Locating Fuel Cut Address 32bit

Puddles · **Posted:** Mon Oct 14, 2019 8:59 am

Hey guys,

I am currently in the process of trying to port Kerchakone's version of MerpMod for use and testing on a ADM WRX. This is partly because I would like to use some of features offered, but more so as an exercise and understanding ECU disassembly and modification and keeping these projects alive if possible!
https://github.com/PuddlesSmit/MerpMod

At this stage I am working through locating all the addresses used in A8DH202X.h and tracking them down in A8DH200V.h, which so far I believe has been quite successful. However...

I can't, for the life of me, find the address for what is labelled "pFuelCut" under "NonSpecific Engine params".
I have traced it back up to a subroutine within *202X that has a pointer to the RAM address but can't find anything that even resembles the same thing in the ADM code.

A8DH202X - address required is at FFFF6F74

Code:

ROM:00016C44 ; =============== S U B R O U T I N E =======================================
ROM:00016C44
ROM:00016C44
ROM:00016C44 sub_16C44:                              ; CODE XREF: sub_13704+5BAp
ROM:00016C44                                         ; DATA XREF: sub_13704+5B8o ...
ROM:00016C44                 mov.l   r13, @-r15
ROM:00016C46                 mov     #0, r5
ROM:00016C48                 mov.l   #off_55948, r4
ROM:00016C4A                 mov     #h'10, r0
ROM:00016C4C                 mov.l   #unk_FFFF6F74, r3
ROM:00016C4E                 mov     r5, r7
ROM:00016C50                 mov.w   @r3, r13
ROM:00016C52                 mov     r5, r6

Every other address I've tracked down has been relatively straight forward, so I'm a little lost as to why I'm missing this one!

I've attached both the disassembled files for use in IDA (I assume you can just open them from these?) along with the actual ROM for my car, hopefully this helps.

Also as a side note, what could Merp and others be referencing when defining items as "hFuelCut" and then "pFuelCut"?

Any help would be sweet!

andea79 · **Posted:** Mon Oct 14, 2019 1:06 pm

had a quick look, pFuelCut seems to be FFFF6C78 and hFuelCut 000321FC

Puddles · **Posted:** Mon Oct 14, 2019 8:21 pm

Thanks for having a look.

But now I'm questioning whether what I have is right as I'd already found the hFuelCut address at 321F8 comparing to 202X's 35BD0, both pointing to a RAM location, while yours is 4 bytes down from that pointing to a sub?

andea79 · **Posted:** Tue Oct 15, 2019 6:05 am

sorry , yes, it's 000321F8 for hFuelCut , just copy/pasted the address below as I was in a hurry ...

andea79 · **Posted:** Tue Oct 15, 2019 6:12 am

I see in your zip you work with A8DH202X patched dissasembled -> maybe it's easier to work with A8DH202X oem dissasembled when comparing code to A8DH200V because the patch modifies exactly those areas ...

for example in A8DH202X oem you have
ROM:00035BD0 off_35BD0: .data.l unk_FFFF6F74

and in A8DH202X patched you have
ROM:00035BD0 off_35BD0: .data.l unk_FFFF980C

Puddles · **Posted:** Tue Oct 15, 2019 8:14 pm

Ah, cool. Thanks for double checking!

andea79 wrote:

maybe it's easier to work with A8DH202X oem dissasembled

Good point!
I did think this may be why I was getting lost with some of the addresses, but never thought to actually check the oem rom :roll:

I might go through and verify my findings against the oem rom just in case, and hopefully I can clear up a few errors I'm getting when trying to build.

RomRaider

Locating Fuel Cut Address 32bit

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