LXR qemu/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 */
  51static inline uint32_t
  52qemu_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
 101static inline uint32_t qemu_xxhash2(uint64_t ab)
 102{
 103    return qemu_xxhash7(ab, 0, 0, 0, 0);
 104}
 105
 106static inline uint32_t qemu_xxhash4(uint64_t ab, uint64_t cd)
 107{
 108    return qemu_xxhash7(ab, cd, 0, 0, 0);
 109}
 110
 111static 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
 116static 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 */
 123