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