CD32 - File reading / closing query

Galahad/FLT · 20 October 2014, 01:21

I've just done something for CD32, and it has a problem. On Amiga hard drive, it works exactly as expected, but on CD32 it crashes.

Basically i'm loading a big-ish file (768K), and using AmigaDOS to do it all, and as soon as the file is loaded, I kill the system, transfer some code low down in memory and make sure everything relocates as it should.

However, if I allow this to happen from loading from the CD32 it will crash after loading the file.

If however, everything is copied to RAM: and then run from there, it works perfectly.

I'm assuming its got something to do with having to wait until the CD spins down or gets the signal from the CD32 to stop spinning.

Is there a required wait period thats supposed to occur before system shutdown after reading a file?

musashi5150 · 20 October 2014, 08:28

I've heard this mentioned before - but never heard a concrete period that should be waited before killing the system. I guess it's a couple of seconds.

When initially booting your first executable the problem can be avoided by opening and then immediately closing the freeanim.library to remove the startup animation correctly. The OS will block execution of your code until the animation is complete, which is also more than enough time for the cd.device to finish any caching it might be doing before you bin the system.

Toni Wilen · 20 October 2014, 08:52

It happens because cd device always prefetches next 16 CD sectors and each sector causes level 2 interrupt which can be only cleared by writing to Akiko interrupt register.

I don't know if there is any official method, perhaps sending CMD_STOP or CD_MOTOR IO command stops it or at least IO call returns only after prefetch has finished.

Some CD32 games have CPU busy wait..

Galahad/FLT · 20 October 2014, 12:39

Thanks chaps, i've now put in a close for the opened Intuition library and put in a couple of seconds delay in there and it appears to have done the trick.

Obviously if I wasn't shutting down the system it wouldn't have been a problem as the multitasking would have enabled everything to sort itself out in the background.

Ta

20 October 2014, 01:21	#1
Galahad/FLT Going nowhere Join Date: Oct 2001 Location: United Kingdom Age: 50 Posts: 8,986	CD32 - File reading / closing query I've just done something for CD32, and it has a problem. On Amiga hard drive, it works exactly as expected, but on CD32 it crashes. Basically i'm loading a big-ish file (768K), and using AmigaDOS to do it all, and as soon as the file is loaded, I kill the system, transfer some code low down in memory and make sure everything relocates as it should. However, if I allow this to happen from loading from the CD32 it will crash after loading the file. If however, everything is copied to RAM: and then run from there, it works perfectly. I'm assuming its got something to do with having to wait until the CD spins down or gets the signal from the CD32 to stop spinning. Is there a required wait period thats supposed to occur before system shutdown after reading a file?

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20 October 2014, 08:28	#2
musashi5150 move.w #$4489,$dff07e Join Date: Sep 2005 Location: Norfolk, UK Age: 42 Posts: 2,351	I've heard this mentioned before - but never heard a concrete period that should be waited before killing the system. I guess it's a couple of seconds. When initially booting your first executable the problem can be avoided by opening and then immediately closing the freeanim.library to remove the startup animation correctly. The OS will block execution of your code until the animation is complete, which is also more than enough time for the cd.device to finish any caching it might be doing before you bin the system.

20 October 2014, 08:52	#3
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	It happens because cd device always prefetches next 16 CD sectors and each sector causes level 2 interrupt which can be only cleared by writing to Akiko interrupt register. I don't know if there is any official method, perhaps sending CMD_STOP or CD_MOTOR IO command stops it or at least IO call returns only after prefetch has finished. Some CD32 games have CPU busy wait..

20 October 2014, 12:39	#4
Galahad/FLT Going nowhere Join Date: Oct 2001 Location: United Kingdom Age: 50 Posts: 8,986	Thanks chaps, i've now put in a close for the opened Intuition library and put in a couple of seconds delay in there and it appears to have done the trick. Obviously if I wasn't shutting down the system it wouldn't have been a problem as the multitasking would have enabled everything to sort itself out in the background. Ta

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