Refine _bleio

This PR refines the _bleio API. It was originally motivated by
the addition of a new CircuitPython service that enables reading
and modifying files on the device. Moving the BLE lifecycle outside
of the VM motivated a number of changes to remove heap allocations
in some APIs.

It also motivated unifying connection initiation to the Adapter class
rather than the Central and Peripheral classes which have been removed.
Adapter now handles the GAP portion of BLE including advertising, which
has moved but is largely unchanged, and scanning, which has been enhanced
to return an iterator of filtered results.

Once a connection is created (either by us (aka Central) or a remote
device (aka Peripheral)) it is represented by a new Connection class.
This class knows the current connection state and can discover and
instantiate remote Services along with their Characteristics and
Descriptors.

Relates to #586

1 files changed, 23 insertions, 10 deletions

diff --git a/shared-bindings/_bleio/Characteristic.c b/shared-bindings/_bleio/Characteristic.c
index 198155589..d89da2a2f 100644
--- a/shared-bindings/_bleio/Characteristic.c
+++ b/shared-bindings/_bleio/Characteristic.c
@@ -45,8 +45,8 @@
 //|
 //|   There is no regular constructor for a Characteristic. A new local Characteristic can be created
 //|   and attached to a Service by calling `add_to_service()`.
-//|   Remote Characteristic objects are created by `Central.discover_remote_services()`
-//|   or `Peripheral.discover_remote_services()` as part of remote Services.
+//|   Remote Characteristic objects are created by `Connection.discover_remote_services()`
+//|   as part of remote Services.
 //|
 
 //|   .. method:: add_to_service(service, uuid, *, properties=0, read_perm=`Attribute.OPEN`, write_perm=`Attribute.OPEN`, max_length=20, fixed_length=False, initial_value=None)
@@ -134,12 +134,10 @@ STATIC mp_obj_t bleio_characteristic_add_to_service(size_t n_args, const mp_obj_
     // Range checking on max_length arg is done by the common_hal layer, because
     // it may vary depending on underlying BLE implementation.
     common_hal_bleio_characteristic_construct(
-        characteristic, MP_OBJ_TO_PTR(service_obj), MP_OBJ_TO_PTR(uuid_obj),
+        characteristic, MP_OBJ_TO_PTR(service_obj), 0, MP_OBJ_TO_PTR(uuid_obj),
         properties, read_perm, write_perm,
         max_length, fixed_length, &initial_value_bufinfo);
 
-    common_hal_bleio_service_add_characteristic(service_obj, characteristic);
-
     return MP_OBJ_FROM_PTR(characteristic);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(bleio_characteristic_add_to_service_fun_obj, 3, bleio_characteristic_add_to_service);
@@ -170,7 +168,8 @@ const mp_obj_property_t bleio_characteristic_properties_obj = {
 //|   .. attribute:: uuid
 //|
 //|     The UUID of this characteristic. (read-only)
-//|       Will be ``None`` if the 128-bit UUID for this characteristic is not known.
+//|     
+//|     Will be ``None`` if the 128-bit UUID for this characteristic is not known.
 //|
 STATIC mp_obj_t bleio_characteristic_get_uuid(mp_obj_t self_in) {
     bleio_characteristic_obj_t *self = MP_OBJ_TO_PTR(self_in);
@@ -194,7 +193,9 @@ const mp_obj_property_t bleio_characteristic_uuid_obj = {
 STATIC mp_obj_t bleio_characteristic_get_value(mp_obj_t self_in) {
     bleio_characteristic_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
-    return common_hal_bleio_characteristic_get_value(self);
+    uint8_t temp[512];
+    size_t actual_len = common_hal_bleio_characteristic_get_value(self, temp, sizeof(temp));
+    return mp_obj_new_bytearray(actual_len, temp);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(bleio_characteristic_get_value_obj, bleio_characteristic_get_value);
 
@@ -224,8 +225,20 @@ const mp_obj_property_t bleio_characteristic_value_obj = {
 STATIC mp_obj_t bleio_characteristic_get_descriptors(mp_obj_t self_in) {
     bleio_characteristic_obj_t *self = MP_OBJ_TO_PTR(self_in);
     // Return list as a tuple so user won't be able to change it.
-    mp_obj_list_t *char_list = common_hal_bleio_characteristic_get_descriptor_list(self);
-    return mp_obj_new_tuple(char_list->len, char_list->items);
+    bleio_descriptor_obj_t *descriptors = common_hal_bleio_characteristic_get_descriptor_list(self);
+    bleio_descriptor_obj_t *head = descriptors;
+    size_t len = 0;
+    while (head != NULL) {
+        len++;
+        head = head->next;
+    }
+    mp_obj_tuple_t * t = MP_OBJ_TO_PTR(mp_obj_new_tuple(len, NULL));
+    head = descriptors;
+    for (size_t i = len - 1; i >= 0; i--) {
+        t->items[i] = MP_OBJ_FROM_PTR(head);
+        head = head->next;
+    }
+    return MP_OBJ_FROM_PTR(t);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(bleio_characteristic_get_descriptors_obj, bleio_characteristic_get_descriptors);
 
@@ -282,7 +295,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(bleio_characteristic_set_cccd_obj, 1, bleio_ch
 
 STATIC const mp_rom_map_elem_t bleio_characteristic_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_add_to_service), MP_ROM_PTR(&bleio_characteristic_add_to_service_obj) },
-    { MP_ROM_QSTR(MP_QSTR_properties),     MP_ROM_PTR(&bleio_characteristic_get_properties_obj) },
+    { MP_ROM_QSTR(MP_QSTR_properties),     MP_ROM_PTR(&bleio_characteristic_properties_obj) },
     { MP_ROM_QSTR(MP_QSTR_uuid),           MP_ROM_PTR(&bleio_characteristic_uuid_obj) },
     { MP_ROM_QSTR(MP_QSTR_value),          MP_ROM_PTR(&bleio_characteristic_value_obj) },
     { MP_ROM_QSTR(MP_QSTR_set_cccd),       MP_ROM_PTR(&bleio_characteristic_set_cccd_obj) },