/*
 * 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: http://cyan4973.github.io/xxHash/
 * - xxHash source repository: https://github.com/Cyan4973/xxHash
 */

#include "xxhash.h"

/*-*************************************
 * Macros
 **************************************/
#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 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;

/*-**************************
 *  Utils
 ***************************/

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;
}

/*-**************************************************
 * 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));
}

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 -1;

	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;
}

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;
}
