include/qemu/xxhash.h

   1 /*
   2  * xxHash - Fast Hash algorithm
   3  * Copyright (C) 2012-2016, Yann Collet
   4  *
   5  * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are
   9  * met:
  10  *
  11  * + Redistributions of source code must retain the above copyright
  12  * notice, this list of conditions and the following disclaimer.
  13  * + Redistributions in binary form must reproduce the above
  14  * copyright notice, this list of conditions and the following disclaimer
  15  * in the documentation and/or other materials provided with the
  16  * distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * You can contact the author at :
  31  * - xxHash source repository : https://github.com/Cyan4973/xxHash
  32  */
  33
  34 #ifndef QEMU_XXHASH_H
  35 #define QEMU_XXHASH_H
  36
  37 #include "qemu/bitops.h"
  38
  39 #define PRIME32_1   2654435761U
  40 #define PRIME32_2   2246822519U
  41 #define PRIME32_3   3266489917U
  42 #define PRIME32_4    668265263U
  43 #define PRIME32_5    374761393U
  44
  45 #define QEMU_XXHASH_SEED 1
  46
  47 /*
  48  * xxhash32, customized for input variables that are not guaranteed to be
  49  * contiguous in memory.
  50  */
  51 static inline uint32_t
  52 qemu_xxhash7(uint64_t ab, uint64_t cd, uint32_t e, uint32_t f, uint32_t g)
  53 {
  54     uint32_t v1 = QEMU_XXHASH_SEED + PRIME32_1 + PRIME32_2;
  55     uint32_t v2 = QEMU_XXHASH_SEED + PRIME32_2;
  56     uint32_t v3 = QEMU_XXHASH_SEED + 0;
  57     uint32_t v4 = QEMU_XXHASH_SEED - PRIME32_1;
  58     uint32_t a = ab;
  59     uint32_t b = ab >> 32;
  60     uint32_t c = cd;
  61     uint32_t d = cd >> 32;
  62     uint32_t h32;
  63
  64     v1 += a * PRIME32_2;
  65     v1 = rol32(v1, 13);
  66     v1 *= PRIME32_1;
  67
  68     v2 += b * PRIME32_2;
  69     v2 = rol32(v2, 13);
  70     v2 *= PRIME32_1;
  71
  72     v3 += c * PRIME32_2;
  73     v3 = rol32(v3, 13);
  74     v3 *= PRIME32_1;
  75
  76     v4 += d * PRIME32_2;
  77     v4 = rol32(v4, 13);
  78     v4 *= PRIME32_1;
  79
  80     h32 = rol32(v1, 1) + rol32(v2, 7) + rol32(v3, 12) + rol32(v4, 18);
  81     h32 += 28;
  82
  83     h32 += e * PRIME32_3;
  84     h32  = rol32(h32, 17) * PRIME32_4;
  85
  86     h32 += f * PRIME32_3;
  87     h32  = rol32(h32, 17) * PRIME32_4;
  88
  89     h32 += g * PRIME32_3;
  90     h32  = rol32(h32, 17) * PRIME32_4;
  91
  92     h32 ^= h32 >> 15;
  93     h32 *= PRIME32_2;
  94     h32 ^= h32 >> 13;
  95     h32 *= PRIME32_3;
  96     h32 ^= h32 >> 16;
  97
  98     return h32;
  99 }
 100
 101 static inline uint32_t qemu_xxhash2(uint64_t ab)
 102 {
 103     return qemu_xxhash7(ab, 0, 0, 0, 0);
 104 }
 105
 106 static inline uint32_t qemu_xxhash4(uint64_t ab, uint64_t cd)
 107 {
 108     return qemu_xxhash7(ab, cd, 0, 0, 0);
 109 }
 110
 111 static inline uint32_t qemu_xxhash5(uint64_t ab, uint64_t cd, uint32_t e)
 112 {
 113     return qemu_xxhash7(ab, cd, e, 0, 0);
 114 }
 115
 116 static inline uint32_t qemu_xxhash6(uint64_t ab, uint64_t cd, uint32_t e,
 117                                     uint32_t f)
 118 {
 119     return qemu_xxhash7(ab, cd, e, f, 0);
 120 }
 121
 122 /*
 123  * Component parts of the XXH64 algorithm from
 124  * https://github.com/Cyan4973/xxHash/blob/v0.8.0/xxhash.h
 125  *
 126  * The complete algorithm looks like
