Add reliable Android BLE ride recorder

main/trikke_ble_protocol.c

@@ -15,6 +15,12 @@ static uint32_t get_u32_le(const uint8_t *input)
            ((uint32_t)input[2] << 16) | ((uint32_t)input[3] << 24);
 }
 
+static uint64_t get_u64_le(const uint8_t *input)
+{
+    return (uint64_t)get_u32_le(input) |
+           ((uint64_t)get_u32_le(input + 4) << 32);
+}
+
 static void put_u16_le(uint8_t *output, uint16_t value)
 {
     output[0] = (uint8_t)value;
@@ -89,3 +95,31 @@ bool trikke_ble_decode_ack(
     *packet_sequence = get_u32_le(ack + 4);
     return true;
 }
+
+bool trikke_ble_decode_begin_session(
+    const uint8_t *command,
+    size_t command_size,
+    uint64_t *session_token)
+{
+    if (command == NULL || session_token == NULL ||
+        command_size != TRIKKE_BLE_BEGIN_SESSION_SIZE ||
+        memcmp(command, "BGN1", 4) != 0) {
+        return false;
+    }
+    *session_token = get_u64_le(command + 4);
+    return true;
+}
+
+bool trikke_ble_update_subscription(
+    bool notify_enabled,
+    bool session_connection_ready,
+    bool *subscribed)
+{
+    if (subscribed == NULL) {
+        return false;
+    }
+    const bool effective = notify_enabled && session_connection_ready;
+    const bool changed = effective != *subscribed;
+    *subscribed = effective;
+    return changed;
+}