SpookyV2.h

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
//
// 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)          // 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(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:
  //
  // 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 (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
};