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c6cf7263 SW |
1 | |
2 | #include <linux/types.h> | |
3d14c5d2 | 3 | #include <linux/crush/hash.h> |
c6cf7263 SW |
4 | |
5 | /* | |
6 | * Robert Jenkins' function for mixing 32-bit values | |
7 | * http://burtleburtle.net/bob/hash/evahash.html | |
8 | * a, b = random bits, c = input and output | |
9 | */ | |
10 | #define crush_hashmix(a, b, c) do { \ | |
11 | a = a-b; a = a-c; a = a^(c>>13); \ | |
12 | b = b-c; b = b-a; b = b^(a<<8); \ | |
13 | c = c-a; c = c-b; c = c^(b>>13); \ | |
14 | a = a-b; a = a-c; a = a^(c>>12); \ | |
15 | b = b-c; b = b-a; b = b^(a<<16); \ | |
16 | c = c-a; c = c-b; c = c^(b>>5); \ | |
17 | a = a-b; a = a-c; a = a^(c>>3); \ | |
18 | b = b-c; b = b-a; b = b^(a<<10); \ | |
19 | c = c-a; c = c-b; c = c^(b>>15); \ | |
20 | } while (0) | |
21 | ||
22 | #define crush_hash_seed 1315423911 | |
23 | ||
fb690390 | 24 | static __u32 crush_hash32_rjenkins1(__u32 a) |
c6cf7263 SW |
25 | { |
26 | __u32 hash = crush_hash_seed ^ a; | |
27 | __u32 b = a; | |
28 | __u32 x = 231232; | |
29 | __u32 y = 1232; | |
30 | crush_hashmix(b, x, hash); | |
31 | crush_hashmix(y, a, hash); | |
32 | return hash; | |
33 | } | |
34 | ||
fb690390 | 35 | static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b) |
c6cf7263 SW |
36 | { |
37 | __u32 hash = crush_hash_seed ^ a ^ b; | |
38 | __u32 x = 231232; | |
39 | __u32 y = 1232; | |
40 | crush_hashmix(a, b, hash); | |
41 | crush_hashmix(x, a, hash); | |
42 | crush_hashmix(b, y, hash); | |
43 | return hash; | |
44 | } | |
45 | ||
fb690390 | 46 | static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c) |
c6cf7263 SW |
47 | { |
48 | __u32 hash = crush_hash_seed ^ a ^ b ^ c; | |
49 | __u32 x = 231232; | |
50 | __u32 y = 1232; | |
51 | crush_hashmix(a, b, hash); | |
52 | crush_hashmix(c, x, hash); | |
53 | crush_hashmix(y, a, hash); | |
54 | crush_hashmix(b, x, hash); | |
55 | crush_hashmix(y, c, hash); | |
56 | return hash; | |
57 | } | |
58 | ||
fb690390 | 59 | static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d) |
c6cf7263 SW |
60 | { |
61 | __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d; | |
62 | __u32 x = 231232; | |
63 | __u32 y = 1232; | |
64 | crush_hashmix(a, b, hash); | |
65 | crush_hashmix(c, d, hash); | |
66 | crush_hashmix(a, x, hash); | |
67 | crush_hashmix(y, b, hash); | |
68 | crush_hashmix(c, x, hash); | |
69 | crush_hashmix(y, d, hash); | |
70 | return hash; | |
71 | } | |
72 | ||
fb690390 SW |
73 | static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d, |
74 | __u32 e) | |
c6cf7263 SW |
75 | { |
76 | __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e; | |
77 | __u32 x = 231232; | |
78 | __u32 y = 1232; | |
79 | crush_hashmix(a, b, hash); | |
80 | crush_hashmix(c, d, hash); | |
81 | crush_hashmix(e, x, hash); | |
82 | crush_hashmix(y, a, hash); | |
83 | crush_hashmix(b, x, hash); | |
84 | crush_hashmix(y, c, hash); | |
85 | crush_hashmix(d, x, hash); | |
86 | crush_hashmix(y, e, hash); | |
87 | return hash; | |
88 | } | |
fb690390 SW |
89 | |
90 | ||
91 | __u32 crush_hash32(int type, __u32 a) | |
92 | { | |
93 | switch (type) { | |
94 | case CRUSH_HASH_RJENKINS1: | |
95 | return crush_hash32_rjenkins1(a); | |
96 | default: | |
97 | return 0; | |
98 | } | |
99 | } | |
100 | ||
101 | __u32 crush_hash32_2(int type, __u32 a, __u32 b) | |
102 | { | |
103 | switch (type) { | |
104 | case CRUSH_HASH_RJENKINS1: | |
105 | return crush_hash32_rjenkins1_2(a, b); | |
106 | default: | |
107 | return 0; | |
108 | } | |
109 | } | |
110 | ||
111 | __u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c) | |
112 | { | |
113 | switch (type) { | |
114 | case CRUSH_HASH_RJENKINS1: | |
115 | return crush_hash32_rjenkins1_3(a, b, c); | |
116 | default: | |
117 | return 0; | |
118 | } | |
119 | } | |
120 | ||
121 | __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d) | |
122 | { | |
123 | switch (type) { | |
124 | case CRUSH_HASH_RJENKINS1: | |
125 | return crush_hash32_rjenkins1_4(a, b, c, d); | |
126 | default: | |
127 | return 0; | |
128 | } | |
129 | } | |
130 | ||
131 | __u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e) | |
132 | { | |
133 | switch (type) { | |
134 | case CRUSH_HASH_RJENKINS1: | |
135 | return crush_hash32_rjenkins1_5(a, b, c, d, e); | |
136 | default: | |
137 | return 0; | |
138 | } | |
139 | } | |
140 | ||
141 | const char *crush_hash_name(int type) | |
142 | { | |
143 | switch (type) { | |
144 | case CRUSH_HASH_RJENKINS1: | |
145 | return "rjenkins1"; | |
146 | default: | |
147 | return "unknown"; | |
148 | } | |
149 | } |