summaryrefslogtreecommitdiffstats
path: root/drivers/md/dm-vdo/murmurhash3.c
blob: 3a989efae1420a0f2e5b965b55555fe8a85a4037 (plain)
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
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
// SPDX-License-Identifier: LGPL-2.1+
/*
 * MurmurHash3 was written by Austin Appleby, and is placed in the public
 * domain. The author hereby disclaims copyright to this source code.
 *
 * Adapted by John Wiele (jwiele@redhat.com).
 */

#include "murmurhash3.h"

#include <asm/unaligned.h>

static inline u64 rotl64(u64 x, s8 r)
{
	return (x << r) | (x >> (64 - r));
}

#define ROTL64(x, y) rotl64(x, y)

/* Finalization mix - force all bits of a hash block to avalanche */

static __always_inline u64 fmix64(u64 k)
{
	k ^= k >> 33;
	k *= 0xff51afd7ed558ccdLLU;
	k ^= k >> 33;
	k *= 0xc4ceb9fe1a85ec53LLU;
	k ^= k >> 33;

	return k;
}

void murmurhash3_128(const void *key, const int len, const u32 seed, void *out)
{
	const u8 *data = key;
	const int nblocks = len / 16;

	u64 h1 = seed;
	u64 h2 = seed;

	const u64 c1 = 0x87c37b91114253d5LLU;
	const u64 c2 = 0x4cf5ad432745937fLLU;

	u64 *hash_out = out;

	/* body */

	const u64 *blocks = (const u64 *)(data);

	int i;

	for (i = 0; i < nblocks; i++) {
		u64 k1 = get_unaligned_le64(&blocks[i * 2]);
		u64 k2 = get_unaligned_le64(&blocks[i * 2 + 1]);

		k1 *= c1;
		k1 = ROTL64(k1, 31);
		k1 *= c2;
		h1 ^= k1;

		h1 = ROTL64(h1, 27);
		h1 += h2;
		h1 = h1 * 5 + 0x52dce729;

		k2 *= c2;
		k2 = ROTL64(k2, 33);
		k2 *= c1;
		h2 ^= k2;

		h2 = ROTL64(h2, 31);
		h2 += h1;
		h2 = h2 * 5 + 0x38495ab5;
	}

	/* tail */

	{
		const u8 *tail = (const u8 *)(data + nblocks * 16);

		u64 k1 = 0;
		u64 k2 = 0;

		switch (len & 15) {
		case 15:
			k2 ^= ((u64)tail[14]) << 48;
			fallthrough;
		case 14:
			k2 ^= ((u64)tail[13]) << 40;
			fallthrough;
		case 13:
			k2 ^= ((u64)tail[12]) << 32;
			fallthrough;
		case 12:
			k2 ^= ((u64)tail[11]) << 24;
			fallthrough;
		case 11:
			k2 ^= ((u64)tail[10]) << 16;
			fallthrough;
		case 10:
			k2 ^= ((u64)tail[9]) << 8;
			fallthrough;
		case 9:
			k2 ^= ((u64)tail[8]) << 0;
			k2 *= c2;
			k2 = ROTL64(k2, 33);
			k2 *= c1;
			h2 ^= k2;
			fallthrough;

		case 8:
			k1 ^= ((u64)tail[7]) << 56;
			fallthrough;
		case 7:
			k1 ^= ((u64)tail[6]) << 48;
			fallthrough;
		case 6:
			k1 ^= ((u64)tail[5]) << 40;
			fallthrough;
		case 5:
			k1 ^= ((u64)tail[4]) << 32;
			fallthrough;
		case 4:
			k1 ^= ((u64)tail[3]) << 24;
			fallthrough;
		case 3:
			k1 ^= ((u64)tail[2]) << 16;
			fallthrough;
		case 2:
			k1 ^= ((u64)tail[1]) << 8;
			fallthrough;
		case 1:
			k1 ^= ((u64)tail[0]) << 0;
			k1 *= c1;
			k1 = ROTL64(k1, 31);
			k1 *= c2;
			h1 ^= k1;
			break;
		default:
			break;
		}
	}
	/* finalization */

	h1 ^= len;
	h2 ^= len;

	h1 += h2;
	h2 += h1;

	h1 = fmix64(h1);
	h2 = fmix64(h2);

	h1 += h2;
	h2 += h1;

	put_unaligned_le64(h1, &hash_out[0]);
	put_unaligned_le64(h2, &hash_out[1]);
}