Proper support for registering builtin modules in ROM.

Comes with some refactoring of code and renaming of files.  All modules
are now named mod*.[ch].

26 files changed, 297 insertions, 196 deletions

diff --git a/py/builtin.h b/py/builtin.h
index 69b94e0181..45da172d10 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -32,5 +32,7 @@ MP_DECLARE_CONST_FUN_OBJ(mp_builtin_sum_obj);
 
 MP_DECLARE_CONST_FUN_OBJ(mp_namedtuple_obj);
 
+extern const mp_obj_module_t mp_module_array;
+extern const mp_obj_module_t mp_module_collections;
 extern const mp_obj_module_t mp_module_math;
 extern const mp_obj_module_t mp_module_micropython;
diff --git a/py/builtinimport.c b/py/builtinimport.c
index d4d56b5171..882b128df1 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -12,6 +12,7 @@
 #include "lexerunix.h"
 #include "parse.h"
 #include "obj.h"
+#include "objmodule.h"
 #include "parsehelper.h"
 #include "compile.h"
 #include "runtime0.h"
@@ -156,7 +157,7 @@ mp_obj_t mp_builtin___import__(uint n_args, mp_obj_t *args) {
     const char *mod_str = (const char*)mp_obj_str_get_data(args[0], &mod_len);
 
     // check if module already exists
-    mp_obj_t module_obj = mp_obj_module_get(mp_obj_str_get_qstr(args[0]));
+    mp_obj_t module_obj = mp_module_get(mp_obj_str_get_qstr(args[0]));
     if (module_obj != MP_OBJ_NULL) {
         // If it's not a package, return module right away
         char *p = strchr(mod_str, '.');
@@ -169,7 +170,7 @@ mp_obj_t mp_builtin___import__(uint n_args, mp_obj_t *args) {
         }
         // Otherwise, we need to return top-level package
         qstr pkg_name = qstr_from_strn(mod_str, p - mod_str);
-        return mp_obj_module_get(pkg_name);
+        return mp_module_get(pkg_name);
     }
 
     uint last = 0;
@@ -200,7 +201,7 @@ mp_obj_t mp_builtin___import__(uint n_args, mp_obj_t *args) {
                 nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_ImportError, "ImportError: No module named '%s'", qstr_str(mod_name)));
             }
 
-            module_obj = mp_obj_module_get(mod_name);
+            module_obj = mp_module_get(mod_name);
             if (module_obj == MP_OBJ_NULL) {
                 // module not already loaded, so load it!
 
