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/*
* Author : Rishi Gupta
*
* This file is part of 'serial communication manager' library.
* Copyright (C) <2014-2016>
*
* This 'serial communication manager' is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* The 'serial communication manager' is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with 'serial communication manager'. If not, see Utility class to calculate and generate CRC values for a given message. This can be used
* in X/Y/Z modem etc protocol implementations and in developing custom protocols for transmitting
* data over serial port.
*
* @author Rishi Gupta
*/
public final class SerialComCRCUtil {
private int[] crc8wire1Table = {
0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83, 0xc2, 0x9c, 0x7e,
0x20, 0xa3, 0xfd, 0x1f, 0x41, 0x9d, 0xc3, 0x21, 0x7f, 0xfc, 0xa2,
0x40, 0x1e, 0x5f, 0x01, 0xe3, 0xbd, 0x3e, 0x60, 0x82, 0xdc, 0x23,
0x7d, 0x9f, 0xc1, 0x42, 0x1c, 0xfe, 0xa0, 0xe1, 0xbf, 0x5d, 0x03,
0x80, 0xde, 0x3c, 0x62, 0xbe, 0xe0, 0x02, 0x5c, 0xdf, 0x81, 0x63,
0x3d, 0x7c, 0x22, 0xc0, 0x9e, 0x1d, 0x43, 0xa1, 0xff, 0x46, 0x18,
0xfa, 0xa4, 0x27, 0x79, 0x9b, 0xc5, 0x84, 0xda, 0x38, 0x66, 0xe5,
0xbb, 0x59, 0x07, 0xdb, 0x85, 0x67, 0x39, 0xba, 0xe4, 0x06, 0x58,
0x19, 0x47, 0xa5, 0xfb, 0x78, 0x26, 0xc4, 0x9a, 0x65, 0x3b, 0xd9,
0x87, 0x04, 0x5a, 0xb8, 0xe6, 0xa7, 0xf9, 0x1b, 0x45, 0xc6, 0x98,
0x7a, 0x24, 0xf8, 0xa6, 0x44, 0x1a, 0x99, 0xc7, 0x25, 0x7b, 0x3a,
0x64, 0x86, 0xd8, 0x5b, 0x05, 0xe7, 0xb9, 0x8c, 0xd2, 0x30, 0x6e,
0xed, 0xb3, 0x51, 0x0f, 0x4e, 0x10, 0xf2, 0xac, 0x2f, 0x71, 0x93,
0xcd, 0x11, 0x4f, 0xad, 0xf3, 0x70, 0x2e, 0xcc, 0x92, 0xd3, 0x8d,
0x6f, 0x31, 0xb2, 0xec, 0x0e, 0x50, 0xaf, 0xf1, 0x13, 0x4d, 0xce,
0x90, 0x72, 0x2c, 0x6d, 0x33, 0xd1, 0x8f, 0x0c, 0x52, 0xb0, 0xee,
0x32, 0x6c, 0x8e, 0xd0, 0x53, 0x0d, 0xef, 0xb1, 0xf0, 0xae, 0x4c,
0x12, 0x91, 0xcf, 0x2d, 0x73, 0xca, 0x94, 0x76, 0x28, 0xab, 0xf5,
0x17, 0x49, 0x08, 0x56, 0xb4, 0xea, 0x69, 0x37, 0xd5, 0x8b, 0x57,
0x09, 0xeb, 0xb5, 0x36, 0x68, 0x8a, 0xd4, 0x95, 0xcb, 0x29, 0x77,
0xf4, 0xaa, 0x48, 0x16, 0xe9, 0xb7, 0x55, 0x0b, 0x88, 0xd6, 0x34,
0x6a, 0x2b, 0x75, 0x97, 0xc9, 0x4a, 0x14, 0xf6, 0xa8, 0x74, 0x2a,
0xc8, 0x96, 0x15, 0x4b, 0xa9, 0xf7, 0xb6, 0xe8, 0x0a, 0x54, 0xd7,
0x89, 0x6b, 0x35
};
private int[] crc16Table = {
0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,
0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,
0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,
0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
};
private int[] crc16ccittTable = {
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 int[] crc16dnpTable = {
0x0000, 0x365e, 0x6cbc, 0x5ae2, 0xd978, 0xef26, 0xb5c4, 0x839a,
0xff89, 0xc9d7, 0x9335, 0xa56b, 0x26f1, 0x10af, 0x4a4d, 0x7c13,
0xb26b, 0x8435, 0xded7, 0xe889, 0x6b13, 0x5d4d, 0x07af, 0x31f1,
0x4de2, 0x7bbc, 0x215e, 0x1700, 0x949a, 0xa2c4, 0xf826, 0xce78,
0x29af, 0x1ff1, 0x4513, 0x734d, 0xf0d7, 0xc689, 0x9c6b, 0xaa35,
0xd626, 0xe078, 0xba9a, 0x8cc4, 0x0f5e, 0x3900, 0x63e2, 0x55bc,
