src/xt_hash.h

   1 /*
   2  * Lightweight Autonomic Network Architecture
   3  *
   4  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,
   5  * Swiss federal institute of technology (ETH Zurich)
   6  * Subject to the GPL.
   7  */
   8
   9 #ifndef XT_HASH_H
  10 #define XT_HASH_H
  11
  12 #include <linux/types.h>
  13
  14 /* Default: 512 slots */
  15 #define HASHTPO2SIZ   9
  16 #define HASHSIZE(n)   ((__u32) 1 << (n))
  17 #define HASHTSIZ      (HASHSIZE(HASHTPO2SIZ))
  18 #define HASHMASK(n)   (HASHSIZE(n) - 1)
  19 #define HASHSLOT(n)   ((n) & HASHMASK(HASHTPO2SIZ))
  20 #define HASHINITVAL   0xACDC
  21
  22 #define ROT(x,k) (((x) << (k)) | ((x) >> (32 - (k))))
  23
  24 #define MIX(a, b, c) {                      \
  25         a -= c;  a ^= ROT(c,  4);  c += b;  \
  26         b -= a;  b ^= ROT(a,  6);  a += c;  \
  27         c -= b;  c ^= ROT(b,  8);  b += a;  \
  28         a -= c;  a ^= ROT(c, 16);  c += b;  \
  29         b -= a;  b ^= ROT(a, 19);  a += c;  \
  30         c -= b;  c ^= ROT(b,  4);  b += a; }
  31
  32 #define FINAL(a, b, c) {                   \
  33         c ^= b; c -= ROT(b, 14);           \
  34         a ^= c; a -= ROT(c, 11);           \
  35         b ^= a; b -= ROT(a, 25);           \
  36         c ^= b; c -= ROT(b, 16);           \
  37         a ^= c; a -= ROT(c,  4);           \
  38         b ^= a; b -= ROT(a, 14);           \
  39         c ^= b; c -= ROT(b, 24); }
  40
  41 static inline __u32 hash_idp(const idp_t k)
  42 {
  43         return HASHSLOT(k);
  44 }
  45
  46 static inline __u32 hash_idp2(const idp_t k)
  47 {
  48         __u32 a,b,c;
  49         a = b = c = 0xdeadbeef + (((uint32_t) 1) << 2) + HASHINITVAL;
  50         a =+ k;
  51         FINAL(a, b, c);
  52         return HASHSLOT(c);
  53 }
  54
  55 #endif /* XT_HASH_H */