checksum.h

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//
// srecord - manipulate eprom load files
// Copyright (C) 1998, 1999, 2001, 2002, 2005-2008, 2010, 2013 Peter Miller
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program. If not, see
// <http://www.gnu.org/licenses/>.
//
 
#ifndef SRECORD_INPUT_FILTER_CHECKSUM_H
#define SRECORD_INPUT_FILTER_CHECKSUM_H
 
 
#include <srecord/endian.h>
#include <srecord/interval.h>
#include <srecord/input/filter.h>
#include <srecord/record.h>
 
namespace srecord {
 
/**
  * The srecord::input_filter_checksum class is an abstraction of various
  * checksums to be ammplied to input sources.
  */
class input_filter_checksum:
    public input_filter
{
public:
    /**
      * The destructor.
      */
    virtual ~input_filter_checksum();
 
protected:
    // See bas class for documentation.
    bool read(record &record);
 
    /**
      * The constructor.
      * May only be called by derived classes.
      *
      * @param deeper
      *     The deeper input source being checksummed.
      * @param address
      *     The address to place the checksum.
      * @param length
      *     The number of bytes of checksum to be placed into the result.
      * @param end
      *     The byte order
      * @param width
      *     The width of the values being summed.  Usually 1 byte, but
      *     wider combinations are possible.  If you use something
      *     wider, it is assumed that they are alligned on multiples of
      *     that width, no provision for an offset is provided.
      */
    input_filter_checksum(input::pointer deeper, int address,
        int length, endian_t end, int width = 1);
 
    typedef unsigned long sum_t;
 
    /**
      * The checksum_address instance variable is used to remember where
      * to place the checksum at the end of the data.
      */
    int checksum_address;
 
    /**
      * The length instance variable is used to remember how many bytes
      * of checksum are to be emitted.
      */
    int length;
 
    /**
      * The end instance variable is used to remember whether the
      * summation for the checksum is bigendian or little endian.
      */
    endian_t end;
 
    /**
      * The sum instance variable is used to remember the running
      * checksum of the incoming data source.
      */
    sum_t sum;
 
    /**
      * The width instance variable is used to remember the swathe width
      * as the incoming bytes are added to the running sum.
      * That is, now many bytes wide.
      */
    int width;
 
    /**
      * The calculate method is used to calculate the checksum to be
      * written into the output, based on the "sum" instance variable.
      */
    virtual sum_t calculate(void) = 0;
 
    /**
      * The generate method is used to generate the final data record,
      * once all of the deeper input has been passed through, based on
      * the calculated checksum.
      *
      * @param record
      *     Where to place the returned data.
      * @returns
      *     bool; false if end-of-file, true if data available
      */
    bool generate(record &record);
 
private:
    /**
      * The default constructor.  Do not use.
      */
    input_filter_checksum();
 
    /**
      * The copy constructor.  Do not use.
      */
    input_filter_checksum(const input_filter_checksum &);
 
    /**
      * The assignment operator.  Do not use.
      */
    input_filter_checksum &operator=(const input_filter_checksum &);
};
 
};
 
#endif // SRECORD_INPUT_FILTER_CHECKSUM_H
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