hash.h

 1/* SPDX-License-Identifier: GPL-2.0-only */
 2
 3#ifndef _SELINUX_HASH_H_
 4#define _SELINUX_HASH_H_
 5
 6/*
 7 * Based on MurmurHash3, written by Austin Appleby and placed in the
 8 * public domain.
 9 */
10static inline u32 av_hash(u32 key1, u32 key2, u32 key3, u32 mask)
11{
12	static const u32 c1 = 0xcc9e2d51;
13	static const u32 c2 = 0x1b873593;
14	static const u32 r1 = 15;
15	static const u32 r2 = 13;
16	static const u32 m = 5;
17	static const u32 n = 0xe6546b64;
18
19	u32 hash = 0;
20
21#define mix(input)                                         \
22	do {                                               \
23		u32 v = input;                             \
24		v *= c1;                                   \
25		v = (v << r1) | (v >> (32 - r1));          \
26		v *= c2;                                   \
27		hash ^= v;                                 \
28		hash = (hash << r2) | (hash >> (32 - r2)); \
29		hash = hash * m + n;                       \
30	} while (0)
31
32	mix(key1);
33	mix(key2);
34	mix(key3);
35
36#undef mix
37
38	hash ^= hash >> 16;
39	hash *= 0x85ebca6b;
40	hash ^= hash >> 13;
41	hash *= 0xc2b2ae35;
42	hash ^= hash >> 16;
43
44	return hash & mask;
45}
46
47#endif /* _SELINUX_HASH_H_ */