crc32_ex1_calculateCrc16.c

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//******************************************************************************
//******************************************************************************
#include "driverlib.h"
 
#define CRC16_POLY              0x1021
#define CRC16_INIT              0xFFFF
 
static const uint8_t myData[9] = {0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39};
static uint16_t calculateCRC16(uint8_t* data, uint32_t length);
 
int main(void)
{
    volatile uint16_t hwCalculatedCRC, swCalculatedCRC;
    uint32_t ii;
 
   //Stop WDT
    WDT_A_hold(WDT_A_BASE);
 
    CRC32_setSeed(CRC16_INIT, CRC16_MODE);
 
    for(ii=0;ii<9;ii++)
        CRC32_set8BitDataReversed(myData[ii], CRC16_MODE);
 
    /* Getting the result from the hardware module */
    hwCalculatedCRC = CRC32_getResult(CRC16_MODE);
 
    /* Calculating the CRC16 checksum through software */
    swCalculatedCRC = calculateCRC16((uint8_t*)myData, 9);
 
    /* Pause for the debugger */
    __no_operation();
}
 
 
/* Standard software calculation of CRC16 */
static uint16_t calculateCRC16(uint8_t* data, uint32_t length)
{
    uint16_t i, j;
    uint16_t msg;
    uint16_t crc = 0xFFFF;
    uint8_t* pmsg = data;
 
    uint32_t msg_size = length;
 
    for(i = 0 ; i < msg_size ; i ++)
    {
        msg = (pmsg[i] << 8);
        for(j = 0 ; j < 8 ; j++)
        {
            if((msg ^ crc) >> 15) crc = (crc << 1) ^ CRC16_POLY;
            else crc <<= 1;
            msg <<= 1;
        }
    }
 
    return(crc);
}