1 // 2 // SpookyHash: a 128-bit noncryptographic hash function 3 // By Bob Jenkins, public domain 4 // Oct 31 2010: alpha, framework + SpookyHash::Mix appears right 5 // Oct 31 2011: alpha again, Mix only good to 2^^69 but rest appears right 6 // Dec 31 2011: beta, improved Mix, tested it for 2-bit deltas 7 // Feb 2 2012: production, same bits as beta 8 // Feb 5 2012: adjusted definitions of uint* to be more portable 9 // 10 // Up to 4 bytes/cycle for long messages. Reasonably fast for short messages. 11 // All 1 or 2 bit deltas achieve avalanche within 1% bias per output bit. 12 // 13 // This was developed for and tested on 64-bit x86-compatible processors. 14 // It assumes the processor is little-endian. There is a macro 15 // controlling whether unaligned reads are allowed (by default they are). 16 // This should be an equally good hash on big-endian machines, but it will 17 // compute different results on them than on little-endian machines. 18 // 19 // Google's CityHash has similar specs to SpookyHash, and CityHash is faster 20 // on some platforms. MD4 and MD5 also have similar specs, but they are orders 21 // of magnitude slower. CRCs are two or more times slower, but unlike 22 // SpookyHash, they have nice math for combining the CRCs of pieces to form 23 // the CRCs of wholes. There are also cryptographic hashes, but those are even 24 // slower than MD5. 25 // 26 27 #include "Platform.h" 28 #include <stddef.h> 29 30 #ifdef _MSC_VER 31 # define INLINE __forceinline 32 typedef unsigned __int64 uint64; 33 typedef unsigned __int32 uint32; 34 typedef unsigned __int16 uint16; 35 typedef unsigned __int8 uint8; 36 #else 37 # include <stdint.h> 38 # define INLINE inline 39 typedef uint64_t uint64; 40 typedef uint32_t uint32; 41 typedef uint16_t uint16; 42 typedef uint8_t uint8; 43 #endif 44 45 46 class SpookyHash 47 { 48 public: 49 // 50 // SpookyHash: hash a single message in one call, produce 128-bit output 51 // 52 static void Hash128( 53 const void *message, // message to hash 54 size_t length, // length of message in bytes 55 uint64 *hash1, // in/out: in seed 1, out hash value 1 56 uint64 *hash2); // in/out: in seed 2, out hash value 2 57 58 // 59 // Hash64: hash a single message in one call, return 64-bit output 60 // 61 static uint64 Hash64( 62 const void *message, // message to hash 63 size_t length, // length of message in bytes 64 uint64 seed) // seed 65 { 66 uint64 hash1 = seed; 67 Hash128(message, length, &hash1, &seed); 68 return hash1; 69 } 70 71 // 72 // Hash32: hash a single message in one call, produce 32-bit output 73 // 74 static uint32 Hash32( 75 const void *message, // message to hash 76 size_t length, // length of message in bytes 77 uint32 seed) // seed 78 { 79 uint64 hash1 = seed, hash2 = seed; 80 Hash128(message, length, &hash1, &hash2); 81 return (uint32)hash1; 82 } 83 84 // 85 // Init: initialize the context of a SpookyHash 86 // 87 void Init( 88 uint64 seed1, // any 64-bit value will do, including 0 89 uint64 seed2); // different seeds produce independent hashes 90 91 // 92 // Update: add a piece of a message to a SpookyHash state 93 // 94 void Update( 95 const void *message, // message fragment 96 size_t length); // length of message fragment in bytes 97 98 99 // 100 // Final: compute the hash for the current SpookyHash state 101 // 102 // This does not modify the state; you can keep updating it afterward 103 // 104 // The result is the same as if SpookyHash() had been called with 105 // all the pieces concatenated into one message. 106 // 107 void Final( 108 uint64 *hash1, // out only: first 64 bits of hash value. 