Updates for G6 support (#101)

Author: ps2

CGMBLEKit/Messages/GlucoseBackfillMessage.swift

@@ -110,8 +110,13 @@ struct GlucoseBackfillFrameBuffer {
             from: glucoseData.startIndex,
             to: glucoseData.endIndex,
             by: GlucoseSubMessage.size
-        ).map {
-            return GlucoseSubMessage(data: glucoseData[$0..<$0.advanced(by: GlucoseSubMessage.size)])!
+        ).compactMap {
+            let range = $0..<$0.advanced(by: GlucoseSubMessage.size)
+            guard glucoseData.endIndex >= range.endIndex else {
+                return nil
+            }
+
+            return GlucoseSubMessage(data: glucoseData[range])
         }
     }
 }

CGMBLEKit/Messages/GlucoseRxMessage.swift

@@ -19,7 +19,7 @@ public struct GlucoseSubMessage: TransmitterRxMessage {
     public let trend: Int8
 
     init?(data: Data) {
-        guard data.count == GlucoseSubMessage.size else {
+        guard data.count >= GlucoseSubMessage.size else {
             return nil
         }
 
@@ -50,18 +50,18 @@ public struct GlucoseRxMessage: TransmitterRxMessage {
     public let glucose: GlucoseSubMessage
 
     init?(data: Data) {
-        guard data.count == 16 && data.isCRCValid else {
+        guard data.count >= 16 && data.isCRCValid else {
             return nil
         }
 
-        guard data.starts(with: .glucoseRx) else {
+        guard data.starts(with: .glucoseRx) || data.starts(with: .glucoseG6Rx) else {
             return nil
         }
 
         status = data[1]
         sequence = data[2..<6].toInt()
 
-        guard let glucose = GlucoseSubMessage(data: data[6..<14]) else {
+        guard let glucose = GlucoseSubMessage(data: data[6...]) else {
             return nil
         }
         self.glucose = glucose

CGMBLEKit/Opcode.swift

@@ -14,11 +14,13 @@ enum Opcode: UInt8 {
     case authRequestRx = 0x03
     case authChallengeTx = 0x04
     case authChallengeRx = 0x05
-    case keepAlive = 0x06
+    case keepAlive = 0x06 // auth; setAdvertisementParametersTx for control
     case bondRequest = 0x07
 
     // Control
     case disconnectTx = 0x09
+    
+    case setAdvertisementParametersRx = 0x1c
 
     case firmwareVersionTx = 0x20
     case firmwareVersionRx = 0x21
@@ -45,6 +47,9 @@ enum Opcode: UInt8 {
 
     case transmitterVersionTx = 0x4a
     case transmitterVersionRx = 0x4b
+    
+    case glucoseG6Tx = 0x4e
+    case glucoseG6Rx = 0x4f
 
     case glucoseBackfillTx = 0x50
     case glucoseBackfillRx = 0x51

CGMBLEKit/Transmitter.swift

@@ -230,7 +230,7 @@ public final class Transmitter: BluetoothManagerDelegate {
         guard response.count > 0 else { return }
 
         switch Opcode(rawValue: response[0]) {
-        case .glucoseRx?:
+        case .glucoseRx?, .glucoseG6Rx?:
             if  let glucoseMessage = GlucoseRxMessage(data: response),
                 let timeMessage = lastTimeMessage,
                 let activationDate = activationDate

CGMBLEKitTests/GlucoseBackfillMessageTests.swift

@@ -62,4 +62,12 @@ class GlucoseBackfillMessageTests: XCTestCase {
         XCTAssertEqual(.known(.ok), CalibrationState(rawValue: messages[4].state))
         XCTAssertEqual(-08, messages[4].trend)
     }
+
+    func testMalformedBackfill() {
+        var buffer = GlucoseBackfillFrameBuffer(identifier: 0)
+        buffer.append(Data(hexadecimalString: "0100bc460000b7ff52008b0006eee30053008500")!)
+        buffer.append(Data(hexadecimalString: "020006eb0f025300800006ee3a0353007e0006")!)
+
+        XCTAssertEqual(3, buffer.glucose.count)
+    }
 }