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Re: 32 bit flash checksums


Hello all,

After a few problems with my client throwing in html code in the email, i've got some additional questions and clarification of the problem.

I'll preface this by saying i have a port of Redboot for the Cirrus Logic EP93XX family of chips. While many things are different, with regards to checksumming and the areas of memory i'm looking at there shouldn't be much different.

I think the place to start with is to explain what i am seeing. Most of the "Magic numbers" are stored in the FIS Directory partition. This is not the case though for the Redboot Config partition. Through some experimentation i've noted that it appears to store the checksum for this partition in the last 4 bytes of the partition, preceded by what looks like an identifier of 0xADDEADED . (So the final 8 bytes are 0xADDEADEDZZZZZZZZ where ZZZZZZZZ coresponds to the magic number).

The question is how to deal with this checksum in particular. Is it the same algorithm, and if so, what does it use as its length? Does it reduce the 0x1000 partition to cut off the last 4 bytes? Treat them as 0's, 1's?

Many thanks again, and apologies for the confusion and problems earlier,

-Adam

--
Adam Yergovich
Engineer
JK Microsystems

1403 Fifth St. Suite D
Davis, CA 95616

Tel:(530) 297-6073


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