Checksum Calculator

[Gobo]

I'm using Aftermath mod on SP and I corrupted my file with too many items and now the d2s is too large, giving me an error. I had hoped I could jump in with a hex editor and delete some items on the list but then I fail the checksum. I see on this forum is the algorithm posted a lot but is there any stand alone programs that I can use to repair the checksum after I delete enough items to lower the size limit?

Thanks,
Gobo