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 17package com.android.dx.dex.code.form; 18 19import com.android.dx.dex.code.DalvInsn; 20import com.android.dx.dex.code.InsnFormat; 21import com.android.dx.dex.code.TargetInsn; 22import com.android.dx.util.AnnotatedOutput; 23 24/** 25 * Instruction format {@code 20t}. See the instruction format spec 26 * for details. 27 */ 28public final class Form20t extends InsnFormat { 29 /** {@code non-null;} unique instance of this class */ 30 public static final InsnFormat THE_ONE = new Form20t(); 31 32 /** 33 * Constructs an instance. This class is not publicly 34 * instantiable. Use {@link #THE_ONE}. 35 */ 36 private Form20t() { 37 // This space intentionally left blank. 38 } 39 40 /** {@inheritDoc} */ 41 @Override 42 public String insnArgString(DalvInsn insn) { 43 return branchString(insn); 44 } 45 46 /** {@inheritDoc} */ 47 @Override 48 public String insnCommentString(DalvInsn insn, boolean noteIndices) { 49 return branchComment(insn); 50 } 51 52 /** {@inheritDoc} */ 53 @Override 54 public int codeSize() { 55 return 2; 56 } 57 58 /** {@inheritDoc} */ 59 @Override 60 public boolean isCompatible(DalvInsn insn) { 61 if (!((insn instanceof TargetInsn) && 62 (insn.getRegisters().size() == 0))) { 63 return false; 64 } 65 66 TargetInsn ti = (TargetInsn) insn; 67 return ti.hasTargetOffset() ? branchFits(ti) : true; 68 } 69 70 /** {@inheritDoc} */ 71 @Override 72 public boolean branchFits(TargetInsn insn) { 73 int offset = insn.getTargetOffset(); 74 75 // Note: A zero offset would fit, but it is prohibited by the spec. 76 return (offset != 0) && signedFitsInShort(offset); 77 } 78 79 /** {@inheritDoc} */ 80 @Override 81 public void writeTo(AnnotatedOutput out, DalvInsn insn) { 82 int offset = ((TargetInsn) insn).getTargetOffset(); 83 84 write(out, opcodeUnit(insn, 0), (short) offset); 85 } 86} 87