[Other✓] Var location

[Mickey`]

Hi everyone, I'm sorry if I'm not in the good section, and I'm sorry for my bad English too, I'm French... :(

After many researches, I haven't been able to find the location where variables are stored.

For example, I know thanks to many tuts that the var 0x8000 is stored at 0x20370B8. But I want to find, for example, the location where the var 0x4200 is stored.

Can someone help me ?

Thanks ! :)

 

[esperance]

I believe the variables start at 0x020275D8 for Emerald and 0x020270B8 for FireRed. To get the correct offset, you need to multiply the desired number by 2, because each variable is a half-word stored in the RAM.

Although, not every offset is actually a variable, so be careful with what you use.


EDIT: If you wanna access a variable you don't know the address to, try using the variable decrypter. It's documented here: Click

 

[Mickey`]

So if I want to find the location of the var 0x4200 :

20270B8 + (4200 * 2) = 202F4B8

But the value at 0x202F4B8 doesn't change when I set the var 0x4200 to any value.

I don't understand how to use the variable decrypter...

 

[esperance]

Well, assuming we're talking ASM here, and you want to use the variable decrypter, you would need to load the number of your variable into r0, call the routine, and the appropriate RAM location would be returned in r0.

 

[Mickey`]

I can't understand the problem... What's wrong in my routine ?

.align 2
.thumb

main:
	push {r0-r1}
	ldr r0, var4200
	ldr r1, decrypt
	bx r1
	pop {r0-r1}

.align 2
var4200:
	.word 0x4200

decrypt:
	.word 0x0806E455

Ps : Is it possible that the offset of the variable decrypter is different in a French ROM ? Because I found the same data at 0x6E454 in the English ROM and at 0x6E478 in the French ROM. But even with this second offset, the routine doesn't work...

 

[daniilS]

I can't understand the problem... What's wrong in my routine ?

.align 2
.thumb

main:
	push {r0-r1}
	ldr r0, var4200
	ldr r1, decrypt
	bx r1
	pop {r0-r1}

.align 2
var4200:
	.word 0x4200

decrypt:
	.word 0x0806E455

Ps : Is it possible that the offset of the variable decrypter is different in a French ROM ? Because I found the same data at 0x6E454 in the English ROM and at 0x6E478 in the French ROM. But even with this second offset, the routine doesn't work...

Yes, the routine is probably located somewhere else in the French ROM.
Another thing with your routine is that while it works, it will never return. So if you want to know the var address, you'll have to find the end of the var decrypter. To make it return so you can read the addres with a break at the end of your routine (and let the game safely continue after) you will need something like this:

.text
.align 2
.thumb
.thumb_func
.global getvar

main:
	push {lr}
	ldr r0, var4200
	ldr r1, decrypt
	bl bxr1
	pop {pc}
bxr1:
	bx r1

.align 2
var4200:	.word 0x4200
decrypt:	.word 0x0806E478+1

Also, why hack a French ROM? Foreign ROMs aren't usually documented that well and some tools don't support them.

 

[Mickey`]

Oh, sorry, I was in holidays. Thanks a lot for your help !

I'm French, so I usually use French ROMs :)

 

[daniilS]

Oh, sorry, I was in holidays. Thanks a lot for your help !

I'm French, so I usually use French ROMs :)

Yeah, I understand that. I just personally think it would be easier to translate an English ROM to French than to find all offsets we know in BPRE in BPRF.

 

[Mickey`]

Yeah, I think so, but I realized that when my projet was aleready started...