de.fub.bytecode.generic
Class BranchInstruction

java.lang.Object
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  +--de.fub.bytecode.generic.Instruction
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        +--de.fub.bytecode.generic.BranchInstruction

All Implemented Interfaces:

java.lang.Cloneable, InstructionTargeter, java.io.Serializable

Direct Known Subclasses:

GotoInstruction, IfInstruction, JsrInstruction, Select

public abstract class BranchInstruction

extends Instruction

implements InstructionTargeter

Abstract super class for branching instructions like GOTO, IFEQ, etc.. Branch instructions may have a variable length, namely GOTO, JSR, LOOKUPSWITCH and TABLESWITCH.

Version:

$Id: BranchInstruction.java,v 1.4 2001/07/03 08:20:18 dahm Exp $

Author:

M. Dahm

See Also:

InstructionList, Serialized Form

Field Summary

protected int	index
protected int	position
protected InstructionHandle	target

Fields inherited from class de.fub.bytecode.generic.Instruction

length, opcode

Constructor Summary

protected

BranchInstruction(short opcode, InstructionHandle target) Common super constructor

Method Summary

boolean	containsTarget(InstructionHandle ih)
void	dump(java.io.DataOutputStream out) Dump instruction as byte code to stream out.
int	getIndex()
InstructionHandle	getTarget()
protected int	getTargetOffset()
protected int	getTargetOffset(InstructionHandle target)
protected void	initFromFile(ByteSequence bytes, boolean wide) Read needed data (e.g.
void	setTarget(InstructionHandle target) Set branch target
java.lang.String	toString(boolean verbose) Long output format: <position in byte code> <name of opcode> "["<opcode number>"]" "("<length of instruction>")" "<"<target instruction>">" "@"<branch target offset>
protected int	updatePosition(int offset, int max_offset) Called by InstructionList.setPositions when setting the position for every instruction.
void	updateTarget(InstructionHandle old_ih, InstructionHandle new_ih)

Methods inherited from class de.fub.bytecode.generic.Instruction

accept, consumeStack, consumeStack, copy, getLength, getOpcode, getTag, produceStack, produceStack, readInstruction, toString, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

index

protected int index

target

protected InstructionHandle target

position

protected int position

Constructor Detail

BranchInstruction

protected BranchInstruction(short opcode,
                            InstructionHandle target)

Common super constructor

Parameters:

opcodee - Instruction opcode

target - instruction to branch to

Method Detail

dump

public void dump(java.io.DataOutputStream out)
          throws java.io.IOException

Dump instruction as byte code to stream out.

Overrides:

dump in class Instruction

Parameters:

out - Output stream

getTargetOffset

protected int getTargetOffset(InstructionHandle target)

Parameters:

target - branch target

Returns:

the offset to `target' relative to this instruction

getTargetOffset

protected int getTargetOffset()

Returns:

the offset to this instruction's target

updatePosition

protected int updatePosition(int offset,
                             int max_offset)

Called by InstructionList.setPositions when setting the position for every instruction. In the presence of variable length instructions `setPositions' performs multiple passes over the instruction list to calculate the correct (byte) positions and offsets by calling this function.

Parameters:

offset - additional offset caused by preceding (variable length) instructions

max_offset - the maximum offset that may be caused by these instructions

Returns:

additional offset caused by possible change of this instruction's length

toString

public java.lang.String toString(boolean verbose)

Long output format: <position in byte code> <name of opcode> "["<opcode number>"]" "("<length of instruction>")" "<"<target instruction>">" "@"<branch target offset>

Overrides:

toString in class Instruction

Parameters:

verbose - long/short format switch

Returns:

mnemonic for instruction

initFromFile

protected void initFromFile(ByteSequence bytes,
                            boolean wide)
                     throws java.io.IOException

Read needed data (e.g. index) from file. Conversion to a InstructionHandle is done in InstructionList(byte[]).

Overrides:

initFromFile in class Instruction

Parameters:

bytes - input stream

wide - wide prefix?

See Also:

InstructionList

getIndex

public final int getIndex()

Returns:

target offset in byte code

getTarget

public InstructionHandle getTarget()

Returns:

target of branch instruction

setTarget

public void setTarget(InstructionHandle target)

Set branch target

Parameters:

target - branch target

updateTarget

public void updateTarget(InstructionHandle old_ih,
                         InstructionHandle new_ih)

Specified by:

updateTarget in interface InstructionTargeter

Parameters:

old_ih - old target

new_ih - new target

containsTarget

public boolean containsTarget(InstructionHandle ih)

Specified by:

containsTarget in interface InstructionTargeter

Returns:

true, if ih is target of this instruction