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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.dx.dex.code;
     18 
     19 import com.android.dx.rop.code.RegisterSpecList;
     20 import com.android.dx.rop.code.SourcePosition;
     21 
     22 /**
     23  * Pseudo-instruction which is used to track an address within a code
     24  * array. Instances are used for such things as branch targets and
     25  * exception handler ranges. Its code size is zero, and so instances
     26  * do not in general directly wind up in any output (either
     27  * human-oriented or binary file).
     28  */
     29 public final class CodeAddress extends ZeroSizeInsn {
     30     /** If this address should bind closely to the following real instruction */
     31     private final boolean bindsClosely;
     32 
     33     /**
     34      * Constructs an instance. The output address of this instance is initially
     35      * unknown ({@code -1}).
     36      *
     37      * @param position {@code non-null;} source position
     38      */
     39     public CodeAddress(SourcePosition position) {
     40         this(position, false);
     41     }
     42 
     43     /**
     44      * Constructs an instance. The output address of this instance is initially
     45      * unknown ({@code -1}).
     46      *
     47      * @param position {@code non-null;} source position
     48      * @param bindsClosely if the address should bind closely to the following
     49      *                     real instruction.
     50      */
     51     public CodeAddress(SourcePosition position, boolean bindsClosely) {
     52         super(position);
     53         this.bindsClosely = bindsClosely;
     54     }
     55 
     56     /** {@inheritDoc} */
     57     @Override
     58     public final DalvInsn withRegisters(RegisterSpecList registers) {
     59         return new CodeAddress(getPosition());
     60     }
     61 
     62     /** {@inheritDoc} */
     63     @Override
     64     protected String argString() {
     65         return null;
     66     }
     67 
     68     /** {@inheritDoc} */
     69     @Override
     70     protected String listingString0(boolean noteIndices) {
     71         return "code-address";
     72     }
     73 
     74     /**
     75      * Gets whether this address binds closely to the following "real"
     76      * (non-zero-length) instruction.
     77      *
     78      * When a prefix is added to an instruction (for example, to move a value
     79      * from a high register to a low register), this determines whether this
     80      * {@code CodeAddress} will point to the prefix, or to the instruction
     81      * itself.
     82      *
     83      * If bindsClosely is true, the address will point to the instruction
     84      * itself, otherwise it will point to the prefix (if any)
     85      *
     86      * @return true if this address binds closely to the next real instruction
     87      */
     88     public boolean getBindsClosely() {
     89         return bindsClosely;
     90     }
     91 }
     92