/* Software Name : AsmDex
* Version : 1.0
*
* Copyright © 2012 France Télécom
* 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. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS 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 COPYRIGHT OWNER OR 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.
*/
package org.ow2.asmdex.instruction;
import org.ow2.asmdex.lowLevelUtils.ByteVector;
import org.ow2.asmdex.lowLevelUtils.IDalvikValueReader;
import org.ow2.asmdex.structureCommon.Label;
import org.ow2.asmdex.structureWriter.ConstantPool;
/**
* Encodes and decodes an instruction built with the Dalvik format 31T.
*
* @author Julien Névo
*/
public class InstructionFormat31T extends Instruction
implements IOneRegisterInstruction, IOffsetInstruction {
private static final int INSTRUCTION_SIZE = 6; // Instruction size in bytes.
private int registerA;
private int offsetB;
/**
* Offset in bytes of the instruction from the beginning of the method.
*/
private int instructionOffset;
@Override
public int getRegisterA() {
return registerA;
}
/**
* Returns the offset pointing to the beginning of the table, from the start of the Dex file.
* @return offset pointing to the beginning of the table, from the start of
* the Dex file.
*/
@Override
public int getOffset() {
return offsetB;
}
/**
* Label to switch to jump.
*/
private Label label;
/**
* Returns the label to which the instruction jumps.
* @return the label to which the instruction jumps.
*/
@Override
public Label getLabel() { return label; }
/**
* Constructor of the Instruction, using a Reader to parse its bytecode.
* @param reader reader on the Instruction to parse, pointing after the 16-bit opcode.
* @param opcode 16-bit opcode.
*/
// public InstructionFormat31T(IDalvikValueReader reader, int opcode) {
// super(opcode);
//
// // The format is AA|op BBBBlo BBBBhi.
// registerA = opcodeHighOrderByte;
// int opcodeOffset = reader.getPos() - 2;
// // Offset points to the beginning of the table, from the start of the Dex file.
// offsetB = reader.sint() * 2 + opcodeOffset; // * 2 because branch offsets are word based.
// }
/**
* Returns the RegisterA encoded in the given 16-bit opcode.
* @return the RegisterA.
*/
public static int getRegisterA(int opcode) {
return (opcode >> 8) & 0xff;
}
/**
* Returns the Offset encoded in the given 16-bit opcode. <i>It must be performed only once after
* having read the opcode.</i>
* @param reader reader on the Instruction to parse, pointing after the 16-bit opcode.
* @param opcode the 16-bit opcode.
* @return the Offset from the beginning of the Dex file.
*/
public static int getOffset(IDalvikValueReader reader, int opcode) {
int opcodeOffset = reader.getPos() - 2;
// Offset points to the beginning of the table, from the start of the Dex file.
return reader.sint() * 2 + opcodeOffset; // * 2 because branch offsets are word based.
}
/**
* Skips the data of this Instruction.
* @param reader reader on the Instruction to parse, pointing after the 16-bit opcode.
*/
public static void skip(IDalvikValueReader reader) {
reader.relativeSeek(INSTRUCTION_SIZE - 2); // The first word has already been read.
}
/**
* Constructor of the Instruction.
* @param opcode 8 or 16 bits opcode.
* @param label Label held by this Instruction.
* @param register the register.
* @param instructionOffset the offset of this Instruction, from the beginning of its Method.
*/
public InstructionFormat31T(int opcode, Label label, int register, int instructionOffset) {
super(opcode);
this.instructionOffset = instructionOffset;
this.label = label;
registerA = register;
}
@Override
public int getSize() {
return INSTRUCTION_SIZE;
}
// @Override
// public int[] getUsedRegisters() {
// return new int[] { registerA };
// }
// @Override
// public int getNbEncodedRegisters() {
// return 1;
// }
@Override
public int getInstructionOffset() {
return instructionOffset;
}
@Override
public void setInstructionOffset(int instructionOffset) {
this.instructionOffset = instructionOffset;
};
@Override
public void write(ByteVector out, ConstantPool constantPool) {
// The format is AA|op BBBBlo BBBBhi.
test8BitsLimit(registerA);
out.putShort(((registerA & 0xff) << 8) + opcodeByte);
int branchOffset = (label.getOffset() - instructionOffset) / 2; // / 2 because offsets are word-based.
out.putShort(branchOffset & 0xffff);
out.putShort((branchOffset >> 16) & 0xffff);
}
}