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| /*
| * Copyright 2001-2010 Georges Menie (www.menie.org)
| * Copyright 2010 Salvatore Sanfilippo (adapted to Redis coding style)
| * Copyright 2015 Zihua Li (http://zihua.li) (ported to JavaScript)
| * Copyright 2016 Mike Diarmid (http://github.com/salakar) (re-write for performance, ~700% perf inc)
| * All rights reserved.
| * 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.
| * * Neither the name of the University of California, Berkeley nor the
| * names of its contributors may be used to endorse or promote products
| * derived from this software without specific prior written permission.
| *
| * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS AND 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.
| */
|
| /* CRC16 implementation according to CCITT standards.
| *
| * Note by @antirez: this is actually the XMODEM CRC 16 algorithm, using the
| * following parameters:
| *
| * Name : "XMODEM", also known as "ZMODEM", "CRC-16/ACORN"
| * Width : 16 bit
| * Poly : 1021 (That is actually x^16 + x^12 + x^5 + 1)
| * Initialization : 0000
| * Reflect Input byte : False
| * Reflect Output CRC : False
| * Xor constant to output CRC : 0000
| * Output for "123456789" : 31C3
| */
|
| var lookup = [
| 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
| ];
|
| /**
| * Convert a string to a UTF8 array - faster than via buffer
| * @param str
| * @returns {Array}
| */
| var toUTF8Array = function toUTF8Array(str) {
| var char;
| var i = 0;
| var p = 0;
| var utf8 = [];
| var len = str.length;
|
| for (; i < len; i++) {
| char = str.charCodeAt(i);
| if (char < 128) {
| utf8[p++] = char;
| } else if (char < 2048) {
| utf8[p++] = (char >> 6) | 192;
| utf8[p++] = (char & 63) | 128;
| } else if (
| ((char & 0xFC00) === 0xD800) && (i + 1) < str.length &&
| ((str.charCodeAt(i + 1) & 0xFC00) === 0xDC00)) {
| char = 0x10000 + ((char & 0x03FF) << 10) + (str.charCodeAt(++i) & 0x03FF);
| utf8[p++] = (char >> 18) | 240;
| utf8[p++] = ((char >> 12) & 63) | 128;
| utf8[p++] = ((char >> 6) & 63) | 128;
| utf8[p++] = (char & 63) | 128;
| } else {
| utf8[p++] = (char >> 12) | 224;
| utf8[p++] = ((char >> 6) & 63) | 128;
| utf8[p++] = (char & 63) | 128;
| }
| }
|
| return utf8;
| };
|
| /**
| * Convert a string into a redis slot hash.
| * @param str
| * @returns {number}
| */
| var generate = module.exports = function generate(str) {
| var char;
| var i = 0;
| var start = -1;
| var result = 0;
| var resultHash = 0;
| var utf8 = typeof str === 'string' ? toUTF8Array(str) : str;
| var len = utf8.length;
|
| while (i < len) {
| char = utf8[i++];
| if (start === -1) {
| if (char === 0x7B) {
| start = i;
| }
| } else if (char !== 0x7D) {
| resultHash = lookup[(char ^ (resultHash >> 8)) & 0xFF] ^ (resultHash << 8);
| } else if (i - 1 !== start) {
| return resultHash & 0x3FFF;
| }
|
| result = lookup[(char ^ (result >> 8)) & 0xFF] ^ (result << 8);
| }
|
| return result & 0x3FFF;
| };
|
| /**
| * Convert an array of multiple strings into a redis slot hash.
| * Returns -1 if one of the keys is not for the same slot as the others
| * @param keys
| * @returns {number}
| */
| module.exports.generateMulti = function generateMulti(keys) {
| var i = 1;
| var len = keys.length;
| var base = generate(keys[0]);
|
| while (i < len) {
| if (generate(keys[i++]) !== base) return -1;
| }
|
| return base;
| };
|
|
