make BateryStats::updateAvailable wrap-around-safe

helgeerbe · Mar 5, 2024 · e432f0e · e432f0e
1 parent fe7e622
commit e432f0e
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/include/BatteryStats.h b/include/BatteryStats.h
@@ -15,7 +15,7 @@ class BatteryStats {
 
         // the last time *any* datum was updated
         uint32_t getAgeSeconds() const { return (millis() - _lastUpdate) / 1000; }
-        bool updateAvailable(uint32_t since) const { return _lastUpdate > since; }
+        bool updateAvailable(uint32_t since) const;
 
         uint8_t getSoC() const { return _soc; }
         uint32_t getSoCAgeSeconds() const { return (millis() - _lastUpdateSoC) / 1000; }

diff --git a/src/BatteryStats.cpp b/src/BatteryStats.cpp
@@ -51,6 +51,12 @@ static void addLiveViewAlarm(JsonVariant& root, std::string const& name,
     root["issues"][name] = 2;
 }
 
+bool BatteryStats::updateAvailable(uint32_t since) const
+{
+    auto constexpr halfOfAllMillis = std::numeric_limits<uint32_t>::max() / 2;
+    return (_lastUpdate - since) < halfOfAllMillis;
+}
+
 void BatteryStats::getLiveViewData(JsonVariant& root) const
 {
     root[F("manufacturer")] = _manufacturer;