lib/libvtreefs/sdbm.c

   1 /* VTreeFS - sdbm.c - by Alen Stojanov and David van Moolenbroek */
   2
   3 /*
   4  * sdbm - ndbm work-alike hashed database library
   5  * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
   6  * author: oz@nexus.yorku.ca
   7  * status: public domain. keep it that way.
   8  *
   9  * hashing routine
  10  */
  11
  12 #include "inc.h"
  13 /*
  14  * polynomial conversion ignoring overflows
  15  * [this seems to work remarkably well, in fact better
  16  * than the ndbm hash function. Replace at your own risk]
  17  * use: 65599   nice.
  18  *      65587   even better.
  19  */
  20 long sdbm_hash(char *str, int len)
  21 {
  22         unsigned long n = 0;
  23
  24         while (len--)
  25                 n = *str++ + (n << 6) + (n << 16) - n;
  26
  27         return n;
  28 }