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 #include <mgba-util/hash.h>
5
6 #if defined(_MSC_VER)
7
8 #define FORCE_INLINE __forceinline
9
10 #include <stdlib.h>
11
12 #define ROTL32(x,y) _rotl(x,y)
13
14 #else
15
16 #define FORCE_INLINE inline __attribute__((always_inline))
17
rotl32(uint32_t x,int8_t r)18 static inline uint32_t rotl32 ( uint32_t x, int8_t r ) {
19 return (x << r) | (x >> (32 - r));
20 }
21
22 #define ROTL32(x,y) rotl32(x,y)
23
24 #endif
25
26 //-----------------------------------------------------------------------------
27 // Block read - if your platform needs to do endian-swapping or can only
28 // handle aligned reads, do the conversion here
29
getblock32(const uint32_t * p,int i)30 static FORCE_INLINE uint32_t getblock32 ( const uint32_t * p, int i ) {
31 uint32_t ret;
32 LOAD_32LE(ret, i << 2, p);
33 return ret;
34 }
35
36 //-----------------------------------------------------------------------------
37 // Finalization mix - force all bits of a hash block to avalanche
38
fmix32(uint32_t h)39 static FORCE_INLINE uint32_t fmix32 (uint32_t h) {
40 h ^= h >> 16;
41 h *= 0x85ebca6b;
42 h ^= h >> 13;
43 h *= 0xc2b2ae35;
44 h ^= h >> 16;
45
46 return h;
47 }
48
49 //-----------------------------------------------------------------------------
50
hash32(const void * key,int len,uint32_t seed)51 uint32_t hash32(const void* key, int len, uint32_t seed) {
52 const uint8_t * data = (const uint8_t*)key;
53 const int nblocks = len / 4;
54
55 uint32_t h1 = seed;
56
57 const uint32_t c1 = 0xcc9e2d51;
58 const uint32_t c2 = 0x1b873593;
59
60 //----------
61 // body
62
63 const uint32_t * blocks = (const uint32_t *)(data + nblocks*4);
64
65 int i;
66 for(i = -nblocks; i; i++)
67 {
68 uint32_t k1 = getblock32(blocks,i);
69
70 k1 *= c1;
71 k1 = ROTL32(k1,15);
72 k1 *= c2;
73
74 h1 ^= k1;
75 h1 = ROTL32(h1,13);
76 h1 = h1*5+0xe6546b64;
77 }
78
79 //----------
80 // tail
81
82 const uint8_t * tail = (const uint8_t*)(data + nblocks*4);
83
84 uint32_t k1 = 0;
85
86 switch(len & 3)
87 {
88 case 3:
89 k1 ^= tail[2] << 16;
90 // Fall through
91 case 2:
92 k1 ^= tail[1] << 8;
93 // Fall through
94 case 1:
95 k1 ^= tail[0];
96 k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
97 };
98
99 //----------
100 // finalization
101
102 h1 ^= len;
103
104 h1 = fmix32(h1);
105
106 return h1;
107 }
108