owner-nrf52sdk/nRF5_SDK_17.0.2/components/libraries/crc32/crc32.c

/**
 * Copyright (c) 2013 - 2020, Nordic Semiconductor ASA
 *
 * All rights reserved.
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 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
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 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
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#include "sdk_common.h"
#if NRF_MODULE_ENABLED(CRC32)
#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) ^ (0xEDB88320U & ((crc & 1) ? 0xFFFFFFFF : 0));
        }
    }
    return ~crc;
}
#endif //NRF_MODULE_ENABLED(CRC32)