 127  *
 128  *  i = 0;
 129  *  if (len >= 32) {
 130  *      v1 = seed + XXH_PRIME64_1 + XXH_PRIME64_2;
 131  *      v2 = seed + XXH_PRIME64_2;
 132  *      v3 = seed + 0;
 133  *      v4 = seed - XXH_PRIME64_1;
 134  *      do {
 135  *          v1 = XXH64_round(v1, get64bits(input + i));
 136  *          v2 = XXH64_round(v2, get64bits(input + i + 8));
 137  *          v3 = XXH64_round(v3, get64bits(input + i + 16));
 138  *          v4 = XXH64_round(v4, get64bits(input + i + 24));
 139  *      } while ((i += 32) <= len);
 140  *      h64 = XXH64_mergerounds(v1, v2, v3, v4);
 141  *  } else {
 142  *      h64 = seed + XXH_PRIME64_5;
 143  *  }
 144  *  h64 += len;
 145  *
 146  *  for (; i + 8 <= len; i += 8) {
 147  *      h64 ^= XXH64_round(0, get64bits(input + i));
 148  *      h64 = rol64(h64, 27) * XXH_PRIME64_1 + XXH_PRIME64_4;
 149  *  }
 150  *  for (; i + 4 <= len; i += 4) {
 151  *      h64 ^= get32bits(input + i) * PRIME64_1;
 152  *      h64 = rol64(h64, 23) * XXH_PRIME64_2 + XXH_PRIME64_3;
 153  *  }
 154  *  for (; i < len; i += 1) {
 155  *      h64 ^= get8bits(input + i) * XXH_PRIME64_5;
 156  *      h64 = rol64(h64, 11) * XXH_PRIME64_1;
 157  *  }
 158  *
 159  *  return XXH64_avalanche(h64)
 160  *
 161  * Exposing the pieces instead allows for simplified usage when
 162  * the length is a known constant and the inputs are in registers.
 163  */
 164 #define XXH_PRIME64_1   0x9E3779B185EBCA87ULL
 165 #define XXH_PRIME64_2   0xC2B2AE3D27D4EB4FULL
 166 #define XXH_PRIME64_3   0x165667B19E3779F9ULL
 167 #define XXH_PRIME64_4   0x85EBCA77C2B2AE63ULL
 168 #define XXH_PRIME64_5   0x27D4EB2F165667C5ULL
 169
 170 static inline uint64_t XXH64_round(uint64_t acc, uint64_t input)
 171 {
 172     return rol64(acc + input * XXH_PRIME64_2, 31) * XXH_PRIME64_1;
 173 }
 174
 175 static inline uint64_t XXH64_mergeround(uint64_t acc, uint64_t val)
 176 {
 177     return (acc ^ XXH64_round(0, val)) * XXH_PRIME64_1 + XXH_PRIME64_4;
 178 }
 179
 180 static inline uint64_t XXH64_mergerounds(uint64_t v1, uint64_t v2,
 181                                          uint64_t v3, uint64_t v4)
 182 {
 183     uint64_t h64;
 184
 185     h64 = rol64(v1, 1) + rol64(v2, 7) + rol64(v3, 12) + rol64(v4, 18);
 186     h64 = XXH64_mergeround(h64, v1);
 187     h64 = XXH64_mergeround(h64, v2);
 188     h64 = XXH64_mergeround(h64, v3);
 189     h64 = XXH64_mergeround(h64, v4);
 190
 191     return h64;
 192 }
 193
 194 static inline uint64_t XXH64_avalanche(uint64_t h64)
 195 {
 196     h64 ^= h64 >> 33;
 197     h64 *= XXH_PRIME64_2;
 198     h64 ^= h64 >> 29;
 199     h64 *= XXH_PRIME64_3;
 200     h64 ^= h64 >> 32;
 201     return h64;
 202 }
 203
 204 static inline uint64_t qemu_xxhash64_4(uint64_t a, uint64_t b,
 205                                        uint64_t c, uint64_t d)
 206 {
 207     uint64_t v1 = QEMU_XXHASH_SEED + XXH_PRIME64_1 + XXH_PRIME64_2;
 208     uint64_t v2 = QEMU_XXHASH_SEED + XXH_PRIME64_2;
 209     uint64_t v3 = QEMU_XXHASH_SEED + 0;
 210     uint64_t v4 = QEMU_XXHASH_SEED - XXH_PRIME64_1;
 211
 212     v1 = XXH64_round(v1, a);
 213     v2 = XXH64_round(v2, b);
 214     v3 = XXH64_round(v3, c);
 215     v4 = XXH64_round(v4, d);
 216
 217     return XXH64_avalanche(XXH64_mergerounds(v1, v2, v3, v4));
 218 }
 219
 220 #endif /* QEMU_XXHASH_H */