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).

1 files changed, 1 insertions, 1 deletions

diff --git a/stmhal/usb.c b/stmhal/usb.c
index c522b6443..4211c8829 100644
--- a/stmhal/usb.c
+++ b/stmhal/usb.c
@@ -50,7 +50,7 @@ STATIC mp_obj_t mp_const_vcp_interrupt = MP_OBJ_NULL;
 
 void pyb_usb_init0(void) {
     // create an exception object for interrupting by VCP
-    mp_const_vcp_interrupt = mp_obj_new_exception_msg(&mp_type_OSError, "VCPInterrupt");
+    mp_const_vcp_interrupt = mp_obj_new_exception(&mp_type_KeyboardInterrupt);
     USBD_CDC_SetInterrupt(VCP_CHAR_NONE, mp_const_vcp_interrupt);
 }