-
Notifications
You must be signed in to change notification settings - Fork 6
/
murmur2.go
83 lines (69 loc) · 1.39 KB
/
murmur2.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
package murmur
import "encoding/binary"
// Taken from https://github.com/RedisBloom/RedisBloom/blob/master/contrib/MurmurHash2.c
// MurmurHash2, 64-bit versions, by Austin Appleby
// 64-bit hash for 64-bit platforms
// MurmurHash64A_Bloom returns the murmur hash of the given data
func MurmurHash64A_Bloom(key []byte, length, seed uint64) uint64 {
m := uint64(0xc6a4a7935bd1e995)
r := 47
h := uint64(seed) ^ (length * m)
data := uint64(key[0])
for i := 1; i < len(key); i++ {
switch i {
case 1:
data |= uint64(key[i]) << 8
case 2:
data |= uint64(key[i]) << 16
case 3:
data |= uint64(key[i]) << 24
case 4:
data |= uint64(key[i]) << 32
case 5:
data |= uint64(key[i]) << 40
case 6:
data |= uint64(key[i]) << 48
case 7:
data |= uint64(key[i]) << 56
}
}
end := data + uint64(length/8)
for data != end {
data++
k := data
k *= m
k ^= k >> r
k *= m
h ^= k
h *= m
}
data2 := make([]byte, 8)
binary.PutUvarint(data2, data)
switch length & 7 {
case 7:
h ^= uint64(data2[6]) << 48
fallthrough
case 6:
h ^= uint64(data2[5]) << 40
fallthrough
case 5:
h ^= uint64(data2[4]) << 32
fallthrough
case 4:
h ^= uint64(data2[3]) << 24
fallthrough
case 3:
h ^= uint64(data2[2]) << 16
fallthrough
case 2:
h ^= uint64(data2[1]) << 8
fallthrough
case 1:
h ^= uint64(data2[0])
h *= m
}
h ^= h >> r
h *= m
h ^= h >> r
return h
}