Help Thread: ASM & Disassembly

Blah · Dec 26, 2014

JoshTheTrainer said:
And that's in the assembly of my rom, right? So I just need a disassembler and assembler or is it just basic script editing?

This is done in hex, you can use the disassembler builtin in the VBA Emulator for this level of work.

JoshTheTrainer · Dec 26, 2014

FBI agent said:
This is done in hex, you can use the disassembler builtin in the VBA Emulator for this level of work.

Oh okay, I'll try it out. Thanks anyway :-)

Joexv · Dec 26, 2014

Alright, Fbi Agent how would I go about adding the flag check to the routines like you suggested?
Is it just adding this to it?

Code:

push {r0-r4}
	mov r0, #0xBF @flag to check divided by 4
	lsl r0, r0, #0x2

HidoranBlaze · Dec 26, 2014

joexv said:
Alright, Fbi Agent how would I go about adding the flag check to the routines like you suggested?
Is it just adding this to it?

Code:

push {r0-r4} mov r0, #0xBF @flag to check divided by 4 lsl r0, r0, #0x2

If you want to check a flag in one of your routines, you'll have to bl call the flag decrypt function, which takes the flag you want to check in r0, and returns the status of that flag to r0. I forget where that function was in FR, but basically do something like this:
(load flag # in r0)
...
bl flagcheck

flagcheck:
ldr r1, function
bx r1

You can use any free register of course, I just used r1 as an example. Hope this helps.

Blah · Dec 26, 2014

HidoranBlaze said:
If you want to check a flag in one of your routines, you'll have to bl call the flag decrypt function, which takes the flag you want to check in r0, and returns the status of that flag to r0. I forget where that function was in FR, but basically do something like this:
(load flag # in r0)
...
bl flagcheck

flagcheck:
ldr r1, function
bx r1

You can use any free register of course, I just used r1 as an example. Hope this helps.

Yeah, but I make a point to have to ldr in the main function body. That way you can use the linker for more than just a single case. I also believe it's slightly more readable (maybe :P).

But yeah, what HidoranBlaze did is what you'd do. Make sure to push the low registers you want to save before calling the function, it overwrites r0-r3 :D

Joexv · Dec 26, 2014

FBI agent said:
Yeah, but I make a point to have to ldr in the main function body. That way you can use the linker for more than just a single case. I also believe it's slightly more readable (maybe :P).

But yeah, what HidoranBlaze did is what you'd do. Make sure to push the low registers you want to save before calling the function, it overwrites r0-r3 :D

Ok, but how would I load the flag number into bl?
I suck at asm so sry for any stupid questions.

Blah · Dec 26, 2014

joexv said:
Ok, but how would I load the flag number into bl?
I suck at asm so sry for any stupid questions.

The flag checking function is a subroutine. If you're familiar with other programming languages they call things like these "functions" or sometimes "methods'.

Anyways, the flag checker function has a parameter which is the flag number. By definition, this parameter would be in r0. So you would just load into r0 your flag's number and then call the flag checker function.

The process of how we're "calling" the subroutine is a little harder to understand. It's a clever trick having to do with manipulation of the Stack. You see, bl is limited to within approximately 20 bytes (I don't recall the exact amount, but around that neighborhood) and obviously the function we're calling is somewhere near the start of the ROM (definitely not 20 bytes), so the only good way to get to it is to use bx. However, bx doesn't have a return, because it doesn't write anything to the lr. So we use this convention of bl to a bx, because bl overwrites the current lr value. So that way once the subroutine we call ends, it will go back to where the lr is pointing. However, it's important to note that bl overwrites lr without preserving it, so to make sure you're not messing anything up, push {lr} before doing any links, unless you know what you're doing :D

To answer your question, you're not loading the flag number into lr, you're going to be loading the flag number into r0, then doing the aforementioned method to link to the flag checker subroutine. That routine would, again by definition, return 0 or 1 in r0. So after your link, you would simply check r0.

Hopefully that made sense, I'm not very good at explaining.

Joexv · Dec 26, 2014

FBI agent said:
The flag checking function is a subroutine. If you're familiar with other programming languages they call things like these "functions" or sometimes "methods'.

