include/qemu/xxhash.h

/*
 * xxHash - Fast Hash algorithm
 * Copyright (C) 2012-2016, Yann Collet
 *
 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * + Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * + Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * You can contact the author at :
 * - xxHash source repository : https://github.com/Cyan4973/xxHash
 */

#ifndef QEMU_XXHASH_H
#define QEMU_XXHASH_H

#include "qemu/bitops.h"

#define PRIME32_1   2654435761U
#define PRIME32_2   2246822519U
#define PRIME32_3   3266489917U
#define PRIME32_4    668265263U
#define PRIME32_5    374761393U

#define QEMU_XXHASH_SEED 1

/*
 * xxhash32, customized for input variables that are not guaranteed to be
 * contiguous in memory.
 */
static inline uint32_t
qemu_xxhash7(uint64_t ab, uint64_t cd, uint32_t e, uint32_t f, uint32_t g)
{
    uint32_t v1 = QEMU_XXHASH_SEED + PRIME32_1 + PRIME32_2;
    uint32_t v2 = QEMU_XXHASH_SEED + PRIME32_2;
    uint32_t v3 = QEMU_XXHASH_SEED + 0;
    uint32_t v4 = QEMU_XXHASH_SEED - PRIME32_1;
    uint32_t a = ab;
    uint32_t b = ab >> 32;
    uint32_t c = cd;
    uint32_t d = cd >> 32;
    uint32_t h32;

    v1 += a * PRIME32_2;
    v1 = rol32(v1, 13);
    v1 *= PRIME32_1;

    v2 += b * PRIME32_2;
    v2 = rol32(v2, 13);
    v2 *= PRIME32_1;

    v3 += c * PRIME32_2;
    v3 = rol32(v3, 13);
    v3 *= PRIME32_1;

    v4 += d * PRIME32_2;
    v4 = rol32(v4, 13);
    v4 *= PRIME32_1;

    h32 = rol32(v1, 1) + rol32(v2, 7) + rol32(v3, 12) + rol32(v4, 18);
    h32 += 28;

    h32 += e * PRIME32_3;
    h32  = rol32(h32, 17) * PRIME32_4;

    h32 += f * PRIME32_3;
    h32  = rol32(h32, 17) * PRIME32_4;

    h32 += g * PRIME32_3;
    h32  = rol32(h32, 17) * PRIME32_4;

    h32 ^= h32 >> 15;
    h32 *= PRIME32_2;
    h32 ^= h32 >> 13;
    h32 *= PRIME32_3;
    h32 ^= h32 >> 16;

    return h32;
}

static inline uint32_t qemu_xxhash2(uint64_t ab)
{
    return qemu_xxhash7(ab, 0, 0, 0, 0);
}

static inline uint32_t qemu_xxhash4(uint64_t ab, uint64_t cd)
{
    return qemu_xxhash7(ab, cd, 0, 0, 0);
}

static inline uint32_t qemu_xxhash5(uint64_t ab, uint64_t cd, uint32_t e)
{
    return qemu_xxhash7(ab, cd, e, 0, 0);
}

static inline uint32_t qemu_xxhash6(uint64_t ab, uint64_t cd, uint32_t e,
                                    uint32_t f)
{
    return qemu_xxhash7(ab, cd, e, f, 0);
}

#endif /* QEMU_XXHASH_H */