/*
 * This file is part of the EasyFlash Library.
 *
 * Copyright (c) 2015-2017, Armink, <armink.ztl@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * 'Software'), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Function: Some utils for this library.
 * Created on: 2015-01-14
 */

#include <easyflash.h>

extern uint32_t om_crc32_tab[];

/**
 * Calculate the CRC32 value of a memory buffer.
 *
 * @param crc accumulated CRC32 value, must be 0 on first call
 * @param buf buffer to calculate CRC32 value for
 * @param size bytes in buffer
 *
 * @return calculated CRC32 value
 */
uint32_t ef_calc_crc32(uint32_t crc, const void *buf, size_t size) {
  const uint8_t *p;

  p = (const uint8_t *)buf;
  crc = crc ^ ~0U;

  while (size--) {
    crc = om_crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8);
  }

  return crc ^ ~0U;
}