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 #endif /* QEMU_XXHASH_H */