Anyways, the flag checker function has a parameter which is the flag number. By definition, this parameter would be in r0. So you would just load into r0 your flag's number and then call the flag checker function.

The process of how we're "calling" the subroutine is a little harder to understand. It's a clever trick having to do with manipulation of the Stack. You see, bl is limited to within approximately 20 bytes (I don't recall the exact amount, but around that neighborhood) and obviously the function we're calling is somewhere near the start of the ROM (definitely not 20 bytes), so the only good way to get to it is to use bx. However, bx doesn't have a return, because it doesn't write anything to the lr. So we use this convention of bl to a bx, because bl overwrites the current lr value. So that way once the subroutine we call ends, it will go back to where the lr is pointing. However, it's important to note that bl overwrites lr without preserving it, so to make sure you're not messing anything up, push {lr} before doing any links, unless you know what you're doing :D

To answer your question, you're not loading the flag number into lr, you're going to be loading the flag number into r0, then doing the aforementioned method to link to the flag checker subroutine. That routine would, again by definition, return 0 or 1 in r0. So after your link, you would simply check r0.

Hopefully that made sense, I'm not very good at explaining.

OK that makes slightly more sense... but I'm still confused as to how im loading the flag number and value.
I understand that ldr reads so it would require that. But a way that i've learned helps me learn is to examine premade code. And looking at yours

Code:

main
	push {r0-r4}
	mov r0, #0xBF @flag to check divided by 4
	lsl r0, r0, #0x2
	ldr r1, =(0x806E6D0 +1)
	bl linker
	cmp r0, #0x0
	beq noCrash
	ldr r4, .table

Im having troubles understanding it. How does it get where the flag is stored and the value? And how does it check it?

Blah · Dec 26, 2014

joexv said:
OK that makes slightly more sense... but I'm still confused as to how im loading the flag number and value.
I understand that ldr reads so it would require that. But a way that i've learned helps me learn is to examine premade code. And looking at yours

Code:

main push {r0-r4} mov r0, #0xBF @flag to check divided by 4 lsl r0, r0, #0x2 ldr r1, =(0x806E6D0 +1) bl linker cmp r0, #0x0 beq noCrash ldr r4, .table

Im having troubles understanding it. How does it get where the flag is stored and the value? And how does it check it?

0x806E6D0 that's the function for reading the flag. It does everything internally including finding/checking and simply returns a 0 or 1 (unset or set) in r0.

Joexv · Dec 26, 2014

FBI agent said:
0x806E6D0 that's the function for reading the flag. It does everything internally including finding/checking and simply returns a 0 or 1 (unset or set) in r0.

Ohhh.. Ok.
So inorder to check a new flag it would be

Code:

	push {r0-r4}
	mov r0, #0x40
	lsl r0, r0, #0x2
	ldr r1, =(0x806E6D0 +1)
	cmp r0, #0x0

To check flag 0x160 right?
If so how then would I stop the script if its not set?
Would it be?

Code:

beq noscript @wheres noscript is another hunk a code

Blah · Dec 26, 2014

joexv said:
Ohhh.. Ok.
So inorder to check a new flag it would be

Code:

push {r0-r4} mov r0, #0x40 lsl r0, r0, #0x2 ldr r1, =(0x806E6D0 +1) cmp r0, #0x0

To check flag 0x160 right?
If so how then would I stop the script if its not set?
Would it be?

Code:

beq noscript @wheres noscript is another hunk a code

Actually you need a linker still. All you've done is load into r1 a pointer. Now to go to that pointer, you need bx r1. Though like I said that doesn't write anything to the lr so you don't have a return spot. To fix this we had the "bl linker".

Joexv · Dec 26, 2014

FBI agent said:
Actually you need a linker still. All you've done is load into r1 a pointer. Now to go to that pointer, you need bx r1. Though like I said that doesn't write anything to the lr so you don't have a return spot. To fix this we had the "bl linker".

