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/*
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* reserved comment block
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* DO NOT REMOVE OR ALTER!
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*/
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package com.sun.org.apache.bcel.internal.generic;
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2001 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution,
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* if any, must include the following acknowledgment:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "Apache" and "Apache Software Foundation" and
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* "Apache BCEL" must not be used to endorse or promote products
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* derived from this software without prior written permission. For
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* written permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache",
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* "Apache BCEL", nor may "Apache" appear in their name, without
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* prior written permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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/**
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* SWITCH - Branch depending on int value, generates either LOOKUPSWITCH or
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* TABLESWITCH instruction, depending on whether the match values (int[]) can be
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* sorted with no gaps between the numbers.
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*
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* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
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*/
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public final class SWITCH implements CompoundInstruction {
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private int[] match;
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private InstructionHandle[] targets;
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private Select instruction;
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private int match_length;
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/**
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* Template for switch() constructs. If the match array can be
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* sorted in ascending order with gaps no larger than max_gap
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* between the numbers, a TABLESWITCH instruction is generated, and
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* a LOOKUPSWITCH otherwise. The former may be more efficient, but
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* needs more space.
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*
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* Note, that the key array always will be sorted, though we leave
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* the original arrays unaltered.
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*
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* @param match array of match values (case 2: ... case 7: ..., etc.)
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* @param targets the instructions to be branched to for each case
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* @param target the default target
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* @param max_gap maximum gap that may between case branches
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*/
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public SWITCH(int[] match, InstructionHandle[] targets,
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InstructionHandle target, int max_gap) {
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this.match = (int[])match.clone();
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this.targets = (InstructionHandle[])targets.clone();
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if((match_length = match.length) < 2) // (almost) empty switch, or just default
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instruction = new TABLESWITCH(match, targets, target);
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else {
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sort(0, match_length - 1);
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if(matchIsOrdered(max_gap)) {
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fillup(max_gap, target);
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instruction = new TABLESWITCH(this.match, this.targets, target);
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}
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else
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instruction = new LOOKUPSWITCH(this.match, this.targets, target);
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}
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}
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public SWITCH(int[] match, InstructionHandle[] targets,
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InstructionHandle target) {
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this(match, targets, target, 1);
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}
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private final void fillup(int max_gap, InstructionHandle target) {
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int max_size = match_length + match_length * max_gap;
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int[] m_vec = new int[max_size];
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InstructionHandle[] t_vec = new InstructionHandle[max_size];
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int count = 1;
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m_vec[0] = match[0];
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t_vec[0] = targets[0];
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for(int i=1; i < match_length; i++) {
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int prev = match[i-1];
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int gap = match[i] - prev;
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for(int j=1; j < gap; j++) {
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m_vec[count] = prev + j;
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t_vec[count] = target;
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count++;
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}
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m_vec[count] = match[i];
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t_vec[count] = targets[i];
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count++;
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}
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match = new int[count];
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targets = new InstructionHandle[count];
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System.arraycopy(m_vec, 0, match, 0, count);
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System.arraycopy(t_vec, 0, targets, 0, count);
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}
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/**
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* Sort match and targets array with QuickSort.
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*/
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private final void sort(int l, int r) {
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int i = l, j = r;
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int h, m = match[(l + r) / 2];
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InstructionHandle h2;
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do {
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while(match[i] < m) i++;
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while(m < match[j]) j--;
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if(i <= j) {
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h=match[i]; match[i]=match[j]; match[j]=h; // Swap elements
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h2=targets[i]; targets[i]=targets[j]; targets[j]=h2; // Swap instructions, too
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i++; j--;
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}
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} while(i <= j);
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if(l < j) sort(l, j);
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if(i < r) sort(i, r);
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}
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/**
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* @return match is sorted in ascending order with no gap bigger than max_gap?
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*/
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private final boolean matchIsOrdered(int max_gap) {
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for(int i=1; i < match_length; i++)
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if(match[i] - match[i-1] > max_gap)
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return false;
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return true;
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}
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public final InstructionList getInstructionList() {
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return new InstructionList(instruction);
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}
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public final Instruction getInstruction() {
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return instruction;
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}
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}
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