Expose RSSI property

This adds rssi to PeripheralProperties to complement tx_power_level
that's already reported.

This exposes the rssi as i16 which is consistent with bluez and Windows.

This also updates tx_power_level to be an i16 for consistency - though
it is a small public API change.

Note: the corebluetooth backend currently always reports None for the TX
and RSSI power levels.

Addresses: deviceplug#76

CHANGELOG.md

@@ -1,8 +1,13 @@
 # Unreleased
 
+## Features
+
+- Added Received Signal Strength Indicator (RSSI) peripheral property
+
 ## Breaking changes
 
 - Removed `CentralEvent::DeviceLost`. It wasn't emitted anywhere.
+- Changed tx_power_level type from i8 to i16
 
 # 0.8.1 (2021-08-14)
 

src/api/mod.rs

@@ -151,7 +151,9 @@ pub struct PeripheralProperties {
     /// The local name. This is generally a human-readable string that identifies the type of device.
     pub local_name: Option<String>,
     /// The transmission power level for the device
-    pub tx_power_level: Option<i8>,
+    pub tx_power_level: Option<i16>,
+    /// The most recent Received Signal Strength Indicator for the device
+    pub rssi: Option<i16>,
     /// Advertisement data specific to the device manufacturer. The keys of this map are
     /// 'manufacturer IDs', while the values are arbitrary data.
     pub manufacturer_data: HashMap<u16, Vec<u8>>,

src/bluez/peripheral.rs

@@ -68,7 +68,8 @@ impl api::Peripheral for Peripheral {
             address: (&device_info.mac_address).into(),
             address_type: Some(device_info.address_type.into()),
             local_name: device_info.name,
-            tx_power_level: device_info.tx_power.map(|tx_power| tx_power as i8),
+            tx_power_level: device_info.tx_power,
+            rssi: device_info.rssi,
             manufacturer_data: device_info.manufacturer_data,
             service_data: device_info.service_data,
             services: device_info.services,

src/corebluetooth/peripheral.rs

@@ -71,6 +71,7 @@ impl Peripheral {
             address_type: None,
             local_name,
             tx_power_level: None,
+            rssi: None,
             manufacturer_data: HashMap::new(),
             service_data: HashMap::new(),
             services: Vec::new(),

src/winrtble/peripheral.rs

@@ -170,9 +170,12 @@ impl Peripheral {
             // all panic here without returning a Result as documented.
             // Value() is apparently the _right_ way to extract something from an IReference<T>...
             if let Ok(tx) = tx_reference.Value() {
-                properties.tx_power_level = Some(tx as i8);
+                properties.tx_power_level = Some(tx);
             }
         }
+        if let Ok(rssi) = args.RawSignalStrengthInDBm() {
+            properties.rssi = Some(rssi);
+        }
     }
 }