Implement ROMable modules. Add math module.

mp_module_obj_t can now be put in ROM.

Configuration of float type is now similar to longint: can now choose
none, float or double as the implementation.

math module has basic math functions.  For STM port, these are not yet
implemented (they are just stub functions).

1 files changed, 28 insertions, 14 deletions

diff --git a/py/objmodule.c b/py/objmodule.c
index ab460fbd39..791932dc7f 100644
--- a/py/objmodule.c
+++ b/py/objmodule.c
@@ -10,12 +10,7 @@
 #include "obj.h"
 #include "runtime.h"
 #include "map.h"
-
-typedef struct _mp_obj_module_t {
-    mp_obj_base_t base;
-    qstr name;
-    mp_map_t *globals;
-} mp_obj_module_t;
+#include "builtin.h"
 
 STATIC void module_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
     mp_obj_module_t *self = self_in;
@@ -37,7 +32,7 @@ STATIC bool module_store_attr(mp_obj_t self_in, qstr attr, mp_obj_t value) {
     return true;
 }
 
-const mp_obj_type_t module_type = {
+const mp_obj_type_t mp_type_module = {
     { &mp_type_type },
     .name = MP_QSTR_module,
     .print = module_print,
@@ -46,32 +41,51 @@ const mp_obj_type_t module_type = {
 };
 
 mp_obj_t mp_obj_new_module(qstr module_name) {
-    mp_map_elem_t *el =  mp_map_lookup(rt_loaded_modules_get(), MP_OBJ_NEW_QSTR(module_name), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
+    mp_map_elem_t *el = mp_map_lookup(rt_loaded_modules_get(), MP_OBJ_NEW_QSTR(module_name), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
     // We could error out if module already exists, but let C extensions
     // add new members to existing modules.
     if (el->value != MP_OBJ_NULL) {
         return el->value;
     }
 
+    // create new module object
     mp_obj_module_t *o = m_new_obj(mp_obj_module_t);
-    o->base.type = &module_type;
+    o->base.type = &mp_type_module;
     o->name = module_name;
     o->globals = mp_map_new(1);
-    el->value = o;
+
+    // store __name__ entry in the module
     mp_map_lookup(o->globals, MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = MP_OBJ_NEW_QSTR(module_name);
+
+    // store the new module into the slot in the global dict holding all modules
+    el->value = o;
+
+    // return the new module
     return o;
 }
 
 mp_obj_t mp_obj_module_get(qstr module_name) {
+    // lookup module
     mp_map_elem_t *el = mp_map_lookup(rt_loaded_modules_get(), MP_OBJ_NEW_QSTR(module_name), MP_MAP_LOOKUP);
-    if (el == NULL) {
-        return MP_OBJ_NULL;
+
+    // module found, return it
+    if (el != NULL) {
+        return el->value;
     }
-    return el->value;
+
+    // module not found, look for builtin module names
+#if MICROPY_ENABLE_FLOAT
+    if (module_name == MP_QSTR_math) {
+        return (mp_obj_t)&mp_module_math;
+    }
+#endif
+
+    // no module found, return NULL object
+    return MP_OBJ_NULL;
 }
 
 mp_map_t *mp_obj_module_get_globals(mp_obj_t self_in) {
-    assert(MP_OBJ_IS_TYPE(self_in, &module_type));
+    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_module));
     mp_obj_module_t *self = self_in;
     return self->globals;
 }