#ifndef __CRC_H
#define __CRC_H

// Copyright ***********************************************************
//
//      The information in this file is copyright 1991 by David Orme.
//
//            Anyone may use this information for any purpose as long as he takes
//            responsability for any and all libility incurred from its use
//            or misuse and acknowledges its use in the user documentation.  This
//            information is provided AS IS with no warrenty of any kind, either
//            expressed or implied.
//
// End *****************************************************************


// Contents *********************************************************
//
//      CRC class definition
//
// Description
//
//      Implements a CRC class using the CCITT CRC-16 polynomial using
//      inline assembly to perform the calculation.  Suitable for XModem
//      or CIS B+ protocol implementations.
//
// End **************************************************************


// Interface Dependencies -------------------------------------------

// --None--


// Implementation Dependencies --------------------------------------

// --None--



class CRC {
private:
        unsigned                crc_16;        // CRC accumulator
public:
        // Constructor...
        CRC(int initialize=0)   { crc_16=initialize; }

        // Member funcs...
        void            initialize(unsigned value)      { crc_16=value; }
                                        operator unsigned int()                         { return crc_16; }
        unsigned                operator +=( unsigned int value );
};

// Description -------------------------------------------------------------
//
//            Defines the CRC class.  The CRC is initialized upon construction,
//            and a running value is kept in the local crc_16 accumulator.
//
// Constructor
//
//            CRC( int initialize )
//
//      Initialize to 0 for XMODEM and -1 for CIS B+ protocol.
//
// Public Members
//
//      operator unsigned int()
//
//            This operator defines an explicit or implict cast from a CRC object
//            to an unsigned integer.  It returns the current value of the CRC
//            accumulator.
//
//            unsigned int operator +=( unsigned int value )
//
//            Adds value to the current CRC accumulator and returns the result--
//            the new current CRC.
//
// End ---------------------------------------------------------------------



#endif