Copper ASM

[LeCaravage]

Need your help guys,

2 questions about Copper coding.

- Is it mandatory to use the first wait to pass the 255th raster line ?

dc.w $FFDF,$FFFE
dc.w $10XX,$FFFE

- How it comes the raster bug appears to the right side of the screen with any wait before horizontal pos beam < $07 ?

for instance  : dc.w $xx03

Thanks for enlightening my path to amiga coding.

[Toni Wilen]

Originally Posted by LeCaravage

- Is it mandatory to use the first wait to pass the 255th raster line ?

Yes, unless you are already near the end of line 255. Without this extra wait, line $10 wait would end immediately because $10 is smaller than 255.

- How it comes the raster bug appears to the right side of the screen with any wait before horizontal pos beam < $07 ?

It is internal horizontal counter zero position. For some reason it is before horizontal blanking.

DIWSTOP is also affected by it. Increasing horizontal end will work normally until suddenly ($c8=$1c8) it jumps to full overscan. It happens in exact same zero position

[LeCaravage]

Originally Posted by Toni Wilen

Yes, unless you are already near the end of line 255. Without this extra wait, line $10 wait would end immediately because $10 is smaller than 255.

It means more add bne and bcc in the copper construction loop every frame

Anyway, thanks for taking time to answer my questions.

[Toni Wilen]

If you want to "hide" this extra wait, replace it with MOVE to COPJMP2 and do the extra wait in another copper list, then jump back to original copper list.

[LeCaravage]

So if I understand well. I construct my copperlist. Do my calculations for the $ffdf extra wait, and at end overwrite one or two moves with a copljmp2. In this "second copperlist" do the missing color moves and go back to main copperlist ?

[LeCaravage]

Toni, you're the man. You're trick works like a charm. Makes my construct copper routine easier and faster.