BLE client support on ESP32 (#1177)

Co-authored-by: Ben Buxton <bb@cactii.net>
Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

esphome/components/esp32_ble_tracker/queue.h

@@ -0,0 +1,96 @@
+#pragma once
+#include "esphome/core/component.h"
+#include "esphome/core/helpers.h"
+
+#include <queue>
+#include <mutex>
+
+#ifdef ARDUINO_ARCH_ESP32
+
+#include <esp_gap_ble_api.h>
+#include <esp_gattc_api.h>
+
+/*
+ * BLE events come in from a separate Task (thread) in the ESP32 stack. Rather
+ * than trying to deal wth various locking strategies, all incoming GAP and GATT
+ * events will simply be placed on a semaphore guarded queue. The next time the
+ * component runs loop(), these events are popped off the queue and handed at
+ * this safer time.
+ */
+
+namespace esphome {
+namespace esp32_ble_tracker {
+
+template<class T> class Queue {
+ public:
+  Queue() { m = xSemaphoreCreateMutex(); }
+
+  void push(T *element) {
+    if (element == nullptr)
+      return;
+    if (xSemaphoreTake(m, 5L / portTICK_PERIOD_MS)) {
+      q.push(element);
+      xSemaphoreGive(m);
+    }
+  }
+
+  T *pop() {
+    T *element = nullptr;
+
+    if (xSemaphoreTake(m, 5L / portTICK_PERIOD_MS)) {
+      if (!q.empty()) {
+        element = q.front();
+        q.pop();
+      }
+      xSemaphoreGive(m);
+    }
+    return element;
+  }
+
+ protected:
+  std::queue<T *> q;
+  SemaphoreHandle_t m;
+};
+
+// Received GAP and GATTC events are only queued, and get processed in the main loop().
+// This class stores each event in a single type.
+class BLEEvent {
+ public:
+  BLEEvent(esp_gap_ble_cb_event_t e, esp_ble_gap_cb_param_t *p) {
+    this->event_.gap.gap_event = e;
+    memcpy(&this->event_.gap.gap_param, p, sizeof(esp_ble_gap_cb_param_t));
+    this->type_ = 0;
+  };
+
+  BLEEvent(esp_gattc_cb_event_t e, esp_gatt_if_t i, esp_ble_gattc_cb_param_t *p) {
+    this->event_.gattc.gattc_event = e;
+    this->event_.gattc.gattc_if = i;
+    memcpy(&this->event_.gattc.gattc_param, p, sizeof(esp_ble_gattc_cb_param_t));
+    // Need to also make a copy of notify event data.
+    if (e == ESP_GATTC_NOTIFY_EVT) {
+      memcpy(this->event_.gattc.notify_data, p->notify.value, p->notify.value_len);
+      this->event_.gattc.gattc_param.notify.value = this->event_.gattc.notify_data;
+    }
+    this->type_ = 1;
+  };
+
+  union {
+    struct gap_event {
+      esp_gap_ble_cb_event_t gap_event;
+      esp_ble_gap_cb_param_t gap_param;
+    } gap;
+
+    struct gattc_event {
+      esp_gattc_cb_event_t gattc_event;
+      esp_gatt_if_t gattc_if;
+      esp_ble_gattc_cb_param_t gattc_param;
+      uint8_t notify_data[64];
+    } gattc;
+  } event_;
+  uint8_t type_;  // 0=gap 1=gattc
+};
+
+}  // namespace esp32_ble_tracker
+}  // namespace esphome
+
+#endif