A simple CRC library used to verify configuration data
Fork of CRC by
crc.cpp
- Committer:
- sam_grove
- Date:
- 2013-05-14
- Revision:
- 1:ec8513f94d23
- Parent:
- 0:28e16d33040f
- Child:
- 2:53b7db1f47ea
File content as of revision 1:ec8513f94d23:
#define CRC32_POLYNOMIAL 0xEDB88320L void CRC32Value(unsigned long &CRC, unsigned char c) { ///////////////////////////////////////////////////////////////////////////////////// //CRC must be initialized as zero //c is a character from the sequence that is used to form the CRC //this code is a modification of the code from the Novatel OEM615 specification ///////////////////////////////////////////////////////////////////////////////////// unsigned long ulTemp1 = ( CRC >> 8 ) & 0x00FFFFFFL; unsigned long ulCRC = ((int) CRC ^ c ) & 0xff ; for (int j = 8 ; j > 0; j-- ) { if ( ulCRC & 1 ) { ulCRC = ( ulCRC >> 1 ) ^ CRC32_POLYNOMIAL; } else { ulCRC >>= 1; } } CRC = ulTemp1 ^ ulCRC; } /* -------------------------------------------------------------------------- Calculates the CRC-32 of a block of data all at once //the CRC is from the complete message (header plus data) //but excluding (of course) the CRC at the end -------------------------------------------------------------------------- */ unsigned long CalculateBlockCRC32( unsigned long ulCount, /* Number of bytes in the data block */ unsigned char *ucBuffer ) /* Data block */ { ////////////////////////////////////////////////////////////////////// //the below code tests the CRC32Value procedure used in a markov form ////////////////////////////////////////////////////////////////////// unsigned long CRC = 0; for (int i = 0; i<ulCount; i++) { CRC32Value( CRC, *ucBuffer++ ); } return CRC; } /* unsigned long CalculateBlockCRC32( unsigned long ulCount, unsigned char *ucBuffer ) { //////////////////////////////////////////// //original code from the OEM615 manual //////////////////////////////////////////// unsigned long ulTemp1; unsigned long ulTemp2; unsigned long ulCRC = 0; while ( ulCount-- != 0 ) { ulTemp1 = ( ulCRC >> 8 ) & 0x00FFFFFFL; ulTemp2 = CRC32Value( ((int) ulCRC ^ *ucBuffer++ ) & 0xff ); ulCRC = ulTemp1 ^ ulTemp2; } return( ulCRC ); } */