1 // SPDX-License-Identifier: GPL-2.0
3 # include <linux/crush/hash.h>
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
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); \
25 #define crush_hash_seed 1315423911
27 static __u32 crush_hash32_rjenkins1(__u32 a)
29 __u32 hash = crush_hash_seed ^ a;
33 crush_hashmix(b, x, hash);
34 crush_hashmix(y, a, hash);
38 static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b)
40 __u32 hash = crush_hash_seed ^ a ^ b;
43 crush_hashmix(a, b, hash);
44 crush_hashmix(x, a, hash);
45 crush_hashmix(b, y, hash);
49 static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c)
51 __u32 hash = crush_hash_seed ^ a ^ b ^ c;
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);
62 static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d)
64 __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d;
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);
76 static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d,
79 __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e;
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);
94 __u32 crush_hash32(int type, __u32 a)
97 case CRUSH_HASH_RJENKINS1:
98 return crush_hash32_rjenkins1(a);
104 __u32 crush_hash32_2(int type, __u32 a, __u32 b)
107 case CRUSH_HASH_RJENKINS1:
108 return crush_hash32_rjenkins1_2(a, b);
114 __u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c)
117 case CRUSH_HASH_RJENKINS1:
118 return crush_hash32_rjenkins1_3(a, b, c);
124 __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d)
127 case CRUSH_HASH_RJENKINS1:
128 return crush_hash32_rjenkins1_4(a, b, c, d);
134 __u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
137 case CRUSH_HASH_RJENKINS1:
138 return crush_hash32_rjenkins1_5(a, b, c, d, e);
144 const char *crush_hash_name(int type)
147 case CRUSH_HASH_RJENKINS1: