/* * Copyright 2017-present Facebook, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ // This is version 2 of SpookyHash, incompatible with version 1. // // SpookyHash: a 128-bit noncryptographic hash function // By Bob Jenkins, public domain // Oct 31 2010: alpha, framework + SpookyHash::Mix appears right // Oct 31 2011: alpha again, Mix only good to 2^^69 but rest appears right // Dec 31 2011: beta, improved Mix, tested it for 2-bit deltas // Feb 2 2012: production, same bits as beta // Feb 5 2012: adjusted definitions of uint* to be more portable // Mar 30 2012: 3 bytes/cycle, not 4. Alpha was 4 but wasn't thorough enough. // August 5 2012: SpookyV2 (different results) // // Up to 3 bytes/cycle for long messages. Reasonably fast for short messages. // All 1 or 2 bit deltas achieve avalanche within 1% bias per output bit. // // This was developed for and tested on 64-bit x86-compatible processors. // It assumes the processor is little-endian. There is a macro // controlling whether unaligned reads are allowed (by default they are). // This should be an equally good hash on big-endian machines, but it will // compute different results on them than on little-endian machines. // // Google's CityHash has similar specs to SpookyHash, and CityHash is faster // on new Intel boxes. MD4 and MD5 also have similar specs, but they are orders // of magnitude slower. CRCs are two or more times slower, but unlike // SpookyHash, they have nice math for combining the CRCs of pieces to form // the CRCs of wholes. There are also cryptographic hashes, but those are even // slower than MD5. // #pragma once #include <cstddef> #include <cstdint> namespace folly { namespace hash { // clang-format off class SpookyHashV2 { public: // // SpookyHash: hash a single message in one call, produce 128-bit output // static void Hash128( const void *message, // message to hash size_t length, // length of message in bytes uint64_t *hash1, // in/out: in seed 1, out hash value 1 uint64_t *hash2); // in/out: in seed 2, out hash value 2 // // Hash64: hash a single message in one call, return 64-bit output // static uint64_t Hash64( const void *message, // message to hash size_t length, // length of message in bytes uint64_t seed) // seed { uint64_t hash1 = seed; Hash128(message, length, &hash1, &seed); return hash1; } // // Hash32: hash a single message in one call, produce 32-bit output // static uint32_t Hash32( const void *message, // message to hash size_t length, // length of message in bytes uint32_t seed) // seed { uint64_t hash1 = seed, hash2 = seed; Hash128(message, length, &hash1, &hash2); return (uint32_t)hash1; } // // Init: initialize the context of a SpookyHash // void Init( uint64_t seed1, // any 64-bit value will do, including 0 uint64_t seed2); // different seeds produce independent hashes // // Update: add a piece of a message to a SpookyHash state // void Update( const void *message, // message fragment size_t length); // length of message fragment in bytes // // Final: compute the hash for the current SpookyHash state // // This does not modify the state; you can keep updating it afterward // // The result is the same as if SpookyHash() had been called with // all the pieces concatenated into one message. // void Final( uint64_t *hash1, // out only: first 64 bits of hash value. uint64_t *hash2) const; // out only: second 64 bits of hash value. // // left rotate a 64-bit value by k