MarlinFirmware/Marlin/src/libs/crc16.cpp

/**
 * Marlin 3D Printer Firmware
 * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 *
 * Based on Sprinter and grbl.
 * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

#include "crc16.h"

void crc16(uint16_t *crc, const void * const data, uint16_t cnt) {
  uint8_t *ptr = (uint8_t *)data;
  while (cnt--) {
    *crc = (uint16_t)(*crc ^ (uint16_t)(((uint16_t)*ptr++) << 8));
    for (uint8_t i = 0; i < 8; i++)
      *crc = (uint16_t)((*crc & 0x8000) ? ((uint16_t)(*crc << 1) ^ 0x1021) : (*crc << 1));
  }
}