diff --git a/py/builtintables.c b/py/builtintables.c
new file mode 100644
index 0000000000..e9c1bcab2d
--- /dev/null
+++ b/py/builtintables.c
@@ -0,0 +1,154 @@
+#include <stdlib.h>
+
+#include "misc.h"
+#include "mpconfig.h"
+#include "qstr.h"
+#include "obj.h"
+#include "builtin.h"
+#include "builtintables.h"
+#include "objarray.h"
+
+// builtins
+// we put these tables in ROM because they're always needed and take up quite a bit of room in RAM
+// in fact, it uses less ROM here in table form than the equivalent in code form initialising a dynamic mp_map_t object in RAM
+// at the moment it's a linear table, but we could convert it to a const mp_map_t table with a simple preprocessing script
+
+typedef struct _mp_builtin_elem_t {
+    qstr qstr;
+    mp_obj_t elem;
+} mp_builtin_elem_t;
+
+STATIC const mp_builtin_elem_t builtin_object_table[] = {
+    // built-in core functions
+    { MP_QSTR___build_class__, (mp_obj_t)&mp_builtin___build_class___obj },
+    { MP_QSTR___import__, (mp_obj_t)&mp_builtin___import___obj },
+    { MP_QSTR___repl_print__, (mp_obj_t)&mp_builtin___repl_print___obj },
+
+    // built-in types
+    { MP_QSTR_bool, (mp_obj_t)&bool_type },
+    { MP_QSTR_bytes, (mp_obj_t)&bytes_type },
+#if MICROPY_ENABLE_FLOAT
+    { MP_QSTR_complex, (mp_obj_t)&mp_type_complex },
+#endif
+    { MP_QSTR_dict, (mp_obj_t)&dict_type },
+    { MP_QSTR_enumerate, (mp_obj_t)&enumerate_type },
+    { MP_QSTR_filter, (mp_obj_t)&filter_type },
+#if MICROPY_ENABLE_FLOAT
+    { MP_QSTR_float, (mp_obj_t)&mp_type_float },
+#endif
+    { MP_QSTR_int, (mp_obj_t)&int_type },
+    { MP_QSTR_list, (mp_obj_t)&list_type },
+    { MP_QSTR_map, (mp_obj_t)&map_type },
+    { MP_QSTR_object, (mp_obj_t)&mp_type_object },
+    { MP_QSTR_set, (mp_obj_t)&set_type },
+    { MP_QSTR_str, (mp_obj_t)&str_type },
+    { MP_QSTR_super, (mp_obj_t)&super_type },
+    { MP_QSTR_tuple, (mp_obj_t)&tuple_type },
+    { MP_QSTR_type, (mp_obj_t)&mp_type_type },
+    { MP_QSTR_zip, (mp_obj_t)&zip_type },
+
+    { MP_QSTR_classmethod, (mp_obj_t)&mp_type_classmethod },
+    { MP_QSTR_staticmethod, (mp_obj_t)&mp_type_staticmethod },
+
+    // built-in user functions
+    { MP_QSTR_abs, (mp_obj_t)&mp_builtin_abs_obj },
+    { MP_QSTR_all, (mp_obj_t)&mp_builtin_all_obj },
+    { MP_QSTR_any, (mp_obj_t)&mp_builtin_any_obj },
+    { MP_QSTR_callable, (mp_obj_t)&mp_builtin_callable_obj },
+    { MP_QSTR_chr, (mp_obj_t)&mp_builtin_chr_obj },
+    { MP_QSTR_dir, (mp_obj_t)&mp_builtin_dir_obj },
+    { MP_QSTR_divmod, (mp_obj_t)&mp_builtin_divmod_obj },
+    { MP_QSTR_eval, (mp_obj_t)&mp_builtin_eval_obj },
+    { MP_QSTR_exec, (mp_obj_t)&mp_builtin_exec_obj },
+    { MP_QSTR_hash, (mp_obj_t)&mp_builtin_hash_obj },
+    { MP_QSTR_id, (mp_obj_t)&mp_builtin_id_obj },
+    { MP_QSTR_isinstance, (mp_obj_t)&mp_builtin_isinstance_obj },
+    { MP_QSTR_issubclass, (mp_obj_t)&mp_builtin_issubclass_obj },
+    { MP_QSTR_iter, (mp_obj_t)&mp_builtin_iter_obj },
+    { MP_QSTR_len, (mp_obj_t)&mp_builtin_len_obj },
+    { MP_QSTR_max, (mp_obj_t)&mp_builtin_max_obj },
+    { MP_QSTR_min, (mp_obj_t)&mp_builtin_min_obj },
+    { MP_QSTR_next, (mp_obj_t)&mp_builtin_next_obj },
+    { MP_QSTR_ord, (mp_obj_t)&mp_builtin_ord_obj },
+    { MP_QSTR_pow, (mp_obj_t)&mp_builtin_pow_obj },
+    { MP_QSTR_print, (mp_obj_t)&mp_builtin_print_obj },
+    { MP_QSTR_range, (mp_obj_t)&mp_builtin_range_obj },
+    { MP_QSTR_repr, (mp_obj_t)&mp_builtin_repr_obj },
+    { MP_QSTR_sorted, (mp_obj_t)&mp_builtin_sorted_obj },
+    { MP_QSTR_sum, (mp_obj_t)&mp_builtin_sum_obj },
+    { MP_QSTR_bytearray, (mp_obj_t)&mp_builtin_bytearray_obj },
+
+    // built-in exceptions
+    { MP_QSTR_BaseException, (mp_obj_t)&mp_type_BaseException },
+    { MP_QSTR_ArithmeticError, (mp_obj_t)&mp_type_ArithmeticError },
+    { MP_QSTR_AssertionError, (mp_obj_t)&mp_type_AssertionError },
+    { MP_QSTR_AttributeError, (mp_obj_t)&mp_type_AttributeError },
+    { MP_QSTR_BufferError, (mp_obj_t)&mp_type_BufferError },
+    { MP_QSTR_EOFError, (mp_obj_t)&mp_type_EOFError },
+    { MP_QSTR_EnvironmentError, (mp_obj_t)&mp_type_EnvironmentError },
+    { MP_QSTR_Exception, (mp_obj_t)&mp_type_Exception },
+    { MP_QSTR_FloatingPointError, (mp_obj_t)&mp_type_FloatingPointError },
+    { MP_QSTR_GeneratorExit, (mp_obj_t)&mp_type_GeneratorExit },
+    { MP_QSTR_IOError, (mp_obj_t)&mp_type_IOError },
+    { MP_QSTR_ImportError, (mp_obj_t)&mp_type_ImportError },
+    { MP_QSTR_IndentationError, (mp_obj_t)&mp_type_IndentationError },
+    { MP_QSTR_IndexError, (mp_obj_t)&mp_type_IndexError },
+    { MP_QSTR_KeyError, (mp_obj_t)&mp_type_KeyError },
+    { MP_QSTR_LookupError, (mp_obj_t)&mp_type_LookupError },
+    { MP_QSTR_MemoryError, (mp_obj_t)&mp_type_MemoryError },
+    { MP_QSTR_NameError, (mp_obj_t)&mp_type_NameError },
+    { MP_QSTR_NotImplementedError, (mp_obj_t)&mp_type_NotImplementedError },
+    { MP_QSTR_OSError, (mp_obj_t)&mp_type_OSError },
