Odometer Manual Calculations

[rgmaster3]

* This thread is for posting manual calculation of algorithms ONLY! This does not include scripts.

You can also use a hex calculator.

The location of the main mileage varies, as this algo can have 4, 9, or 49 places for single digits but they are always in the top lines. The main mileage will always end with an F bit regardless (except for files with only 4 singles), and easier to do any new calculations to end in 00.

Each 80FF is a single Km (or Mi), when the singles string, 4,9, or 49 is full it is re-writen to all ff ff and the main mileage will increment 5, 10 or 50 respectively. If the singles are showing as FF80, the file is byte swapped.

Main mileage remember this table (0-5 are never used):
Dec/Hex
0=f
1=e
2=d
3=c
4=b
5=a
6=9
7=8
8=7
9=6

To decipher the mileage find the mileage string and read it inverted (backwards), use the above table to convert it to decimal or use a hex calculator and xor with FFFFFFFF. Then add the single digits.

Original file with 156799 Km:
0000: 80 FF 80 FF 80 FF 80 FF 80 FF 80 FF 80 FF 80 FF
0010: 80 FF 6F 98 EA FF 6F 98 EA FF 6F 98 EA FF FF FF

Hex inverted: FF EA 98 6F
Dec or xored: 00 15 67 90
Add single digits............09
Total mileage: 156799

To go the other way, enter mileage into hex calculator and xor with FFFFFFFF, or use the table above. Example:

New mileage: 125000 hex = FF ED AF FF inverted FF AF ED FF repeated 3 times so your mileage string is FF AF ED FF FF AF ED FF FF AF ED FF

0000: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
0010: FF FF FF AF ED FF FF AF ED FF FF AF ED FF FF FF