vmcryptorandomnumber.cpp

TOOL (Tiny Object Oriented Language) is an easily-embedded, object-oriented, C++-like-language inter

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/*                              SOURCE FILE                                  */
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/*
       $Archive:   $

      $Revision:   $
          $Date:   $
        $Author:   $

    Description:   Implementation of a class that creates random numbers.

                   Based on work put into the public domain by William S. England
                   (Oct 1988) based on an article by: 
                   Stephen K. Park and Keith W. Miller. 
                   RANDOM NUMBER GENERATORS: GOOD ONES ARE HARD TO FIND. 
                   Communications of the ACM, New York, NY.,October 1988 p.1192

                   The modulus and multiplier have been extensively tested and 
                   should not be changed except by someone who is a professional 
                   Lehmer generator writer. 

                   THIS GENERATOR REPRESENTS THE MINIMUM STANDARD AGAINST WHICH
                   OTHER GENERATORS SHOULD BE JUDGED. 
                   ("Quote from the referenced article's authors. WSE" )
*/
static char OBJECT_ID[] = "$Revision: 1 $ : $Date: 2/04/99 10:16a $";
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#include "VMCryptoRandomNumber.h"


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  The values for culq and ciur are pre-calculated below to compensate 
  for compilers that may overflow when building the code.
  culq = ( culm / cuia )
  cuir = ( culm % cuia )

******************************************************************************/

const unsigned long culm    = 2147483647;
const unsigned int  cuia    = 16807;
const unsigned long culq    = 127773;
const unsigned int  cuir    = 2836;
const unsigned long cultest = 1043618065;


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 F(z)	= ( cuia * z ) % culm
	    = ( cuia * z ) - ( culm * ( az / culm ) )

 F(z)  = G(z) + ( culm * T(z) )
 G(z)  = ( cuia * ( z % culq ) )- ( cuir * ( z / culq ) )
 T(z)  = ( z / culq ) - ( ( cuia * z ) / culm )

 F(z)  = ( cuia * ( z % culq ) ) - (( cuir * z ) / culq ) 
       + ( culm * ( ( z / culq ) - ( cuia * ( z / culm ) ) ) )
 	 
 F(z)  = ( cuia * ( z % culq ) ) - ( ( cuir * z )/ culq ) + ( culm * ( z / culq ) ) - ( cuia * z )

******************************************************************************/



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/*
     FUNCTION NAME:  VMCryptoRandomNumber::SetSeed

       DESCRIPTION:  seed the class

             INPUT:  ulSeed - the new seed value
            OUTPUT:  none

           RETURNS:  void
*/
void VMCryptoRandomNumber::SetSeed( unsigned long ulSeed )
{
  m_ulSeed = ulSeed; 
}
/* End of function "VMCryptoRandomNumber::SetSeed"
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/*
     FUNCTION NAME:  VMCryptoRandomNumber::GetRandomNumber

       DESCRIPTION:  get the next one

             INPUT:  void 
            OUTPUT:  none

           RETURNS:  unsigned long
*/
unsigned long VMCryptoRandomNumber::GetRandomNumber( void )
{
  int iLow;
  int iHigh;
  int iTest;

  iHigh = m_ulSeed / culq;
  iLow  = m_ulSeed % culq;
  iTest = ( cuia * iLow ) - ( cuir * iHigh );

  if ( iTest > 0 )
    m_ulSeed = iTest;
  else
    m_ulSeed = iTest + culm;

  return m_ulSeed;
}
/* End of function "VMCryptoRandomNumber::GetRandomNumber"
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/* Check-in history */
/*
 *$Log:   $
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