include/minix/hash.h

   1
   2 #ifndef _MINIX_HASH_H
   3 #define _MINIX_HASH_H 1
   4
   5 #include <stdint.h>
   6
   7 /* This code is taken from:
   8  * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
   9  * (macro names modified)
  10  */
  11
  12 #define hash_rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
  13
  14 #define hash_mix(a,b,c) \
  15 { \
  16   a -= c;  a ^= hash_rot(c, 4);  c += b; \
  17   b -= a;  b ^= hash_rot(a, 6);  a += c; \
  18   c -= b;  c ^= hash_rot(b, 8);  b += a; \
  19   a -= c;  a ^= hash_rot(c,16);  c += b; \
  20   b -= a;  b ^= hash_rot(a,19);  a += c; \
  21   c -= b;  c ^= hash_rot(b, 4);  b += a; \
  22 }
  23
  24 #define hash_final(a,b,c) \
  25 { \
  26   c ^= b; c -= hash_rot(b,14); \
  27   a ^= c; a -= hash_rot(c,11); \
  28   b ^= a; b -= hash_rot(a,25); \
  29   c ^= b; c -= hash_rot(b,16); \
  30   a ^= c; a -= hash_rot(c,4);  \
  31   b ^= a; b -= hash_rot(a,14); \
  32   c ^= b; c -= hash_rot(b,24); \
  33 }
  34
  35 #define hash_i_64(a, u, v) {                            \
  36         u32_t i1 = (a), i2 = ex64lo(u), i3 = ex64hi(u); \
  37         hash_mix(i1, i2, i3);                           \
  38         hash_final(i1, i2, i3);                         \
  39         (v) = i3;                                       \
  40 }
  41
  42 #define hash_32(n, v) {                                 \
  43         u32_t i1 = 0xa5a5a5a5, i2 = 0x12345678, i3 = n; \
  44         hash_mix(i1, i2, i3);                           \
  45         hash_final(i1, i2, i3);                         \
  46         (v) = i3;                                       \
  47 }
  48
  49 #endif