+    { MP_QSTR_OverflowError, (mp_obj_t)&mp_type_OverflowError },
+    { MP_QSTR_ReferenceError, (mp_obj_t)&mp_type_ReferenceError },
+    { MP_QSTR_RuntimeError, (mp_obj_t)&mp_type_RuntimeError },
+    { MP_QSTR_SyntaxError, (mp_obj_t)&mp_type_SyntaxError },
+    { MP_QSTR_SystemError, (mp_obj_t)&mp_type_SystemError },
+    { MP_QSTR_SystemExit, (mp_obj_t)&mp_type_SystemExit },
+    { MP_QSTR_TabError, (mp_obj_t)&mp_type_TabError },
+    { MP_QSTR_TypeError, (mp_obj_t)&mp_type_TypeError },
+    { MP_QSTR_UnboundLocalError, (mp_obj_t)&mp_type_UnboundLocalError },
+    { MP_QSTR_ValueError, (mp_obj_t)&mp_type_ValueError },
+    { MP_QSTR_ZeroDivisionError, (mp_obj_t)&mp_type_ZeroDivisionError },
+    { MP_QSTR_StopIteration, (mp_obj_t)&mp_type_StopIteration },
+    // Somehow CPython managed to have OverflowError not inherit from ValueError ;-/
+    // TODO: For MICROPY_CPYTHON_COMPAT==0 use ValueError to avoid exc proliferation
+
+    // Extra builtins as defined by a port
+    MICROPY_EXTRA_BUILTINS
+
+    { MP_QSTR_, MP_OBJ_NULL }, // end of list sentinel
+};
+
+STATIC const mp_builtin_elem_t builtin_module_table[] = {
+    { MP_QSTR_micropython, (mp_obj_t)&mp_module_micropython },
+
+    { MP_QSTR_array, (mp_obj_t)&mp_module_array },
+    { MP_QSTR_collections, (mp_obj_t)&mp_module_collections },
+
+#if MICROPY_ENABLE_FLOAT
+    { MP_QSTR_math, (mp_obj_t)&mp_module_math },
+#endif
+
+    // extra builtin modules as defined by a port
+    MICROPY_EXTRA_BUILTIN_MODULES
+
+    { MP_QSTR_, MP_OBJ_NULL }, // end of list sentinel
+};
+
+STATIC mp_obj_t mp_builtin_tables_lookup(const mp_builtin_elem_t *table, qstr q) {
+    for (; table->qstr != MP_QSTR_; table++) {
+        if (table->qstr == q) {
+            return table->elem;
+        }
+    }
+    return MP_OBJ_NULL;
+}
+
+mp_obj_t mp_builtin_tables_lookup_object(qstr q) {
+    return mp_builtin_tables_lookup(&builtin_object_table[0], q);
+}
+
+mp_obj_t mp_builtin_tables_lookup_module(qstr q) {
+    return mp_builtin_tables_lookup(&builtin_module_table[0], q);
+}
diff --git a/py/builtintables.h b/py/builtintables.h
new file mode 100644
index 0000000000..9b22b66e03
--- /dev/null
+++ b/py/builtintables.h
@@ -0,0 +1,2 @@
+mp_obj_t mp_builtin_tables_lookup_object(qstr q);
+mp_obj_t mp_builtin_tables_lookup_module(qstr q);
diff --git a/py/modarray.c b/py/modarray.c
new file mode 100644
index 0000000000..2544f7ed59
--- /dev/null
+++ b/py/modarray.c
@@ -0,0 +1,25 @@
+#include "misc.h"
+#include "mpconfig.h"
+#include "qstr.h"
+#include "obj.h"
+#include "map.h"
+#include "builtin.h"
+
+STATIC const mp_map_elem_t mp_module_array_globals_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_array) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_array), (mp_obj_t)&mp_type_array },
+};
+
+STATIC const mp_map_t mp_module_array_globals = {
+    .all_keys_are_qstrs = 1,
+    .table_is_fixed_array = 1,
+    .used = sizeof(mp_module_array_globals_table) / sizeof(mp_map_elem_t),
+    .alloc = sizeof(mp_module_array_globals_table) / sizeof(mp_map_elem_t),
+    .table = (mp_map_elem_t*)mp_module_array_globals_table,
+};
+
+const mp_obj_module_t mp_module_array = {
+    .base = { &mp_type_module },
+    .name = MP_QSTR_array,
+    .globals = (mp_map_t*)&mp_module_array_globals,
+};
diff --git a/py/modcollections.c b/py/modcollections.c
new file mode 100644
index 0000000000..ad951d5e9e
--- /dev/null
+++ b/py/modcollections.c
@@ -0,0 +1,25 @@
+#include "misc.h"
+#include "mpconfig.h"
+#include "qstr.h"
+#include "obj.h"
+#include "map.h"
+#include "builtin.h"
+
+STATIC const mp_map_elem_t mp_module_collections_globals_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_collections) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_namedtuple), (mp_obj_t)&mp_namedtuple_obj },
+};
+
+STATIC const mp_map_t mp_module_collections_globals = {
+    .all_keys_are_qstrs = 1,
+    .table_is_fixed_array = 1,
+    .used = sizeof(mp_module_collections_globals_table) / sizeof(mp_map_elem_t),
+    .alloc = sizeof(mp_module_collections_globals_table) / sizeof(mp_map_elem_t),
+    .table = (mp_map_elem_t*)mp_module_collections_globals_table,
+};
+
+const mp_obj_module_t mp_module_collections = {
+    .base = { &mp_type_module },
+    .name = MP_QSTR_collections,
+    .globals = (mp_map_t*)&mp_module_collections_globals,
+};
diff --git a/py/builtinmath.c b/py/modmath.c
index b814822531..b814822531 100644
--- a/py/builtinmath.c
+++ b/py/modmath.c
diff --git a/py/builtinmp.c b/py/modmicropython.c
index 3b73517963..96ceb811c9 100644
--- a/py/builtinmp.c
+++ b/py/modmicropython.c
@@ -1,4 +1,3 @@
-
 #include "misc.h"
 #include "mpconfig.h"
 #include "qstr.h"
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 5b13c46480..09cc37913a 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -125,10 +125,16 @@ typedef double mp_float_t;
 #define MICROPY_PATH_MAX (512)
 #endif
 
