(Solved) Batari Basic 1.1d screen jitter

[iesposta]

My last few projects compile fine and run on Stella fine, but on Harmony on real hardware when Player0 sprite gets halfway down the screen, the playfield jitters.

See attached .bin

I'll add more files tomorrow.

Could it be the high resolution playfields?

Oh, press the button and then move the joystick left or right to start.

Stunt_Bike10-21-12.bas.bin

[jrok]

Be sure to define the values of DF0FRACINC - DF6FRACINC for <i>every</i> drawscreen (Without seeing your code, I'm thinking that this is your problem; it seems to be a universal issue with the 1.1d build)

Also, try inserting the following at the beginning of each bank designation (bank 1, bank 2, etc):

   temp1 = temp1

[RevEng]

Are you using vblank, or are you performing any calls in your main loop that would use ARM code? (playfield pixel commands, etc)

 

Stella doesn't accurately calculate ARM processing time, so anything that calls ARM code is instantly performed on Stella. Really easy to blow cycles that way. To make matters worse, the DPC+ bB kernel doesn't have any free time left during vblank to speak of, so it's not really viable to use it.

 

There was a bug in bB 1.1b that caused bouncing with certain DFxFRACINC values, but I think that was fixed with 1.1c.

[iesposta]

"define the values of DF0FRACINC - DF6FRACINC for every drawscreen"

That was it, thanks. Never saw that tip before. There's a 2nd drawscreen for the middle and a 3rd for the bottom.

I have the temp1 = temp1 and not using vblank.

I am pushing the DFxFRaCINC values way up.

Again, you guys are so great, how would I ever have figured that out?

[+stephena]

Until Stella is updated to do cycle counting of ARM code, you're recommended to test on Harmony occasionally to make sure you haven't gone past the cycle count limit.