Api16.h

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#ifndef Cpl_Checksum_Api16_h_
#define Cpl_Checksum_Api16_h_
/*-----------------------------------------------------------------------------
* This file is part of the Colony.Core Project.  The Colony.Core Project is an
* open source project with a BSD type of licensing agreement.  See the license
* agreement (license.txt) in the top/ directory or on the Internet at
* http://integerfox.com/colony.core/license.txt
*
* Copyright (c) 2014-2022  John T. Taylor
*
* Redistributions of the source code must retain the above copyright notice.
*----------------------------------------------------------------------------*/
/** @file */
 
#include <stdint.h>
 
 
 
///
namespace Cpl {
///
namespace Checksum {
 
/** This class provides an interface for calculate a 16 bit wide
    Checksum.  The specific of the checksum is determine by
    the concrete class implementing this interface.
 
    How to generate a Checksum:
        1. Call reset() initialize the Checksum
        2. Call accumulate() method for every byte being Checksum'd
        3. Call finalize() to get the CRC value.  The method can optionally
           appended the CRC to the buffer being Checksum'd
 
    How to verify a Checksum:
        1. Call reset() initialize the Checksum
        2. Call accumulate() method for every byte being Checksum'd
           INCLUDING the previously generated Checksum bytes.
        3. Call isOk() which returns true if the buffer passes the Checksum
           check.
 */
class Api16
{
public:
    /// Used to re-use/restart the Checksum object
    virtual void reset( void ) noexcept = 0;
 
    /** Call the method for every byte being Checksum'd
     */
    virtual void accumulate( const void* bytes, unsigned numbytes=1 ) noexcept = 0;
 
    /** Call this method to finalize the Checksum.  The calculated Checksum
        value is returned.  If 'destBuffer' is NOT null, then the
        Checksum value is appended to the buffer starting at the address
        specified by 'destBuffer'.  Note: the application is responsible
        for ensure there is sufficient space (and additional 2 bytes) for
        the appended Checksum value.
     */
    virtual uint16_t finalize( void* destBuffer=0 ) noexcept = 0;
 
    /** This method returns true if the data and the incoming Checksum bytes,
        that accumulate() has been called on, is good.  Returns true if
        the Checksum check passes; else false is returned
     */
    virtual bool isOkay( void ) noexcept = 0;
 
 
public:
    /// Virtual destructor
    ~Api16() {}
 
};
 
};      // end namespaces
};
#endif  // end header latch