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From: Eric W B. <ebi...@ln...> - 2002-08-23 19:21:45
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ke...@us... (Ken Yap) writes: > >Ken has all of the utilities in perl, and I have a one as well that > >prepare network bootable images. And for the longest time I could > >not figure out how to perl to do a reasonably fast job of computing > >the ip checksum. Reasonable as in under a minute. The attached > >code accomplishes that. > > Your code runs in 0.1s on a 1MB vmlinuz file on my system (350MHz K6-2). > Congratulations. Nice. Then I won't worry about the code to much. > >Does anyone have any objects to included this checksum ability > >into mknbi? > > Go for it. O.k. it is on my Todo/wishlist. So I will implement it the first decent opportunity I get. > >Or ideas on how to speed of the ckecksum computation, > >even more? > > You can get 20% improvement by using pass by reference. Call > compute_ip_checksum(\$string). In the routine, replace all but the first > $str with $$str. Nice. Do you know if the substr hurts? I guess at 0.1s it isn't too bad. Last time I was messing with the code and I complained checksums in perl were terribly slow, you speculated that the problem was that I was using substr. And it has taken me a long time to think of a substitute. Eric |
