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166 lines
6.5 KiB
166 lines
6.5 KiB
/* |
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* Copyright 2001-2010 Georges Menie (www.menie.org) |
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* Copyright 2010 Salvatore Sanfilippo (adapted to Redis coding style) |
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* Copyright 2015 Zihua Li (http://zihua.li) (ported to JavaScript) |
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* Copyright 2016 Mike Diarmid (http://github.com/salakar) (re-write for performance, ~700% perf inc) |
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* All rights reserved. |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions are met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* * Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* * Neither the name of the University of California, Berkeley nor the |
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* names of its contributors may be used to endorse or promote products |
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* derived from this software without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY |
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY |
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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/* CRC16 implementation according to CCITT standards. |
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* |
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* Note by @antirez: this is actually the XMODEM CRC 16 algorithm, using the |
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* following parameters: |
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* |
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* Name : "XMODEM", also known as "ZMODEM", "CRC-16/ACORN" |
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* Width : 16 bit |
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* Poly : 1021 (That is actually x^16 + x^12 + x^5 + 1) |
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* Initialization : 0000 |
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* Reflect Input byte : False |
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* Reflect Output CRC : False |
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* Xor constant to output CRC : 0000 |
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* Output for "123456789" : 31C3 |
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*/ |
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var lookup = [ |
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0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, |
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0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, |
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0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, |
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0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, |
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0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, |
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0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, |
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0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, |
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0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, |
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0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, |
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0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, |
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0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, |
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0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, |
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0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, |
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0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, |
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0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, |
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0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, |
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0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, |
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0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, |
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0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, |
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0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, |
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0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, |
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0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, |
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0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, |
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0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, |
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0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, |
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0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, |
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0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, |
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0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, |
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0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, |
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0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, |
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0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, |
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0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0 |
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]; |
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/** |
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* Convert a string to a UTF8 array - faster than via buffer |
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* @param str |
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* @returns {Array} |
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*/ |
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var toUTF8Array = function toUTF8Array(str) { |
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var char; |
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var i = 0; |
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var p = 0; |
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var utf8 = []; |
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var len = str.length; |
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for (; i < len; i++) { |
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char = str.charCodeAt(i); |
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if (char < 128) { |
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utf8[p++] = char; |
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} else if (char < 2048) { |
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utf8[p++] = (char >> 6) | 192; |
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utf8[p++] = (char & 63) | 128; |
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} else if ( |
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((char & 0xFC00) === 0xD800) && (i + 1) < str.length && |
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((str.charCodeAt(i + 1) & 0xFC00) === 0xDC00)) { |
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char = 0x10000 + ((char & 0x03FF) << 10) + (str.charCodeAt(++i) & 0x03FF); |
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utf8[p++] = (char >> 18) | 240; |
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utf8[p++] = ((char >> 12) & 63) | 128; |
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utf8[p++] = ((char >> 6) & 63) | 128; |
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utf8[p++] = (char & 63) | 128; |
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} else { |
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utf8[p++] = (char >> 12) | 224; |
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utf8[p++] = ((char >> 6) & 63) | 128; |
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utf8[p++] = (char & 63) | 128; |
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} |
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} |
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return utf8; |
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}; |
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/** |
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* Convert a string into a redis slot hash. |
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* @param str |
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* @returns {number} |
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*/ |
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var generate = module.exports = function generate(str) { |
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var char; |
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var i = 0; |
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var start = -1; |
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var result = 0; |
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var resultHash = 0; |
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var utf8 = toUTF8Array(str); |
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var len = utf8.length; |
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while (i < len) { |
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char = utf8[i++]; |
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if (start === -1) { |
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if (char === 0x7B) { |
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start = i; |
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} |
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} else if (char !== 0x7D) { |
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resultHash = lookup[(char ^ (resultHash >> 8)) & 0xFF] ^ (resultHash << 8); |
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} else if (i - 1 !== start) { |
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return resultHash & 0x3FFF; |
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} |
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result = lookup[(char ^ (result >> 8)) & 0xFF] ^ (result << 8); |
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} |
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return result & 0x3FFF; |
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}; |
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/** |
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* Convert an array of multiple strings into a redis slot hash. |
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* Returns -1 if one of the keys is not for the same slot as the others |
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* @param keys |
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* @returns {number} |
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*/ |
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module.exports.generateMulti = function generateMulti(keys) { |
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var i = 1; |
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var len = keys.length; |
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var base = generate(keys[0]); |
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while (i < len) { |
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if (generate(keys[i++]) !== base) return -1; |
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} |
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return base; |
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};
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