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whitequark / prjbureau

Documenting the Microchip (Atmel) ATF15xx CPLD fuse maps and programming algorithms
https://whitequark.github.io/prjbureau
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Issues with transmission checksum of JED files when using jesd3.py #12

Open peterzieba opened 1 year ago

peterzieba commented 1 year ago

Hi,

I think the transmission checksum calculation of JED files is incorrect within jesd3.py

I am using a file which was generated by CUPL and am following the spec verbatim wherein it says: The transmission checksum is the 16-bit sum (i.e., modulo 65,535) of all ASCII characters transmitted between and including the STX and ETX...

I've included a file as a testcase where the sum I calculate to be is 0x7F8A, which matches what is within the file.

jesd3.py calculates the actual sum to be 7B05, which I believe to be incorrect.

testcase.jed.txt

The more important bit (the fusemap checksum) I believe is working as expected.

peterzieba commented 1 year ago

The issue appears to be that the file is opened as "text" mode. It looks like the CRLF from a Windows/DOS .JED file ends up as just LF in the buffer.

This ultimately looks like what is breaking the transmission checksum.

Unfortunately, opening the file as binary breaks a bunch of the regular expression searches...

whitequark commented 1 year ago

Ah that would make sense.

whitequark commented 11 months ago

This actually affects things on Linux just as it affects them on Windows.

whitequark commented 11 months ago

This is now fixed in Glasgow (once https://github.com/GlasgowEmbedded/glasgow/pull/450 is merged). @peterzieba Could you please copy the file out of the Glasgow source tree (https://github.com/GlasgowEmbedded/glasgow/blob/main/software/glasgow/protocol/jesd3.py), put it in this project, update the file open mode (r to rb) and test the resulting changes?