system_exit.traceback_data = NULL;
@@ -79,11 +67,6 @@ void pbsys_main_stop_program(bool force_stop) {
         MP_STATE_VM(sched_state) = MP_SCHED_PENDING;
     }
     #endif
-
-    // IDE stop button and long-press power button will force an exit.
-    if (force_stop) {
-        pyexec_system_exit = PYEXEC_FORCED_EXIT;
-    }
 }
 
 bool pbsys_main_stdin_event(uint8_t c) {
@@ -128,15 +111,16 @@ static void mp_vfs_map_minimal_new_reader(mp_reader_t *reader, mp_vfs_map_minima
 static void run_repl() {
     // Reset REPL history.
     readline_init0();
-    if (nlr_push(&nlr_main) == 0) {
+    nlr_buf_t nlr;
+    if (nlr_push(&nlr) == 0) {
         // Run the REPL.
         pyexec_friendly_repl();
         nlr_pop();
     } else {
         // clear any pending exceptions (and run any callbacks).
         mp_handle_pending(false);
         // Print which exception triggered this.
-        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr_main.ret_val);
+        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
     }
 }
 #endif
@@ -224,7 +208,8 @@ static mpy_info_t *mpy_data_find(qstr name) {
  */
 static void run_user_program(void) {
 
-    if (nlr_push(&nlr_main) == 0) {
+    nlr_buf_t nlr;
+    if (nlr_push(&nlr) == 0) {
         mpy_info_t *info = mpy_data_find(MP_QSTR___main__);
 
         if (!info) {
@@ -255,11 +240,11 @@ static void run_user_program(void) {
         mp_handle_pending(false);
 
         // Print which exception triggered this.
-        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr_main.ret_val);
+        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
 
         #if PYBRICKS_OPT_COMPILER
         // On KeyboardInterrupt, drop to REPL for debugging.
-        if (mp_obj_exception_match((mp_obj_t)nlr_main.ret_val, &mp_type_KeyboardInterrupt)) {
+        if (mp_obj_exception_match((mp_obj_t)nlr.ret_val, &mp_type_KeyboardInterrupt)) {
 
             // The global scope is preserved to facilitate debugging, but we
             // stop active resources like motors and sounds. They are stopped