-Bird

...Just took a closer look at your question and the code I was pointing you to. Looks like the PERL_HASH macro (if my C terminology is correct) in "hv.h" is the implementation of the algorithm you're looking for. Hope this helps (Also hope I'm right. If not, sorry!).

Update: Turns out I was right, according to saouq's perl 5 porters link below. (for anyone who was doubting me, myself included ;)

Update: You might also find this one useful.

-sauoq
"My two cents aren't worth a dime.";

Interestingly, the two links give different functions. I suppose the meaning of "current" in the Perl Porter's summary refers to the 5.8 version. If that's the new one, it looks much simpler.

It also mentions 8 buckets. Exactly 8? I thought it used a dynamic number.

Speaking of, that project isn't dead, it's just limping.

~Cybercosis

nemo accipere quod non merere

#define PERL_HASH(hash,str,len) \
     STMT_START    { \
    register char *s_PeRlHaSh = str; \
    register I32 i_PeRlHaSh = len; \
    register U32 hash_PeRlHaSh = 0; \
    while (i_PeRlHaSh--) \
        hash_PeRlHaSh = hash_PeRlHaSh * 33 + *s_PeRlHaSh++; \
    (hash) = hash_PeRlHaSh; \
    } STMT_END
[download]

This is defined in hv.v of the perl-5.7.2 source. The article mentioned in the comment is here.

/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins */
/* from requirements by Colin Plumb. */
/* (http://burtleburtle.net/bob/hash/doobs.html) */
#define PERL_HASH(hash,str,len) \
     STMT_START    { \
    register const char *s_PeRlHaSh = str; \
    register I32 i_PeRlHaSh = len; \
    register U32 hash_PeRlHaSh = 0; \
    while (i_PeRlHaSh--) { \
        hash_PeRlHaSh += *s_PeRlHaSh++; \
        hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
        hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \
    } \
    hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
    hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
    (hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \
    } STMT_END
[download]

For anyone who is interested, these hashing functions are also implemented in Ralf Engershall's Str library.

--
John.

Thanks for the clear answers, jmcnamara.

So where is the stuff that sauoq referred to?

FWIW, the one I decided on for my project is similar, but uses a prime close to the golden ratio.

I don't see how Jenkins' hash can be any faster on machines that have multiplication as a fast instruction.