doxygen/spooky_8h_source.html

//

// 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.

//

// 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 some platforms.  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 INFINISQLSPOOKY_H

#define INFINISQLSPOOKY_H


#include <stddef.h>


#ifdef _MSC_VER

# define INLINE __forceinline

typedef  unsigned __int64 uint64;

typedef  unsigned __int32 uint32;

typedef  unsigned __int16 uint16;

typedef  unsigned __int8  uint8;

#else

# include <stdint.h>

# define INLINE inline

typedef  uint64_t  uint64;

typedef  uint32_t  uint32;

typedef  uint16_t  uint16;

typedef  uint8_t   uint8;

#endif


class SpookyHash

{

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 *hash1,        // in/out: in seed 1, out hash value 1

    uint64 *hash2);       // in/out: in seed 2, out hash value 2


  //

  // Hash64: hash a single message in one call, return 64-bit output

  //

  static uint64 Hash64(

    const void *message,  // message to hash

    size_t length,        // length of message in bytes

    uint64 seed)          // seed

  {

    uint64 hash1 = seed;

    Hash128(message, length, &hash1, &seed);

    return hash1;

  }


  //

  // Hash32: hash a single message in one call, produce 32-bit output

  //

  static uint32 Hash32(

    const void *message,  // message to hash

    size_t length,        // length of message in bytes

    uint32 seed)          // seed

  {

    uint64 hash1 = seed, hash2 = seed;

    Hash128(message, length, &hash1, &hash2);

    return (uint32)hash1;

  }


  //

  // Init: initialize the context of a SpookyHash

  //

  void Init(

    uint64 seed1,       // any 64-bit value will do, including 0

    uint64 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 *hash1,    // out only: first 64 bits of hash value.

    uint64 *hash2);   // out only: second 64 bits of hash value.


  //

  // left rotate a 64-bit value by k bytes

  //

  static INLINE uint64 Rot64(uint64 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 *data,

    uint64 &s0, uint64 &s1, uint64 &s2, uint64 &s3,

    uint64 &s4, uint64 &s5, uint64 &s6, uint64 &s7,

    uint64 &s8, uint64 &s9, uint64 &s10,uint64 &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 &h0, uint64 &h1, uint64 &h2, uint64 &h3,

    uint64 &h4, uint64 &h5, uint64 &h6, uint64 &h7,

    uint64 &h8, uint64 &h9, uint64 &h10,uint64 &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(

    uint64 &h0, uint64 &h1, uint64 &h2, uint64 &h3,

    uint64 &h4, uint64 &h5, uint64 &h6, uint64 &h7,

    uint64 &h8, uint64 &h9, uint64 &h10,uint64 &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);

    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 &h0, uint64 &h1, uint64 &h2, uint64 &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 &h0, uint64 &h1, uint64 &h2, uint64 &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,

    size_t length,

    uint64 *hash1,

    uint64 *hash2);


  // number of uint64'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 sc_const = 0xdeadbeefdeadbeefLL;


  uint64 m_data[2*sc_numVars];   // unhashed data, for partial messages

  uint64 m_state[sc_numVars];  // internal state of the hash

  size_t m_length;             // total length of the input so far

  uint8  m_remainder;          // length of unhashed data stashed in m_data

};


#endif  /* INFINISQLSPOOKY_H */