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
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
package farm
func hash32Len5to12(s []byte, seed uint32) uint32 {
slen := len(s)
a := uint32(len(s))
b := uint32(len(s) * 5)
c := uint32(9)
d := b + seed
a += fetch32(s, 0)
b += fetch32(s, slen-4)
c += fetch32(s, ((slen >> 1) & 4))
return fmix(seed ^ mur(c, mur(b, mur(a, d))))
}
// Hash32 hashes a byte slice and returns a uint32 hash value
func Hash32(s []byte) uint32 {
slen := len(s)
if slen <= 24 {
if slen <= 12 {
if slen <= 4 {
return hash32Len0to4(s, 0)
}
return hash32Len5to12(s, 0)
}
return hash32Len13to24Seed(s, 0)
}
// len > 24
h := uint32(slen)
g := c1 * uint32(slen)
f := g
a0 := rotate32(fetch32(s, slen-4)*c1, 17) * c2
a1 := rotate32(fetch32(s, slen-8)*c1, 17) * c2
a2 := rotate32(fetch32(s, slen-16)*c1, 17) * c2
a3 := rotate32(fetch32(s, slen-12)*c1, 17) * c2
a4 := rotate32(fetch32(s, slen-20)*c1, 17) * c2
h ^= a0
h = rotate32(h, 19)
h = h*5 + 0xe6546b64
h ^= a2
h = rotate32(h, 19)
h = h*5 + 0xe6546b64
g ^= a1
g = rotate32(g, 19)
g = g*5 + 0xe6546b64
g ^= a3
g = rotate32(g, 19)
g = g*5 + 0xe6546b64
f += a4
f = rotate32(f, 19) + 113
iters := (slen - 1) / 20
for {
a := fetch32(s, 0)
b := fetch32(s, 4)
c := fetch32(s, 8)
d := fetch32(s, 12)
e := fetch32(s, 16)
h += a
g += b
f += c
h = mur(d, h) + e
g = mur(c, g) + a
f = mur(b+e*c1, f) + d
f += g
g += f
s = s[20:]
iters--
if iters == 0 {
break
}
}
g = rotate32(g, 11) * c1
g = rotate32(g, 17) * c1
f = rotate32(f, 11) * c1
f = rotate32(f, 17) * c1
h = rotate32(h+g, 19)
h = h*5 + 0xe6546b64
h = rotate32(h, 17) * c1
h = rotate32(h+f, 19)
h = h*5 + 0xe6546b64
h = rotate32(h, 17) * c1
return h
}
// Hash32WithSeed hashes a byte slice and a uint32 seed and returns a uint32 hash value
func Hash32WithSeed(s []byte, seed uint32) uint32 {
slen := len(s)
if slen <= 24 {
if slen >= 13 {
return hash32Len13to24Seed(s, seed*c1)
}
if slen >= 5 {
return hash32Len5to12(s, seed)
}
return hash32Len0to4(s, seed)
}
h := hash32Len13to24Seed(s[:24], seed^uint32(slen))
return mur(Hash32(s[24:])+seed, h)
}
|
