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, 138 insertions, 0 deletions

diff --git a/shared-module/_bleio/ScanResults.c b/shared-module/_bleio/ScanResults.c
new file mode 100644
index 000000000..9f23a836c
--- /dev/null
+++ b/shared-module/_bleio/ScanResults.c
@@ -0,0 +1,138 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Dan Halbert for Adafruit Industries
+ * Copyright (c) 2018 Artur Pacholec
+ * Copyright (c) 2017 Glenn Ruben Bakke
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "py/objstr.h"
+#include "py/runtime.h"
+#include "shared-bindings/_bleio/ScanEntry.h"
+#include "shared-bindings/_bleio/ScanResults.h"
+
+bleio_scanresults_obj_t* shared_module_bleio_new_scanresults(size_t buffer_size, uint8_t* prefixes, size_t prefixes_len, mp_int_t minimum_rssi) {
+    bleio_scanresults_obj_t* self = m_new_obj(bleio_scanresults_obj_t);
+    self->base.type = &bleio_scanresults_type;
+    ringbuf_alloc(&self->buf, buffer_size, false);
+    self->prefixes = prefixes;
+    self->prefix_length = prefixes_len;
+    self->minimum_rssi = minimum_rssi;
+    return self;
+}
+
+mp_obj_t common_hal_bleio_scanresults_next(bleio_scanresults_obj_t *self) {
+    while (ringbuf_count(&self->buf) == 0 && !self->done && !mp_exception_pending()) {
+        RUN_BACKGROUND_TASKS;
+    }
+    if (ringbuf_count(&self->buf) == 0 || mp_exception_pending()) {
+        return mp_const_none;
+    }
+
+    // Create a ScanEntry out of the data on the buffer.
+    uint8_t type = ringbuf_get(&self->buf);
+    bool connectable = (type & (1 << 0)) != 0;
+    bool scan_response = (type & (1 << 1)) != 0;
+    uint64_t ticks_ms; 
+    ringbuf_get_n(&self->buf, (uint8_t*) &ticks_ms, sizeof(ticks_ms));
+    uint8_t rssi = ringbuf_get(&self->buf);
+    uint8_t peer_addr[NUM_BLEIO_ADDRESS_BYTES];
+    ringbuf_get_n(&self->buf, peer_addr, sizeof(peer_addr));
+    uint8_t addr_type = ringbuf_get(&self->buf);
+    uint16_t len;
+    ringbuf_get_n(&self->buf, (uint8_t*) &len, sizeof(len));
+
+    mp_obj_str_t *o = MP_OBJ_TO_PTR(mp_obj_new_bytes_of_zeros(len));
+    ringbuf_get_n(&self->buf, (uint8_t*) o->data, len);
+
+    bleio_scanentry_obj_t *entry = m_new_obj(bleio_scanentry_obj_t);
+    entry->base.type = &bleio_scanentry_type;
+    entry->rssi = rssi;
+
+    bleio_address_obj_t *address = m_new_obj(bleio_address_obj_t);
+    address->base.type = &bleio_address_type;
+    common_hal_bleio_address_construct(MP_OBJ_TO_PTR(address), peer_addr, addr_type);
+    entry->address = address;
+
+    entry->data = o;
+    entry->time_received = ticks_ms;
+    entry->connectable = connectable;
+    entry->scan_response = scan_response;
+    
+    return MP_OBJ_FROM_PTR(entry);
+}
+
+
+void shared_module_bleio_scanresults_append(bleio_scanresults_obj_t* self,
+                                            uint64_t ticks_ms,
+                                            bool connectable,
+                                            bool scan_response,
+                                            int8_t rssi,
+                                            uint8_t *peer_addr,
+                                            uint8_t addr_type,
+                                            uint8_t *data,
+                                            uint16_t len) {
+    int32_t packet_size = sizeof(uint8_t) + sizeof(ticks_ms) + sizeof(rssi) + NUM_BLEIO_ADDRESS_BYTES +
+        sizeof(addr_type) + sizeof(len) + len;
+    int32_t empty_space = self->buf.size - ringbuf_count(&self->buf);
+    if (packet_size >= empty_space) {
+        // We can't fit the packet so skip it.
+        return;
+    }
+    // Filter the packet.
+    if (rssi < self->minimum_rssi) {
+        return;
+    }
+
+    // If any prefixes are provided, then only include packets that include at least one of them.
+    if (!bleio_scanentry_data_matches(data, len, self->prefixes, self->prefix_length, true)) {
+        return;
+    }
+    uint8_t type = 0;
+    if (connectable) {
+        type |= 1 << 0;
+    }
+    if (scan_response) {
+        type |= 1 << 1;
+    }
+
+    // Add the packet to the buffer.
+    ringbuf_put(&self->buf, type);
+    ringbuf_put_n(&self->buf, (uint8_t*) &ticks_ms, sizeof(ticks_ms));
+    ringbuf_put(&self->buf, rssi);
+    ringbuf_put_n(&self->buf, peer_addr, NUM_BLEIO_ADDRESS_BYTES);
+    ringbuf_put(&self->buf, addr_type);
+    ringbuf_put_n(&self->buf, (uint8_t*) &len, sizeof(len));
+    ringbuf_put_n(&self->buf, data, len);
+}
+
+bool shared_module_bleio_scanresults_get_done(bleio_scanresults_obj_t* self) {
+    return self->done;
+}
+
+void shared_module_bleio_scanresults_set_done(bleio_scanresults_obj_t* self, bool done) {
+    self->done = done;
+    self->common_hal_data = NULL;
+}