-// Additional builtin function definitions - see runtime.c:builtin_table for format.
+// Additional builtin function definitions - see builtintables.c:builtin_object_table for format.
 #ifndef MICROPY_EXTRA_BUILTINS
 #define MICROPY_EXTRA_BUILTINS
 #endif
+
+// Additional builtin module definitions - see builtintables.c:builtin_module_table for format.
+#ifndef MICROPY_EXTRA_BUILTIN_MODULES
+#define MICROPY_EXTRA_BUILTIN_MODULES
+#endif
+
 /*****************************************************************************/
 /* Miscellaneous settings                                                    */
 
diff --git a/py/obj.h b/py/obj.h
index dcb43c0748..d4f9144ea8 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -417,7 +417,7 @@ void mp_obj_slice_get(mp_obj_t self_in, machine_int_t *start, machine_int_t *sto
 extern const mp_obj_type_t zip_type;
 
 // array
-extern const mp_obj_type_t array_type;
+extern const mp_obj_type_t mp_type_array;
 uint mp_obj_array_len(mp_obj_t self_in);
 mp_obj_t mp_obj_new_bytearray_by_ref(uint n, void *items);
 
@@ -454,9 +454,6 @@ typedef struct _mp_obj_module_t {
     struct _mp_map_t *globals;
 } mp_obj_module_t;
 extern const mp_obj_type_t mp_type_module;
-mp_obj_t mp_obj_new_module(qstr module_name);
-mp_obj_t mp_obj_module_get(qstr module_name);
-void mp_obj_module_register(qstr qstr, mp_obj_t module); //use for loading statically allocated modules
 struct _mp_map_t *mp_obj_module_get_globals(mp_obj_t self_in);
 
 // staticmethod and classmethod types; defined here so we can make const versions
diff --git a/py/objarray.c b/py/objarray.c
index ee43bde960..69f60e000a 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -121,7 +121,7 @@ STATIC mp_obj_t array_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
 }
 
 STATIC mp_obj_t array_append(mp_obj_t self_in, mp_obj_t arg) {
-    assert(MP_OBJ_IS_TYPE(self_in, &array_type));
+    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_array));
     mp_obj_array_t *self = self_in;
     if (self->free == 0) {
         int item_sz = mp_binary_get_size(self->typecode);
@@ -154,7 +154,7 @@ STATIC const mp_method_t array_type_methods[] = {
     { NULL, NULL },
 };
 
-const mp_obj_type_t array_type = {
+const mp_obj_type_t mp_type_array = {
     { &mp_type_type },
     .name = MP_QSTR_array,
     .print = array_print,
@@ -169,7 +169,7 @@ const mp_obj_type_t array_type = {
 
 STATIC mp_obj_array_t *array_new(char typecode, uint n) {
     mp_obj_array_t *o = m_new_obj(mp_obj_array_t);
-    o->base.type = &array_type;
+    o->base.type = &mp_type_array;
     o->typecode = typecode;
     o->free = 0;
     o->len = n;
@@ -190,7 +190,7 @@ mp_obj_t mp_obj_new_bytearray(uint n, void *items) {
 // Create bytearray which references specified memory area
 mp_obj_t mp_obj_new_bytearray_by_ref(uint n, void *items) {
     mp_obj_array_t *o = m_new_obj(mp_obj_array_t);
-    o->base.type = &array_type;
+    o->base.type = &mp_type_array;
     o->typecode = BYTEARRAY_TYPECODE;
     o->free = 0;
     o->len = n;
@@ -207,7 +207,7 @@ typedef struct _mp_obj_array_it_t {
     machine_uint_t cur;
 } mp_obj_array_it_t;
 
-mp_obj_t array_it_iternext(mp_obj_t self_in) {
+STATIC mp_obj_t array_it_iternext(mp_obj_t self_in) {
     mp_obj_array_it_t *self = self_in;
     if (self->cur < self->array->len) {
         return mp_binary_get_val(self->array->typecode, self->array->items, self->cur++);
@@ -222,7 +222,7 @@ STATIC const mp_obj_type_t array_it_type = {
     .iternext = array_it_iternext,
 };
 
-mp_obj_t array_iterator_new(mp_obj_t array_in) {
+STATIC mp_obj_t array_iterator_new(mp_obj_t array_in) {
     mp_obj_array_t *array = array_in;
     mp_obj_array_it_t *o = m_new_obj(mp_obj_array_it_t);
     o->base.type = &array_it_type;
diff --git a/py/objmodule.c b/py/objmodule.c
index 21fec9e866..a388ca3f37 100644
--- a/py/objmodule.c
+++ b/py/objmodule.c
@@ -6,9 +6,12 @@
 #include "mpconfig.h"
 #include "qstr.h"
 #include "obj.h"
+#include "objmodule.h"
 #include "runtime.h"
 #include "map.h"
-#include "builtin.h"
+#include "builtintables.h"
+
+STATIC mp_map_t mp_loaded_modules_map; // TODO: expose as sys.modules
 
 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;
@@ -39,7 +42,7 @@ const mp_obj_type_t mp_type_module = {
 };
 
 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(&mp_loaded_modules_map, 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) {
@@ -62,9 +65,27 @@ mp_obj_t mp_obj_new_module(qstr module_name) {
     return o;
 }
 
-mp_obj_t mp_obj_module_get(qstr module_name) {
+mp_map_t *mp_obj_module_get_globals(mp_obj_t self_in) {
+    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_module));
+    mp_obj_module_t *self = self_in;
+    return self->globals;
+}
+
+/******************************************************************************/
+// Global module table and related functions
+
+void mp_module_init(void) {
+    mp_map_init(&mp_loaded_modules_map, 3);
+}
+
+void mp_module_deinit(void) {
+    mp_map_deinit(&mp_loaded_modules_map);
+}
+
+// returns MP_OBJ_NULL if not found
+mp_obj_t mp_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);
+    mp_map_elem_t *el = mp_map_lookup(&mp_loaded_modules_map, MP_OBJ_NEW_QSTR(module_name), MP_MAP_LOOKUP);
 
     // module found, return it
     if (el != NULL) {
@@ -72,23 +93,10 @@ mp_obj_t mp_obj_module_get(qstr module_name) {
     }
 
