obd_iso15765/BleCanBoxCode/NRF51802/components/libraries/crc32/crc32.c

/* Copyright (c) 2013 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is property of Nordic Semiconductor ASA.
 * Terms and conditions of usage are described in detail in NORDIC
 * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
 *
 * Licensees are granted free, non-transferable use of the information. NO
 * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
 * the file.
 *
 */

#include "crc32.h"

#include <stdlib.h>

uint32_t crc32_compute(uint8_t const * p_data, uint32_t size, uint32_t const * p_crc)
{
    uint32_t crc;

    crc = (p_crc == NULL) ? 0xFFFFFFFF : ~(*p_crc);
    for (uint32_t i = 0; i < size; i++)
    {
        crc = crc ^ p_data[i];
        for (uint32_t j = 8; j > 0; j--)
        {
            crc = (crc >> 1) ^ (0xEDB88320 & -(crc & 1));
        }
    }
    return ~crc;
}