OK so to add a flag to the white out routine it would be:

Code:

.text
.align 2
.thumb
.thumb_func

main:	
	push {r0-r3, lr}
       mov r2, #0xBF @flag to check divided by 4
	lsl r2, r2, #0x2
	ldr r3, =(0x806E6D0 +1)
	bl linker
	cmp r2, #0x0
	ldr r0, =(0x2023E8A)
	ldrb r1, [r0]
	cmp r1, #0x1
	bhi setZero
	b end

linker:
	bx r3
	

setZero:
	cmp r1, #0x5
	beq end
	mov r1, #0x0
	strb r1, [r0]

end:
	pop {r0-r1, pc}

Correct? Sorry about asking so many questions this is really confusing...

Blah · Dec 26, 2014

joexv said:
OK so to add a flag to the white out routine it would be:

Code:

.text .align 2 .thumb .thumb_func main: push {r0-r3, lr} mov r2, #0xBF @flag to check divided by 4 lsl r2, r2, #0x2 ldr r3, =(0x806E6D0 +1) bl linker cmp r2, #0x0 ldr r0, =(0x2023E8A) ldrb r1, [r0] cmp r1, #0x1 bhi setZero b end linker: bx r3 setZero: cmp r1, #0x5 beq end mov r1, #0x0 strb r1, [r0] end: pop {r0-r1, pc}

Correct? Sorry about asking so many questions this is really confusing...

No there's a lot more wrong now. I'll just fix it for you and you can see what's wrong for yourself.

Code:

.text
.align 2
.thumb
.thumb_func

main:	
	push {r0-r3, lr}
        mov r0, #0xBF @flag to check divided by 4
	lsl r0, r0, #0x2
	ldr r3, =(0x806E6D0 +1)
	bl linker
	cmp r0, #0x0 @with flag magic you don't need this cmp even, but nvm that
	beq end
	ldr r0, =(0x2023E8A)
	ldrb r1, [r0]
	cmp r1, #0x1
	ble end

setZero:
	cmp r1, #0x5
	beq end
	mov r1, #0x0
	strb r1, [r0]

end:
	pop {r0-r3, pc}

linker:
	bx r3

~~You can owe me back with a ROM base with all the Pokemon, moves and abilities inserted.~~

Red John · Dec 29, 2014

I do not know whether this should be here but...well Mr. FBI Agent posted a silent evolution code in his thread. Well i am learning the way of third generation battle mechanism and found a way to call a ASM in battle. So, my question is that if i adjust the party slot value in the variable and then call the ASM 1, would it change anything?

TheRabbit · Dec 29, 2014

I posted this in the ASM resource thread but didn't get an answer.

Does anyone know of an ASM routine where I can change which events give you a trainer star in FR? Or if this requires ASM at all?

Blah · Dec 30, 2014

TheRabbit said:
I posted this in the ASM resource thread but didn't get an answer.

Does anyone know of an ASM routine where I can change which events give you a trainer star in FR? Or if this requires ASM at all?

Someone did answer it actually. The stickers in your card are determined by a few variables being certain values. Take a look at the script at 0x1B2938, and play around with the non-temporary variables in that script.

Knight of Duty said:
I do not know whether this should be here but...well Mr. FBI Agent posted a silent evolution code in his thread. Well i am learning the way of third generation battle mechanism and found a way to call a ASM in battle. So, my question is that if i adjust the party slot value in the variable and then call the ASM 1, would it change anything?

Yeah, it would evolve your Pokemon. It's not that simple though. The sprite isn't updated, so you will need to update the sprite in battle yourself.

TheRabbit · Dec 30, 2014

FBI agent said:
Someone did answer it actually. The stickers in your card are determined by a few variables being certain values. Take a look at the script at 0x1B2938, and play around with the non-temporary variables in that script.

I'm not talking about stickers though. That script isn't related to the Dodrio game, or completing the pokedex. Those are just the random dumb stickers you get for hatching a certain amount of eggs and stuff. I'm referring to the events that add a star to your card and completely change the color.

