[export only, enter at your own risk] ASM help needed

[hydroflame]

so with the help of this guide http://download.forge.objectweb.org/asm/asm4-guide.pdf

i was able to understand a bit more about how the JVM works and bytecode is assembled. (note i already did assembly in university before). Thing is everything i seem to try when visiting a method seems to result in a crash. I did search on the wiki to find a ASM tutorial and its only to change visibility of fields and methods, i need a bit more (make method call and load variable inside method)

Is there anyone that make these kind of things that would share his knowledge with me ?

[Mazetar]

The asm website recommends using their eclipse extension.

Then create a simple class and convert it to asm instructions using the plugin.

Then add to the class some more stuff, and look at the new set of asm, then you can compare the two files of asm instructions to see what had to change for the asm to generate the additions

[pelep]

What are you attempting to do exactly?

[hydroflame]

@mazetar yea that would help a lot, thanks, at least i learned more about how the jvm works

@pelep: dynamicly implement vanilla change that i had to hard code before

list(maybe incomplete):

block place/break event

entity living heal event

player right click event

redirect visible equipped item in hand

 

btw maybe some of those are new feature in recent forge version but they werent when i started coding (6-7 month ago) so i also need to check the latest event/feature to checkthat i still need asm/vanilla transforms to implement my mod correctly

[pelep]

well, you can actually do what mazetar said. should be easy enough with the eclipse plugin. you can also check out dynamic light's source (atomic stryker). he does some modifications to the World.class to get his mod working. if you still need help after that, i can help if all you're all you're doing is what you listed above and nothing else too extravagant

[hydroflame]

@pelep: i will deffinitely also check out that mod

but yeah my hard coded things are usually one line it shoulnt be a problem to implement in asm

can i pm you if i need more help?

and the thing is, i understand in assembly what im supposed to be doing. i just cant seem to call the right bethods in the right order to realise what i want. so if i at least know what im doing i would be able to do the "extravagant" asm on my own without any problem

[pelep]

sure, though i think you'd be able to get the info you need in his source already. if you need more help, you can pm me, but just so you know, even though i've used asm, i'm in no way an expert in it. so... nothing too huge please. lol

[hydroflame]

nah dont just copy paste from his mod into the forums, i can do that too i do it all the time for java newbie.

[pelep]

copy paste? wait. what? i'm lost. who said anything about copy-pasting? lol.

[hydroflame]

oh shit my bad. i misread like crazy

"i think youd be able to get the info" became "i thin id be able to get the info" so i tought you were gonna copy pasta some code

 

my bad

[pelep]

haha no worries. and just a heads-up: once you get your asm stuff running in your dev environment, compiling it is gonna be a bitch. you're gonna have to get the obfuscated names of the classes that you used in the lines you injected. nothing difficult, but soooo f*cking tedious .___.

[hydroflame]

yeah i heard about that. i didnt start making a mapping but it looks easy enough

 

is there any way to know if youre working a obfucsated/deobf environnement? (i didnt not search so fell free to tell me to look harder or look at the wili etc )

[pelep]

well, i know of one way, but i don't use it. forge injects the data through injectData(Map) in your IFMLLoadingPlugin class, but the last time i tried using it, it was called after the transformers started running. so, if the class you want to modify was "modified" before the data's injected, you miss your chance for that class. i got too lazy too keep digging around after that, so the way i do it now is i have a boolean in the constructor of my transformer which i manually change every time before i recompile. if you find out another way to do it, feel free to tell me hahah

 

 

EDIT: i just looked into it now, and it might have changed. it seems to be called before the transformers are ran now. gonna have to look around the stuff first to see if it really is. if it is... <3

[Mazetar]

You have probably seen or knowlegde of this already:

https://www.google.no/url?sa=t&source=web&cd=1&ved=0CC8QFjAA&url=http%3A%2F%2Fwww.minecraftforum.net%2Ftopic%2F1854988-tutorial-152161-changing-vanilla-without-editing-base-classes-coremods-and-events-very-advanced%2F&ei=DU7uUbTMH4iC4ASe24HgBQ&usg=AFQjCNFiKTE2wJjA0G5jxeVsCQKv-ljOHQ

 

I found the included video to be quite informative, even tough they say its not needed to know I like to know as much as possible when doing stuff

[hydroflame]

i was thinking to decide obfuscated or not

 

pick a class (any class)

use reflection to check if that class exists

 

something like

Class.forName("net.minecraft.block.Block") != null;

(or is it throwing an exception if it cant find it? dont remember)

 

if it doesnt find it try the same class with its obfuscated name (if it finds it you are in deob environnement)

Class.forName("jd") != null;//i have no idea what Block class obfuscated name is btw, didnt bother to look in the configs

if it finds it you are in obf envir, if it doesnt (and you have correct names) you're screwed

 

would that work ?

 

[Cuchaz]

If you want to dynamically change class files at runtime, I recommend using a tool called Javassist. It will make your life much easier.

 

http://www.csg.ci.i.u-tokyo.ac.jp/~chiba/javassist/

 

[hydroflame]

and then force my mod users to download another library, thanks but ill stick with ASM, it works i jsut need to figure out how and why

[hydroflame]

the eclipse plugin is at the same time the craziest things I've seen in my life (coding life ) and the worst curse you could give me. basicly the plugin will allot you to have a ASM view of the code and you can just kinda copy paste what you need WITHOUT knowing what you're doing(welll ... without knowing too much, you still have to understand what you're doing). ill end up doing whatever i want without ever exactly knowing what's going on in ASM .....

 

thanks mazetar

[Cuchaz]

Or just distribute Javassist with your library. Up to you.

[GotoLink]

Or just distribute Javassist with your library. Up to you.

Or tell Forge to download it for your you.

I support javassist.

[hydroflame]

too late guys, already made an api for ASM that work great (2-3 minute per modification so far) but thanks for the help

[GotoLink]

too late guys, already made an api for ASM that work great (2-3 minute per modification so far) but thanks for the help

Nice would you share it ?

[hydroflame]

i tought you were a fanboy of javassist ?

 

the answer is yes btw but ill clean it up first to make things clearer adn more generic ( MyModNameClassReplacer isnt exactly generic )

[hydroflame]

im even going to make a tutorial for it

[Cuchaz]

Nice. That would be interesting to see.

 

Cuchaz