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vlong.cpp in RSA_file_encryption.

			
#include "stdafx.h"
// very long integer - can be used like long
// this is a draft useful class:)
#include "vlong.h"

class vlong_value;

class flex_unit // Provides storage allocation and index checking
{
  unsigned * a; // array of units
  unsigned z; // units allocated
public:
  unsigned n; // used units (read-only)
  flex_unit();
  ~flex_unit();
  void clear(); // set n to zero
  unsigned get( unsigned i ) const;     // get ith unsigned
  void set( unsigned i, unsigned x );   // set ith unsigned
  void reserve( unsigned x );           // storage hint
  
  unsigned get_z(void) const;     // get allocated units count
  
  // Time critical routine
  void fast_mul( flex_unit &x, flex_unit &y, unsigned n );
};

class vlong_value : public flex_unit
{
  public:
  unsigned share; // share count, used by vlong to delay physical copying
  int is_zero() const;
  int test( unsigned i ) const;
  unsigned bits() const;
  int cf( vlong_value& x ) const;
  void shl();
  void shr();
  void shr( unsigned n );
  void add( vlong_value& x );
  void subtract( vlong_value& x );
  void init( unsigned x );
  void copy( vlong_value& x );
  operator unsigned(); // Unsafe conversion to unsigned
  vlong_value();
  void mul( vlong_value& x, vlong_value& y );
  void divide( vlong_value& x, vlong_value& y, vlong_value& rem );
};

unsigned flex_unit::get_z() const
{
  return z;
}

unsigned flex_unit::get( unsigned i ) const
{
  if ( i >= n ) return 0;
  return a[i];
}

void flex_unit::clear()
{
   n = 0;
}

flex_unit::flex_unit()
{
  z = 0;
  a = 0;
  n = 0;
}

flex_unit::~flex_unit()
{
  unsigned i=z;
  while (i) { i-=1; a[i] = 0; } // burn
  delete [] a;
}

void flex_unit::reserve( unsigned x )
{
  if (x > z)
  {
    unsigned * na = new unsigned[x];
    for (unsigned i=0;i<n;i+=1) na[i] = a[i];
    delete [] a;
    a = na;
    z = x;
  }
}

void flex_unit::set( unsigned i, unsigned x )
{
  if ( i < n )
  {
    a[i] = x;
    if (x==0) while (n && 			

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