1/* Public domain. */
2
3#ifndef _LINUX_HASH_H
4#define _LINUX_HASH_H
5
6#include <sys/types.h>
7
8/* 2^32 * ((sqrt(5) - 1) / 2) from Knuth */
9#define GOLDEN_RATIO_32 0x9e3779b9
10
11static inline uint32_t
12hash_32(uint32_t val, unsigned int bits)
13{
14	return (val * GOLDEN_RATIO_32) >> (32 - bits);
15}
16
17/* 2^64 * ((sqrt(5) - 1) / 2) from Knuth */
18#define GOLDEN_RATIO_64 0x9e3779b97f4a7c16ULL
19
20static inline uint32_t
21hash_64(uint64_t val, unsigned int bits)
22{
23	return (val * GOLDEN_RATIO_64) >> (64 - bits);
24}
25
26#ifdef __LP64__
27#define hash_long(val, bits) hash_64(val, bits)
28#else
29#define hash_long(val, bits) hash_32(val, bits)
30#endif
31
32#endif
33