trying to draw tiles with VDP

[cyberyoyo]

Hi, I'm new on these boards
first of all a big thank you to Devster and all the hard working sega community you guys are great.

This is my problem:
I'm trying to use ASM in Basiegaxorz to display tiles on screen (because the basic commands don't really do what I want to do and I think it might be less tressful in the long term to just use ASM)

here is my code


Palettes newpalette, 0,0,16
Palettes pallete2, 1,0,16
LoadTiles newtiles, 230, 256

testdraw


declare asm function testdraw
       move.l  $C00000, a0        ; VDP DATA port
       move.l  $C00004, a1        ;VDP CTRL port
       move.w $8F02, (a1) ;Set autoincrement (register 15) to 2

move.l $E000, (a1) ;start of PLANE_B
move.w  #2000,  d1 ; number of bytes
move.l $20, d2 ;tile reference $20 = 00000000000100000  = tile 1
@loop:
move.w d2, (a0)
subq.w #1, d1
bne @loop

end function


'============== GAME DATA ====================
newtiles:
datafile t2.bin, BIN

newpalette:
DATAINT $0E0E,$0244,$024A,$0224,$0222,$0268,$0000,$006C
DATAINT $02AE,$068C,$0ACE,$04AC,$0000,$0000,$0000,$0000

DATAINT $0244,$024A,$0224,$0222,$0268,$0000,$006C,$02AE
DATAINT $068C,$0ACE,$04AC,$0000,$0000,$0000,$0000,$0000
pallete2:
DATAINT $0E0E,$0000,$0CCC,$0A88,$0AEE,$0644,$0442,$0000
DATAINT $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000






I have made the ASM function testdraw that is supposed to fill the screen with tile number 1.
The tiles are correctly loaded because I have tested with the basic drawtile command and they are okay.

Unfortunately gthe screen remains blank, What am I doing wrong?

[Deleted]

I have no idea how ASM works. This thread has an example of a working DrawTiles routine in ASM:
devster.proboards.com/index.cgi?action=display&board=basiegaxorz&thread=792&page=1

Welcome to the forum!!!

[cyberyoyo]

thanks a bunch, the routine in question should help me get on the right tracks

[Mairtrus]

Hello dude, and welcome to the forums!

The problem with your code is in this line:
move.l $E000, (a1) ;start of PLANE_B
Unfortunately, is not that easy to set the write address on the VDP, since it's made to be managed with commands. I will not go in detail in this because it's large and boring (you can find more details in the old-but-still-awesome collection of documents called "gen_tech"), but to convert a "write address" into a command you can do this:

move.l $E000,d0 ; start of PLANE_B
lsl.l #2,d0
lsr.w #2,d0
swap d0
addi.l #$40000000,d0
move.l d0,4(a6)

[cyberyoyo]

ok thanks a lot, I have found a bit more informations on the net and indeed, the VDP is not that easy to use