109 uint64 *hash2); // out only: second 64 bits of hash value. 110 111 // 112 // left rotate a 64-bit value by k bytes 113 // 114 static INLINE uint64 Rot64(uint64 x, int k) 115 { 116 return (x << k) | (x >> (64 - k)); 117 } 118 119 // 120 // This is used if the input is 96 bytes long or longer. 121 // 122 // The internal state is fully overwritten every 96 bytes. 123 // Every input bit appears to cause at least 128 bits of entropy 124 // before 96 other bytes are combined, when run forward or backward 125 // For every input bit, 126 // Two inputs differing in just that input bit 127 // Where "differ" means xor or subtraction 128 // And the base value is random 129 // When run forward or backwards one Mix 130 // I tried 3 pairs of each; they all differed by at least 212 bits. 131 // 132 static INLINE void Mix( 133 const uint64 *data, 134 uint64 &s0, uint64 &s1, uint64 &s2, uint64 &s3, 135 uint64 &s4, uint64 &s5, uint64 &s6, uint64 &s7, 136 uint64 &s8, uint64 &s9, uint64 &s10,uint64 &s11) 137 { 138 s0 += data[0]; s2 ^= s10; s11 ^= s0; s0 = Rot64(s0,11); s11 += s1; 139 s1 += data[1]; s3 ^= s11; s0 ^= s1; s1 = Rot64(s1,32); s0 += s2; 140 s2 += data[2]; s4 ^= s0; s1 ^= s2; s2 = Rot64(s2,43); s1 += s3; 141 s3 += data[3]; s5 ^= s1; s2 ^= s3; s3 = Rot64(s3,31); s2 += s4; 142 s4 += data[4]; s6 ^= s2; s3 ^= s4; s4 = Rot64(s4,17); s3 += s5; 143 s5 += data[5]; s7 ^= s3; s4 ^= s5; s5 = Rot64(s5,28); s4 += s6; 144 s6 += data[6]; s8 ^= s4; s5 ^= s6; s6 = Rot64(s6,39); s5 += s7; 145 s7 += data[7]; s9 ^= s5; s6 ^= s7; s7 = Rot64(s7,57); s6 += s8; 146 s8 += data[8]; s10 ^= s6; s7 ^= s8; s8 = Rot64(s8,55); s7 += s9; 147 s9 += data[9]; s11 ^= s7; s8 ^= s9; s9 = Rot64(s9,54); s8 += s10; 148 s10 += data[10]; s0 ^= s8; s9 ^= s10; s10 = Rot64(s10,22); s9 += s11; 149 s11 += data[11]; s1 ^= s9; s10 ^= s11; s11 = Rot64(s11,46); s10 += s0; 150 } 151 152 // 153 // Mix all 12 inputs together so that h0, h1 are a hash of them all. 154 // 155 // For two inputs differing in just the input bits 156 // Where "differ" means xor or subtraction 157 // And the base value is random, or a counting value starting at that bit 158 // The final result will have each bit of h0, h1 flip 159 // For every input bit, 160 // with probability 50 +- .3% 161 // For every pair of input bits, 162 // with probability 50 +- 3% 163 // 164 // This does not rely on the last Mix() call having already mixed some. 165 // Two iterations was almost good enough for a 64-bit result, but a 166 // 128-bit result is reported, so End() does three iterations. 167 // 168 static INLINE void EndPartial( 169 uint64 &h0, uint64 &h1, uint64 &h2, uint64 &h3, 170 uint64 &h4, uint64 &h5, uint64 &h6, uint64 &h7, 171 uint64 &h8, uint64 &h9, uint64 &h10,uint64 &h11) 172 { 173 h11+= h1; h2 ^= h11; h1 = Rot64(h1,44); 174 h0 += h2; h3 ^= h0; h2 = Rot64(h2,15); 175 h1 += h3; h4 ^= h1; h3 = Rot64(h3,34); 176 h2 += h4; h5 ^= h2; h4 = Rot64(h4,21); 177 h3 += h5; h6 ^= h3; h5 = Rot64(h5,38); 178 h4 += h6; h7 ^= h4; h6 = Rot64(h6,33); 179 h5 += h7; h8 ^= h5; h7 = Rot64(h7,10); 180 h6 += h8; h9 ^= h6; h8 = Rot64(h8,13); 181 h7 += h9; h10^= h7; h9 = Rot64(h9,38); 182 h8 += h10; h11^= h8; h10= Rot64(h10,53); 183 h9 += h11; h0 ^= h9; h11= Rot64(h11,42); 184 h10+= h0; h1 ^= h10; h0 = Rot64(h0,54); 185 } 186 187 static INLINE void End( 188 uint64 &h0, uint64 &h1, uint64 &h2, uint64 &h3, 189 uint64 &h4, uint64 &h5, uint64 &h6, uint64 &h7, 190 uint64 &h8, uint64 &h9, uint64 &h10,uint64 &h11) 191 { 192 EndPartial(h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11); 193 EndPartial(h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11); 194 EndPartial(h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11); 195 } 196 197 // 198 // The goal is for each bit of the input to expand into 128 bits of 199 // apparent entropy before it is fully overwritten. 