0 /*

1 * MurmurHash3 was written by Austin Appleby, and is placed in the public

2 * domain. The author hereby disclaims copyright to this source code.

3 */

4

5 #include <stdint.h>

6 #include "murmur3.h"

7

8 #define ROTL32(x,r) ((x << r) | (x >> (32 - r)))

9 #define CONST1 0xcc9e2d51

10 #define CONST2 0x1b873593

11

12 uint32_t murmur3(const void *key, int len, uint32_t seed) {

13

14 const uint8_t *data = (const uint8_t*)key;

15 const int nblocks = len / 4;

16 int i;

17

18 uint32_t h1 = seed, k1;

19

20 const uint32_t *blocks;

21 const uint8_t *tail;

22

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

24

25 for (i = -nblocks; i; i++) {

26 k1 = blocks[i];

27

28 k1 *= CONST1;

29 k1 = ROTL32(k1, 15);

30 k1 *= CONST2;

31

32 h1 ^= k1;

33 h1 = ROTL32(h1, 13);

34 h1 = h1 * 5 + 0xe6546b64;

35 }

36

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

38

39 k1 = 0;

40

41 switch (len & 3) {

42 case 3:

43 k1 ^= tail[2] << 16;

44 /* fallthrough */

45 case 2:

46 k1 ^= tail[1] << 8;

47 /* fallthrough */

48 case 1:

49 k1 ^= tail[0];

50 k1 *= CONST1;

51 k1 = ROTL32(k1, 15);

52 k1 *= CONST2;

53 h1 ^= k1;

54 };

55

56 h1 ^= len;

57

58 h1 ^= h1 >> 16;

59 h1 *= 0x85ebca6b;

60 h1 ^= h1 >> 13;

61 h1 *= 0xc2b2ae35;

62 h1 ^= h1 >> 16;

63

64 return h1;

65 }

66