Good idea about splitting the CPUID into two halves. I'll try that, thank you! Joakim Gebart Managing Director Eistec AB
Aurorum 1C 977 75 Luleå Tel: +46(0)730-65 13 83 [email protected] www.eistec.se On Tue, Jan 27, 2015 at 12:50 PM, Martine Lenders <[email protected]> wrote: > Hey Joakim, > There is already a collection of hashing implementations in > sys/include/hashes.h. > Unfortunally all of them yield 32 bit integers. I did however also used the > CPU ID and djb2_hash() in [1] to initialize an IEEE 802.15.4 device's EUI-64 > - which is the link-layer pendent to the IPv6 host suffix [2] - by spliting > the CPU ID in half, generating a 32-bit hash from each half and splicing > them together again as a 64-bit number. > > Best regards, > Martine > > [1] > https://github.com/RIOT-OS/RIOT/blob/master/sys/auto_init/auto_init.c#L136 > [2] https://tools.ietf.org/html/rfc4291#page-20 > > 2015-01-27 12:39 GMT+01:00 Joakim Gebart <[email protected]>: >> >> Hello, >> I am looking for a simple (few lines to implement) hashing function to >> reduce a 128 bit integer to 64 bits. >> >> I want to use the hash to derive a 64 bit IPv6 host address from a 128 >> bit CPU ID. >> >> I want all of the bits of the CPUID to affect the result, instead of >> just grabbing the top/bottom 8 bytes of the ID. I'm guessing there are >> lots of options for hashes, but many are made to generate hashes from >> much longer messages than 128 bit. >> >> Any suggestions? >> >> Best regards, >> Joakim Gebart >> Eistec AB >> www.eistec.se >> _______________________________________________ >> users mailing list >> [email protected] >> http://lists.riot-os.org/mailman/listinfo/users > > > > _______________________________________________ > users mailing list > [email protected] > http://lists.riot-os.org/mailman/listinfo/users > _______________________________________________ users mailing list [email protected] http://lists.riot-os.org/mailman/listinfo/users
