08011: ddp2 and clones: Desyncs on inp playback

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
08011	Misc.	Minor	Always	Jun 20, 2021, 16:07	Jul 2, 2021, 09:34

Tester	Kale	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Open	OS	Windows Vista/7/8 (64-bit)
Status [?]	Acknowledged			Driver	igs/pgm.cpp
Version	0.232	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	08011: ddp2 and clones: Desyncs on inp playback
Description	DoDonPachi II (IGS) reportedly fails to .inp playback on prolonged sessions.
Steps To Reproduce	Playback from attached inp in version 0.232 with ddp2100 set, it's supposed to reach 628M and last stage, to me it only reach 24M.
Additional Information	Suspected culprits: - the two speedups installed may be unsafe on multisession cfr. https://github.com/mamedev/mame/blob/master/src/mame/machine/pgmprot_igs027a_type2.cpp#L220 - the RTC device may not restore state from an inp correctly https://github.com/mamedev/mame/blob/master/src/devices/machine/v3021.cpp
Github Commit

Flags
Regression Version
Affected Sets / Systems	ddp2 and clones

Attached Files	bbh_ddp2100_628207170_wolf232.zip (455,243 bytes) Jun 20, 2021, 16:07 Uploaded by Kale

No.19002 mahlemiut Developer Jun 20, 2021, 21:51	I'd go with the speedup hacks, as I'm pretty sure INP playback works fine with other PGM games.
No.19003 Haze Senior Tester Jun 20, 2021, 23:27 edited on: Jun 20, 2021, 23:28	There's no reason the speedups should cause inp desync, they're deterministic. Nothing in the driver is threaded.
No.19004 dink Tester Jun 21, 2021, 01:02	I found the cause of this issue about 2 years ago; ddp2 is using the rtc (v3021) as a prng seed. best regards, - dink
No.19010 mahlemiut Developer Jun 21, 2021, 21:59	The RTC is a good suspect, although I'd expect more than just one PGM game to use it as a random seed. Could be easily tested, though.
No.19047 dink Tester Jul 2, 2021, 04:13	The way I fixed the problem in fbneo (then: fbalpha) - the date/time inside the movie file (input recording file) is used to set-up the v3021 rtc.
No.19048 mahlemiut Developer Jul 2, 2021, 04:59 edited on: Jul 2, 2021, 05:00	MAME already does this (just tested it now in 0.232), at least based on the date/time displayed on boot.
No.19050 Haze Senior Tester Jul 2, 2021, 09:34	I wonder how MAME keeps the time updated, I thought it was timers, which should be deterministic, but maybe the core is doing something else? could just be there's something uninitialized in the driver of course, or some start-up order thing, that differs when getting the clock data from an inp vs. the system?