py: Add mp_pending_exception global variable, for VM soft interrupt.
This allows to implement KeyboardInterrupt on unix, and a much safer
ctrl-C in stmhal port. First ctrl-C is a soft one, with hope that VM
will notice it; second ctrl-C is a hard one that kills anything (for
both unix and stmhal).
One needs to check for a pending exception in the VM only for jump
opcodes. Others can't produce an infinite loop (infinite recursion is
caught by stack check).
diff --git a/py/runtime.h b/py/runtime.h
index 967a1fc..5be4703 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -116,6 +116,7 @@
mp_obj_t mp_native_call_function_n_kw(mp_obj_t fun_in, mp_uint_t n_args_kw, const mp_obj_t *args);
NORETURN void mp_native_raise(mp_obj_t o);
+extern mp_obj_t mp_pending_exception;
extern struct _mp_obj_list_t mp_sys_path_obj;
extern struct _mp_obj_list_t mp_sys_argv_obj;
#define mp_sys_path ((mp_obj_t)&mp_sys_path_obj)