| /* |
| * Copyright 2015 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. |
| // |
| |
| #ifndef FOLLY_SPOOKYHASHV2_H_ |
| #define FOLLY_SPOOKYHASHV2_H_ |
| |
| #include <cstddef> |
| #include <cstdint> |
| |
| namespace folly { |
| namespace hash { |
| |
| 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); // 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 const size_t sc_numVars = 12; |
| |
| // size of the internal state |
| static const size_t sc_blockSize = sc_numVars*8; |
| |
| // size of buffer of unhashed data, in bytes |
| static const 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 const uint64_t sc_const = 0xdeadbeefdeadbeefLL; |
| |
| 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 |
| }; |
| |
| } // namespace hash |
| } // namespace folly |
| |
| #endif |
