/*
 * xxHash - Extremely 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.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by the
 * Free Software Foundation. This program is dual-licensed; you may select
 * either version 2 of the GNU General Public License ("GPL") or BSD license
 * ("BSD").
 *
 * You can contact the author at:
 * - xxHash homepage: https://cyan4973.github.io/xxHash/
 * - xxHash source repository: https://github.com/Cyan4973/xxHash
 */

#include <linux/unaligned.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/xxhash.h>

/*-*************************************
 * Macros
 **************************************/
#define xxh_rotl32(x, r) ((x << r) | (x >> (32 - r)))
#define xxh_rotl64(x, r) ((x << r) | (x >> (64 - r)))

#ifdef __LITTLE_ENDIAN
# define XXH_CPU_LITTLE_ENDIAN 1
#else
# define XXH_CPU_LITTLE_ENDIAN 0
#endif

/*-*************************************
 * Constants
 **************************************/
static const uint32_t PRIME32_1 = 2654435761U;
static const uint32_t PRIME32_2 = 2246822519U;
static const uint32_t PRIME32_3 = 3266489917U;
static const uint32_t PRIME32_4 =  668265263U;
static const uint32_t PRIME32_5 =  374761393U;

static const uint64_t PRIME64_1 = 11400714785074694791ULL;
static const uint64_t PRIME64_2 = 14029467366897019727ULL;
static const uint64_t PRIME64_3 =  1609587929392839161ULL;
static const uint64_t PRIME64_4 =  9650029242287828579ULL;
static const uint64_t PRIME64_5 =  2870177450012600261ULL;

/*-***************************
 * Simple Hash Functions
 ****************************/
static uint32_t xxh32_round(uint32_t seed, const uint32_t input)
{
        seed += input * PRIME32_2;
        seed = xxh_rotl32(seed, 13);
        seed *= PRIME32_1;
        return seed;
}

uint32_t xxh32(const void *input, const size_t len, const uint32_t seed)
{
        const uint8_t *p = (const uint8_t *)input;
        const uint8_t *b_end = p + len;
        uint32_t h32;

        if (len >= 16) {
                const uint8_t *const limit = b_end - 16;
                uint32_t v1 = seed + PRIME32_1 + PRIME32_2;
                uint32_t v2 = seed + PRIME32_2;
                uint32_t v3 = seed + 0;
                uint32_t v4 = seed - PRIME32_1;

                do {
                        v1 = xxh32_round(v1, get_unaligned_le32(p));
                        p += 4;
                        v2 = xxh32_round(v2, get_unaligned_le32(p));
                        p += 4;
                        v3 = xxh32_round(v3, get_unaligned_le32(p));
                        p += 4;
                        v4 = xxh32_round(v4, get_unaligned_le32(p));
                        p += 4;
                } while (p <= limit);

                h32 = xxh_rotl32(v1, 1) + xxh_rotl32(v2, 7) +
                        xxh_rotl32(v3, 12) + xxh_rotl32(v4, 18);
        } else {
                h32 = seed + PRIME32_5;
        }

        h32 += (uint32_t)len;

        while (p + 4 <= b_end) {
                h32 += get_unaligned_le32(p) * PRIME32_3;
                h32 = xxh_rotl32(h32, 17) * PRIME32_4;
                p += 4;
        }

        while (p < b_end) {
                h32 += (*p) * PRIME32_5;
                h32 = xxh_rotl32(h32, 11) * PRIME32_1;
                p++;
        }

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

        return h32;
}
EXPORT_SYMBOL(xxh32);

static uint64_t xxh64_round(uint64_t acc, const uint64_t input)
{
        acc += input * PRIME64_2;
        acc = xxh_rotl64(acc, 31);
        acc *= PRIME64_1;
        return acc;
}

static uint64_t xxh64_merge_round(uint64_t acc, uint64_t val)
{
        val = xxh64_round(0, val);
        acc ^= val;
        acc = acc * PRIME64_1 + PRIME64_4;
        return acc;
}

uint64_t xxh64(const void *input, const size_t len, const uint64_t seed)
{
        const uint8_t *p = (const uint8_t *)input;
        const uint8_t *const b_end = p + len;
        uint64_t h64;

        if (len >= 32) {
                const uint8_t *const limit = b_end - 32;
                uint64_t v1 = seed + PRIME64_1 + PRIME64_2;
                uint64_t v2 = seed + PRIME64_2;
                uint64_t v3 = seed + 0;
                uint64_t v4 = seed - PRIME64_1;

                do {
                        v1 = xxh64_round(v1, get_unaligned_le64(p));
                        p += 8;
                        v2 = xxh64_round(v2, get_unaligned_le64(p));
                        p += 8;
                        v3 = xxh64_round(v3, get_unaligned_le64(p));
                        p += 8;
                        v4 = xxh64_round(v4, get_unaligned_le64(p));
                        p += 8;
                } while (p <= limit);

                h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +
                        xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);
                h64 = xxh64_merge_round(h64, v1);
                h64 = xxh64_merge_round(h64, v2);
                h64 = xxh64_merge_round(h64, v3);
                h64 = xxh64_merge_round(h64, v4);

