RTC: Automatically detect timezone

Author: TheTechnician27

pcsx2-qt/Settings/EmulationSettingsWidget.cpp

@@ -159,9 +159,9 @@ EmulationSettingsWidget::EmulationSettingsWidget(SettingsWindow* settings_dialog
 	dialog()->registerWidgetHelp(m_ui.manuallySetRealTimeClock, tr("Manually Set Real-Time Clock"), tr("Unchecked"),
 		tr("Manually set a real-time clock to use for the virtual PlayStation 2 instead of using your OS' system clock."));
 	dialog()->registerWidgetHelp(m_ui.rtcDateTime, tr("Real-Time Clock"), tr("Current date and time"),
-		tr("Real-time clock (RTC) used by the virtual PlayStation 2. Date format is the same as the one used by your OS. "
-		   "This time is only applied upon booting the PS2; changing it while in-game will have no effect. "
-		   "NOTE: This assumes you have your PS2 set to the default timezone of GMT+0 and default DST of Summer Time. "
+		tr("Real-time clock (RTC) used by the virtual PlayStation 2. Date format is the same as the one used by your OS.<br>"
+		   "This time is only applied upon booting the PS2; changing it while in-game will have no effect.<br>"
+		   "NOTE: This assumes you have your PS2's DST set to Winter Time.<br>"
 		   "Some games require an RTC date/time set after their release date."));
 
 	updateOptimalFramePacing();

pcsx2/CDVD/CDVD.cpp

@@ -922,23 +922,26 @@ void cdvdReset()
 
 	if (EmuConfig.ManuallySetRealTimeClock)
 	{
-		// Convert to GMT+9 (assumes GMT+0)
 		std::tm tm{};
 		tm.tm_sec = EmuConfig.RtcSecond;
 		tm.tm_min = EmuConfig.RtcMinute;
 		tm.tm_hour = EmuConfig.RtcHour;
 		tm.tm_mday = EmuConfig.RtcDay;
 		tm.tm_mon = EmuConfig.RtcMonth - 1;
 		tm.tm_year = EmuConfig.RtcYear + 100; // 2000 - 1900
-		tm.tm_isdst = 1;
+		tm.tm_isdst = 0;
+
+		ReadOSDConfigParames();
 
 		// Need this instead of mktime for timezone independence
 		std::time_t t = 0;
+
+		// Convert to GMT+9
 		#if defined(_WIN32)
-			t = _mkgmtime(&tm) + 32400; //60 * 60 * 9 for GMT+9
+			t = _mkgmtime(&tm) + 32400 - (configParams1.timezoneOffset * 60);
 			gmtime_s(&tm, &t);
 		#else
-			t = timegm(&tm) + 32400;
+			t = timegm(&tm) + 32400 - (configParams1.timezoneOffset * 60);
 			gmtime_r(&t, &tm);
 		#endif