Why do Windows files show "modified" dates before "created" dates?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Because they are susceptible to user actions.
They are just fields that the operating system can update. Or, that you can ask the operating system to update (to damn near anything you choose!)
That's what happens when a file is copied.
Also, you might want to ignore last access time metadata. Systems that use SSD (solid state drives) tweak the OS to disable writing last access time (atime) to reduce unnecessary writes and improve SSD drive life. If the last access time appears insane, it came from a machine with an SSD. It also means you can't tell if someone else has looked at the file.
You can check your settings without screwing up the registry with: C:\> fsutil behavior query disablelastaccess disablelastaccess is not currently set In double negative speak, that means that my XP machine is writing last access times. Time to turn it off. C:\> fsutil behavior set disablelastaccess 1 C:\> fsutil behavior query disablelastaccess disablelastaccess = 1 Done. If you're reading this message, it worked so far.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Win zip (and WinRAR IIRC) compute a CRC for each file in the archive - that would go a long way to a solution
Check this out
It does, if you know your source isn't making undocumented changes.
MD5 of entire directories-at-a-time is common. I hope your ARM code is binary, because if you compile it with different compilers (or even different compile-time options) the result won't be controlled. Version control is a hard problem. MD5 helps.
Even the same compiler and options can result in different images. E.g., imagine __DATE__ or __TIME__ present in the sources!
About 10 years ago, I wrote a batch file plus some C code to collect sha1 hashes of files recursively, then sort them by sha1 hash, then sort them again descending by size, to find duplicates.
It would be really bad if a file were marked duplicate when it wasn't, just because the hash was the same.
Michael
md5sum is pretty common. It is standard in *nix systems, and there are plenty of binaries for Windows. Whether that is acceptable or not to their IT folk is another matter.
Alternatively, just use zip files. The chances of two zip'ed versions of the files being the same size but different contents are very small, and zip files include a checksum in their headers that is shown by most popular zip programs.
o:
So you get N versions of the same file and you don't know what is the corre ct one. And you want to be able to ask for the hash of the correct file so you can find out which of the N files you have is the correct one right? Why don't ask directly for the correct file? You'll have less work to do, a nd after a while maybe they improve their doc.
Bye Jack
Some time ago I used a CRC32 program. It is old, but it worked. I don't u se it anymore. The download website is gone. I have it if you want it. I think the ExactFile tool looks interesting. I'd try that first if it were me.
The following is the readme.txt file for the CRC32.exe program I have:
CRC32 for Windows 9x/NT ======================= Version 1.30.0024
CRC32 calculates the 32-bit cyclic redundancy checksum (CRC-32) of a file and displays it along with other useful file information in a window. The checksum calculation algorithm used in CRC32 is exactly the same as that internally used by PKZIP and WinZip, i.e. the 32-bit CRC values calculated by PKZIP and CRC32 are identical.
Though you can use CRC32 to calculate 32-bit checksums of any file the real strength and usefulness of CRC32 is in comparing Wave Sound Files to see if their non-silent music parts are identical. In particular CRC32 may come in handy when comparing two different extractions of a CD Digital Audio track to ensure that the performed digital copy is perfect.
Click on 'CRC32.hlp' to see a more detailed description of CRC32.
Start the Windows Explorer. Right-click the file "Install.inf" then choose Install in the pop-up menu.
After the installation you can start the program through the system menu Start->Programs->CRC32 ...
Click the Add/Remove Programs option in Control Panel. In the Install/Uninstall dialog box, click the item "CRC32 ..." and then click the Add/Remove button to remove it.
CRC32 was created by Cyberdyne Software as a free helper application for those who deal with grabbing CD digital audio to provide an easy and convenient way of monitoring the quality of the resulting .wav sound files. CRC32 can be distributed only with no charge.
You can always find the latest release of CRC32 and other great Windows 9x/NT applications on the Cyberdyne?s Web Site
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