[DanielAllsopp]

So, another lunch time used constructively figuring out this lovely little language :-)

I've managed to get rid of my dirty lines, which has inevitably caused some more questions. Here's what I did first though:

As Graeme pointed out, I put the calculation for the blittersize into memory:

BlitterSize: dc.l h*bpls*64+bpl/2

and used it thus:

ClearScreen:
  bsr WaitBlitter
  clr.w BLTDMOD(a6)
  move.l #$01000000,BLTCON0(a6)
  move.l a1,BLTDPTH(a6)
  move.w BlitterSize,BLTSIZE(a6)
  rts

I also changed the DDFSTOP value:

dc.w DDFSTOP,$b0

I based this off the size of the fetches in 4x mode, basically it fetches 64bits instead of the normal 16bits (hence the 4x).

However, I know this is short of the full display width using my rudimentary table:

Address Locations: $38 $40 $48 $50 $58 $60 $68 $70 $78 $80 $88 $90 $98 $a0 $a8 $b0 $b8 $c0 $c8 $d0 $d8 $e0 $e8 $f0
x1 fetch mode: SRT|       |       |       |       |       |       |       |       |       |       |STP
x4 fethc mode: SRT|                               |                               |                               |

So the fetch (for DMA?) is 32bits short?

Shoot me down for the stupid assumptions and questions but:

1. How do I ensure that the fetch actually fetches to the end of the screen. I've already determined stopping later causes issues. Do we use $98?

2. I had a look at the BLTSIZV and BLTSIZH register documentation but couldn't find any examples. Can someone explain how they work? I think one is the width, and one the height. But in what? I'm assuming bits?

Thanks again for any help!