py/make_root_pointers: Add MP_REGISTER_ROOT_POINTER parser/generator.

This adds new compile-time infrastructure to parse source code files for
`MP_REGISTER_ROOT_POINTER()` and generates a new `root_pointers.h` header
file containing the collected declarations.  This works the same as the
existing `MP_REGISTER_MODULE()` feature.

Signed-off-by: David Lechner <david@pybricks.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/py/obj.h b/py/obj.h
index c94d09afa..7ba4c0a5f 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -416,13 +416,18 @@ typedef struct _mp_rom_obj_t { mp_const_obj_t o; } mp_rom_obj_t;
 #define MP_DEFINE_CONST_STATICMETHOD_OBJ(obj_name, fun_name) const mp_rom_obj_static_class_method_t obj_name = {{&mp_type_staticmethod}, fun_name}
 #define MP_DEFINE_CONST_CLASSMETHOD_OBJ(obj_name, fun_name) const mp_rom_obj_static_class_method_t obj_name = {{&mp_type_classmethod}, fun_name}
 
+#ifndef NO_QSTR
+
 // Declare a module as a builtin, processed by makemoduledefs.py
 // param module_name: MP_QSTR_<module name>
 // param obj_module: mp_obj_module_t instance
-
-#ifndef NO_QSTR
 #define MP_REGISTER_MODULE(module_name, obj_module)
-#endif
+
+// Declare a root pointer (to avoid garbage collection of a global static variable).
+// param variable_declaration: a valid C variable declaration
+#define MP_REGISTER_ROOT_POINTER(variable_declaration)
+
+#endif // NO_QSTR
 
 // Underlying map/hash table implementation (not dict object or map function)