Streamline datetime code, adjust precision to the one actually used

2 files changed, 17 insertions, 23 deletions

diff --git a/src/components/datetime/DateTimeController.cpp b/src/components/datetime/DateTimeController.cpp
index 6022474..90ce3fe 100644
--- a/src/components/datetime/DateTimeController.cpp
+++ b/src/components/datetime/DateTimeController.cpp
@@ -14,7 +14,7 @@ namespace {
 DateTime::DateTime(Controllers::Settings& settingsController) : settingsController {settingsController} {
 }
 
-void DateTime::SetCurrentTime(std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> t) {
+void DateTime::SetCurrentTime(std::chrono::time_point<std::chrono::system_clock, std::chrono::seconds> t) {
   this->currentDateTime = t;
   UpdateTime(previousSystickCounter); // Update internal state without updating the time
 }
@@ -30,7 +30,7 @@ void DateTime::SetTime(
     /* .tm_year = */ year - 1900,
   };
   tm.tm_isdst = -1; // Use DST value from local time zone
-  currentDateTime = std::chrono::system_clock::from_time_t(std::mktime(&tm));
+  currentDateTime = std::chrono::time_point_cast<std::chrono::seconds>(std::chrono::system_clock::from_time_t(std::mktime(&tm)));
 
   NRF_LOG_INFO("%d %d %d ", day, month, year);
   NRF_LOG_INFO("%d %d %d ", hour, minute, second);
@@ -45,27 +45,20 @@ void DateTime::SetTime(
 
 void DateTime::UpdateTime(uint32_t systickCounter) {
   // Handle systick counter overflow
-  uint32_t systickDelta = 0;
-  if (systickCounter < previousSystickCounter) {
-    systickDelta = 0xffffff - previousSystickCounter;
-    systickDelta += systickCounter + 1;
-  } else {
-    systickDelta = systickCounter - previousSystickCounter;
-  }
+  uint32_t systickDelta = (systickCounter - previousSystickCounter) & 0xffffff;
+  previousSystickCounter = systickCounter;
 
   /*
    * 1000 ms = 1024 ticks
    */
-  auto correctedDelta = systickDelta / 1024;
-  auto rest = (systickDelta - (correctedDelta * 1024));
-  if (systickCounter >= rest) {
-    previousSystickCounter = systickCounter - rest;
-  } else {
-    previousSystickCounter = 0xffffff - (rest - systickCounter);
-  }
-
-  currentDateTime += std::chrono::seconds(correctedDelta);
-  uptime += std::chrono::seconds(correctedDelta);
+  // auto newSeconds = systickDelta >> 10;
+  // auto rest = systickDelta & ((1 << 10)-1);
+  subsecondTicks += systickDelta & ((1 << 10)-1);
+  systickDelta = (systickDelta >> 10) + (subsecondTicks >> 10);
+  subsecondTicks &= ((1 << 10)-1);
+
+  currentDateTime += std::chrono::seconds(systickDelta);
+  uptime += std::chrono::seconds(systickDelta);
 
   auto dp = date::floor<date::days>(currentDateTime);
   auto time = date::make_time(currentDateTime - dp);
diff --git a/src/components/datetime/DateTimeController.h b/src/components/datetime/DateTimeController.h
index e964b4c..ca2a0fe 100644
--- a/src/components/datetime/DateTimeController.h
+++ b/src/components/datetime/DateTimeController.h
@@ -65,7 +65,7 @@ namespace Pinetime {
       const char* DayOfWeekShortToString() const;
       static const char* MonthShortToStringLow(Months month);
 
-      std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> CurrentDateTime() const {
+      std::chrono::time_point<std::chrono::system_clock, std::chrono::seconds> CurrentDateTime() const {
         return currentDateTime;
       }
       std::chrono::seconds Uptime() const {
@@ -73,7 +73,7 @@ namespace Pinetime {
       }
 
       void Register(System::SystemTask* systemTask);
-      void SetCurrentTime(std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> t);
+      void SetCurrentTime(std::chrono::time_point<std::chrono::system_clock, std::chrono::seconds> t);
       std::string FormattedTime();
 
     private:
@@ -84,9 +84,10 @@ namespace Pinetime {
       uint8_t hour = 0;
       uint8_t minute = 0;
       uint8_t second = 0;
+      uint16_t subsecondTicks = 0;
 
-      uint32_t previousSystickCounter = 0;
-      std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> currentDateTime;
+      uint32_t previousSystickCounter = 0; // FIXME: This could probably be 16 bits?
+      std::chrono::time_point<std::chrono::system_clock, std::chrono::seconds> currentDateTime;
       std::chrono::seconds uptime {0};
 
       bool isMidnightAlreadyNotified = false;