Zoltan Hudak / CRC16_CCITT

Implementation of CRC16-CCITT using polynomial 0x1021 = x^16 + x^12 + x^5 + 1

CRC16_CCITT.cpp@1:6ecc3a64bf7b, 2017-09-03 (annotated)

Committer:
hudakz
Date:
Sun Sep 03 08:29:38 2017 +0000
Revision:
1:6ecc3a64bf7b
Parent:
0:253105d48c3c 
Function parameter added for setting initial CRC value. Defaults to 0x0000.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 0:253105d48c3c 1 /*
hudakz 0:253105d48c3c 2 * This is a fork of the CRC16 library COPYRIGHT(c) Emilie Laverge
hudakz 0:253105d48c3c 3 * published at [https://developer.mbed.org/users/EmLa/code/CRC16/]
hudakz 0:253105d48c3c 4 *
hudakz 0:253105d48c3c 5 * Modified by Zoltan Hudak to implement CRC16-CCITT
hudakz 0:253105d48c3c 6 * using the polynomial 0x1021: X^16 + X^15 + X^2 + 1.
hudakz 1:6ecc3a64bf7b 7 * Default initial CRC value = 0x0000
hudakz 0:253105d48c3c 8 */
hudakz 0:253105d48c3c 9
hudakz 0:253105d48c3c 10 #include "CRC16_CCITT.h"
hudakz 0:253105d48c3c 11
hudakz 0:253105d48c3c 12 const unsigned int CRC16_CCITT::SHIFTER = 0x00FF;
hudakz 0:253105d48c3c 13
hudakz 0:253105d48c3c 14 const unsigned short CRC16_CCITT::TABLE[] = {
hudakz 0:253105d48c3c 15 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
hudakz 0:253105d48c3c 16 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
hudakz 0:253105d48c3c 17 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
hudakz 0:253105d48c3c 18 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
hudakz 0:253105d48c3c 19 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
hudakz 0:253105d48c3c 20 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
hudakz 0:253105d48c3c 21 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
hudakz 0:253105d48c3c 22 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
hudakz 0:253105d48c3c 23 0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
hudakz 0:253105d48c3c 24 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
hudakz 0:253105d48c3c 25 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
hudakz 0:253105d48c3c 26 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
hudakz 0:253105d48c3c 27 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
hudakz 0:253105d48c3c 28 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
hudakz 0:253105d48c3c 29 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
hudakz 0:253105d48c3c 30 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
hudakz 0:253105d48c3c 31 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
hudakz 0:253105d48c3c 32 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
hudakz 0:253105d48c3c 33 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
hudakz 0:253105d48c3c 34 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
hudakz 0:253105d48c3c 35 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
hudakz 0:253105d48c3c 36 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
hudakz 0:253105d48c3c 37 0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
hudakz 0:253105d48c3c 38 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
hudakz 0:253105d48c3c 39 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
hudakz 0:253105d48c3c 40 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
hudakz 0:253105d48c3c 41 0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
hudakz 0:253105d48c3c 42 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
hudakz 0:253105d48c3c 43 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
hudakz 0:253105d48c3c 44 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
hudakz 0:253105d48c3c 45 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
hudakz 0:253105d48c3c 46 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
hudakz 0:253105d48c3c 47 };
hudakz 0:253105d48c3c 48
hudakz 1:6ecc3a64bf7b 49 unsigned short CRC16_CCITT::calc(char input[], int length, unsigned short crc /*=0x0000*/) {
hudakz 0:253105d48c3c 50 for(int i = 0; i < length; i++) {
hudakz 1:6ecc3a64bf7b 51 unsigned short tableValue = TABLE[((crc >> 8) ^ *(char*)input++) & SHIFTER];
hudakz 1:6ecc3a64bf7b 52 crc = (crc << 8) ^ tableValue;
hudakz 0:253105d48c3c 53 }
hudakz 0:253105d48c3c 54
hudakz 1:6ecc3a64bf7b 55 return crc;
hudakz 0:253105d48c3c 56 }
hudakz 0:253105d48c3c 57
hudakz 0:253105d48c3c 58
hudakz 1:6ecc3a64bf7b 59
hudakz 1:6ecc3a64bf7b 60