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Author Topic: What does this line of assembly code mean?  (Read 59362 times)
terminator
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« Reply #60 on: October 11, 2014, 04:03:22 PM »

Thank you very much as usual) Your help is always useful.
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terminator
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« Reply #61 on: October 17, 2014, 04:38:55 PM »

Solved
« Last Edit: October 18, 2014, 03:51:57 PM by terminator » Logged
elRey
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« Reply #62 on: January 07, 2015, 10:36:02 AM »

Code:
mov     r4, #1Eh
mov     r5, #120h
extp    r5, #1
movb    rl3, [r4]
movb    byte_3809B2, rl3
mov     r4, #20h ; ' '
mov     r5, #120h
extp    r5, #1
movb    rl2, [r4]
movb    byte_3809B3, rl2

How can I find out what is being moved into the RAM locations?

what are:

mov     r4, #1Eh
and
mov     r4, #20h

Also, what's the purpose of the mov     r5, #120h lines?

I'm guess #120h together with #1Eh point to somewhere. How can I decipher to where?

From the context I would guess an IRAM address like F71E or F61E.

Thanks,
Rey
« Last Edit: January 07, 2015, 10:43:06 AM by elRey » Logged
terminator
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« Reply #63 on: January 07, 2015, 11:59:52 AM »

mov     r4, #1Eh
mov     r5, #120h
extp    r5, #1
movb    rl3, [r4];               
movb    byte_3809B2, rl3; move byte from 48001E to 3809B2


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elRey
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« Reply #64 on: January 08, 2015, 12:07:13 PM »

48001E ?

where that ?
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terminator
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« Reply #65 on: January 08, 2015, 01:05:55 PM »

48001E ?

where that ?

I don't know, but its according to this part of code. Its Bosch or Siemens?
In my opinion the code could be much shorter also.
« Last Edit: January 08, 2015, 01:14:20 PM by terminator » Logged
MIL_on
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« Reply #66 on: January 21, 2015, 02:22:29 PM »

i found this several times, but i dont get what it is good for to double the high and low byte of mul? I'm sure its kind of a standard structure and someone can give me a useful hint  Grin

Code:
mov     r5, word_FE0E
add     r5, r5
mov     r5, word_FE0C
addc    r5, r5          ; Warum 2*r5?
jmpr    cc_NC, loc_8064CA6
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elRey
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« Reply #67 on: February 17, 2015, 01:47:42 PM »

extp    #120h, #1

I get when it's #204h - #208h, etc but where is #120h ?

Thanks,
Rey
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terminator
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« Reply #68 on: February 18, 2015, 11:09:42 AM »

480000
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elRey
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« Reply #69 on: February 21, 2015, 08:03:59 PM »

That didn't make any sense until I read this -> http://nefariousmotorsports.com/forum/index.php?topic=1386.0
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Cloudforce
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« Reply #70 on: March 13, 2015, 02:07:34 AM »

(edit)

got it
« Last Edit: March 13, 2015, 03:34:49 AM by Cloudforce » Logged
A4Rich
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« Reply #71 on: May 20, 2015, 08:32:58 PM »

Trying my hand at IDA again...  I am looking for the axes for KFZKLAMFAW (@26B04) in the 518AK 003 bin.  I located the following code, am I heading in the right direction.  Huh
 
Code:
sub_1BF574:
mov     [-r0], r6
mov     r12, #2B20h
movbz   r13, nmot
mov     r14, loc_AE62
calls   0, loc_2862
mov     loc_AE62, r4
movbz   r5, 2B04h ; 812B04h
and     r5, #1
jmpr    cc_NZ, loc_1BF596
bset    USR0
jmpr    cc_UC, loc_1BF598
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TijnCU
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flying brick


« Reply #72 on: April 01, 2016, 02:13:11 AM »

Bump. I thought this was a usefull topic!
I'm disassembling Phila_dot's map switching routine by first just naming every operation in the funtion. I am very unfamiliar with assembly code, so I feel I learn the operations better this way.
As I move further through the code, I begin to get a tiny bit of understanding about how this code works, but now I have arrived at a section where hex code gets moved into adresses.
Am I right to say that for example
Code:
mov     r6, #****h
mov     word_012345, r6
means move #****h as code into r6?
**=BSET bitoff.6   **=CMPD2 Rw, #data4 according to the C166 instruction set manual.
Or is it supposed to be just a hex value? Or an adress? I have not looked at word_012345 yet because I just copied the code section of the function into a txt file to get some basic understanding by "translating" it.
Any hints? Thanks!
« Last Edit: April 01, 2016, 10:07:17 AM by TijnCU » Logged

DT
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« Reply #73 on: April 01, 2016, 03:30:29 AM »

I think you should ask phila if he wants to release the code to public instead of discussing his code which he also protected slightly from beeing stolen without giving him credit.
You really need to learn more before working with this. The 2 lines simply place #6fb0h at 383f54.
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TijnCU
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flying brick


« Reply #74 on: April 01, 2016, 10:05:03 AM »

DT was right, I needed to learn more about this.  Grin
To make up for my stupid question I will try to help A4Rich.

Trying my hand at IDA again...  I am looking for the axes for KFZKLAMFAW (@26B04) in the 518AK 003 bin.  I located the following code, am I heading in the right direction.  Huh
 

To me it looks like your nmot axis could possibly be at 2B20h, but its hard to know from just this little section of code..  what size is the axis?

In my binary I dont have KF-ZKLAMFAW but there is ZKLAMFAW (time constant). It is a word and it is moved in r12 right after lamrlmn_w is moved in r8. I have an older ecu (4B), but maybe it is worth to check in your idb if your ecu uses similar code.
Code:
extp #0E1h, #1
cmp  r8, lamrlmn_w
jmpr  cc_ULE, loc_zklamfaw
extp  #0E1h, #1
mov  r8, lamrlmn_w

loc_zklamfaw:

extp  #207h, #1
mov  r12, word_81xxxx ; this is zklamfaw
mov  r13, r8
mov  r14, word_38xxxx
mov  r15, word_38xxxx
calls  0, sub_xxxx
« Last Edit: December 09, 2016, 03:35:14 AM by TijnCU » Logged

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