Re: [hatari-devel] Hatari screen test

[ Thread Index | Date Index | More Archives ]


On 5/25/20 7:54 PM, Thomas Huth wrote:
Am Mon, 25 May 2020 17:32:55 +0300
schrieb Eero Tamminen <oak@xxxxxxxxxxxxxx>:
NOTE: I tested the 0xFFFF820A register value
with a breakpoint, and that can be there much
before screen looks correct. Therefore I think
something like VBL wait would be more robust.

I thought about that, too, but I think the current code should be
relatively safe: As far as I can see, the function that checks the
command fifo is only polled approx. once per VBL.
So between the
"hatari-debug r" and the "hatari-shortcut screenshot", there should be
at least one VBL, leaving enough time to render a proper picture.

Yes, cmd-fifo input is checked in mainloop i.e.
only every VBL, whereas debugger does check on
every instruction.

Your check uses 0.2s sleep i.e. it checks the
register only at 5Hz i.e. every 10th or 12th VBL.

But if I'm wrong and we hit some unexpected test failures here in the
future, sure I'll rework the code in that case.

When I changed breakpoint to check register value
only on VBL change:
breakpoint  VBL ! VBL  &&  a0 = 0xFFFF820A  :trace :file screenshot.ini

I still got the wrong picture on first VBL.

I.e. what you're doing can still fail, if it
happens to catch first VBL on which that register

With 50Hz screen updates, probability for that is

You can actually do the whole thing with
the debugger, now that I added "screenshot"
command to it:
	$hatari --parse debug.ini ...

----------- debugger.ini -----------
# parse screenshot.ini after 400 VBLs

breakpoint VBL > 400 :trace :file screenshot.ini

---------- screenshot.ini ----------
# take screenshot and quit Hatari

screenshot verify.png

(Quit flag is parsed in Hatari main loop.
Breakpoint ":trace" flag use avoids Hatari
stopping to debugger, so it gets back to

Nice trick, I'll try to remember that for the future!

Image comparison might also be slightly shorter
by using ImageMagick "compare" command instead
of "identify" one.

How do you use "compare" for automatic tests? It rather seems useful
for visual inspection of the differences only?

Using return value:
Two images are considered similar if their difference according to the specified metric and fuzz value is 0, with the exception of the normalized cross correlation metric (NCC), where two images are considered similar when
       their normalized cross correlation is 1. The default metric is NCC.

The compare program returns 2 on error, 0 if the images are similar, or a value between 0 and 1 if they are not

If there actually is a difference, it's good to
have a picture that highlights the differences
because sometimes they can be very subtle.

In case of EmuTOS, there are slight differences between boots, which I think come from host-
impacted, small interrupt startup timing
differences.  Those might also affect some tests
outcome, or is instructions flow 100% reproducible
for "--tos none"?

Btw. Would it be a lot of work to change this to
be a reset demo, as that would test a bit more
Hatari functionality?  :-)

:-) ... but unfortunately yes, it would be quite a bit of work, since
the "--tos none" mode does not support reset handlers yet.

I see.  Forget that then. :-)

	- Eero

Mail converted by MHonArc 2.6.19+