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File org.dgpf.gp.vm.instructions.arith.CompareHandler.java

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/*
 * Copyright (c) 2006 Thomas Weise
 * 
 * E-Mail           : tweise@gmx.de
 * Creation Date    : 2006-07-03 09:40:46
 * Original Filename: org.dgpf.gp.vm.instructions.arith.CompareHandler.java
 * Version          : 1.0.0
 * Last modification: 2006-07-03
 *                by: Thomas Weise
 * 
 * License          : GNU LESSER GENERAL PUBLIC LICENSE
 *                    Version 2.1, February 1999
 *                    You should have received a copy of this license along
 *                    with this library; if not, write to the Free Software
 *                    Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *                    MA 02111-1307, USA or download the license under
 *                    http://www.gnu.org/copyleft/lesser.html.
 *                    
 * Warranty         : This software is provided "as is" 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.
 */

 
package org.dgpf.gp.vm.instructions.arith;

import org.dgpf.gp.vm.base.IInstructionHandler;
import org.dgpf.gp.vm.base.Instruction;
import org.dgpf.gp.vm.base.VMContext;
import org.dgpf.gp.vm.instructions.base.MemInstr2Handler;
import org.dgpf.gp.vm.mutation.MutationInfo;
import org.dgpf.search.api.utils.IMutator;
import org.dgpf.search.api.utils.WeightedSetBuilder;
import org.sfc.math.stochastic.Randomizer;


/**
 * The instruction handler for the compare instruction.
 *
 * @author Thomas Weise
 */

public final class CompareHandler extends  MemInstr2Handler
  {
/**
 * The serial version uid.
 */

  private static final long serialVersionUID = 1;
/**
 * The globally shared instance of the compare handler.
 */

  public  static  final IInstructionHandler  INSTANCE =
                                        new CompareHandler();

  
/**
 * Create a new compare handler - you cannot do this, use the shared
 * instance.
 * @see #INSTANCE
 */

  private CompareHandler()
    {
    super(build());
    }
  
/**
 * Build the weighted set internally.
 * @return The weighted set to be used internally.
 */
  
  private static  final WeightedSetBuilder<IMutator
                       <Instruction, VMContext, MutationInfo>> build()
   {
   WeightedSetBuilder<IMutator<Instruction, VMContext, MutationInfo>> l_m;
      
   l_m = new WeightedSetBuilder<IMutator
         <Instruction, VMContext, MutationInfo>>(IMutator.class);
   
   l_m.add(new IMutator<Instruction, VMContext, MutationInfo>()
      {
      public  final  Instruction  mutate  (final Instruction  p_source,
                                           final VMContext    p_context,
                                           final MutationInfo p_info)
        {
        Compare     l_c;
        int         l_j, l_i;
        Randomizer  l_r;
        
        l_c = ((Compare)(p_source.clone()));
        l_j = l_c.m_op;
        l_r = p_context.get_randomizer();
        
        do
          {
          l_i = ((int)(l_r.normal(l_j, 1.0d)));
          } while(l_i == l_j);
        
        l_c.m_op = ((byte)l_i);
            
        return l_c;
        }
      }, 10.0d);
   
   return l_m;
   }
  
/**
 * Create a new randomized instance of this instruction.
 * @param p_context The vm context to be used.
 * @param p_info    The information record holding the infos on the
 *                  instruction to be created.
 * @return  The new instruction instance.
 */

  public  final     Instruction create      (final VMContext    p_context,
                                             final MutationInfo p_info)
    {
    Addresses l_a;
    
    l_a = new Addresses(2, p_context, p_info);
    
    return new Compare(l_a.m_addr[0], l_a.m_rel[0],
                       l_a.m_addr[1], l_a.m_rel[1],
                      ((byte)(p_context.get_randomizer().nextInt(
                       Compare.CMP_MOD))));
    }
  

/**
 * This method tells if this instruction can be useful at the end of a
 * procedure. A comparison, for example, will never be useful, since
 * its result will always get lost.
 * @return <code>true</code> if and only if an instruction is useful at the
 *         end of a procedure.
 */

  @Override
  public boolean is_useful_at_end()
    {
    return false;
    }
  
  
/**
 * Get an instruction that better represents the passed in instruction.
 * @param p_i   The instruction to replace.
 * @return  An instruction that better represents <code>p_i</code>, or
 *          <code>p_i</code> if it is already perfect, or <code>null</code>
 *          if <code>p_i</code> itself is totally useless.
 */

  @Override
  public Instruction get_replacement (final Instruction p_i)
    {
    Compare l_c;
    
    l_c = ((Compare)p_i);
    
    if( (l_c.get_addr_1() == l_c.get_addr_2()) &&
        (l_c.is_relative_1() == l_c.is_relative_2()) )
      {
      switch(l_c.m_op)
        {
        case Compare.CMP_EQUAL : 
        case Compare.CMP_GTE   : 
        case Compare.CMP_LTE   : return SetZeroFlag.SET_FLAG;
        default                : return SetZeroFlag.CLEAR_FLAG;
        }
      }
    
    return p_i;
    }
  
/**
 * Try to melt two instructions together. The second instruction is of
 * the type this instruction handler handles.
 * @param p_first   The first instruction.
 * @param p_second  The second instruction.
 * @return  An instruction able to replace the sequence of these both
 *          instructions, or <code>null</code> if no valid replacement
 *          coult be found.
 */
  
  @Override
  public  Instruction try_melt  (final Instruction p_first,
                                 final Instruction p_second)
    {
    if( (p_first instanceof Compare) || (p_first instanceof SetZeroFlag) )
      {
      return p_second;
      }
    
    return super.try_melt(p_first, p_second);
    }
  }

File Information:

file name:CompareHandler.java
package:org.dgpf.gp.vm.instructions.arith
qualified name:org.dgpf.gp.vm.instructions.arith.CompareHandler.java
file type:Java Source File
download location:download http://dgpf.sourceforge.net/source/org/dgpf/gp/vm/instructions/arith/CompareHandler.java
size:5.964 KB (6108 B)
uploaded: 2015-07-22 04:10:57 GMT+0000
last update: 2006-07-11 03:17:35 GMT+0000
last access: 2017-11-22 10:29:38 GMT+0000

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