NeoGeo and Asm - Page 1

Hello

Someone know a way to put asm code in NeoDev.

We want read a sprite memory and move in another memory to change the order of Draw list.

We see here : https://wiki.neogeodev.org/index.php?title=VRAM

$8600 $867F Sprite list for even scanlines
$8680 $86FF Sprite list for odd scanlines

If we use SpriteInit , Neodev own his order list of sprite . And we want to change le order in memory, if we have create sprite 1 before sprite 2
we want change in memory by Sprite2 before Sprite 1

Thanks For your help

Thanks to Black_Jack, now we can insert the asm with __asm __ ("move.w ...");

I can write VRAM with 0x3C000X

So I'd like now to change the display order of sprites. I have my first sprite 1 and the second in 2 one above the other. I think (with the docs) the first sprite is in 0x0040 or 64 in decimal and I would swap the two sprites. 0x0040 <-> 0x0080.

Do we must copy via temporary variables every word of 64-128 and how we do it ?

If someone can give us a clue, please, please.

sounds interesting but this is not yet documented (only m.a.m.e. source refers to this locations) so I have done some tests (on hardware):

pro:
- this memorylocations are writable
- you can change drawing order of sprites

con:
- this memory is updated/rewritten every scanline(!) by the system itself (so it's just for internal use?)
- manual rewrite/update have to be done every scanline (via irq2)
- update is slow (via VRAM_ADDR/VRAM_RW), only 3 oder 4 sprite changes are possible per scanline

sorry, it seems this idea ist very limited and not practicable. :-(

Thanks for your answer and tests.

Can you share the code for "change drawing order of sprites" so I can make some test in my code.

If this idea is not praticable, do you use an another way to ordering sprites?

be warned, you will see no effect until you set this every scanline. i put this litte code into wait_vblank without doing anything in mainloop.
screenshots are from mame but on real hardware it works and looks the same.

this example shows 1st sprite (0x0040 = $1) vs last sprite (0x5f00 = $17c = #380)

many many thanks, I'll try that

another way to ordering sprites? it depends how many sprites you use.
the easiest way is to make a sprite for every layer and to "disable" unneeded sprites by moving it out of screen (ypos+240).

I wish to try making game like sengoku 3, a side-scrolling beat up game. So my sprite order change often, I don't think I can use multiple sprite on different layers. The sprite moving in a third dimension forcing me to use the scb_even / scb_odd.

I use the .Datlib framework from HPMan and It's already using a Vblank function. I think I need to write my own vblank to change the sprite order.

I success with the sprite order, with a vblank function (I understand, we need to change the 96 lin sprite every blank) but I can't go out my new Vblank function. Infinite loop ?
Vblank2: MOVE.W #0x1,0x3C0004 MOVE.W #0x8600+1,0x3C0000 MOVE.W #0x02,0x3C0002 MOVE.W #0x1,0x3C0002 MOVE.W #0x8680+1,0x3C0000 MOVE.W #0x02,0x3C0002 MOVE.W #0x1,0x3C0002 cmp.w #1, 0x100000 bne Vblank2 clr.w 0x100000 rts



My new vblank function but infinite loop? I use the code from Frog Feast NG
Vblank2: cmp.w #1, 0x100000 bne Vblank2 clr.w 0x100000 rts

Can you help me again ?

0x100000 refers to a memorylocation, this location is set to #1 by another internal function (vblank-irq/irq1), wait_vblank waits until this location is #1.
i dont know how Datlib works, maybe another memorylocation, long instead of word (or byte?), waits until #0?
maybe HPMAN can help?

i think you can not use SCB_EVEN/ODD ingame!

Unfortunately we no longer sees HPMAN on the net.

You're right, I'll find another way. I just like to understand the hardware and do tests to find the best solution.

blastar (./9) :
0x100000 refers to a memorylocation, this location is set to #1 by another internal function (vblank-irq/irq1), wait_vblank waits until this location is #1.
i dont know how Datlib works, maybe another memorylocation, long instead of word (or byte?), waits until #0?
maybe HPMAN can help?
i think you can not use SCB_EVEN/ODD ingame!

There's a flag somewhere, placed by the compiler depending of your application. Not a fixed position.

Don't write to 0x100000, it's 100% sure compiler will have stuff here (SBSS section).

Check compiler output map file for used ram end location (also variable _end in C code), or edit the gcc config file (neocart.x) and reduce ram section for the compiler to use.

Good to see you

Thank you, I never checked the output map file. I'll look inside.