     // 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;
-}
-
-void mp_obj_module_register(qstr qstr, mp_obj_t module)
-{
-    mp_map_lookup(rt_loaded_modules_get(), MP_OBJ_NEW_QSTR(qstr), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = module;
+    // it will return MP_OBJ_NULL if nothing found
+    return mp_builtin_tables_lookup_module(module_name);
 }
 
-mp_map_t *mp_obj_module_get_globals(mp_obj_t self_in) {
-    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_module));
-    mp_obj_module_t *self = self_in;
-    return self->globals;
+void mp_module_register(qstr qstr, mp_obj_t module) {
+    mp_map_lookup(&mp_loaded_modules_map, MP_OBJ_NEW_QSTR(qstr), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = module;
 }
diff --git a/py/objmodule.h b/py/objmodule.h
new file mode 100644
index 0000000000..270551da4f
--- /dev/null
+++ b/py/objmodule.h
@@ -0,0 +1,4 @@
+void mp_module_init(void);
+void mp_module_deinit(void);
+mp_obj_t mp_module_get(qstr module_name);
+void mp_module_register(qstr qstr, mp_obj_t module);
diff --git a/py/py.mk b/py/py.mk
index 624797d823..2247b6babb 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -74,8 +74,11 @@ PY_O_BASENAME = \
 	builtin.o \
 	builtinimport.o \
 	builtinevex.o \
-	builtinmp.o \
-	builtinmath.o \
+	builtintables.o \
+	modarray.o \
+	modcollections.o \
+	modmath.o \
+	modmicropython.o \
 	vm.o \
 	showbc.o \
 	repl.o \
diff --git a/py/runtime.c b/py/runtime.c
index 17a9e778d1..0f5d1229f2 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -12,12 +12,13 @@
 #include "mpconfig.h"
 #include "qstr.h"
 #include "obj.h"
+#include "objmodule.h"
 #include "parsenum.h"
 #include "runtime0.h"
 #include "runtime.h"
 #include "map.h"
 #include "builtin.h"
-#include "objarray.h"
+#include "builtintables.h"
 #include "bc.h"
 #include "intdivmod.h"
 
@@ -35,7 +36,6 @@
 STATIC mp_map_t *map_locals;
 STATIC mp_map_t *map_globals;
 STATIC mp_map_t map_builtins;
-STATIC mp_map_t map_loaded_modules; // TODO: expose as sys.modules
 
 typedef enum {
     MP_CODE_NONE,
@@ -72,119 +72,6 @@ STATIC mp_code_t *unique_codes = NULL;
 FILE *fp_write_code = NULL;
 #endif
 