DizzyEgg · Jan 1, 2015

Hello, I don't quite understand something about certain routine. It's KDS's Wide Lens(FR) routine. Here's the code:

Spoiler:

So the first thing is "At 1E050: 00 4A 10 47 XX+1 XX XX 08". Does it mean that if I inserted the code into, say 0078D540, I'm supposed to go to the offset "1E050" and change the XX bytes to "79(because 78+1?) D5 40"?

Another thing is that "mystery byte". I'm supposed to change the "0xZZ" in the code to...what exactly? I'm thinking about indices of items. For example there's a ??????? item with the index 112 (70 in hex). So I put 0x70 and everything's fine?

The last thing I'm confused is where exactly is this item. Is it in the place of the ??????? item that I was talking about before? Or do I have to do something else to place it there?

I'd be very glad if someone could explain this to me. Thanks in advance.

daniilS · Jan 1, 2015

DizzyEgg said:
Hello, I don't quite understand something about certain routine. It's KDS's Wide Lens(FR) routine. Here's the code:

Spoiler:

At 1E050: 00 4A 10 47 XX+1 XX XX 08
ZZ is the mystery byte of your item.
.text
.align 2
.thumb
.thumb_func

ldr r0, =0x2023d6b
ldrb r0, [r0, #0x0]
mul r0, r5
add r0, r0, r7
add r0, #0x2e
ldrh r0, [r0, #0x0]
bl geteffect
cmp r0, #0xZZ
bne noboost

mov r0, #0x6E
mul r0, r4
mov r1, #0x64
bl divide
lsl r0, r0, #0x10
lsr r4, r0, #0x10

noboost:
mov r0, #0x0
str r0, [sp, #0x0]
mov r0, #0x13
mov r1, #0x0
ldr r2, return
bx r2

divide:
ldr r2, divider
bx r2

geteffect:
ldr r1, getbyte
bx r1

.align 2
getbyte: .word 0x0809A925
divider: .word 0x081E4019
return: .word 0x0801E059

So the first thing is "At 1E050: 00 4A 10 47 XX+1 XX XX 08". Does it mean that if I inserted the code into, say 0078D540, I'm supposed to go to the offset "1E050" and change the XX bytes to "79(because 78+1?) D5 40"?
You'd have to reverse the bytes, making 41 D5 78.

Another thing is that "mystery byte". I'm supposed to change the "0xZZ" in the code to...what exactly? I'm thinking about indices of items. For example there's a ??????? item with the index 112 (70 in hex). So I put 0x70 and everything's fine?
I think you have to change the item's mystery byte with an item editor and change ZZ to what you put there.

The last thing I'm confused is where exactly is this item. Is it in the place of the ??????? item that I was talking about before?
Yes.
Or do I have to do something else to place it there?
Yes, you have to change the item's mystery byte like I said.

I'd be very glad if someone could explain this to me. Thanks in advance.

Replies are in bold.

DizzyEgg · Jan 1, 2015

Hello, I've got another problem and I still don't understand basic things. Help would be appreciated.
So, I tried to insert [S-HIGHLIGHT]this routine[/S-HIGHLIGHT]. Now, the routine consists of two parts. I inserted the first one, the item check routine, to offset 0x78D310. However I had some trouble with the other one. Here's the code

Spoiler:

The first thing is

#0x4A @change this number to your desired held item effect number.

I tried many item editors, but there's no such thing as "effect number". There's mystery bytes, index, special, but no effect number. So, my question is what do I write here?

Another thing is that the author of the routine wrote

If you look closely, you'll notice .routine: .word 0x08800001 in every one of the rock routines(there were 4, I chose heat rock one). Change the address to the address you inserted your first routine (the item check routine) at.

I thought I knew what I should do however I was wrong.

.routine: .word 0x08800001

The problem is my offset was 0x78D310. And that would mean that there's one digit missing. So, my second question is how do I write the offset here. Do I write it "0x8myoffset" or "0xmyoffset"? Oh and also do I reverse the order or is reversing only necessary to pointers?

There's something else. Let's assume I inserted both routines. Where is this item? Does the place depend on the "effect number"? Also, what's the index of this new item? How would I give it to player if I don't know the index? Besides, do I have to write a script to make this item work or is it unnecessary?

Help Thread: ASM & Disassembly

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