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04-20-24 11:29 AM |
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| Main - ROM Hacking - 65816 Tracing Tutorial?! | New thread | New reply |
| FloBo |
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Newcomer Level: 6 Posts: 3/4 EXP: 627 Next: 280 Since: 06-26-07 From: Germany Last post: 6095 days Last view: 6067 days |
Hi there.
As this has always been some kind of myth to me, I just wanted to know if anyone of you guys knows some descent 65816 tracing tutorial, showing how to trace data (like tilemaps, etc.) using geigers snes9x debugger... I mean, I know that you have to somehow figure out, where your data might be (using corruption or something similar), then trace the according address using the debugger... thus, you can find out where the data is loaded from/stored to and what compression it uses... you just have to identify some of the most important asm-routines, right? So... having read a whole lot about snes-hardware-internals and 55816 asm and having all that theoretical how-to knowledge explained above, I'd just like to see, how it is done in reality... So is there some tutorial existing or any volunteer wanting to help me out on this one? Thanks in advance  ____________________ check my fabulous website Digisalt online |
| Sukasa |
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 Red Birdo Level: 92 Posts: 409/2112 EXP: 7685703 Next: 71234 Since: 02-19-07 Last post: 4442 days Last view: 3213 days |
well, mostly when your'e looking for data you need to find how it's stored. if you're looking for something like level tilemaps, it's not as bad. try corrupting sections of RAM, possibly by using a lot of PAR codes or by using ZSNES savestates, altering the RAM in them, and repeating until you find bytes then when changed affect what you're trying to find out, such as corrupting collision data in the game.
then, once you've found the RAM location, you might use a SNES9X debugger breakpoint to look for writes to the start of that RAM section, and then finally 'step out', then place an execution breakpoint on the bytes just before the command you're currently at. reset, and you'll have found the routine that handles data you're interested in. of course, you'd need to expand on that greatly and find other ways of locating data, but this is one example. |
| FloBo |
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Newcomer Level: 6 Posts: 4/4 EXP: 627 Next: 280 Since: 06-26-07 From: Germany Last post: 6095 days Last view: 6067 days |
Posted by Sukasa What exactly do you mean by the start of the RAM section? the start of the rom bank? And just for my understanding: when I 'step out', I get to the point, where the routine started, that actually messed around with the offset I set my first breakpoint to, right? Alright then... having the knowledge of where my tileset is stored in rom (compressed) and where it finally is loaded to ram, I should be able to figure out the compression routine using just what you said. take a read-breakpoint, push step out, take an execute breakpoint and push next op as often as needed to figure out what the compression algorithm does, right? ____________________ check my fabulous website Digisalt online |
| Main - ROM Hacking - 65816 Tracing Tutorial?! | New thread | New reply |
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