| /* |
| * reserved comment block |
| * DO NOT REMOVE OR ALTER! |
| */ |
| 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 apache@apache.org. |
| * |
| * 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 |
| * <http://www.apache.org/>. |
| */ |
| |
| /** |
| * 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. |
| * |
| * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> |
| */ |
| 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; |
| } |
| } |