0x9bc4, 0xad9a, 0xf778, 0xc126, 0x42bc, 0x74e2, 0x2e00, 0x185e,
0x644d, 0x5213, 0x08f1, 0x3eaf, 0xbd35, 0x8b6b, 0xd189, 0xe7d7,
0x535e, 0x6500, 0x3fe2, 0x09bc, 0x8a26, 0xbc78, 0xe69a, 0xd0c4,
0xacd7, 0x9a89, 0xc06b, 0xf635, 0x75af, 0x43f1, 0x1913, 0x2f4d,
0xe135, 0xd76b, 0x8d89, 0xbbd7, 0x384d, 0x0e13, 0x54f1, 0x62af,
0x1ebc, 0x28e2, 0x7200, 0x445e, 0xc7c4, 0xf19a, 0xab78, 0x9d26,
0x7af1, 0x4caf, 0x164d, 0x2013, 0xa389, 0x95d7, 0xcf35, 0xf96b,
0x8578, 0xb326, 0xe9c4, 0xdf9a, 0x5c00, 0x6a5e, 0x30bc, 0x06e2,
0xc89a, 0xfec4, 0xa426, 0x9278, 0x11e2, 0x27bc, 0x7d5e, 0x4b00,
0x3713, 0x014d, 0x5baf, 0x6df1, 0xee6b, 0xd835, 0x82d7, 0xb489,
0xa6bc, 0x90e2, 0xca00, 0xfc5e, 0x7fc4, 0x499a, 0x1378, 0x2526,
0x5935, 0x6f6b, 0x3589, 0x03d7, 0x804d, 0xb613, 0xecf1, 0xdaaf,
0x14d7, 0x2289, 0x786b, 0x4e35, 0xcdaf, 0xfbf1, 0xa113, 0x974d,
0xeb5e, 0xdd00, 0x87e2, 0xb1bc, 0x3226, 0x0478, 0x5e9a, 0x68c4,
0x8f13, 0xb94d, 0xe3af, 0xd5f1, 0x566b, 0x6035, 0x3ad7, 0x0c89,
0x709a, 0x46c4, 0x1c26, 0x2a78, 0xa9e2, 0x9fbc, 0xc55e, 0xf300,
0x3d78, 0x0b26, 0x51c4, 0x679a, 0xe400, 0xd25e, 0x88bc, 0xbee2,
0xc2f1, 0xf4af, 0xae4d, 0x9813, 0x1b89, 0x2dd7, 0x7735, 0x416b,
0xf5e2, 0xc3bc, 0x995e, 0xaf00, 0x2c9a, 0x1ac4, 0x4026, 0x7678,
0x0a6b, 0x3c35, 0x66d7, 0x5089, 0xd313, 0xe54d, 0xbfaf, 0x89f1,
0x4789, 0x71d7, 0x2b35, 0x1d6b, 0x9ef1, 0xa8af, 0xf24d, 0xc413,
0xb800, 0x8e5e, 0xd4bc, 0xe2e2, 0x6178, 0x5726, 0x0dc4, 0x3b9a,
0xdc4d, 0xea13, 0xb0f1, 0x86af, 0x0535, 0x336b, 0x6989, 0x5fd7,
0x23c4, 0x159a, 0x4f78, 0x7926, 0xfabc, 0xcce2, 0x9600, 0xa05e,
0x6e26, 0x5878, 0x029a, 0x34c4, 0xb75e, 0x8100, 0xdbe2, 0xedbc,
0x91af, 0xa7f1, 0xfd13, 0xcb4d, 0x48d7, 0x7e89, 0x246b, 0x1235
};
private int[] crc16ibmTable = {
0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,
0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,
0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,
0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
};
/**
* Allocates a new SerialComCRCUtil object.
*/
public SerialComCRCUtil() {
}
/**
* Calculates 8 bit checksum value for the data bytes given. The data bytes at start and
* end index are included in calculation. The checksum returned is the sum of all bytes in
* the data packet modulo 256.
*
* @param data byte type buffer for whom checksum is to be calculated.
* @param start offset in supplied data buffer from where checksum calculation should start.
* @param end offset in data buffer till which checksum should be calculated.
* @return checksum value for the given data bytes packet.
*/
public byte getChecksumValue(byte[] data, int start, int end) {
int x = start;
int checksum = 0x00;
while (x <= end) {
checksum = checksum + data[x];
x++;
}
return (byte) (checksum % 256);
}
/**
* Calculates longitudinal redundancy checksum value for the given byte array.
*
* @param data byte type buffer for whom LRC checksum is to be calculated.
* @param offset position in supplied data buffer from where LRC calculation should start.
* @param length position in data buffer till which LRC should be calculated from offset.