bytes // static inline uint64_t Rot64(uint64_t x, int k) { return (x << k) | (x >> (64 - k)); } // // This is used if the input is 96 bytes long or longer. // // The internal state is fully overwritten every 96 bytes. // Every input bit appears to cause at least 128 bits of entropy // before 96 other bytes are combined, when run forward or backward // For every input bit, // Two inputs differing in just that input bit // Where "differ" means xor or subtraction // And the base value is random // When run forward or backwards one Mix // I tried 3 pairs of each; they all differed by at least 212 bits. // static inline void Mix( const uint64_t *data, uint64_t &s0, uint64_t &s1, uint64_t &s2, uint64_t &s3, uint64_t &s4, uint64_t &s5, uint64_t &s6, uint64_t &s7, uint64_t &s8, uint64_t &s9, uint64_t &s10,uint64_t &s11) { s0 += data[0]; s2 ^= s10; s11 ^= s0; s0 = Rot64(s0,11); s11 += s1; s1 += data[1]; s3 ^= s11; s0 ^= s1; s1 = Rot64(s1,32); s0 += s2; s2 += data[2]; s4 ^= s0; s1 ^= s2; s2 = Rot64(s2,43); s1 += s3; s3 += data[3]; s5 ^= s1; s2 ^= s3; s3 = Rot64(s3,31); s2 += s4; s4 += data[4]; s6 ^= s2; s3 ^= s4; s4 = Rot64(s4,17); s3 += s5; s5 += data[5]; s7 ^= s3; s4 ^= s5; s5 = Rot64(s5,28); s4 += s6; s6 += data[6]; s8 ^= s4; s5 ^= s6; s6 = Rot64(s6,39); s5 += s7; s7 += data[7]; s9 ^= s5; s6 ^= s7; s7 = Rot64(s7,57); s6 += s8; s8 += data[8]; s10 ^= s6; s7 ^= s8; s8 = Rot64(s8,55); s7 += s9; s9 += data[9]; s11 ^= s7; s8 ^= s9; s9 = Rot64(s9,54); s8 += s10; s10 += data[10]; s0 ^= s8; s9 ^= s10; s10 = Rot64(s10,22); s9 += s11; s11 += data[11]; s1 ^= s9; s10 ^= s11; s11 = Rot64(s11,46); s10 += s0; } // // Mix all 12 inputs together so that h0, h1 are a hash of them all. // // For two inputs differing in just the input bits // Where "differ" means xor or subtraction // And the base value is random, or a counting value starting at that bit // The final result will have each bit of h0, h1 flip // For every input bit, // with probability 50 +- .3% // For every pair of input bits, // with probability 50 +- 3% // // This does not rely on the last Mix() call having already mixed some. // Two iterations was almost good enough for a 64-bit result, but a // 128-bit result is reported, so End() does three iterations. // static inline void EndPartial( uint64_t &h0, uint64_t &h1, uint64_t &h2, uint64_t &h3, uint64_t &h4, uint64_t &h5, uint64_t &h6, uint64_t &h7, uint64_t &h8, uint64_t &h9, uint64_t &h10,uint64_t &h11) { h11+= h1; h2 ^= h11; h1 = Rot64(h1,44); h0 += h2; h3 ^= h0; h2 = Rot64(h2,15); h1 += h3; h4 ^= h1; h3 = Rot64(h3,34); h2 += h4; h5 ^= h2; h4 = Rot64(h4,21); h3 += h5; h6 ^= h3; h5 = Rot64(h5,38); h4 += h6; h7 ^= h4; h6 = Rot64(h6,33); h5 += h7; h8 ^= h5; h7 = Rot64(h7,10); h6 += h8; h9 ^= h6; h8 = Rot64(h8,13); h7 += h9; h10^= h7; h9 = Rot64(h9,38); h8 += h10; h11^= h8; h10= Rot64(h10,53); h9 += h11; h0 ^= h9; h11= Rot64(h11,42); h10+= h0; h1 ^= h10; h0 = Rot64(h0,54); } static inline void End( const uint64_t *data, uint64_t &h0, uint64_t &h1, uint64_t &h2, uint64_t &h3, uint64_t &h4, uint64_t &h5, uint64_t &h6, uint64_t &h7, uint64_t &h8, uint64_t &h9, uint64_t &h10,uint64_t &h11) { h0 += data[0]; h1 += data[1]; h2 += data[2]; h3 += data[3]; h4 += data[4]; h5 += data[5]; h6 += data[6]; h7 += data[7]; h8 += data[8]; h9 += data[9]; h10 += data[10]; h11 += data[11]; EndPartial(h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11); EndPartial(h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11); EndPartial(h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11); } // // The