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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
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 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
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 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
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 */

package com.sun.org.apache.bcel.internal.generic;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 */

/** 
 * SWITCH - Branch depending on int value, generates either LOOKUPSWITCH or
 * TABLESWITCH instruction, depending on whether the match values (int[]) can be
 * sorted with no gaps between the numbers.
 *
 * @version $Id: SWITCH.java,v 1.3 2007-07-19 04:34:48 ofung Exp $
 * @author  M. Dahm
 */
public final class SWITCH implements CompoundInstruction {
  private int[]               match;
  private InstructionHandle[] targets;
  private Select              instruction;
  private int                 match_length;

  /**
   * Template for switch() constructs. If the match array can be
   * sorted in ascending order with gaps no larger than max_gap
   * between the numbers, a TABLESWITCH instruction is generated, and
   * a LOOKUPSWITCH otherwise. The former may be more efficient, but
   * needs more space.
   * 
   * Note, that the key array always will be sorted, though we leave
   * the original arrays unaltered.
   *
   * @param match array of match values (case 2: ... case 7: ..., etc.)
   * @param targets the instructions to be branched to for each case
   * @param target the default target
   * @param max_gap maximum gap that may between case branches
   */
  public SWITCH(int[] match, InstructionHandle[] targets,
		InstructionHandle target, int max_gap) {
    this.match   = (int[])match.clone();
    this.targets = (InstructionHandle[])targets.clone();

    if((match_length = match.length) < 2) // (almost) empty switch, or just default
      instruction = new TABLESWITCH(match, targets, target);
    else {
      sort(0, match_length - 1);
      
      if(matchIsOrdered(max_gap)) {
	fillup(max_gap, target);

	instruction = new TABLESWITCH(this.match, this.targets, target);
      }
      else
	instruction = new LOOKUPSWITCH(this.match, this.targets, target);
    }
  }

  public SWITCH(int[] match, InstructionHandle[] targets,
		InstructionHandle target) {
    this(match, targets, target, 1);
  }
  
  private final void fillup(int max_gap, InstructionHandle target) {
    int                 max_size = match_length + match_length * max_gap;
    int[]               m_vec    = new int[max_size];
    InstructionHandle[] t_vec    = new InstructionHandle[max_size];
    int                 count    = 1;

    m_vec[0] = match[0];
    t_vec[0] = targets[0];

    for(int i=1; i < match_length; i++) {
      int prev = match[i-1];
      int gap  = match[i] - prev; 

      for(int j=1; j < gap; j++) {
	m_vec[count] = prev + j;
	t_vec[count] = target;
	count++;
      }

      m_vec[count] = match[i];
      t_vec[count] = targets[i];
      count++;
    }	

    match   = new int[count];
    targets = new InstructionHandle[count];

    System.arraycopy(m_vec, 0, match, 0, count);
    System.arraycopy(t_vec, 0, targets, 0, count);
  }

  /**
   * Sort match and targets array with QuickSort.
   */
  private final void sort(int l, int r) {
    int i = l, j = r;
    int h, m = match[(l + r) / 2];
    InstructionHandle h2;

    do {
      while(match[i] < m) i++;
      while(m < match[j]) j--;

      if(i <= j) {
	h=match[i]; match[i]=match[j]; match[j]=h; // Swap elements
	h2=targets[i]; targets[i]=targets[j]; targets[j]=h2; // Swap instructions, too
	i++; j--;
      }
    } while(i <= j);

    if(l < j) sort(l, j);
    if(i < r) sort(i, r);
  }

  /**
   * @return match is sorted in ascending order with no gap bigger than max_gap?
   */
  private final boolean matchIsOrdered(int max_gap) {
    for(int i=1; i < match_length; i++)
      if(match[i] - match[i-1] > max_gap)
	return false;

    return true;
  }

  public final InstructionList getInstructionList() {
    return new InstructionList(instruction);
  }

  public final Instruction getInstruction() {
    return instruction;
  }
}




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