-// builtins
-// we put this table in ROM because it's always needed and takes up quite a bit of room in RAM
-// in fact, it uses less ROM here in table form than the equivalent in code form initialising a dynamic mp_map_t object in RAM
-// at the moment it's a linear table, but we could convert it to a const mp_map_t table with a simple preprocessing script
-// if we wanted to allow dynamic modification of the builtins, we could provide an mp_map_t object which is searched before this one
-
-typedef struct _mp_builtin_elem_t {
-    qstr qstr;
-    mp_obj_t fun;
-} mp_builtin_elem_t;
-
-STATIC const mp_builtin_elem_t builtin_table[] = {
-    // built-in core functions
-    { MP_QSTR___build_class__, (mp_obj_t)&mp_builtin___build_class___obj },
-    { MP_QSTR___import__, (mp_obj_t)&mp_builtin___import___obj },
-    { MP_QSTR___repl_print__, (mp_obj_t)&mp_builtin___repl_print___obj },
-
-    // built-in types
-    { MP_QSTR_bool, (mp_obj_t)&bool_type },
-    { MP_QSTR_bytes, (mp_obj_t)&bytes_type },
-#if MICROPY_ENABLE_FLOAT
-    { MP_QSTR_complex, (mp_obj_t)&mp_type_complex },
-#endif
-    { MP_QSTR_dict, (mp_obj_t)&dict_type },
-    { MP_QSTR_enumerate, (mp_obj_t)&enumerate_type },
-    { MP_QSTR_filter, (mp_obj_t)&filter_type },
-#if MICROPY_ENABLE_FLOAT
-    { MP_QSTR_float, (mp_obj_t)&mp_type_float },
-#endif
-    { MP_QSTR_int, (mp_obj_t)&int_type },
-    { MP_QSTR_list, (mp_obj_t)&list_type },
-    { MP_QSTR_map, (mp_obj_t)&map_type },
-    { MP_QSTR_object, (mp_obj_t)&mp_type_object },
-    { MP_QSTR_set, (mp_obj_t)&set_type },
-    { MP_QSTR_str, (mp_obj_t)&str_type },
-    { MP_QSTR_super, (mp_obj_t)&super_type },
-    { MP_QSTR_tuple, (mp_obj_t)&tuple_type },
-    { MP_QSTR_type, (mp_obj_t)&mp_type_type },
-    { MP_QSTR_zip, (mp_obj_t)&zip_type },
-
-    { MP_QSTR_classmethod, (mp_obj_t)&mp_type_classmethod },
-    { MP_QSTR_staticmethod, (mp_obj_t)&mp_type_staticmethod },
-
-    // built-in user functions
-    { MP_QSTR_abs, (mp_obj_t)&mp_builtin_abs_obj },
-    { MP_QSTR_all, (mp_obj_t)&mp_builtin_all_obj },
-    { MP_QSTR_any, (mp_obj_t)&mp_builtin_any_obj },
-    { MP_QSTR_callable, (mp_obj_t)&mp_builtin_callable_obj },
-    { MP_QSTR_chr, (mp_obj_t)&mp_builtin_chr_obj },
-    { MP_QSTR_dir, (mp_obj_t)&mp_builtin_dir_obj },
-    { MP_QSTR_divmod, (mp_obj_t)&mp_builtin_divmod_obj },
-    { MP_QSTR_eval, (mp_obj_t)&mp_builtin_eval_obj },
-    { MP_QSTR_exec, (mp_obj_t)&mp_builtin_exec_obj },
-    { MP_QSTR_hash, (mp_obj_t)&mp_builtin_hash_obj },
-    { MP_QSTR_id, (mp_obj_t)&mp_builtin_id_obj },
-    { MP_QSTR_isinstance, (mp_obj_t)&mp_builtin_isinstance_obj },
-    { MP_QSTR_issubclass, (mp_obj_t)&mp_builtin_issubclass_obj },
-    { MP_QSTR_iter, (mp_obj_t)&mp_builtin_iter_obj },
-    { MP_QSTR_len, (mp_obj_t)&mp_builtin_len_obj },
-    { MP_QSTR_max, (mp_obj_t)&mp_builtin_max_obj },
-    { MP_QSTR_min, (mp_obj_t)&mp_builtin_min_obj },
-    { MP_QSTR_next, (mp_obj_t)&mp_builtin_next_obj },
-    { MP_QSTR_ord, (mp_obj_t)&mp_builtin_ord_obj },
-    { MP_QSTR_pow, (mp_obj_t)&mp_builtin_pow_obj },
-    { MP_QSTR_print, (mp_obj_t)&mp_builtin_print_obj },
-    { MP_QSTR_range, (mp_obj_t)&mp_builtin_range_obj },
-    { MP_QSTR_repr, (mp_obj_t)&mp_builtin_repr_obj },
-    { MP_QSTR_sorted, (mp_obj_t)&mp_builtin_sorted_obj },
-    { MP_QSTR_sum, (mp_obj_t)&mp_builtin_sum_obj },
-    { MP_QSTR_bytearray, (mp_obj_t)&mp_builtin_bytearray_obj },
-
-    // built-in exceptions
-    { MP_QSTR_BaseException, (mp_obj_t)&mp_type_BaseException },
-    { MP_QSTR_ArithmeticError, (mp_obj_t)&mp_type_ArithmeticError },
-    { MP_QSTR_AssertionError, (mp_obj_t)&mp_type_AssertionError },
-    { MP_QSTR_AttributeError, (mp_obj_t)&mp_type_AttributeError },
-    { MP_QSTR_BufferError, (mp_obj_t)&mp_type_BufferError },
-    { MP_QSTR_EOFError, (mp_obj_t)&mp_type_EOFError },
-    { MP_QSTR_EnvironmentError, (mp_obj_t)&mp_type_EnvironmentError },
-    { MP_QSTR_Exception, (mp_obj_t)&mp_type_Exception },
-    { MP_QSTR_FloatingPointError, (mp_obj_t)&mp_type_FloatingPointError },
-    { MP_QSTR_GeneratorExit, (mp_obj_t)&mp_type_GeneratorExit },
-    { MP_QSTR_IOError, (mp_obj_t)&mp_type_IOError },
-    { MP_QSTR_ImportError, (mp_obj_t)&mp_type_ImportError },
-    { MP_QSTR_IndentationError, (mp_obj_t)&mp_type_IndentationError },
-    { MP_QSTR_IndexError, (mp_obj_t)&mp_type_IndexError },
-    { MP_QSTR_KeyError, (mp_obj_t)&mp_type_KeyError },
-    { MP_QSTR_LookupError, (mp_obj_t)&mp_type_LookupError },
-    { MP_QSTR_MemoryError, (mp_obj_t)&mp_type_MemoryError },
-    { MP_QSTR_NameError, (mp_obj_t)&mp_type_NameError },
-    { MP_QSTR_NotImplementedError, (mp_obj_t)&mp_type_NotImplementedError },
-    { MP_QSTR_OSError, (mp_obj_t)&mp_type_OSError },
-    { MP_QSTR_OverflowError, (mp_obj_t)&mp_type_OverflowError },
-    { MP_QSTR_ReferenceError, (mp_obj_t)&mp_type_ReferenceError },
-    { MP_QSTR_RuntimeError, (mp_obj_t)&mp_type_RuntimeError },
-    { MP_QSTR_SyntaxError, (mp_obj_t)&mp_type_SyntaxError },
-    { MP_QSTR_SystemError, (mp_obj_t)&mp_type_SystemError },
-    { MP_QSTR_SystemExit, (mp_obj_t)&mp_type_SystemExit },
-    { MP_QSTR_TabError, (mp_obj_t)&mp_type_TabError },
-    { MP_QSTR_TypeError, (mp_obj_t)&mp_type_TypeError },
-    { MP_QSTR_UnboundLocalError, (mp_obj_t)&mp_type_UnboundLocalError },
-    { MP_QSTR_ValueError, (mp_obj_t)&mp_type_ValueError },
-    { MP_QSTR_ZeroDivisionError, (mp_obj_t)&mp_type_ZeroDivisionError },
-    { MP_QSTR_StopIteration, (mp_obj_t)&mp_type_StopIteration },
-    // Somehow CPython managed to have OverflowError not inherit from ValueError ;-/
-    // TODO: For MICROPY_CPYTHON_COMPAT==0 use ValueError to avoid exc proliferation
-
-    // Extra builtins as defined by a port
-    MICROPY_EXTRA_BUILTINS
-
-    { MP_QSTR_, MP_OBJ_NULL }, // end of list sentinel
-};
-
 // a good optimising compiler will inline this if necessary
 STATIC void mp_map_add_qstr(mp_map_t *map, qstr qstr, mp_obj_t value) {
     mp_map_lookup(map, MP_OBJ_NEW_QSTR(qstr), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
@@ -193,23 +80,17 @@ STATIC void mp_map_add_qstr(mp_map_t *map, qstr qstr, mp_obj_t value) {
 void rt_init(void) {
     // locals = globals for outer module (see Objects/frameobject.c/PyFrame_New())
     map_locals = map_globals = mp_map_new(1);
-    mp_map_add_qstr(map_globals, MP_QSTR___name__, MP_OBJ_NEW_QSTR(MP_QSTR___main__));
 
