1 //-----------------------------------------------------------------------------
2 // MurmurHash3 was written by Austin Appleby, and is placed in the public
3 // domain. The author hereby disclaims copyright to this source code.
4
5 // Note - The x86 and x64 versions do _not_ produce the same results, as the
6 // algorithms are optimized for their respective platforms. You can still
7 // compile and run any of them on any platform, but your performance with the
8 // non-native version will be less than optimal.
9
10 #include "murmur3_hash.h"
11
12 //-----------------------------------------------------------------------------
13 // Platform-specific functions and macros
14
15 // Microsoft Visual Studio
16
17 #if defined(_MSC_VER)
18
19 #define FORCE_INLINE __forceinline
20
21 #include <stdlib.h>
22
23 #define ROTL32(x,y) _rotl(x,y)
24
25 #define BIG_CONSTANT(x) (x)
26
27 // Other compilers
28
29 #else // defined(_MSC_VER)
30
31 #define FORCE_INLINE inline __attribute__((always_inline))
32
rotl32(uint32_t x,int8_t r)33 static inline uint32_t rotl32 ( uint32_t x, int8_t r )
34 {
35 return (x << r) | (x >> (32 - r));
36 }
37
38 #define ROTL32(x,y) rotl32(x,y)
39
40 #define BIG_CONSTANT(x) (x##LLU)
41
42 #endif // !defined(_MSC_VER)
43
44 //-----------------------------------------------------------------------------
45 // Block read - if your platform needs to do endian-swapping or can only
46 // handle aligned reads, do the conversion here
47
getblock32(const uint32_t * p,int i)48 static FORCE_INLINE uint32_t getblock32 ( const uint32_t * p, int i )
49 {
50 return p[i];
51 }
52
53 //-----------------------------------------------------------------------------
54 // Finalization mix - force all bits of a hash block to avalanche
55
fmix32(uint32_t h)56 static FORCE_INLINE uint32_t fmix32 ( uint32_t h )
57 {
58 h ^= h >> 16;
59 h *= 0x85ebca6b;
60 h ^= h >> 13;
61 h *= 0xc2b2ae35;
62 h ^= h >> 16;
63
64 return h;
65 }
66
67 //-----------------------------------------------------------------------------
68
69 /* Definition modified slightly from the public domain interface (no seed +
70 * return value */
MurmurHash3_x86_32(const void * key,size_t length)71 uint32_t MurmurHash3_x86_32 ( const void * key, size_t length)
72 {
73 const uint8_t * data = (const uint8_t*)key;
74 const int nblocks = length / 4;
75
76 uint32_t h1 = 0;
77
78 uint32_t c1 = 0xcc9e2d51;
79 uint32_t c2 = 0x1b873593;
80
81 //----------
82 // body
83
84 const uint32_t * blocks = (const uint32_t *)(data + nblocks*4);
85
86 for(int i = -nblocks; i; i++)
87 {
88 uint32_t k1 = getblock32(blocks,i);
89
90 k1 *= c1;
91 k1 = ROTL32(k1,15);
92 k1 *= c2;
93
94 h1 ^= k1;
95 h1 = ROTL32(h1,13);
96 h1 = h1*5+0xe6546b64;
97 }
98
99 //----------
100 // tail
101
102 const uint8_t * tail = (const uint8_t*)(data + nblocks*4);
103
104 uint32_t k1 = 0;
105
106 switch(length & 3)
107 {
108 case 3: k1 ^= tail[2] << 16;
109 case 2: k1 ^= tail[1] << 8;
110 case 1: k1 ^= tail[0];
111 k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
112 };
113
114 //----------
115 // finalization
116
117 h1 ^= length;
118
119 h1 = fmix32(h1);
120
121 //*(uint32_t*)out = h1;
122 return h1;
123 }
124
125