hash.h

/*
   american fuzzy lop - hashing function
   -------------------------------------

   The hash32() function is a variant of MurmurHash3, a good
   non-cryptosafe hashing function developed by Austin Appleby.

   For simplicity, this variant does *NOT* accept buffer lengths
   that are not divisible by 4 bytes.

   Austin's original code is public domain; so is this variant.

 */

#ifndef _HAVE_HASH_H
#define _HAVE_HASH_H

#include "types.h"

#ifdef __x86_64__

#define ROL64(_x, _r)  ((((u64)(_x)) << (_r)) | (((u64)(_x)) >> (64 - (_r))))

static inline u32 hash32(const void* key, u32 len, u32 seed) {

  const u64* data = (u64*)key;
  u64 h1 = seed ^ len;

  len >>= 3;

  while (len--) {

    u64 k1 = *data++;

    k1 *= 0x87c37b91114253d5ULL;
    k1  = ROL64(k1, 31);
    k1 *= 0x4cf5ad432745937fULL;

    h1 ^= k1;
    h1  = ROL64(h1, 27);
    h1  = h1 * 5 + 0x52dce729;

  }

  h1 ^= h1 >> 33;
  h1 *= 0xff51afd7ed558ccdULL;
  h1 ^= h1 >> 33;
  h1 *= 0xc4ceb9fe1a85ec53ULL;
  h1 ^= h1 >> 33;

  return h1;

}

#else

#define ROL32(_x, _r)  ((((u32)(_x)) << (_r)) | (((u32)(_x)) >> (32 - (_r))))

static inline u32 hash32(const void* key, u32 len, u32 seed) {

  const u32* data  = (u32*)key;
  u32 h1 = seed ^ len;

  len >>= 2;

  while (len--) {

    u32 k1 = *data++;

    k1 *= 0xcc9e2d51;
    k1  = ROL32(k1, 15);
    k1 *= 0x1b873593;

    h1 ^= k1;
    h1  = ROL32(h1, 13);
    h1  = h1 * 5 + 0xe6546b64;

  }

  h1 ^= h1 >> 16;
  h1 *= 0x85ebca6b;
  h1 ^= h1 >> 13;
  h1 *= 0xc2b2ae35;
  h1 ^= h1 >> 16;

  return h1;

}

#endif /* ^__x86_64__ */

#endif /* !_HAVE_HASH_H */