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
crush_hash32_rjenkins1(__u32 a)27 static __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
crush_hash32_rjenkins1_2(__u32 a,__u32 b)38 static __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
crush_hash32_rjenkins1_3(__u32 a,__u32 b,__u32 c)49 static __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
crush_hash32_rjenkins1_4(__u32 a,__u32 b,__u32 c,__u32 d)62 static __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
crush_hash32_rjenkins1_5(__u32 a,__u32 b,__u32 c,__u32 d,__u32 e)76 static __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
crush_hash32(int type,__u32 a)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
crush_hash32_2(int type,__u32 a,__u32 b)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
crush_hash32_3(int type,__u32 a,__u32 b,__u32 c)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
crush_hash32_4(int type,__u32 a,__u32 b,__u32 c,__u32 d)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
crush_hash32_5(int type,__u32 a,__u32 b,__u32 c,__u32 d,__u32 e)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
crush_hash_name(int type)144 const 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