     // init built-in hash table
     mp_map_init(&map_builtins, 3);
 
-    // init loaded modules table
-    mp_map_init(&map_loaded_modules, 3);
+    // init global module stuff
+    mp_module_init();
 
-    // built-in objects
+    // add some builtins that can't be done in ROM
+    mp_map_add_qstr(map_globals, MP_QSTR___name__, MP_OBJ_NEW_QSTR(MP_QSTR___main__));
     mp_map_add_qstr(&map_builtins, MP_QSTR_Ellipsis, mp_const_ellipsis);
 
-    mp_obj_t m_array = mp_obj_new_module(MP_QSTR_array);
-    rt_store_attr(m_array, MP_QSTR_array, (mp_obj_t)&array_type);
-
-    mp_obj_t m_collections = mp_obj_new_module(MP_QSTR_collections);
-    rt_store_attr(m_collections, MP_QSTR_namedtuple, (mp_obj_t)&mp_namedtuple_obj);
-
 #if MICROPY_CPYTHON_COMPAT
     // Precreate sys module, so "import sys" didn't throw exceptions.
     mp_obj_t m_sys = mp_obj_new_module(MP_QSTR_sys);
@@ -221,10 +102,6 @@ void rt_init(void) {
     //sys_path = mp_obj_new_list(0, NULL);
     //rt_store_attr(m_sys, MP_QSTR_path, sys_path);
 
-    // we pre-import the micropython module
-    // probably shouldn't do this, so we are compatible with CPython
-    rt_store_name(MP_QSTR_micropython, (mp_obj_t)&mp_module_micropython);
-
     // TODO: wastes one mp_code_t structure in mem
     next_unique_code_id = 1; // 0 indicates "no code"
     unique_codes_alloc = 0;
@@ -238,8 +115,8 @@ void rt_init(void) {
 void rt_deinit(void) {
     m_del(mp_code_t, unique_codes, unique_codes_alloc);
     mp_map_free(map_globals);
-    mp_map_deinit(&map_loaded_modules);
     mp_map_deinit(&map_builtins);
+    mp_module_deinit();
 #ifdef WRITE_CODE
     if (fp_write_code != NULL) {
         fclose(fp_write_code);
@@ -428,10 +305,9 @@ mp_obj_t rt_load_global(qstr qstr) {
     if (elem == NULL) {
         elem = mp_map_lookup(&map_builtins, MP_OBJ_NEW_QSTR(qstr), MP_MAP_LOOKUP);
         if (elem == NULL) {
-            for (const mp_builtin_elem_t *e = &builtin_table[0]; e->qstr != MP_QSTR_; e++) {
-                if (e->qstr == qstr) {
-                    return e->fun;
-                }
+            mp_obj_t o = mp_builtin_tables_lookup_object(qstr);
+            if (o != MP_OBJ_NULL) {
+                return o;
             }
             nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_NameError, "name '%s' is not defined", qstr_str(qstr)));
         }
@@ -441,10 +317,13 @@ mp_obj_t rt_load_global(qstr qstr) {
 
 mp_obj_t rt_load_build_class(void) {
     DEBUG_OP_printf("load_build_class\n");
+    // lookup __build_class__ in dynamic table of builtins first
     mp_map_elem_t *elem = mp_map_lookup(&map_builtins, MP_OBJ_NEW_QSTR(MP_QSTR___build_class__), MP_MAP_LOOKUP);
     if (elem != NULL) {
+        // found user-defined __build_class__, return it
         return elem->value;
     } else {
+        // no user-defined __build_class__, return builtin one
         return (mp_obj_t)&mp_builtin___build_class___obj;
     }
 }
@@ -1141,10 +1020,6 @@ void rt_globals_set(mp_map_t *m) {
     map_globals = m;
 }
 
-mp_map_t *rt_loaded_modules_get(void) {
-    return &map_loaded_modules;
-}
-
 // these must correspond to the respective enum
 void *const rt_fun_table[RT_F_NUMBER_OF] = {
     rt_load_const_dec,
diff --git a/stm/main.c b/stm/main.c
index 6ad3111276..44be4d348c 100644
--- a/stm/main.c
+++ b/stm/main.c
@@ -24,6 +24,7 @@
 #include "lexerfatfs.h"
 #include "parse.h"
 #include "obj.h"
+#include "objmodule.h"
 #include "parsehelper.h"
 #include "compile.h"
 #include "runtime0.h"
@@ -273,7 +274,7 @@ soft_reset:
     rt_store_name(MP_QSTR_open, rt_make_function_n(2, pyb_io_open));
 
     // load the pyb module
-    mp_obj_module_register(MP_QSTR_pyb, (mp_obj_t)&pyb_module);
+    mp_module_register(MP_QSTR_pyb, (mp_obj_t)&pyb_module);
 
     // check if user switch held (initiates reset of filesystem)
     bool reset_filesystem = false;
diff --git a/stm/pybmodule.c b/stm/pybmodule.c
index ed705af73d..fde61b513d 100644
--- a/stm/pybmodule.c
+++ b/stm/pybmodule.c
@@ -181,7 +181,8 @@ STATIC mp_obj_t pyb_standby(void) {
 MP_DEFINE_CONST_FUN_OBJ_0(pyb_standby_obj, pyb_standby);
 