        } else {
                h64  = seed + PRIME64_5;
        }

        h64 += (uint64_t)len;

        while (p + 8 <= b_end) {
                const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));

                h64 ^= k1;
                h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;
                p += 8;
        }

        if (p + 4 <= b_end) {
                h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;
                h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;
                p += 4;
        }

        while (p < b_end) {
                h64 ^= (*p) * PRIME64_5;
                h64 = xxh_rotl64(h64, 11) * PRIME64_1;
                p++;
        }

        h64 ^= h64 >> 33;
        h64 *= PRIME64_2;
        h64 ^= h64 >> 29;
        h64 *= PRIME64_3;
        h64 ^= h64 >> 32;

        return h64;
}
EXPORT_SYMBOL(xxh64);

/*-**************************************************
 * Advanced Hash Functions
 ***************************************************/
void xxh64_reset(struct xxh64_state *statePtr, const uint64_t seed)
{
        /* use a local state for memcpy() to avoid strict-aliasing warnings */
        struct xxh64_state state;

        memset(&state, 0, sizeof(state));
        state.v1 = seed + PRIME64_1 + PRIME64_2;
        state.v2 = seed + PRIME64_2;
        state.v3 = seed + 0;
        state.v4 = seed - PRIME64_1;
        memcpy(statePtr, &state, sizeof(state));
}
EXPORT_SYMBOL(xxh64_reset);

int xxh64_update(struct xxh64_state *state, const void *input, const size_t len)
{
        const uint8_t *p = (const uint8_t *)input;
        const uint8_t *const b_end = p + len;

        if (input == NULL)
                return -EINVAL;

        state->total_len += len;

        if (state->memsize + len < 32) { /* fill in tmp buffer */
                memcpy(((uint8_t *)state->mem64) + state->memsize, input, len);
                state->memsize += (uint32_t)len;
                return 0;
        }

        if (state->memsize) { /* tmp buffer is full */
                uint64_t *p64 = state->mem64;

                memcpy(((uint8_t *)p64) + state->memsize, input,
                        32 - state->memsize);

                state->v1 = xxh64_round(state->v1, get_unaligned_le64(p64));
                p64++;
                state->v2 = xxh64_round(state->v2, get_unaligned_le64(p64));
                p64++;
                state->v3 = xxh64_round(state->v3, get_unaligned_le64(p64));
                p64++;
                state->v4 = xxh64_round(state->v4, get_unaligned_le64(p64));

                p += 32 - state->memsize;
                state->memsize = 0;
        }

        if (p + 32 <= b_end) {
                const uint8_t *const limit = b_end - 32;
                uint64_t v1 = state->v1;
                uint64_t v2 = state->v2;
                uint64_t v3 = state->v3;
                uint64_t v4 = state->v4;

                do {
                        v1 = xxh64_round(v1, get_unaligned_le64(p));
                        p += 8;
                        v2 = xxh64_round(v2, get_unaligned_le64(p));
                        p += 8;
                        v3 = xxh64_round(v3, get_unaligned_le64(p));
                        p += 8;
                        v4 = xxh64_round(v4, get_unaligned_le64(p));
                        p += 8;
                } while (p <= limit);

                state->v1 = v1;
                state->v2 = v2;
                state->v3 = v3;
                state->v4 = v4;
        }

        if (p < b_end) {
                memcpy(state->mem64, p, (size_t)(b_end-p));
                state->memsize = (uint32_t)(b_end - p);
        }

        return 0;
}
EXPORT_SYMBOL(xxh64_update);

uint64_t xxh64_digest(const struct xxh64_state *state)
{
        const uint8_t *p = (const uint8_t *)state->mem64;
        const uint8_t *const b_end = (const uint8_t *)state->mem64 +
                state->memsize;
        uint64_t h64;

        if (state->total_len >= 32) {
                const uint64_t v1 = state->v1;
                const uint64_t v2 = state->v2;
                const uint64_t v3 = state->v3;
                const uint64_t v4 = state->v4;

                h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +
                        xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);
                h64 = xxh64_merge_round(h64, v1);
                h64 = xxh64_merge_round(h64, v2);
                h64 = xxh64_merge_round(h64, v3);
                h64 = xxh64_merge_round(h64, v4);
        } else {
                h64  = state->v3 + PRIME64_5;
        }

        h64 += (uint64_t)state->total_len;

        while (p + 8 <= b_end) {
                const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));

                h64 ^= k1;
                h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;
                p += 8;
        }

        if (p + 4 <= b_end) {
                h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;
                h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;
                p += 4;
        }

        while (p < b_end) {
                h64 ^= (*p) * PRIME64_5;
                h64 = xxh_rotl64(h64, 11) * PRIME64_1;
                p++;
        }

        h64 ^= h64 >> 33;
        h64 *= PRIME64_2;
        h64 ^= h64 >> 29;
        h64 *= PRIME64_3;
        h64 ^= h64 >> 32;

        return h64;
}
EXPORT_SYMBOL(xxh64_digest);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("xxHash");