[THUMB MODE] How to run scripts via ASM

[mewthree9000]

Translated by: Mewthree9000

Today we will be running scripts through ASM!
This method only works on overworld events. These will NOT work in bag or in battle.

Minimum requirements:

1. Basic knowledge of routines
2. Knowledge of these ASM commands: Ldr, Bl, push {LR}, pop {pc}, and Branch&Exchange (Bx)
3. Basic Knowledge of Registers

Here is a brief explanation of each command with a scripting analogy, in order to perceive them better:

Ldr, the command used to loadnumbers in the registers and RAM. This command is a kind of loadpointer in the literal sense. This command loads a 32bit number in the memory (in this case, the registers)

Bl, is like the scripting command 'call', which calls a subroutine (In scripting, a subscript, like 'CallStd'). To function properly, the subroutine call must end in Pop {pc}...Pop {pc} is like the command 'Return' in scripting: It returns to the function that has been called.

Bx rX, It's like the command 'Goto' in scripting.
---------------------------------------------

ATTENTION: I DO NOT USE THE COMPILER 'Goldroad'.
THIS CODE IS FOR DEVKITARM and THE BUILDER MID2AGB (as.exe and objcopy.exe)


Example for FireRed:
Code:

Spoiler:

.thumb
.align 2
push {lr}
ldr r0, SCRIPT_ADDRESS
bl SCRIPT_ROUTINE / / subroutine that will run the scripts
pop {pc}

SCRIPT_ROUTINE:
ldr r1, SCRIPT_EXECUTOR
Bx r1

.align 2
SCRIPT_ADDRESS: .word 0x081624F5 / / Here is where you define your script offset.
SCRIPT_EXECUTOR: .word 0x08069AE5 / / This is the routine that executes the scripts. Offset +1

The arguments are:
r0 = Script offset (the offset of a script you want to use)
r1 = Script executor (the offset of the script executor)

These are the offsets for the Script Executors
(NOTE, don't forget to add +1 to the offset!):
Ruby: 080655B8
FireRed: 08069AE4
Emerald: 08098EF8

That's all for now! I hope I have helped!
-------------------------------------
Tutorial originally made by: Sonicarvalho AKA Dark Rayquaza

[karatekid552]

Just to add to this, if you need to run a script from the bag, go here:

http://www.pokecommunity.com/showthread.php?t=281573

[Jisuke]

This get's my THUMBs up
huehuehuehue

[droomph]

.thumb
.align 2
push {lr}
ldr r0, SCRIPT_ADDRESS
bl SCRIPT_ROUTINE / / subroutine that will run the scripts
pop {pc}

SCRIPT_ROUTINE:
ldr r1, SCRIPT_EXECUTOR
Bx r1

.align 2
SCRIPT_ADDRESS: .word 0x081624F5 / / Here is where you define your script offset.
SCRIPT_EXECUTOR: .word 0x08069AE5 / / This is the routine that executes the scripts. Offset +1

I don't quite understand why you would need to bl that.

[Full Metal ★]

Originally Posted by droomph

.thumb
.align 2
push {lr}
ldr r0, SCRIPT_ADDRESS
bl SCRIPT_ROUTINE / / subroutine that will run the scripts
pop {pc}

SCRIPT_ROUTINE:
ldr r1, SCRIPT_EXECUTOR
Bx r1

.align 2
SCRIPT_ADDRESS: .word 0x081624F5 / / Here is where you define your script offset.
SCRIPT_EXECUTOR: .word 0x08069AE5 / / This is the routine that executes the scripts. Offset +1

I don't quite understand why you would need to bl that.

so that...he can return the execution frame to where it was?????? ( ??!!?? )

[droomph]

Originally Posted by Full Metal ★

so that...he can return the execution frame to where it was?????? ( ??!!?? )

it's two lines though. why would you need to make a whole subroutine for that?

also your elitism kinda annoys me. Maybe I don't know everything.

[Full Metal ★]

Originally Posted by droomph

it's two lines though. why would you need to make a whole subroutine for that?

also your elitism kinda annoys me. Maybe I don't know everything.

I'm sorry, I just kinda felt that was a basic concept that was explained in many tutorials / documents / etc. I thought you were actually smarter. uh. Elitist, rah rah. There are lots of things that annoy me about you, also ( o no frick frack the police are coming )

Anyways, I'll explain this for you.

push {lr} // store the link register so that you can return the execution frame.
ldr r0, SCRIPT_ADDRESS // the offset of your script your executing.
bl SCRIPT_ROUTINE / / subroutine that will run the scripts ( so you can return to THIS frame of execution -- there are lots of those )
pop {pc} // go back the frame of execution mentioned on line one.

Now this bit is recyclable, and I imagine it's not really necessary to have this ( you could replace the bl SCRIPT_ROUTINE with the part in bold ) but it's for convenience and as far as I can tell, that's the only real reason for using a branching structure. Maybe it can be worked out that it's a more efficient use of your ROM's available space, but I don't feel like looking at the numbers tbh.
( You'll notice the whole thing is bolded, btw )

SCRIPT_ROUTINE:
ldr r1, SCRIPT_EXECUTOR
Bx r1

I'm not an elitist you're just hypersensitive and fail to realize that I'm just a ickday with a head -- all puns intended

[mewthree9000]

Amazing elaboration, Full Metal! :3

[Diegoisawesome]

Originally Posted by Full Metal ★

Now this bit is recyclable, and I imagine it's not really necessary to have this ( you could replace the bl SCRIPT_ROUTINE with the part in bold ) but it's for convenience and as far as I can tell, that's the only real reason for using a branching structure.

Well, if you don't do a bl to the bx, then it won't return to your routine and pop what you pushed. However, you could just replace everything with the two LDRs and the BX (not even having the push or pop) and it should work fine.

[Full Metal ★]

Originally Posted by diegoisawesome

Well, if you don't do a bl to the bx, then it won't return to your routine and pop what you pushed. However, you could just replace everything with the two LDRs and the BX (not even having the push or pop) and it should work fine.

that's...what I was saying... ;_;