lib/jhash.h

   1 /* jhash.h: Jenkins hash support.
   2  *
   3  * Copyright (C) 1996 Bob Jenkins (bob_jenkins@burtleburtle.net)
   4  *
   5  * http://burtleburtle.net/bob/hash/
   6  *
   7  * These are the credits from Bob's sources:
   8  *
   9  * lookup2.c, by Bob Jenkins, December 1996, Public Domain.
  10  * hash(), hash2(), hash3, and mix() are externally useful functions.
  11  * Routines to test the hash are included if SELF_TEST is defined.
  12  * You can use this free for any purpose.  It has no warranty.
  13  *
  14  * Copyright (C) 2003 David S. Miller (davem@redhat.com)
  15  *
  16  * I've modified Bob's hash to be useful in the Linux kernel, and
  17  * any bugs present are surely my fault.  -DaveM
  18  */
  19
  20 #ifndef _QUAGGA_JHASH_H
  21 #define _QUAGGA_JHASH_H
  22
  23 /* The most generic version, hashes an arbitrary sequence
  24  * of bytes.  No alignment or length assumptions are made about
  25  * the input key.
  26  */
  27 extern u_int32_t jhash(const void *key, u_int32_t length, u_int32_t initval);
  28
  29 /* A special optimized version that handles 1 or more of u_int32_ts.
  30  * The length parameter here is the number of u_int32_ts in the key.
  31  */
  32 extern u_int32_t jhash2(const u_int32_t *k, u_int32_t length, u_int32_t initval);
  33
  34 /* A special ultra-optimized versions that knows they are hashing exactly
  35  * 3, 2 or 1 word(s).
  36  *
  37  * NOTE: In partilar the "c += length; __jhash_mix(a,b,c);" normally
  38  *       done at the end is not done here.
  39  */
  40 extern u_int32_t jhash_3words(u_int32_t a, u_int32_t b, u_int32_t c, u_int32_t initval);
  41 extern u_int32_t jhash_2words(u_int32_t a, u_int32_t b, u_int32_t initval);
  42 extern u_int32_t jhash_1word(u_int32_t a, u_int32_t initval);
  43
  44 #endif /* _QUAGGA_JHASH_H */