Basic Questions & Answers thread

I can't remember exactly the numbers but I recall that they are 4 digits and they sort of sum up in a fashion like, 0002 increments red, 0020 green and 0200 blue. Then when the numbers overlap, you end up with an odd digit so it doesn't mess up with the info. If you toy around a little with Knuckles Chaotix debug menu, you can alter palettes in real time so you can figure out how they work.

 

Not sure about the tiles, but you can edit palettes with this palette editor I wrote some time ago.

I made it for Varion, he knows how to 32x, I'll see if I can get him to reply here.

 

32X doesn't have tiles, it has a framebuffer. Graphics data can be stored in any format the developers want. There's an editor for the Chaotix sprite format in SonLVL.

 

Does anyone know how Sonic 1 loads object palettes in its code? I'm making a character hack base, and I don't want to change the object mappings unless I need to

 

One thing i have wondered about the Neon Cowgirl sign from Sonic Adventure 1 that was censored was if it's "Moan" Sound Effect is still in the sound test, If so which Number?

 

Since I have no idea if and when this question was ever answered here, I must ask:

In 68000 assembly programming, when is it better to use a clr command versus a move command with a source operand that resolves to 0? I'm curious why some functions use one and not the other.

 

Sup people are there any sonic1,2 or 3 hacks that show different character behavior, like castlevania or contra?

 

I've tried to see if I could replace the SEGA sound in Sonic 1 following this tutorial: https://forums.sonicretro.org/index.php?threads/editing-sonic-1s-sega-sound.36957/
However, in-game the sound I use almost sounds like a corrupted version of itself.
It's similar to a problem mentioned in this tutorial: http://info.sonicretro.org/SCHG_How-to:Fix_the_SEGA_Sound, but, since I use the latest disassembly, I couldn't figure out how if it actually has the same cause or how to fix it.

 

Is there any particular reason why the Special Stages in Sonic CD make the sound engine chug balls? It happens on real hardware and on an emulator. I'd almost say it's due to the plane scaling/rotation effects running alongside game code, but the fact that there's no audio issues in the US CD BIOS screens could rule that out. Poor optimization of code perhaps?

 

I don't think you can redefine the 68k mnemonics with ASM68K, I think they get priority over macro definitions.

Two possible alternatives; 1. create a macro with a unique name similar say "mnop" or whatever, 2. alter the exe at offset A7BF and change the two bytes from 4E 71 to 12 34.

 

Actually, it sorta is...

The way ASM68K deals with processing mnemonics is by indexing the first letter against a jump table from a to z. It has a subroutine for each valid letter, so there's a subroutine specifically for instructions that start with "n":

• "neg"
• "negx"
• "nop"
• "not"
• "nbcd".

It checks the next two letters as a word (comparing for "eg", "op", "ot", and finally "bc", for instructions such as "neg" and "negx" the conditional jump for "eg" will then check for "x" in the subsequent routine.

So effectively, all you need to do is nop out (ironically) the comparison and conditional jump for "op" in this subroutine.

Goto offset A655 and replace 66 3D 6F 70 0F 84 4A 01 00 00 with 90's.

The "nop" is now not recognised as a valid instruction by ASM68K. You can now create a macro for nop to do something totally different, and create a macro for bop to place in 4E71 to your liking.

 

Ahhh, you probably should have said, AURORA☆FIELDS has already done this here (link on the post appears to be down, so have a mirror).

For opcodes which are shared with 68k (add, sub, or, and, nop, etc), she prefixed the Z80 versions with a z (e.g. zadd, zsub, and znop and so on...). You should probably consider contacting her, she is very knowledgeable of ASM68K as an assembler, and has a fair number of tricks up her sleeve.

Out of interest; if I'm understanding rightly, it seems you're favouring nop for Z80 rather than 68k, is there a particular reason for this? How comes not the other way around, i.e. "bop" for Z80?

 

Ahhh, awesome idea! That would be absolutely delightful if you can pull it off~

Still not entirely sure why you need "bop" specifically, couldn't you use:

nop: macro
if z80 = true
dc.b 0
else
dc.w $4E71
endc endm

Directly? I assume there must be an alternative reason.

At any rate, I'll stop with the questions, but I am certainly interested in progress on this. Feel free to shoot me a PM if you need a bit of help.