Differing CRC32 values on same file

Hi Friedrich

Not important, but I am wondering why there is a difference in two CRC values.

I see that SB5 reports the CRC32 of the files in the setup package.

I have built a small app to calculate the CRC32 value of a file I include.

My app uses the built in CW6.3 CRC32 function.
I read the whole file into a string, check its length is correct, then pass it to the
SV CRC32 function.

There is a difference in the two values calculated for the same file...

From SB5 I get 35,499,341

From the CW app, I get 967,552,063

Is this difference to be expected?

Is it just that two different CRC32 libraries may be used?

Thanks

John Griffiths

Hi John,

Please zip the file and let me know what CRC-32 WinZip reports.

Friedrich

--
Friedrich Linder
CEO, Lindersoft
www.lindersoft.com
+1.954.252.3910

"point. click. ship" - that's SetupBuilder 5

Hi John,

Just checked this here. I am using the Get File Information(File CRC-32) on
the sbkernel.lib (build 1666) located in the SB5 \Bin32 folder.

Both WinZip and SetupBuilder installers report an e8ac7a27 CRC-32 here on
our machines.

Friedrich

Hi Friedrich

Strange... I downloaded Winzip and installed... (I use PK for Windows and it does not
show CRC ) and in Winzip I get the same as you for the sbkernel.lib (build 1666)
file, but in my app using the CW CRC32...



MODULE('Clarion')
CRC32(UNSIGNED pBuffer, LONG cbBuffer, LONG InitalCRC),LONG,NAME('CLA$CRC32')
END

I get a different value. I will go back to my app and see if I am doing anything
wrong. It may be that the SV CLA$CRC32 function differes from any "standard" that
may be in place.

I will investigate CRC32 some more, and perhaps find a C library to test with so that
I can get a match with that reported by SB5 and Winzip.

I will let you know how I get on. Maybe I will post something on the Clarion Language
group...

Regards

John Griffiths

Hi Friedrich

Update on CRC differences...

The inbuilt (and un-documented) CW CRC32 function may have a limit on the size of the
data being CRC'd...

I added some C Source code to do the CRC32 calculation, and after some trial and
error, the result now matches that from SB5 and WinZip.

Regards

John Griffiths

Hi John,

Thanks for the update.

Friedrich