Can fast-forward cause problems in Pokemon saves?

[cloudropis]

I noticed that fast-forwarding while playing Pokemon also doubles the speed of the in-game clock. May it cause problems when reloading a savefile?
For example, it's 10:00. I grind for 30 minutes with fast-forward, meaning I turn off the game at real-time 10:30 but when saving the game it shows 11:00. I turn on the game and load my save at real-time 10:50, would that cause problems? After all, I'm asking the game to load a file created 10 minutes into the future.
I know it probably wouldn't be a problem since you could change date on the original DS too, and many gameplay exploits live by that, but I'd like to avoid save-corruption issues as I don't like using savestates (also because they seem to have caused quite the share of problems in this forum), so I'm asking to be perfectly safe.

[Fefo]

Probably not, like you said it's no different from saving on a real DS and changing the clock. Savestates could cause some desync depending on how the emulator works, but nothing gamebreaking or capable of corrupting a save file.

Corruptions come mainly from bad writes while saving or copying, or maybe a emulation bug. You can also break your save with cheats, but this wouldn't be a proper corruption.

[Exophase]

I hadn't thought of this before - I would hope it doesn't cause problems but it's not impossible that it will. There's an option to keep the emulated RTC synced with the device time, but honestly I'm not sure which is more potentially dangerous.

I would recommend backing up your save files (the .dsv files in the backup directory) periodically if you can, and if you ever run into save corruption please let us know.

[cloudropis]

I hadn't thought of this before - I would hope it doesn't cause problems but it's not impossible that it will. There's an option to keep the emulated RTC synced with the device time, but honestly I'm not sure which is more potentially dangerous.

I would recommend backing up your save files (the .dsv files in the backup directory) periodically if you can, and if you ever run into save corruption please let us know.

I think the RTC synch is already on, when I load the save fie it displays the current hour.
Yes, I'll start doing backups even more often. I'll report in this topic if I ever get save corruption.
Unrelated, I remember when playing G/S/C on VBA the clock was detached from the speedup function. Ie, while keeping the 2x speedup pressed a in-game minute would still last 60 seconds, not 30. Would that be possible to implement a settings that does the same? I know absolutely nothing about emu development, but if a decade old emu managed to do it I suppose it wouldn't be in the realm of impossibility?

[Kyousuke753]

Fast Forward doesn't affect save, I play multiple Pokemon games and FF helps speed up the level grinding.

[TkSilver]

As far as I have tested pokemon only seems to freakout when you throw it something impossible. For example having a cartridge (nds) save that is from a point in time and then using a savestate to put the emulator into the past before the cartridge save could have been made. I am pretty sure saving cartridge saves inside of savestates fixes this issue but Inam not sure.

Example:
Make a savestate
Play for a week or 2 never updating the save state only using the in game save feature.
Load up drastic one day and decide to load the older savestate and save over the newer in game save.

Sometimes this will cause pokemon to mess up.

[cloudropis]

So I shouldn't have any problems since I'm not using savestates.
Exo, I actually don't have the RTC synch enabled. Why did you say it could possibly be dangerous?

[Exophase]

As far as I have tested pokemon only seems to freakout when you throw it something impossible. For example having a cartridge (nds) save that is from a point in time and then using a savestate to put the emulator into the past before the cartridge save could have been made. I am pretty sure saving cartridge saves inside of savestates fixes this issue but Inam not sure.

Example:
Make a savestate
Play for a week or 2 never updating the save state only using the in game save feature.
Load up drastic one day and decide to load the older savestate and save over the newer in game save.

Sometimes this will cause pokemon to mess up.

This is why the change was made to store the in-game saves in the savestate by default.

So I shouldn't have any problems since I'm not using savestates.
Exo, I actually don't have the RTC synch enabled. Why did you say it could possibly be dangerous?

It could create an inconsistency that the game is not prepared for. Like if you go into the emulator's menu and sit there for 10 hours (or you save a state then load it 10 hours later), to the game it'd look like 10 hours disappeared out of nowhere. This is the sort of thing that wouldn't be possible on a real DS. Normally you'd think that the game wouldn't be explicitly checking the RTC against another time source for consistency, but it's the sort of thing that could result from unintended assumptions in the code. For example, if the game is looking at an elapsed time between two RTC points and that value overflows a variable or something.

By syncing the time only when the game launches it's consistent with what could happen on a real DS, since like you mentioned before it's possible to change the time in the DS's firmware menu before loading the game. You wouldn't think that a game would actively punish you for this, especially when you could lose the time just by letting the battery die and not set it again or set it improperly. But the Pokemon games are known to do some other consistency checks that I wouldn't expect games to do.

(Technically the RTC sync isn't quite right anyway, it advances 1/60th a second per emulated frame when it should be ~1/59.59 of a second. So it drifts a bit, and I really need to fix this.. but even on a real DS the clocks won't match up exactly reliably.)

[Fefo]

Your last point - I noticed strange clock desyncs while playing. It's very inconsistent though: most of the times things are on sync no matter for how long I played, but once or twice the clock was noticeably "slower" on a short burst.

Now I'm curious. Is the DS clock exclusive, or part of the hardware, and can it be used for timing on games? Dunno how computers mark time.