Ublox NINA-B1 Series, System Integration Manual

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NINA-B1 series - System integration manual
UBX-15026175 - R16 Appendix Page 57 of 63
C1-Public
CRC calculation
/* Calculate the 16bit CRC for XMODEM */
/* byte = data buffer in the xmodem block */
/* count = number of data bytes */
/* offset = where to start the calculation */
private ushort xmodemCalcrc ( byte [] buffer , int offset , int count )
{
ushort crc , i ;
int j ;
crc = 0;
for ( j = offset ; j < count + offset ; j ++) {
crc = ( ushort )( crc ^ ( buffer [ j ] << 8));
for ( i = 0; i < 8; i ++) {
if (( crc & 0x8000) > 0) {
crc = ( ushort )(( crc << 1) ^ 0x1021);
} else {
crc = ( ushort )( crc << 1);
}
}
}
return ( ushort )( crc & 0xFFFF);
}