/*
   +----------------------------------------------------------------------+
   | HipHop for PHP                                                       |
   +----------------------------------------------------------------------+
   | Copyright (c) 2010-2013 Facebook, Inc. (http://www.facebook.com)     |
   | Copyright (c) 1997-2010 The PHP Group                                |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.php.net/license/3_01.txt                                  |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
*/

/**
 * This file contains code from MurmurHash, by Austin Appleby. The licensing
 * information for MurmurHash as specified on its website,
 * http://sites.google.com/site/murmurhash/, is as follows: "For business
 * purposes, Murmurhash is under the MIT license.
 */

#include <stddef.h>
#include <stdint.h>
#include "hphp/runtime/ext/hash/hash_murmur.h"

namespace HPHP {

/**
 * MurmurHash2, 64-bit versions, by Austin Appleby
 *
 * The same caveats as 32-bit MurmurHash2 apply here - beware of alignment
 * and endian-ness issues if used across multiple platforms.
 *
 * 64-bit hash for 64-bit platforms
 */
uint64_t murmur_hash_64A(const void* const key, const size_t len,
                         const uint32_t seed) {
    const uint64_t m = 0xc6a4a7935bd1e995ULL;
    const int r = 47;

    uint64_t h = seed ^ (len * m);

    const uint64_t * data = (const uint64_t *)key;
    const uint64_t * end = data + (len/8);

    while(data != end) {
        uint64_t k = *data++;

        k *= m;
        k ^= k >> r;
        k *= m;

        h ^= k;
        h *= m;
    }

    const uint8_t * data2 = (const uint8_t*)data;

    switch(len & 7) {
        case 7: h ^= (uint64_t)data2[6] << 48;
        case 6: h ^= (uint64_t)data2[5] << 40;
        case 5: h ^= (uint64_t)data2[4] << 32;
        case 4: h ^= (uint64_t)data2[3] << 24;
        case 3: h ^= (uint64_t)data2[2] << 16;
        case 2: h ^= (uint64_t)data2[1] << 8;
        case 1: h ^= (uint64_t)data2[0];
                h *= m;
    };

    h ^= h >> r;
    h *= m;
    h ^= h >> r;

    return h;
}

/* MurmurHash64A performance-optimized for hash of uint64_t keys and seed = M0 */
uint64_t murmur_rehash_64A(uint64_t k) {
    const uint64_t m = 0xc6a4a7935bd1e995ULL;
    const int r = 47;

    uint64_t h = (uint64_t)SEED ^ (sizeof(uint64_t) * m);

    k *= m;
    k ^= k >> r;
    k *= m;

    h ^= k;
    h *= m;

    h ^= h >> r;
    h *= m;
    h ^= h >> r;

    return h;
}

}