Merge Date & Time meters' updateValues() functions

This reduces compiled code size.

Signed-off-by: Kang-Che Sung <explorer09@gmail.com>

Author: Explorer09

DateTimeMeter.c

@@ -29,36 +29,26 @@ static const int DateTimeMeter_attributes[] = {
    DATETIME
 };
 
-static void ClockMeter_updateValues(Meter* this) {
-   const Machine* host = this->host;
-
-   struct tm result;
-   const struct tm* lt = localtime_r(&host->realtime.tv_sec, &result);
-   strftime(this->txtBuffer, sizeof(this->txtBuffer), "%H:%M:%S", lt);
-}
-
-static void DateMeter_updateValues(Meter* this) {
-   const Machine* host = this->host;
-
-   struct tm result;
-   const struct tm* lt = localtime_r(&host->realtime.tv_sec, &result);
-   strftime(this->txtBuffer, sizeof(this->txtBuffer), "%F", lt);
-}
-
 static void DateTimeMeter_updateValues(Meter* this) {
    const Machine* host = this->host;
 
    struct tm result;
    const struct tm* lt = localtime_r(&host->realtime.tv_sec, &result);
-   strftime(this->txtBuffer, sizeof(this->txtBuffer), "%F %H:%M:%S", lt);
+   if (As_Meter(this) == &ClockMeter_class) {
+      strftime(this->txtBuffer, sizeof(this->txtBuffer), "%H:%M:%S", lt);
+   } else if (As_Meter(this) == &DateMeter_class) {
+      strftime(this->txtBuffer, sizeof(this->txtBuffer), "%F", lt);
+   } else {
+      strftime(this->txtBuffer, sizeof(this->txtBuffer), "%F %H:%M:%S", lt);
+   }
 }
 
 const MeterClass ClockMeter_class = {
    .super = {
       .extends = Class(Meter),
       .delete = Meter_delete
    },
-   .updateValues = ClockMeter_updateValues,
+   .updateValues = DateTimeMeter_updateValues,
    .defaultMode = TEXT_METERMODE,
    .supportedModes = (1 << TEXT_METERMODE) | (1 << LED_METERMODE),
    .maxItems = 0,
@@ -74,7 +64,7 @@ const MeterClass DateMeter_class = {
       .extends = Class(Meter),
       .delete = Meter_delete
    },
-   .updateValues = DateMeter_updateValues,
+   .updateValues = DateTimeMeter_updateValues,
    .defaultMode = TEXT_METERMODE,
    .supportedModes = (1 << TEXT_METERMODE) | (1 << LED_METERMODE),
    .maxItems = 0,