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/BdbTransfer/BdbPTChecksumSum.h

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//------------------------------------------------------------------------------
// File and Version Information:
//      $Id: BdbPTChecksumSum.h,v 1.5 1999/07/22 00:10:19 svarovsk Exp $
//
// Description:
//      class of function set to calculate checksum in special way.
//      resulting checksum of file is independent of number of blocks
//      it was calculated for if subsums of this blocks are added together
//      in a proper way.
//      most functions made inline for speed
//
// Environment:
//      Software developed for the BaBar Detector at the SLAC B-Factory
//
// Author:
//      Gennadi S. Svarovski (svarovsk@slac.stanford.edu)
//          original author
//
// Copyright Information:
//      Copyright (C) 1999      Stanford Linear Accelerator Center
//
//------------------------------------------------------------------------------

#ifndef BDBPTCHECKSUMSUM_H
#define BDBPTCHECKSUMSUM_H

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

// 32 bits should be enough for everyone
typedef unsigned int sum_t;

class BdbPTChecksumSum {
    private:
        sum_t sum;

    public:
        // default constructor
        inline BdbPTChecksumSum( sum_t c = 0 );

        // arithmetics
        inline const BdbPTChecksumSum  rotate( void );
                                  void rotate( int c );
        inline const BdbPTChecksumSum  operator + ( sum_t c ) const;
        inline       BdbPTChecksumSum& operator +=( sum_t c );
        inline       BdbPTChecksumSum& operator  =( sum_t c );
        inline const BdbPTChecksumSum  operator + ( const BdbPTChecksumSum& c ) const;
        inline       BdbPTChecksumSum& operator +=( const BdbPTChecksumSum& c );
        inline       BdbPTChecksumSum& operator  =( const BdbPTChecksumSum& c );
        // getting size
        inline static size_t size( void );

        // for output and arithmetics
        inline sum_t value( void ) const;

        // calculation of checksum of a given block
        static const BdbPTChecksumSum calculate( const void *buffer, 
                                      size_t len, unsigned* extrashiftp );
};

// default constructor
inline BdbPTChecksumSum::BdbPTChecksumSum( sum_t c ) : sum( c ) {
};

// arithmetics

// cyclic shift
inline const BdbPTChecksumSum BdbPTChecksumSum::rotate( void ) {
    return BdbPTChecksumSum((sum >> 31) + (sum << 1));
}

// addition with carry
// made inline for speed
inline BdbPTChecksumSum& BdbPTChecksumSum::operator +=( sum_t c ) {
    long long lsum = (long long)this->sum + (long long)c;
    while( lsum & 0x100000000LL ) { // while there is carry to bit 32
        lsum = (lsum & 0xFFFFFFFF) + 1;
    }
    this->sum = (sum_t)lsum;
    return *this;
}

inline const BdbPTChecksumSum BdbPTChecksumSum::operator + ( sum_t c ) const {
    return BdbPTChecksumSum( *this ) += c;
}

inline BdbPTChecksumSum& BdbPTChecksumSum::operator  =( sum_t c ) {
    return ( sum = c, *this );
}

inline BdbPTChecksumSum& BdbPTChecksumSum::operator +=( const BdbPTChecksumSum& c ) {
    long long lsum = (long long)this->sum + (long long)c.sum;
    while( lsum & 0x100000000LL ) { // while there is carry to bit 32
        lsum = (lsum & 0xFFFFFFFF) + 1;
    }
    this->sum = (sum_t)lsum;
    return *this;
}

inline const BdbPTChecksumSum BdbPTChecksumSum::operator + ( const BdbPTChecksumSum& c ) const {
    return BdbPTChecksumSum( *this ) += c;
}

inline BdbPTChecksumSum& BdbPTChecksumSum::operator  =( const BdbPTChecksumSum& c ) {
    return ( sum = c.sum, *this );
}

// getting size
inline size_t BdbPTChecksumSum::size( void ) {
    return sizeof( sum_t );
}

// for output and arithmetics
inline sum_t BdbPTChecksumSum::value( void ) const {
    return sum;
}

#endif // BDBPTCHECKSUMSUM_H

 

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