Where is the Seed Table used in calculating ME7.1 checksum

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Topic: Where is the Seed Table used in calculating ME7.1 checksum (Read 11124 times)

FR Wilk

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	Where is the Seed Table used in calculating ME7.1 checksum « on: January 17, 2011, 04:19:30 PM »

According to Andy Whittaker's page, it is used to calculate the ME7.1 checksum. I can not find any reference to it anywhere.
http://andywhittaker.com/ECU/BoschMotronicME71/tabid/68/Default.aspx


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setzi62

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	Re: Where is the Seed Table used in calculating ME7.1 checksum « Reply #1 on: January 18, 2011, 03:50:37 PM »

The "xor seed table" as called in the referenced page is the standard
CRC32 table with 256 entries (see e.g. http://home.earthlink.net/~neilbawd/crc32.txt).
Remember that the seed table contains 32bit numbers and for ME7 they are stored
lowest byte first and highest byte last.


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FR Wilk

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	Re: Where is the Seed Table used in calculating ME7.1 checksum « Reply #2 on: January 18, 2011, 06:41:47 PM »

Thanks for the help setzi62. I was able to find it in the M box at 1:E76Ah. Grin


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setzi62

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	Re: Where is the Seed Table used in calculating ME7.1 checksum « Reply #3 on: January 19, 2011, 03:17:03 AM »

correct, and it gets used in function at 7:A94A


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nyet

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	Re: Where is the Seed Table used in calculating ME7.1 checksum « Reply #4 on: December 31, 2012, 12:35:19 AM »

Can somebody better than me at dissassembly figure out what blocks are checked with CRC and where the CRC values are stored?


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phila_dot

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	Re: Where is the Seed Table used in calculating ME7.1 checksum « Reply #5 on: December 31, 2012, 12:48:30 AM »

The hash table is at 0x1E76A.

I was under the impression that the CRC checksum is only used to ensure runtime data integrity and isn't a concern when modifying static data.

I can give you everything referenced, but I don't think it matters.


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nyet

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	Re: Where is the Seed Table used in calculating ME7.1 checksum « Reply #6 on: December 31, 2012, 12:54:52 AM »

I don't need the hash table location; it is the well known CRC32 polynomial LUT... and can be hardcoded anywhere (it doesn't have to be read from the bin)

What im looking for is what addresses are checked, and where the CRCs are stored....

But yea, if you think they are unneeded, and we only need the multipoint and main checksum, then thats great too Wink

less work for me..

http://nefariousmotorsports.com/forum/index.php?topic=2993.msg29299#msg29299


« Last Edit: December 31, 2012, 12:57:01 AM by nyet »	Logged

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