spooky.h

#ifndef OOCMAP_SPOOKY_H
#define OOCMAP_SPOOKY_H

//
// 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.
//

#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 = 876170670 // 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 = 876170670
    ) {
        uint64 hash1 = seed, hash2 = seed;
        hash128(message, length, &hash1, &hash2);
        return (uint32) hash1;
    }

    SpookyHash(
        uint64 seed1 = 876170670,       // any 64-bit value will do, including 0
        uint64 seed2 = 37156667         // 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(
        const uint64* data,
        uint64& h0, uint64& h1, uint64& h2, uint64& h3,
        uint64& h4, uint64& h5, uint64& h6, uint64& h7,
        uint64& h8, uint64& h9, uint64& h10, uint64& 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& 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:

    //
    // shortHash is used for messages under 192 bytes in length
    // shortHash 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 shortHash(
        const void* message,  // message (array of bytes, not necessarily aligned)
        size_t length,        // length of message (in bytes)
        uint64* hash1,        // in/out: in the seed, out the hash value
        uint64* hash2         // in/out: in the seed, out the hash value
    );

    // 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 //OOCMAP_SPOOKY_H