Recoverable Alert

[CmdrVimes]

Hi chaps,

I have run the attached MyCopperList.s several times and it has worked ok each time - one orange/yellow stripe moving up and down the screen.

I then modified it to MyCopperList1.s and it ran ok until I pressed the left-mouse-button. Then the screen went black and I got the message:

Recoverable Alert
Error 0100 000C Task 003AA2C0

In a flashing orange box.

Can anyone suggest why? All I did was move a code block and add a bsr and rts combination.

EDIT: Of course, it helps to attach the files

[Lonewolf10]

Hmmm...

I ran "MyCopperList1.s" on WinUAE 2.0.1 emulating an A600 (CPU: 68000, Chipset: ECS, 2MB RAM, 8MB Fast RAM). I didn't get the recoverable error message, but the copperlist failed dramatically (nothing at all visible but garbage) until I pressed the mouse button.
What is the target hardware (your settings)?


Regards,
Lonewolf10

[CmdrVimes]

@LoneWolf
Best if I just do this...

[Leffmann]

Most likely because you're clearing more colored lines than you have allocated in your copper program. I counted 216 lines but you're clearing 239 and so you could be poking in memory that is in use by the system or another program.

[CmdrVimes]

@Leffmann

Thank you, thank you, thank you. I knew it'd be something blindingly obvious. Now all I have to do is learn to count...

[Lonewolf10]

You replied too quick!


I compiled both using Devpac 2 (minus the chip ram bit) and they both failed.

I compiled both using Devpac 3 (WITH the chip ram bit) and they both worked - no error. It must be something specific to your settings. Perhaps AGA specific? *shrugs*



Edit: No reply for several hours, then multiple replies at once! typical!!

Regards,
Lonewolf10

[StingRay]

Originally Posted by CmdrVimes

@Leffmann

Thank you, thank you, thank you. I knew it'd be something blindingly obvious. Now all I have to do is learn to count...

In this example you could do it like this: Create a label at the beginning of the copperlist and one at the end and then just let the assembler calculate the correct amount of lines.

    ;move.w    #239-1,d1        ;Counter
    move.w    #(clearend-clearstart)/8-1,d1

.........

copperlist:
    dc.w    $0100,$0200        ;No bitplane
    dc.w    $0180,$0000        ;Backcolour -> black
    dc.w    $1a07,$fffe            
clearstart
    dc.w    $0180,$0000
    dc.w    $1b07,$fffe            
    dc.w    $0180,$0000
    dc.w    $1c07,$fffe            
    .....
    dc.w    $0180,$0000
    dc.w    $ef07,$fffe
    dc.w    $0180,$0000
    dc.w    $f007,$fffe
    dc.w    $0180,$0000
    dc.w    $f107,$fffe
    dc.w    $0180,$0000                                        
clearend
    dc.w    $ffff,$fffe        ;End of copperlist
    dc.w    $0180,$0000        ;Set it to black

Also, please try to avoid these hardcoded offsets otherwise you'll spend a lot of time searching for bugs once you change/update the code. What I mean is code like this f.e.:

lea copperlist(pc),a0
add.w #14,a0

Now, what happens if you decide you need some other copper instructions in your copperlist? There are several ways to avoid problems like that, easiest approach is to just create a label and then use that, e.g.
lea clearstart+2(pc),a0 ; +2 to skip the dc.w $180 word

Hope it's clear what I mean otherwise just ask!

[CmdrVimes]

Morning Everyone.

Originally Posted by StingRay

Hope it's clear what I mean otherwise just ask!

I would not have considered that - I didn't even know it was possible. I have to try and change the way I think about this. If you read/write past the 'end' of a specific location you just end up in the next one which, although perfectly valid as far as the compiler is concerned, may cause all sorts of problems with the code. Alternatively, following your example, you can use it to label specific items within a list without affecting the list itself.

I need to stop thinking in terms of traditional-style variables and arrays. Many thanks for the insight.

[BippyM]

stingray why do you divide by 7 on this line

move.w    #(clearend-clearstart)/8-1,d1

[pmc]

@ bippym - he doesn't

He divides by 8 and then minuses one for the dbra loop.

[Samurai_Crow]

@bippym

Dividing by 8 and then subtracting 1 is not the same as dividing by 7. Check your order of operations. Even in the assemblers that don't support order of operations, they still go from left-to-right.

[BippyM]

okay so why divide by 8??

[pmc]

A copper colour change goes:

dc.w wait_pos,wait_mask
dc.w colour_reg,colour_val

that's four words. Four words = eight bytes

Eight bytes per line of copper colour change, minus one for the dbra loop.

[Samurai_Crow]

@bippym

A copper wait instruction + a copper move instruction = 8 bytes?

-edit-
Ninja'd twice in one thread!

[pmc]

We seem to be on the same wavelength tonight Samurai Crow!

[BippyM]

Cheers chaps, I guess if I had read the source completely and the thread I'd have had a better understanding anyway.. Laziness