MurmurHash3Inl.h File Reference

#include "../Shared/funcannotations.h"

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Macros
#define	ROTL32(x, y)   rotl32(x, y)

Functions
FORCE_INLINE DEVICE uint32_t	rotl32 (uint32_t x, int8_t r)
FORCE_INLINE DEVICE uint32_t	MurmurHash3Impl (const void *key, int len, uint32_t seed)

Macro Definition Documentation

#define ROTL32	(		x,
			y
	)		rotl32(x, y)

Definition at line 9 of file MurmurHash3Inl.h.

Referenced by MurmurHash3Impl().

Function Documentation

FORCE_INLINE DEVICE uint32_t MurmurHash3Impl	(	const void *	key,
		int	len,
		uint32_t	seed
	)

Definition at line 11 of file MurmurHash3Inl.h.

References ROTL32.

Referenced by MurmurHash3().

                                                                                      {
  const uint8_t* data = (const uint8_t*)key;
  const int nblocks = len / 4;

  uint32_t h1 = seed;

  const uint32_t c1 = 0xcc9e2d51;
  const uint32_t c2 = 0x1b873593;

  //----------
  // body

  const uint32_t* blocks = (const uint32_t*)(data + nblocks * 4);

  for (int i = -nblocks; i; i++) {
    uint32_t k1 = blocks[i];

    k1 *= c1;
    k1 = ROTL32(k1, 15);
    k1 *= c2;

    h1 ^= k1;
    h1 = ROTL32(h1, 13);
    h1 = h1 * 5 + 0xe6546b64;
  }

  //----------
  // tail

  const uint8_t* tail = (const uint8_t*)(data + nblocks * 4);

  uint32_t k1 = 0;

  switch (len & 3) {
    case 3:
      k1 ^= tail[2] << 16;
    case 2:
      k1 ^= tail[1] << 8;
    case 1:
      k1 ^= tail[0];
      k1 *= c1;
      k1 = ROTL32(k1, 15);
      k1 *= c2;
      h1 ^= k1;
  };

  //----------
  // finalization

  h1 ^= len;

  //-----------------------------------------------------------------------------
  // Finalization mix - force all bits of a hash block to avalanche

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

  return h1;
}

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FORCE_INLINE DEVICE uint32_t rotl32	(	uint32_t	x,
		int8_t	r
	)

Definition at line 5 of file MurmurHash3Inl.h.

                                                          {
  return (x << r) | (x >> (32 - r));
}