Help Thread: ASM & Disassembly

[jiangzhengwenjzw]

That's all you need yes. The other things do no harm (apart from the .hword 0x0), but they can cause errors in the case of a typo, bring confusion, and I just find it a hassle putting them there every time.

That's really very strange. Hackmew is the developer of his assembler, but he also wrote the ".text", ".thumb_func" in his routine. JPAN used some .hword 0x0 in his routine in his tutorial and he layed emphasis on this issue, believing that the code won't work without them.
Thank you greatly, otherwise I will be misled by these two really awesome people. :)

 

[daniilS]

That's really very strange. Hackmew is the developer of his assembler, but he also wrote the ".text", ".thumb_func" in his routine. JPAN used some .hword 0x0 in his routine in his tutorial and he layed emphasis on this issue, believing that the code won't work without them.
Thank you greatly, otherwise I will be misled by these two really awesome people. :)

Hackmew didn't develop the assembler, just the .bat file that makes assembling easier. The core itself comes from a really old DevkitARM.
As for JPAN: he's a great hacker, but lacked understanding of some things (of course, he was a pioneer in the area) and his routines should never be used as quality examples for they're often really unoptimized and use too many things (example: he wrote a custom pokemon enc/decryptor while there is one ready in the ROM.)

 

[jiangzhengwenjzw]

Hackmew didn't develop the assembler, just the .bat file that makes assembling easier. The core itself comes from a really old DevkitARM.
As for JPAN: he's a great hacker, but lacked understanding of some things (of course, he was a pioneer in the area) and his routines should never be used as quality examples for they're often really unoptimized and use too many things (example: he wrote a custom pokemon enc/decryptor while there is one ready in the ROM.)

Really? Then that's really a mistake to read JPAN's document first for me.;-; I thought it was more detailed when I started learning assembly so I read it first...
Another question if you have time to answer: How can you get the address of the encryptor/decryptor through diassembly? (I use no$gba instead of vba-sdl-h, for vba-sdl-h cannot work properly on my computer and I often get error. ;-;)

 

[daniilS]

Really? Then that's really a mistake to read JPAN's document first for me.;-; I thought it was more detailed when I started learning assembly so I read it first...
Another question if you have time to answer: How can you get the address of the encryptor/decryptor through diassembly? (I use no$gba instead of vba-sdl-h, for vba-sdl-h cannot work properly on my computer and I often get error. ;-;)

Nah, his document is okay, that's the one I used myself to get into ASM. As for the enc/decryptor: www.romhack.me/database/23/fire-red-commonly-used-asm-rom-offsets/

 

[jiangzhengwenjzw]

Nah, his document is okay, that's the one I used myself to get into ASM. As for the enc/decryptor: www.romhack.me/database/23/fire-red-commonly-used-asm-rom-offsets/

This thread seems really useful! Thank you for giving me the link.
But it's still a problem how to get those address. I do not have an idea of how to get them through disassembly.

 

[Edwearth]

Is it possible to create a random number ?

 

[daniilS]

This thread seems really useful! Thank you for giving me the link.
But it's still a problem how to get those address. I do not have an idea of how to get them through disassembly.

You'd probably set a break on reading the Pokémon data then trace back from there.

Is it possible to create a random number ?

Look at the link I just sent.

 

[jiangzhengwenjzw]

You'd probably set a break on reading the Pokémon data then trace back from there.


Look at the link I just sent.

Okay, I will just try. For VBA-SDL-H2, I don't know why the game returns to the very beginning unexpectedly sometimes. Maybe I have made some mistakes? I use VBA-SDL-H2, for the original VBA-SDL-H crashes as soon as it loaded the game. TAT

 

[daniilS]

Okay, I will just try. For VBA-SDL-H2, I don't know why the game returns to the very beginning unexpectedly sometimes. Maybe I have made some mistakes? I use VBA-SDL-H2, for the original VBA-SDL-H crashes as soon as it loaded the game. TAT

Why do you want to find the offset yourself though?

 

[jiangzhengwenjzw]

Why do you want to find the offset yourself though?

Because that's a kind of experience in my opinion. Perhaps it may help me learn disassembly...
But the debugger is a huge problem as almost all ASM tutorials use VBA-SDL-H, from Hackmew several years ago to FBI's tutorial last week..... Maybe the error was caused by my misuse. :(

 

[daniilS]

Because that's a kind of experience in my opinion. Perhaps it may help me learn disassembly...
But the debugger is a huge problem as almost all ASM tutorials use VBA-SDL-H, from Hackmew several years ago to FBI's tutorial last week..... Maybe the error was caused by my misuse. :(

Nocash is better than vba-sdl-h.

