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Parse G7 glucose messages with a nonzero status #88

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Parse G7 glucose messages with a nonzero status #88

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16 changes: 7 additions & 9 deletions G7SensorKit/Messages/G7GlucoseMessage.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,8 @@ import Foundation
import LoopKit

public struct G7GlucoseMessage: SensorMessage, Equatable {
//public let status: UInt8
//public let sequence: UInt32
/// Nonzero when the sensor has no current reading, e.g. 0x80 from a failed sensor; glucose is then nil.
public let status: UInt8
public let glucose: UInt16?
public let predicted: UInt16?
public let glucoseIsDisplayOnly: Bool
Expand Down Expand Up @@ -84,9 +84,7 @@ public struct G7GlucoseMessage: SensorMessage, Equatable {
return nil
}

guard data[1] == 00 else {
return nil
}
status = data[1]

messageTimestamp = data[2..<6].toInt()

Expand All @@ -95,7 +93,7 @@ public struct G7GlucoseMessage: SensorMessage, Equatable {
age = data[10..<12].to(UInt16.self)

let glucoseData = data[12..<14].to(UInt16.self)
if glucoseData != 0xffff {
if glucoseData != 0xffff, status == 0 {
glucose = glucoseData & 0xfff
glucoseIsDisplayOnly = (data[18] & 0x10) > 0
} else {
Expand All @@ -104,15 +102,15 @@ public struct G7GlucoseMessage: SensorMessage, Equatable {
}

let predictionData = data[16..<18].to(UInt16.self)
if predictionData != 0xffff {
if predictionData != 0xffff, status == 0 {
predicted = predictionData & 0xfff
} else {
predicted = nil
}

algorithmState = AlgorithmState(rawValue: data[14])

if data[15] == 0x7f {
if data[15] == 0x7f || status != 0 {
trend = nil
} else {
trend = Double(Int8(bitPattern: data[15])) / 10
Expand All @@ -125,6 +123,6 @@ public struct G7GlucoseMessage: SensorMessage, Equatable {

extension G7GlucoseMessage: CustomDebugStringConvertible {
public var debugDescription: String {
return "G7GlucoseMessage(glucose:\(String(describing: glucose)), sequence:\(sequence) glucoseIsDisplayOnly:\(glucoseIsDisplayOnly) state:\(String(describing: algorithmState)) messageTimestamp:\(messageTimestamp) age:\(age), data:\(data.hexadecimalString))"
return "G7GlucoseMessage(status:\(status) glucose:\(String(describing: glucose)), sequence:\(sequence) glucoseIsDisplayOnly:\(glucoseIsDisplayOnly) state:\(String(describing: algorithmState)) messageTimestamp:\(messageTimestamp) age:\(age), data:\(data.hexadecimalString))"
}
}
15 changes: 15 additions & 0 deletions G7SensorKitTests/G7GlucoseMessageTests.swift
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Expand Up @@ -127,6 +127,21 @@ final class G7GlucoseMessageTests: XCTestCase {
XCTAssertEqual(907385, message.glucoseTimestamp)
}

func testFailedSensorStatusStillReportsAlgorithmState() {
// A failed sensor keeps answering with status 0x80 and its last reading, 103 mg/dL from 2.7 h earlier.
let data = Data(hexadecimalString: "4e80856f0a00f6010001f32567001b02670000")!
let message = G7GlucoseMessage(data: data)!
XCTAssertEqual(0x80, message.status)
XCTAssertEqual(.known(.transmitterFailed), message.algorithmState)
XCTAssertTrue(message.algorithmState.sensorFailed)
XCTAssertNil(message.glucose)
XCTAssertNil(message.predicted)
XCTAssertNil(message.trend)
XCTAssertEqual(683909, message.messageTimestamp)
XCTAssertEqual(9715, message.age)
XCTAssertEqual(502, message.sequence)
}

func testBackfill() {
let data = Data(hexadecimalString: "cf5802008f00060f10")!
let message = G7BackfillMessage(data: data)!
Expand Down