 STATIC mp_obj_t pyb_hid_send_report(mp_obj_t arg) {
-    mp_obj_t *items = mp_obj_get_array_fixed_n(arg, 4);
+    mp_obj_t *items;
+    mp_obj_get_array_fixed_n(arg, 4, &items);
     uint8_t data[4];
     data[0] = mp_obj_get_int(items[0]);
     data[1] = mp_obj_get_int(items[1]);
diff --git a/stmhal/Makefile b/stmhal/Makefile
index 7896849c63..1c9ea55314 100644
--- a/stmhal/Makefile
+++ b/stmhal/Makefile
@@ -74,9 +74,9 @@ SRC_C = \
 	pyexec.c \
 	help.c \
 	input.c \
-	pybmodule.c \
-	osmodule.c \
-	timemodule.c \
+	modpyb.c \
+	modos.c \
+	modtime.c \
 	import.c \
 	lexerfatfs.c \
 	gpio.c \
diff --git a/stmhal/main.c b/stmhal/main.c
index a231ca2507..ab96dcdef2 100644
--- a/stmhal/main.c
+++ b/stmhal/main.c
@@ -21,9 +21,6 @@
 #include "gc.h"
 #include "gccollect.h"
 #include "pyexec.h"
-#include "pybmodule.h"
-#include "osmodule.h"
-#include "timemodule.h"
 #include "usart.h"
 #include "led.h"
 #include "exti.h"
@@ -110,6 +107,7 @@ static const char fresh_boot_py[] =
 "# boot.py -- run on boot-up\n"
 "# can run arbitrary Python, but best to keep it minimal\n"
 "\n"
+"import pyb\n"
 "pyb.source_dir('/src')\n"
 "pyb.main('main.py')\n"
 "#pyb.usb_usr('VCP')\n"
@@ -246,15 +244,6 @@ soft_reset:
 
     pin_map_init();
 
-    // we pre-import the pyb module
-    // probably shouldn't do this, so we are compatible with CPython
-    rt_store_name(MP_QSTR_pyb, (mp_obj_t)&pyb_module);
-
-    // pre-import the os and time modules
-    // TODO don't do this! (need a way of registering builtin modules...)
-    rt_store_name(MP_QSTR_os, (mp_obj_t)&os_module);
-    rt_store_name(MP_QSTR_time, (mp_obj_t)&time_module);
-
     // check if user switch held (initiates reset of filesystem)
     bool reset_filesystem = false;
 #if MICROPY_HW_HAS_SWITCH
diff --git a/stmhal/osmodule.c b/stmhal/modos.c
index 7f32fe6749..0ec9fcbb91 100644
--- a/stmhal/osmodule.c
+++ b/stmhal/modos.c
@@ -10,7 +10,7 @@
 #include "rng.h"
 #include "storage.h"
 #include "ff.h"
-#include "osmodule.h"
+#include "modos.h"
 
 #if _USE_LFN
 static char lfn[_MAX_LFN + 1];   /* Buffer to store the LFN */
diff --git a/stmhal/osmodule.h b/stmhal/modos.h
index e3c13f756e..e3c13f756e 100644
--- a/stmhal/osmodule.h
+++ b/stmhal/modos.h
diff --git a/stmhal/pybmodule.c b/stmhal/modpyb.c
index 5e735903ed..c7bab36665 100644
--- a/stmhal/pybmodule.c
+++ b/stmhal/modpyb.c
@@ -30,7 +30,7 @@
 #include "usb.h"
 #include "i2c.h"
 #endif
-#include "pybmodule.h"
+#include "modpyb.h"
 #include "ff.h"
 
 // get lots of info about the board
diff --git a/stmhal/pybmodule.h b/stmhal/modpyb.h
index 955aaefe3f..955aaefe3f 100644
--- a/stmhal/pybmodule.h
+++ b/stmhal/modpyb.h
diff --git a/stmhal/timemodule.c b/stmhal/modtime.c
index b2dac6a54c..4786c85c72 100644
--- a/stmhal/timemodule.c
+++ b/stmhal/modtime.c
@@ -6,7 +6,7 @@
 #include "qstr.h"
 #include "obj.h"
 #include "map.h"
-#include "timemodule.h"
+#include "modtime.h"
 
 STATIC mp_obj_t time_sleep(mp_obj_t seconds_o) {
 #if MICROPY_ENABLE_FLOAT
diff --git a/stmhal/timemodule.h b/stmhal/modtime.h
index 70e35b1fde..70e35b1fde 100644
--- a/stmhal/timemodule.h
+++ b/stmhal/modtime.h
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index edaee63158..b187c43bbe 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -27,6 +27,15 @@ extern const struct _mp_obj_fun_native_t mp_builtin_open_obj;
     { MP_QSTR_input, (mp_obj_t)&mp_builtin_input_obj }, \
     { MP_QSTR_open, (mp_obj_t)&mp_builtin_open_obj },
 
+// extra built in modules to add to the list of known ones
+extern const struct _mp_obj_module_t os_module;
+extern const struct _mp_obj_module_t pyb_module;
+extern const struct _mp_obj_module_t time_module;
+#define MICROPY_EXTRA_BUILTIN_MODULES \
+    { MP_QSTR_os, (mp_obj_t)&os_module }, \
+    { MP_QSTR_pyb, (mp_obj_t)&pyb_module }, \
+    { MP_QSTR_time, (mp_obj_t)&time_module }, \
+
 // type definitions for the specific machine
 
 #define BYTES_PER_WORD (4)