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