 

[jiangzhengwenjzw]

Nocash is better than vba-sdl-h.

Really? Would you mind giving me a link so I can learn how to use it? I could only use very limited functions, but most tutorials use vba-sdl-h as you know.

 

[Blah]

Ehh, I don't like the syntax on no$GBA, nor do I agree it's better. It's good if you're doing conditional breaks, otherwise VBA-SDL-H is my preferred choice because you can:
1) Speed the emulation speed over 100% (no$ you cannot go much faster)
2) Save states from VBA-SDL-H is supported by VBA emulators
3) Register states are more clearly visible, and it shows the important info we care about
4) A command help that's actually understandable and useful

I wouldn't really say no$GBA's debugger is better. It has more features, but most of those features can be replaced by good debugging skills. An example would be when I tried to track changes in a dynamic address which was being read every frame in the game. I used VBA-SDL-H and instead I broke at the END of the memory randomizing function and was able to track it every time from there. In no$GBA this would've been the same process. So complicated debugging isn't even better, it's just conditional breaking (which is rare in itself).

 

[jiangzhengwenjzw]

Ehh, I don't like the syntax on no$GBA, nor do I agree it's better. It's good if you're doing conditional breaks, otherwise VBA-SDL-H is my preferred choice because you can:
1) Speed the emulation speed over 100% (no$ you cannot go much faster)
2) Save states from VBA-SDL-H is supported by VBA emulators
3) Register states are more clearly visible, and it shows the important info we care about
4) A command help that's actually understandable and useful

I wouldn't really say no$GBA's debugger is better. It has more features, but most of those features can be replaced by good debugging skills. An example would be when I tried to track changes in a dynamic address which was being read every frame in the game. I used VBA-SDL-H and instead I broke at the END of the memory randomizing function and was able to track it every time from there. In no$GBA this would've been the same process. So complicated debugging isn't even better, it's just conditional breaking (which is rare in itself).

I have vba-sdl-h,but it often crashes and vba-sdl-h2 have a problem that sometimes the game returns to the very beginning unexpectedly... Do you know the reason?

 

[Blah]

I have vba-sdl-h,but it often crashes and vba-sdl-h2 have a problem that sometimes the game returns to the very beginning unexpectedly... Do you know the reason?

Nope. I have no such problems. Remember you can't keep playing the game once a breakpoint is reached, or when you've hit F11. You need to hit "c" to get back.

 

[jiangzhengwenjzw]

Nope. I have no such problems. Remember you can't keep playing the game once a breakpoint is reached, or when you've hit F11. You need to hit "c" to get back.

Actually I know that I should use the command c and I'm sure that it's not the problem.

I may show my problem more detailed, in case someone can help.
My problem is that VBA-SDL-H often crashes unexpectedly, I always get a window says that the program didn't work...
For JPAN's VBA-SDL-H2, the game crashes after some progress and automatically returns to the "Game Freak" Screen...

My operation system is Window 8.1.

 

[Blah]

Actually I know that I should use the command c and I'm sure that it's not the problem.

I may show my problem more detailed, in case someone can help.
My problem is that VBA-SDL-H often crashes unexpectedly, I always get a window says that the program didn't work...
For JPAN's VBA-SDL-H2, the game crashes after some progress and automatically returns to the "Game Freak" Screen...

My operation system is Window 8.1.

Yeah, I'm not sure why that would happen. I'm on Windows 7 and it works fine for me. I suppose if no$gba doesn't crash for you, then you should stick with that instead.

 

[jiangzhengwenjzw]

Yeah, I'm not sure why that would happen. I'm on Windows 7 and it works fine for me. I suppose if no$gba doesn't crash for you, then you should stick with that instead.

You're right, but most tutorials taught me how to use vba-sdl-h instead of no$gba. Do U know a tutorial for noobs about debugging with no$gba? I only know how to add breakpoints with it.

 

[Blah]

You're right, but most tutorials taught me how to use vba-sdl-h instead of no$gba. Do U know a tutorial for noobs about debugging with no$gba? I only know how to add breakpoints with it.

Sorry, I do not know one personally. There is a user manual, with a mini tutorial which you could probably find with a quick google search. I don't think it's very beginner friendly though.

 

[jiangzhengwenjzw]

Sorry, I do not know one personally. There is a user manual, with a mini tutorial which you could probably find with a quick google search. I don't think it's very beginner friendly though.

OK, then I will try to find one myself. Thank you for your reply.
For the .hword 0x0 case, I asked someone yesterday, he said that the assember will automatically add "nop" if the label cannot be fetched by "ldr".