1// SPDX-License-Identifier: GPL-2.0
2#ifdef __KERNEL__
3# include <linux/crush/hash.h>
4#else
5# include "hash.h"
6#endif
7
8/*
9 * Robert Jenkins' function for mixing 32-bit values
10 * https://burtleburtle.net/bob/hash/evahash.html
11 * a, b = random bits, c = input and output
12 */
13#define crush_hashmix(a, b, c) do {			\
14		a = a-b;  a = a-c;  a = a^(c>>13);	\
15		b = b-c;  b = b-a;  b = b^(a<<8);	\
16		c = c-a;  c = c-b;  c = c^(b>>13);	\
17		a = a-b;  a = a-c;  a = a^(c>>12);	\
18		b = b-c;  b = b-a;  b = b^(a<<16);	\
19		c = c-a;  c = c-b;  c = c^(b>>5);	\
20		a = a-b;  a = a-c;  a = a^(c>>3);	\
21		b = b-c;  b = b-a;  b = b^(a<<10);	\
22		c = c-a;  c = c-b;  c = c^(b>>15);	\
23	} while (0)
24
25#define crush_hash_seed 1315423911
26
27static __u32 crush_hash32_rjenkins1(__u32 a)
28{
29	__u32 hash = crush_hash_seed ^ a;
30	__u32 b = a;
31	__u32 x = 231232;
32	__u32 y = 1232;
33	crush_hashmix(b, x, hash);
34	crush_hashmix(y, a, hash);
35	return hash;
36}
37
38static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b)
39{
40	__u32 hash = crush_hash_seed ^ a ^ b;
41	__u32 x = 231232;
42	__u32 y = 1232;
43	crush_hashmix(a, b, hash);
44	crush_hashmix(x, a, hash);
45	crush_hashmix(b, y, hash);
46	return hash;
47}
48
49static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c)
50{
51	__u32 hash = crush_hash_seed ^ a ^ b ^ c;
52	__u32 x = 231232;
53	__u32 y = 1232;
54	crush_hashmix(a, b, hash);
55	crush_hashmix(c, x, hash);
56	crush_hashmix(y, a, hash);
57	crush_hashmix(b, x, hash);
58	crush_hashmix(y, c, hash);
59	return hash;
60}
61
62static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d)
63{
64	__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d;
65	__u32 x = 231232;
66	__u32 y = 1232;
67	crush_hashmix(a, b, hash);
68	crush_hashmix(c, d, hash);
69	crush_hashmix(a, x, hash);
70	crush_hashmix(y, b, hash);
71	crush_hashmix(c, x, hash);
72	crush_hashmix(y, d, hash);
73	return hash;
74}
75
76static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d,
77				      __u32 e)
78{
79	__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e;
80	__u32 x = 231232;
81	__u32 y = 1232;
82	crush_hashmix(a, b, hash);
83	crush_hashmix(c, d, hash);
84	crush_hashmix(e, x, hash);
85	crush_hashmix(y, a, hash);
86	crush_hashmix(b, x, hash);
87	crush_hashmix(y, c, hash);
88	crush_hashmix(d, x, hash);
89	crush_hashmix(y, e, hash);
90	return hash;
91}
92
93
94__u32 crush_hash32(int type, __u32 a)
95{
96	switch (type) {
97	case CRUSH_HASH_RJENKINS1:
98		return crush_hash32_rjenkins1(a);
99	default:
100		return 0;
101	}
102}
103
104__u32 crush_hash32_2(int type, __u32 a, __u32 b)
105{
106	switch (type) {
107	case CRUSH_HASH_RJENKINS1:
108		return crush_hash32_rjenkins1_2(a, b);
109	default:
110		return 0;
111	}
112}
113
114__u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c)
115{
116	switch (type) {
117	case CRUSH_HASH_RJENKINS1:
118		return crush_hash32_rjenkins1_3(a, b, c);
119	default:
120		return 0;
121	}
122}
123
124__u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d)
125{
126	switch (type) {
127	case CRUSH_HASH_RJENKINS1:
128		return crush_hash32_rjenkins1_4(a, b, c, d);
129	default:
130		return 0;
131	}
132}
133
134__u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
135{
136	switch (type) {
137	case CRUSH_HASH_RJENKINS1:
138		return crush_hash32_rjenkins1_5(a, b, c, d, e);
139	default:
140		return 0;
141	}
142}
143
144const char *crush_hash_name(int type)
145{
146	switch (type) {
147	case CRUSH_HASH_RJENKINS1:
148		return "rjenkins1";
149	default:
150		return "unknown";
151	}
152}
153