Sonic CD sometime freezes when loading next level

[Former user]

Original [issue 230](https://code.google.com/p/genplus-gx/issues/detail?id=230) created by cheatfreak47 on 2012-07-04T06:34:26.000Z:

Sonic CD freezes while loading levels. all versions ive tried, and ive tried the japanese and usa rom with the v1 bios.

[Former user]

Comment # 1 originally posted by cheatfreak47 on 2012-07-04T06:49:31.000Z:

its inconsistant, but play for about 15 minites, and its sure to happen

[Former user]

Comment # 2 originally posted by ekeeke31 on 2012-07-04T08:15:07.000Z:

I am not sure to understand: you mean you can play (and therefore load) several levels without problem then it freezes when loading a specific level ? Or does the level varies ? If you leave the title screen running 15 minutes, does level 1 still load fine when hitting start ?

Anyway, a savestate before the freeze occurs and a screenshot would be useful, you can upload them here.

[Former user]

Comment # 3 originally posted by ekeeke31 on 2012-07-04T08:17:05.000Z:

[Former user]

Comment # 4 originally posted by cheatfreak47 on 2012-07-04T17:13:01.000Z:

i mean load several levels and it'll likely freeze while loading. It seems random, but the emulator isnt compromised or anything, the game just stays on the loading screen. My USB drive light (indicates read/write activity) doesnt blink, so i assume the emulator isnt reading anything. however, the issue happens on both my SD and USB, both the US and JAP versions of the roms. I'm using the USA v1 bios and the JAP v1 bios.

[Former user]

Comment # 5 originally posted by cheatfreak47 on 2012-07-04T17:33:40.000Z:

ok ill get on the save state then

[Former user]

Comment # 6 originally posted by cheatfreak47 on 2012-07-04T17:46:35.000Z:

ok i zipped my sonic cd save data. including the screenshot from before it happened. i can safely say this state will Always reproduce the problem

[Former user]

Comment # 7 originally posted by cheatfreak47 on 2012-07-04T17:48:53.000Z:

all you have to do is finish the level and it happens.

[Former user]

Comment # 8 originally posted by cheatfreak47 on 2012-07-04T17:51:20.000Z:

The ISO is Sonic CD (U) and the Bios used was the USA v1 bios (most commonly used bios)

both work perfectly in Kega Fusion on my pc. so i doubt its an issue with the bios or rom

[Former user]

Comment # 9 originally posted by ekeeke31 on 2012-07-04T20:06:34.000Z:

Alright thanks, I reproduced it. I will try to find what the problem is when I have some more time for debugging, it's probably a synchronization issue (one CPU waiting for something that never happen or happened to soon).

[Former user]

Comment # 10 originally posted by superballena on 2012-07-05T18:05:28.000Z:

Also happens with the 2.0 US BIOS. It just doesn't load Collision Chaos after Palmtree Panic.

However, if you reset afterwards, the Continue option will let you start at Collision Chaos without any problems.

[Former user]

Comment # 11 originally posted by superballena on 2012-07-05T18:57:20.000Z:

I've managed to load Collision Chaos after beating Palmtree Panic in the 920 prototype.

Again, 2.0 US BIOS.

[Former user]

Comment # 12 originally posted by ekeeke31 on 2012-07-05T19:03:32.000Z:

Since the issue is apparently random or only triggered by some unknown and specific condition, I don't think this has any signification actually.

I have been able to play Collision Chaos many time with both BIOS, only got freezing issue (black screen after the score display) with above savestate.

[Former user]

Comment # 13 originally posted by ekeeke31 on 2012-07-05T23:46:18.000Z:

[Former user]

Comment # 14 originally posted by cluster.phucking on 2012-07-07T15:06:35.000Z:

Happens here too with my USA BIN/CUE copy of the game.

[Former user]

Comment # 15 originally posted by ekeeke31 on 2012-07-08T15:12:18.000Z:

I think this one might be related to simulated audio tracks as well (same as Issue239).

For the record, from analyzing what the game does after loading the above save state, it appears the BIOS is keeping sending invalid CD PLAY commands:

CDD command: 03 00 0b 0c 01 04 01 01

Structure is: CC CC 0M 0M 0S 0S 0F 0F with CC being command id, MM, SS, FF being resp. minutes, seconds & frame of the index to be played, coded in BSD format.

0x0b 0x0c is definitively an invalid "minute field", the maximum being 60 minutes (0x06 0x00) for a Sega CD game. I am not sure if it is done on purpose or happened because i was returning out of spec TOC data when the bios initially requested it (generally done during game init). Anyway, I am now doing differently, by default I always simulate 99 tracks, with 98 audio tracks of 2s following the data track (.iso file), so it remains within Sega CD spec, even with games with very huge data track. I only use original "hard-coded" TOC info for games that actually need it (Snatcher in particular seems quite sensitive to this).

I might post a test dol soon so you can confirm my theory.

[Former user]

Comment # 16 originally posted by [e-mail] on 2012-07-09T18:58:08.000Z:

When I play Sonic CD (All Versions) it freezes after completing the 3rd Act of the 1st Zone you are in. I believe it has to do with the mini anime cutscene with having no audio to support it? I'm just guessing cause the screen just turns and stays black just like this report of the freezing incident!

[Former user]

Comment # 17 originally posted by ekeeke31 on 2012-07-09T21:00:02.000Z:

It's apparently fixed by handling more correct TOC returned from CDD, just like Issue239. At least, I did not experiment any more freeze up to the 3rd stage and not at the end of bonus stages either (was freezing as well before). Here is a test dol with fixed CDD emulation.

[Former user]

Comment # 18 originally posted by ekeeke31 on 2012-07-09T21:11:41.000Z:

Btw, do NOT use savestates from version 1.7.0 with this dol to test your games as the savestate would include the invalid TOC infos (they are stored in RAM by the BIOS on startup)

[Former user]

Comment # 19 originally posted by ekeeke31 on 2012-07-09T21:19:49.000Z:

[Former user]

Comment # 20 originally posted by ekeeke31 on 2012-07-09T23:37:53.000Z:

[Former user]

Comment # 21 originally posted by ekeeke31 on 2012-07-26T19:16:43.000Z:

issue \#261 has been merged into this issue.

[Former user]

Comment # 22 originally posted by boldandwilling on 2012-07-26T19:31:18.000Z:

Just tried this dol and confirm that at least for me, this problem is fixed.

[Former user]

Comment # 23 originally posted by ekeeke31 on 2012-08-05T18:22:50.000Z:

issue \#266 has been merged into this issue.