fasthash-sys-fork 0.4.2

A suite of non-cryptographic hash functions for Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153

// Copyright 2020 Cris Stringfellow
// Licensed under GPL-3.0
// https://github.com/cris691/beamsplitter
#include <cstdio>
#include <inttypes.h>
#include "beamsplitter.h"

#if defined(_MSC_VER)

#define FORCE_INLINE  __forceinline

// Other compilers

#else // defined(_MSC_VER)

#define FORCE_INLINE inline __attribute__((always_inline))

#endif // !defined(_MSC_VER)

const int STATE = 32;
uint8_t buf[STATE] = {0};
uint64_t MASK = 0xffffffffffffff;
uint8_t *state8 = (uint8_t *)buf;
uint64_t *state = (uint64_t *)buf;

  //--------
  // State mix function

    FORCE_INLINE uint64_t rot( uint64_t v, int n) 
    {
      n = n & 63U;
      if (n)
          v = (v >> n) | (v << (64-n));
      return v; 
    }

    FORCE_INLINE uint8_t rot8( uint8_t v, int n) 
    {
      n = n & 7U;
      if (n)
          v = (v >> n) | (v << (8-n));
      return v; 
    }

    FORCE_INLINE void mix(const int A)
    {
      const int B = A+1;
      const int iv = state[A] & 1023;
      const uint64_t M = T[iv];
      state[B] += M + state[A];

      state[A] ^= state[B];
      state[B] ^= state[A];
      state[A] ^= state[B];

      state[B] = rot(state[B], state[A]);
    }

  //---------
  // Hash round function 

    FORCE_INLINE void round( const uint64_t * m64, const uint8_t * m8, int len )
    {
      int index = 0;
      int sindex = 0;

      for( int Len = len >> 3; index < Len; index++) {
        state[sindex] += rot(m64[index] + index + 1, state[sindex] +index +1);
        if ( sindex == 1 ) {
          mix(0);
        } else if ( sindex == 3 ) {
          mix(2);
          sindex = -1;
        }
        sindex++;
      }

      mix(0);

      index <<= 3;
      sindex = index&31;
      for( ; index < len; index++) {
        state8[sindex] += rot8(m8[index] + index + 1, state8[sindex] + index+1);
        // state+[0,1,2]
        mix(index%3);
        if ( sindex >= 31 ) {
          sindex = -1;
        }
        sindex++;
      }

      mix(0);
      mix(1);
      mix(2);
    }

  //---------
  // main hash function

  // Note that a large number of seeds lead to very bad quality, i.e. collisions
  // See some_bad_seeds[] and
  // https://github.com/rurban/smhasher/blob/master/doc/beamsplitter.txt

    void beamsplitter_64 ( const void * key, int len, unsigned seed, void * out )
    {
      const uint8_t *key8Arr = (uint8_t *)key;
      const uint64_t *key64Arr = (uint64_t *)key;

      uint8_t seedbuf[8] = {0};
      uint8_t *seed8Arr = (uint8_t *)seedbuf;
      uint64_t *seed64Arr = (uint64_t *)seedbuf;
      uint32_t *seed32Arr = (uint32_t *)seedbuf;

      // the cali number from the Matrix (1999)
      seed32Arr[0] = 0xc5550690;
      seed32Arr[0] -= seed;
      seed32Arr[1] = ~(1 - seed);

      // nothing up my sleeve
      state[0] = 0x123456789abcdef0;
      state[1] = 0x0fedcba987654321;
      state[2] = 0xaccadacca80081e5;
      state[3] = 0xf00baaf00f00baaa;

      round( key64Arr, key8Arr, len );
      round( key64Arr, key8Arr, len );
      round( key64Arr, key8Arr, len );
      round( seed64Arr, seed8Arr, 8 );
      //round( state, state8, STATE   );
      round( seed64Arr, seed8Arr, 8 );
      round( key64Arr, key8Arr, len );
      round( key64Arr, key8Arr, len );
      round( key64Arr, key8Arr, len );

      /*
      //printf("state = %#018" PRIx64 " %#018" PRIx64 " %#018" PRIx64 " %#018" PRIx64 "\n",
      //  state[0], state[1], state[2], state[3] );
      */

      //printf("state = %#018" PRIx64 " %#018" PRIx64 "\n",
      //  state[0], state[1] );

      uint8_t output[STATE] = {0};
      uint64_t *h = (uint64_t *)output;

      // The new combination step
      h[0] = state[2];
      h[1] = state[3];

      h[0] += h[1];

      ((uint64_t *)out)[0] = h[0];
    }