200 // n trials both set and cleared at least m bits of h0 h1 h2 h3 201 // n: 2 m: 29 202 // n: 3 m: 46 203 // n: 4 m: 57 204 // n: 5 m: 107 205 // n: 6 m: 146 206 // n: 7 m: 152 207 // when run forwards or backwards 208 // for all 1-bit and 2-bit diffs 209 // with diffs defined by either xor or subtraction 210 // with a base of all zeros plus a counter, or plus another bit, or random 211 // 212 static INLINE void ShortMix(uint64 &h0, uint64 &h1, uint64 &h2, uint64 &h3) 213 { 214 h2 = Rot64(h2,50); h2 += h3; h0 ^= h2; 215 h3 = Rot64(h3,52); h3 += h0; h1 ^= h3; 216 h0 = Rot64(h0,30); h0 += h1; h2 ^= h0; 217 h1 = Rot64(h1,41); h1 += h2; h3 ^= h1; 218 h2 = Rot64(h2,54); h2 += h3; h0 ^= h2; 219 h3 = Rot64(h3,48); h3 += h0; h1 ^= h3; 220 h0 = Rot64(h0,38); h0 += h1; h2 ^= h0; 221 h1 = Rot64(h1,37); h1 += h2; h3 ^= h1; 222 h2 = Rot64(h2,62); h2 += h3; h0 ^= h2; 223 h3 = Rot64(h3,34); h3 += h0; h1 ^= h3; 224 h0 = Rot64(h0,5); h0 += h1; h2 ^= h0; 225 h1 = Rot64(h1,36); h1 += h2; h3 ^= h1; 226 } 227 228 // 229 // Mix all 4 inputs together so that h0, h1 are a hash of them all. 230 // 231 // For two inputs differing in just the input bits 232 // Where "differ" means xor or subtraction 233 // And the base value is random, or a counting value starting at that bit 234 // The final result will have each bit of h0, h1 flip 235 // For every input bit, 236 // with probability 50 +- .3% (it is probably better than that) 237 // For every pair of input bits, 238 // with probability 50 +- .75% (the worst case is approximately that) 239 // 240 static INLINE void ShortEnd(uint64 &h0, uint64 &h1, uint64 &h2, uint64 &h3) 241 { 242 h3 ^= h2; h2 = Rot64(h2,15); h3 += h2; 243 h0 ^= h3; h3 = Rot64(h3,52); h0 += h3; 244 h1 ^= h0; h0 = Rot64(h0,26); h1 += h0; 245 h2 ^= h1; h1 = Rot64(h1,51); h2 += h1; 246 h3 ^= h2; h2 = Rot64(h2,28); h3 += h2; 247 h0 ^= h3; h3 = Rot64(h3,9); h0 += h3; 248 h1 ^= h0; h0 = Rot64(h0,47); h1 += h0; 249 h2 ^= h1; h1 = Rot64(h1,54); h2 += h1; 250 h3 ^= h2; h2 = Rot64(h2,32); h3 += h2; 251 h0 ^= h3; h3 = Rot64(h3,25); h0 += h3; 252 h1 ^= h0; h0 = Rot64(h0,63); h1 += h0; 253 } 254 255 private: 256 257 // 258 // Short is used for messages under 192 bytes in length 259 // Short has a low startup cost, the normal mode is good for long 260 // keys, the cost crossover is at about 192 bytes. The two modes were 261 // held to the same quality bar. 262 // 263 static void Short( 264 const void *message, 265 size_t length, 266 uint64 *hash1, 267 uint64 *hash2); 268 269 // number of uint64's in internal state 270 static const size_t sc_numVars = 12; 271 272 // size of the internal state 273 static const size_t sc_blockSize = sc_numVars*8; 274 275 // size of buffer of unhashed data, in bytes 276 static const size_t sc_bufSize = 2*sc_blockSize; 277 278 // 279 // sc_const: a constant which: 280 // * is not zero 281 // * is odd 282 // * is a not-very-regular mix of 1's and 0's 283 // * does not need any other special mathematical properties 284 // 285 static const uint64 sc_const = 0xdeadbeefdeadbeefULL; 286 287 uint64 m_data[2*sc_numVars]; // unhashed data, for partial messages 288 uint64 m_state[sc_numVars]; // internal state of the hash 289 size_t m_length; // total length of the input so far 290 uint8 m_remainder; // length of unhashed data stashed in m_data 291 }; 292 293 294 295
