owner-nrf52sdk/nRF5_SDK_17.0.2/components/libraries/crc16/crc16.c

/**
 * Copyright (c) 2013 - 2020, Nordic Semiconductor ASA
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 * All rights reserved.
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 *    software without specific prior written permission.
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 * 4. This software, with or without modification, must only be used with a
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#include "sdk_common.h"
#if NRF_MODULE_ENABLED(CRC16)
#include "crc16.h"

#include <stdlib.h>

uint16_t crc16_compute(uint8_t const * p_data, uint32_t size, uint16_t const * p_crc)
{
    uint16_t crc = (p_crc == NULL) ? 0xFFFF : *p_crc;

    for (uint32_t i = 0; i < size; i++)
    {
        crc  = (uint8_t)(crc >> 8) | (crc << 8);
        crc ^= p_data[i];
        crc ^= (uint8_t)(crc & 0xFF) >> 4;
        crc ^= (crc << 8) << 4;
        crc ^= ((crc & 0xFF) << 4) << 1;
    }

    return crc;
}
#endif //NRF_MODULE_ENABLED(CRC16)