[asm] diwstrt i vstart

[Asman]

Hi

I am not sure If I find the bug in WinUAE 4.4.0. I am working on Wiz WHDLoad patch and there is something I am not understand, its about diwstrt and vstart.
Game starts and screen with logo appears from down to up. Like in first three seconds on this video ( [ Show youtube player ] )

There is asm snippet (I did minial example of this problem)

;copper part 
		dc.w	$008e
chipDiwStart:	dc.w	$fc81
		dc.w	$0090
		dc.w	$2cc1
;routine

Appear:
.loop		bsr	BeamWait

		lea	chipDiwStart,a0
		cmp.b	#$2c,(a0)
		beq	.exit
		sub.b	#1,(a0)
.next		bra	.loop

.exit		rts

But on WinUAE the screen jumping when is almost (something like that) on position. I checked on A1200 (030) and A500 configuration. In the Zone I am going to put source and executable.

Can someone confirms this behavior on WinUAE and real machine.


Edit: In the Zone I added also short avi from a500 configuration.

[a/b]

Executable works fine for me, it scrolls up smoothly without any jumping (tested with my a500 and a4000 configs in winuae 4.4.0).

[Asman]

@a/b - Thanks for checking. Can you share your a500 config ?

Edit: @a/b - Nevermind. I found that When In Display I tick Centering Horizontal and Vertical then this issue appear. Thanks a/b.

[DamienD]

Originally Posted by Asman

Edit: @a/b - Nevermind. I found that When In Display I tick Centering Horizontal and Vertical then this issue appear. Thanks a/b.

I was about to say... some games do this when vertical centering is ticked

[Asman]

Originally Posted by DamienD

I was about to say... some games do this when vertical centering is ticked

Thanks.

Silly me, first I was sure that is something wrong with game, then I was sure that is something wrong my knowledge about hardware registers or I found a bug in WinUAE. Finally it was tiny ticked vertical centering. I definitely need legendary Toni crystal ball