* @return LRC checksum value for the given byte array.
* @throws NullPointerException if data is null.
* @throws IndexOutOfBoundsException if offset is negative, length is negative, or length is
* greater than data.length - offset.
* @throws IllegalArgumentException if data is not a byte type array.
*/
public byte getLRCCheckSum(final byte[] data, int offset, int length) {
byte checkSum = 0;
if(data == null) {
throw new NullPointerException("Argument data can not be null !");
}
if((offset < 0) || (length < 0) || (length > (data.length - offset))) {
throw new IndexOutOfBoundsException("Index violation detected !");
}
if(!(data instanceof byte[])) {
throw new IllegalArgumentException("Argument data is not byte type array !");
}
for (int i = offset; i < offset + length; i++) {
checkSum ^= data[i];
}
return checkSum;
}
/**
* Calculates CRC-8 Dallas 1-wire value for the data bytes given. The data bytes at start and end index
* are included in calculation. It uses pre-defined table for speedily calculating CRC8-1-wire
* value of the given data.
*
* @param data byte type buffer for whom CRC is to be calculated.
* @param start offset in supplied data buffer from where CRC calculation should start.
* @param end offset in data buffer till which CRC should be calculated.
* @return CRC value of specified data bytes.
*/
public int getCRC8Dallas1WireValue(byte[] data, int start, int end) {
int x = start;
int crcVal = 0x00;
while (x <= end) {
crcVal = (crc8wire1Table[crcVal ^ data[x]]) & 0xFF;
x++;
}
return crcVal;
}
/**
* Calculates CRC-16 value for the data bytes given. The data bytes at start and end index
* are included in calculation. It uses pre-defined table for speedily calculating CRC-16
* value of the given data.
*
* @param data byte type buffer for whom CRC is to be calculated.
* @param start offset in supplied data buffer from where CRC calculation should start.
* @param end offset in data buffer till which CRC should be calculated.
* @return CRC value of specified data bytes.
*/
public int getCRC16Value(byte[] data, int start, int end) {
int x = start;
int crcVal = 0x0000;
while (x <= end) {
crcVal = (crc16Table[(crcVal ^ (data[x])) & 0xFF] ^ (crcVal >> 8)) & 0xFFFF;
x++;
}
return crcVal;
}
/**
* Calculates CRC-16-CCITT value for the data bytes given. The data bytes at start and end index
* are included in calculation. It uses pre-defined table for speedily calculating CRC-16-CCITT
* value of the given data. This algorithm is used in implementing Xmodem protocol.
*
* @param data byte type buffer for whom CRC is to be calculated.
* @param start offset in supplied data buffer from where CRC calculation should start.
* @param end offset in data buffer till which CRC should be calculated.
* @return CRC value of specified data bytes.
*/
public int getCRC16CCITTValue(byte[] data, int start, int end) {
int x = start;
int crcVal = 0x0000;
while (x <= end) {
crcVal = (crc16ccittTable[((crcVal >> 8) ^ (data[x])) & 0xFF] ^ (crcVal << 8)) & 0xFFFF;
x++;
}
return crcVal;
}
/**
* Calculates CRC-16-DNP value for the data bytes given. The data bytes at start and end index
* are included in calculation. It uses pre-defined table for speedily calculating CRC-16-DNP
* value of the given data.
*
* @param data byte type buffer for whom CRC is to be calculated.
* @param start offset in supplied data buffer from where CRC calculation should start.
* @param end offset in data buffer till which CRC should be calculated.
* @return CRC value of specified data bytes.
*/
public int getCRC16DNPValue(byte[] data, int start, int end) {
int x = start;
int crcVal = 0x0000;
while (x <= end) {
crcVal = ((crcVal >> 8) ^ crc16dnpTable[(crcVal ^ data[x]) & 0x00FF]);
x++;
}
crcVal = ~crcVal & 0XFFFF;
int b1 = crcVal & 0xFF;
int b2 = (crcVal >>> 8) & 0xFF;
return (b1 << 8 | b2 << 0) & 0xFFFF;
}
/**
* Calculates CRC-16-IBM value for the data bytes given. The data bytes at start and end index
* are included in calculation. It uses pre-defined table for speedily calculating CRC-16-IBM (modbus)
* value of the given data.
*
* @param data byte type buffer for whom CRC is to be calculated.
* @param start offset in supplied data buffer from where CRC calculation should start.
* @param end offset in data buffer till which CRC should be calculated.
* @return CRC value of specified data bytes.
*/
public int getCRC16IBMValue(byte[] data, int start, int end) {
int x = start;
int crcVal = 0xFFFF;
while (x <= end) {
crcVal = ((crcVal >> 8) ^ crc16ibmTable[(crcVal ^ data[x]) & 0xFF]) & 0xFFFF;
x++;
}
return crcVal;
}
}
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