goal is for each bit of the input to expand into 128 bits of // apparent entropy before it is fully overwritten. // n trials both set and cleared at least m bits of h0 h1 h2 h3 // n: 2 m: 29 // n: 3 m: 46 // n: 4 m: 57 // n: 5 m: 107 // n: 6 m: 146 // n: 7 m: 152 // when run forwards or backwards // for all 1-bit and 2-bit diffs // with diffs defined by either xor or subtraction // with a base of all zeros plus a counter, or plus another bit, or random // static inline void ShortMix(uint64_t &h0, uint64_t &h1, uint64_t &h2, uint64_t &h3) { h2 = Rot64(h2,50); h2 += h3; h0 ^= h2; h3 = Rot64(h3,52); h3 += h0; h1 ^= h3; h0 = Rot64(h0,30); h0 += h1; h2 ^= h0; h1 = Rot64(h1,41); h1 += h2; h3 ^= h1; h2 = Rot64(h2,54); h2 += h3; h0 ^= h2; h3 = Rot64(h3,48); h3 += h0; h1 ^= h3; h0 = Rot64(h0,38); h0 += h1; h2 ^= h0; h1 = Rot64(h1,37); h1 += h2; h3 ^= h1; h2 = Rot64(h2,62); h2 += h3; h0 ^= h2; h3 = Rot64(h3,34); h3 += h0; h1 ^= h3; h0 = Rot64(h0,5); h0 += h1; h2 ^= h0; h1 = Rot64(h1,36); h1 += h2; h3 ^= h1; } // // Mix all 4 inputs together so that h0, h1 are a hash of them all. // // For two inputs differing in just the input bits // Where "differ" means xor or subtraction // And the base value is random, or a counting value starting at that bit // The final result will have each bit of h0, h1 flip // For every input bit, // with probability 50 +- .3% (it is probably better than that) // For every pair of input bits, // with probability 50 +- .75% (the worst case is approximately that) // static inline void ShortEnd(uint64_t &h0, uint64_t &h1, uint64_t &h2, uint64_t &h3) { h3 ^= h2; h2 = Rot64(h2,15); h3 += h2; h0 ^= h3; h3 = Rot64(h3,52); h0 += h3; h1 ^= h0; h0 = Rot64(h0,26); h1 += h0; h2 ^= h1; h1 = Rot64(h1,51); h2 += h1; h3 ^= h2; h2 = Rot64(h2,28); h3 += h2; h0 ^= h3; h3 = Rot64(h3,9); h0 += h3; h1 ^= h0; h0 = Rot64(h0,47); h1 += h0; h2 ^= h1; h1 = Rot64(h1,54); h2 += h1; h3 ^= h2; h2 = Rot64(h2,32); h3 += h2; h0 ^= h3; h3 = Rot64(h3,25); h0 += h3; h1 ^= h0; h0 = Rot64(h0,63); h1 += h0; } private: // // Short is used for messages under 192 bytes in length // Short has a low startup cost, the normal mode is good for long // keys, the cost crossover is at about 192 bytes. The two modes were // held to the same quality bar. // static void Short( const void *message, // message (byte array, not necessarily aligned) size_t length, // length of message (in bytes) uint64_t *hash1, // in/out: in the seed, out the hash value uint64_t *hash2); // in/out: in the seed, out the hash value // number of uint64_t's in internal state static constexpr size_t sc_numVars = 12; // size of the internal state static constexpr size_t sc_blockSize = sc_numVars*8; // size of buffer of unhashed data, in bytes static constexpr size_t sc_bufSize = 2*sc_blockSize; // // sc_const: a constant which: // * is not zero // * is odd // * is a not-very-regular mix of 1's and 0's // * does not need any other special mathematical properties // static constexpr uint64_t sc_const = 0xdeadbeefdeadbeefULL; uint64_t m_data[2*sc_numVars]; // unhashed data, for partial messages uint64_t m_state[sc_numVars]; // internal state of the hash size_t m_length; // total length of the input so far uint8_t m_remainder; // length of unhashed data stashed in m_data }; // clang-format on } // namespace hash } // namespace folly