predis/lib/Predis/Cluster/Hash/CRC16HashGenerator.php

<?php

/*
 * This file is part of the Predis package.
 *
 * (c) Daniele Alessandri <suppakilla@gmail.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Predis\Cluster\Hash;

/**
 * This class implements the CRC-CCITT-16 algorithm used by redis-cluster.
 *
 * @author Daniele Alessandri <suppakilla@gmail.com>
 */
class CRC16HashGenerator implements HashGeneratorInterface
{
/*
        0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
        0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
        0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
        0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
        0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
        0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
        0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
        0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
        0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
        0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
        0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
        0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
        0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
        0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
        0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
        0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
        0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
        0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
        0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
        0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
        0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
        0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
        0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
        0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
        0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
        0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
        0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
        0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
        0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
        0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
        0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
        0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
*/

    private static $CCITT_16 = array(
        0, 4129, 8258, 12387, 16516, 20645, 24774, 28903,
        33032, 37161, 41290, 45419, 49548, 53677, 57806, 61935,
        4657, 528, 12915, 8786, 21173, 17044, 29431, 25302,
        37689, 33560, 45947, 41818, 54205, 50076, 62463, 58334,
        9314, 13379, 1056, 5121, 25830, 29895, 17572, 21637,
        42346, 46411, 34088, 38153, 58862, 62927, 50604, 54669,
        13907, 9842, 5649, 1584, 30423, 26358, 22165, 18100,
        46939, 42874, 38681, 34616, 63455, 59390, 55197, 51132,
        18628, 22757, 26758, 30887, 2112, 6241, 10242, 14371,
        51660, 55789, 59790, 63919, 35144, 39273, 43274, 47403,
        23285, 19156, 31415, 27286, 6769, 2640, 14899, 10770,
        56317, 52188, 64447, 60318, 39801, 35672, 47931, 43802,
        27814, 31879, 19684, 23749, 11298, 15363, 3168, 7233,
        60846, 64911, 52716, 56781, 44330, 48395, 36200, 40265,
        32407, 28342, 24277, 20212, 15891, 11826, 7761, 3696,
        65439, 61374, 57309, 53244, 48923, 44858, 40793, 36728,
        37256, 33193, 45514, 41451, 53516, 49453, 61774, 57711,
        4224, 161, 12482, 8419, 20484, 16421, 28742, 24679,
        33721, 37784, 41979, 46042, 49981, 54044, 58239, 62302,
        689, 4752, 8947, 13010, 16949, 21012, 25207, 29270,
        46570, 42443, 38312, 34185, 62830, 58703, 54572, 50445,
        13538, 9411, 5280, 1153, 29798, 25671, 21540, 17413,
        42971, 47098, 34713, 38840, 59231, 63358, 50973, 55100,
        9939, 14066, 1681, 5808, 26199, 30326, 17941, 22068,
        55628, 51565, 63758, 59695, 39368, 35305, 47498, 43435,
        22596, 18533, 30726, 26663, 6336, 2273, 14466, 10403,
        52093, 56156, 60223, 64286, 35833, 39896, 43963, 48026,
        19061, 23124, 27191, 31254, 2801, 6864, 10931, 14994,
        64814, 60687, 56684, 52557, 48554, 44427, 40424, 36297,
        31782, 27655, 23652, 19525, 15522, 11395, 7392, 3265,
        61215, 65342, 53085, 57212, 44955, 49082, 36825, 40952,
        28183, 32310, 20053, 24180, 11923, 16050, 3793, 7920,
    );

    /**
     * {@inheritdoc}
     */
    public function hash($value)
    {
        // CRC-CCITT-16 algorithm
        $crc = 0;
        $CCITT_16 = self::$CCITT_16;
        $strlen = strlen($value);

        for ($i = 0; $i < $strlen; $i++) {
            $crc = (($crc << 8) ^ $CCITT_16[($crc >> 8) ^ ord($value[$i])]) & 65535; // 0xFFFF
        }

        return $crc;
    }
}