M xywrun.c → xywrun.c

@@ -585,6 +585,23 @@ }
 
 //// Event dispatch (WAITING state)
 
+// Addresses of all event handler slots — add new handlers here.
+// Both has_event_handlers() and feed_next_event() stay in sync via this table.
+static const xyw_word event_handler_addrs[] = {
+    TERMINAL_ON_ARGUMENT,
+    TERMINAL_ON_KEYPRESS,
+    CLOCK_ON_TIMER_ELAPSED,
+};
+#define NUM_EVENT_HANDLERS (sizeof(event_handler_addrs) / sizeof(event_handler_addrs[0]))
+
+static int has_event_handlers(void)
+{
+    for (size_t i = 0; i < NUM_EVENT_HANDLERS; i++)
+        if (XYW_PEEKW(&xyw_memory[event_handler_addrs[i]]))
+            return 1;
+    return 0;
+}
+
 // Feed the next external event and dispatch its handler.
 // Returns 1 if an event was dispatched, 0 if no more events.
 static int feed_next_event(void)
@@ -730,9 +747,7 @@ {
             // clang-format off
             /* HLT */ case 0x00: 
                 xyw_memory[SYSTEM_STATE] &= ~SYSTEM_STATE_RUNNING;
-                if (XYW_PEEKW(&xyw_memory[TERMINAL_ON_ARGUMENT]) ||
-                    XYW_PEEKW(&xyw_memory[TERMINAL_ON_KEYPRESS]) ||
-                    XYW_PEEKW(&xyw_memory[CLOCK_ON_TIMER_ELAPSED]))
+                if (has_event_handlers())
                 {
                     xyw_memory[SYSTEM_STATE] |= SYSTEM_STATE_WAITING;
                 }
@@ -790,6 +805,7 @@ break;
             // clang-format on
         }
         (*pc)++;
+        if (xyw_memory[SYSTEM_ERROR] != XYW_ERROR_NONE) continue;
     }
     // Restore register state saved at entry (protects caller from event handler side-effects)
     *x = saved_x;